use crate::chrome::{ChromeLine, PopupConfig};
use crate::editor::{Context, Effect, Feature};
use crate::plugin::{DocumentEvent, PluginEvent, PluginUpdate, UpdateEffect};
use serde::{Deserialize, Serialize};
use std::io::{self, BufRead, BufReader, Write};
use std::path::{Path, PathBuf};
use std::process::{Child, Command, Stdio};
use std::sync::mpsc::{self, Receiver, RecvTimeoutError, SyncSender};
use std::sync::{Arc, OnceLock};
use std::thread::{self, JoinHandle};
use std::time::{Duration, Instant};
use std::{
    collections::{BTreeMap, HashSet},
    env,
};

const RUNNER: &str = concat!(
    include_str!("ruby_values.rb"),
    "\n",
    include_str!("ruby_config.rb"),
    "\n",
    include_str!("ruby_plugin.rb"),
    "\n",
    include_str!("ruby_host.rb"),
);
const MAX_FRAME: usize = 4 * 1024 * 1024;
const MAX_QUEUE: usize = 64;
const STARTUP_TIMEOUT: Duration = Duration::from_secs(2);
const INVOKE_TIMEOUT: Duration = Duration::from_millis(500);

#[derive(Debug)]
pub struct Config {
    pub plugins: Vec<PluginConfig>,
    pub lsp: Vec<crate::lsp::ServerConfig>,
    pub bindings: Vec<Binding>,
    pub leader: String,
    pub file_explorer_side: String,
    pub file_picker_view: String,
    pub file_explorer_view: String,
    pub clipboard_mode: String,
    pub git_blame: bool,
    pub git_gutter: crate::gutter::GutterStyle,
    pub top_bar: ChromeLine,
    pub bottom_bar: ChromeLine,
    pub popup: PopupConfig,
    pub labels: BTreeMap<String, String>,
    pub diff_context_lines: usize,
    pub diff_expand_lines: usize,
    pub diff_view_mode: crate::diff::ViewMode,
    pub diff_split_orientation: crate::panes::SplitAxis,
    pub diff_follow_working_copy: bool,
}

#[derive(Debug, Deserialize)]
#[serde(deny_unknown_fields)]
pub struct PluginConfig {
    pub path: PathBuf,
    #[serde(deserialize_with = "plugin_options")]
    pub options: serde_json::Value,
}

fn plugin_options<'de, D: serde::Deserializer<'de>>(
    deserializer: D,
) -> Result<serde_json::Value, D::Error> {
    let value = serde_json::Value::deserialize(deserializer)?;
    if value.is_object() {
        Ok(value)
    } else {
        Err(serde::de::Error::custom(
            "plugin options must be a JSON object",
        ))
    }
}

impl Default for Config {
    fn default() -> Self {
        Self {
            plugins: Vec::new(),
            lsp: Vec::new(),
            bindings: Vec::new(),
            leader: "space".into(),
            file_explorer_side: "right".into(),
            file_picker_view: "tree".into(),
            file_explorer_view: "tree".into(),
            clipboard_mode: "system".into(),
            git_blame: true,
            git_gutter: crate::gutter::GutterStyle::default(),
            top_bar: ChromeLine::top(),
            bottom_bar: ChromeLine::bottom(),
            popup: PopupConfig::default(),
            labels: BTreeMap::new(),
            diff_context_lines: 10,
            diff_expand_lines: 15,
            diff_view_mode: crate::diff::ViewMode::Split,
            diff_split_orientation: crate::panes::SplitAxis::Vertical,
            diff_follow_working_copy: true,
        }
    }
}

/// Relative plugin paths are resolved against the configuration file's directory.
pub fn load_config(path: &Path) -> Result<Config, String> {
    let deadline = Instant::now() + STARTUP_TIMEOUT;
    let path = absolute_file(path)?;
    let mut host = Host::spawn("config", &path, &serde_json::json!({}))?;
    let response = host.receive(deadline)?;
    match response {
        Response::Config(response) => {
            let ConfigFrame {
                plugins,
                lsp,
                bindings,
                leader,
                file_explorer_side,
                file_picker_view,
                file_explorer_view,
                clipboard_mode,
                git_blame,
                git_gutter,
                top_bar,
                bottom_bar,
                popup,
                labels,
                diff_context_lines,
                diff_expand_lines,
                diff_view_mode,
                diff_split_orientation,
                diff_follow_working_copy,
                ..
            } = *response;
            let mut config = Config::default();
            let directory = path.parent().expect("absolute file has a parent");
            for plugin in plugins {
                let plugin_path = plugin.path.to_string_lossy();
                if plugin_path.is_empty() || plugin_path.contains('\0') {
                    return Err("Ruby config contains an invalid plugin path".into());
                }
                config.plugins.push(PluginConfig {
                    path: directory.join(plugin.path),
                    options: plugin.options,
                });
            }
            config.bindings = bindings;
            config.lsp =
                crate::lsp_config::resolve(lsp).map_err(|error| format!("Ruby config: {error}"))?;
            config.leader = leader;
            config.file_explorer_side = file_explorer_side;
            config.file_picker_view = file_picker_view;
            config.file_explorer_view = file_explorer_view;
            config.clipboard_mode = clipboard_mode;
            config.git_blame = git_blame;
            config.git_gutter = git_gutter;
            config.top_bar = top_bar;
            config.bottom_bar = bottom_bar;
            config.popup = popup;
            config.labels = labels;
            config.diff_context_lines = diff_context_lines;
            config.diff_expand_lines = diff_expand_lines;
            config.diff_view_mode = diff_view_mode;
            config.diff_split_orientation = diff_split_orientation;
            config.diff_follow_working_copy = diff_follow_working_copy;
            Ok(config)
        }
        Response::Error {
            id: None, message, ..
        } => Err(format!("Ruby config: {message}")),
        _ => Err("Ruby config returned an unexpected protocol frame".into()),
    }
}

pub struct RubyPlugin {
    host: Host,
    next_id: u64,
    asynchronous: bool,
    pending: HashSet<u64>,
}

impl RubyPlugin {
    pub fn start(path: &Path, options: &serde_json::Value) -> Result<(Self, Feature), String> {
        let deadline = Instant::now() + STARTUP_TIMEOUT;
        let path = absolute_file(path)?;
        if !options.is_object() {
            return Err("Ruby plugin options must be a JSON object".into());
        }
        let mut host = Host::spawn("plugin", &path, options)?;
        match host.receive(deadline)? {
            Response::Manifest {
                name,
                requires,
                commands,
                asynchronous,
                ..
            } => {
                if name.is_empty()
                    || requires.iter().any(String::is_empty)
                    || commands.iter().any(String::is_empty)
                {
                    return Err("Ruby plugin manifest contains empty names".into());
                }
                let feature = Feature {
                    name,
                    required_capabilities: requires,
                    commands,
                    core: false,
                };
                Ok((
                    Self {
                        host,
                        next_id: 1,
                        asynchronous,
                        pending: HashSet::new(),
                    },
                    feature,
                ))
            }
            Response::Error {
                id: None, message, ..
            } => Err(format!("Ruby plugin startup: {message}")),
            _ => Err("Ruby plugin returned an unexpected startup frame".into()),
        }
    }

    /// Context coordinates are one-based; effects are queued until a full valid reply arrives.
    /// Any failure shuts down this host. Starting a fresh plugin is the recovery path.
    pub fn invoke(
        &mut self,
        command: &str,
        args: &str,
        context: &Context,
    ) -> Result<Vec<Effect>, String> {
        let deadline = Instant::now() + INVOKE_TIMEOUT;
        let result = self.invoke_inner(command, args, context, deadline);
        if result.is_err() {
            self.disable();
        }
        result
    }

    fn invoke_inner(
        &mut self,
        command: &str,
        args: &str,
        context: &Context,
        deadline: Instant,
    ) -> Result<Vec<Effect>, String> {
        if self.asynchronous {
            return Err("Asynchronous Ruby plugins must use queue_invoke".into());
        }
        let id = self.allocate_id()?;
        let request = Request {
            version: 1,
            kind: "invoke",
            id,
            command,
            args,
            context,
        };
        self.host.send(&request, deadline)?;
        match self.host.receive(deadline)? {
            Response::Result {
                id: response_id,
                effects,
                ..
            } if response_id == id => Ok(convert_effects(effects)),
            Response::Error {
                id: Some(response_id),
                message,
                ..
            } if response_id == id => Err(format!("Ruby plugin: {message}")),
            _ => Err("Ruby plugin response does not match the invocation".into()),
        }
    }

    pub fn is_async(&self) -> bool {
        self.asynchronous
    }

    /// Enqueues without waiting for Ruby to read, invoke, or respond.
    pub fn queue_invoke(
        &mut self,
        command: &str,
        args: &str,
        context: &Context,
    ) -> Result<u64, String> {
        let result = (|| {
            self.require_async()?;
            if self.pending.len() >= MAX_QUEUE {
                return Err("Ruby plugin pending invocation queue is full".into());
            }
            let id = self.allocate_id()?;
            self.host.queue(&Request {
                version: 1,
                kind: "invoke",
                id,
                command,
                args,
                context,
            })?;
            self.pending.insert(id);
            Ok(id)
        })();
        if result.is_err() {
            self.disable();
        }
        result
    }

    pub fn notify_document(&mut self, event: &DocumentEvent) -> Result<(), String> {
        let result = self.require_async().and_then(|()| {
            self.host.queue(&DocumentRequest {
                version: 1,
                kind: "document",
                event,
            })
        });
        if result.is_err() {
            self.disable();
        }
        result
    }

    /// Drains only ready frames. Protocol failures retire this host atomically.
    pub fn poll(&mut self) -> Result<Vec<PluginEvent>, String> {
        let result = self.poll_inner();
        if result.is_err() {
            self.disable();
        }
        result
    }

    fn poll_inner(&mut self) -> Result<Vec<PluginEvent>, String> {
        self.require_async()?;
        let mut events = Vec::new();
        for response in self.host.poll()? {
            match response {
                Response::Result { id, effects, .. } if self.pending.remove(&id) => {
                    events.push(PluginEvent::Response {
                        id,
                        effects: convert_effects(effects),
                    });
                }
                Response::Update {
                    request_id,
                    effects,
                    ..
                } if request_id.is_none_or(|id| id > 0 && id < self.next_id) => {
                    events.push(PluginEvent::Update(PluginUpdate {
                        request_id,
                        effects,
                    }));
                }
                Response::Error { id, message, .. }
                    if id.is_none_or(|id| self.pending.contains(&id)) =>
                {
                    return Err(format!("Ruby plugin: {message}"));
                }
                _ => return Err("Ruby plugin emitted an unexpected protocol frame".into()),
            }
        }
        Ok(events)
    }

    fn require_async(&self) -> Result<(), String> {
        if self.asynchronous {
            Ok(())
        } else {
            Err("Ruby plugin does not support asynchronous events".into())
        }
    }

    fn allocate_id(&mut self) -> Result<u64, String> {
        let id = self.next_id;
        self.next_id = id.checked_add(1).ok_or("Ruby request IDs exhausted")?;
        Ok(id)
    }

    pub fn disable(&mut self) {
        self.host.shutdown();
        self.pending.clear();
    }
}

fn convert_effects(effects: Vec<WireEffect>) -> Vec<Effect> {
    effects
        .into_iter()
        .map(|effect| match effect {
            WireEffect::Insert { text } => Effect::Insert(text),
            WireEffect::Replace { text } => Effect::Replace(text),
            WireEffect::Message { text } => Effect::Message(text),
            WireEffect::Label { name, text } => Effect::Label { name, text },
        })
        .collect()
}

fn absolute_file(path: &Path) -> Result<PathBuf, String> {
    if path.is_absolute() {
        Ok(path.to_path_buf())
    } else {
        env::current_dir()
            .map(|directory| directory.join(path))
            .map_err(|error| format!("Cannot resolve Ruby file path: {error}"))
    }
}

#[derive(Serialize)]
struct Request<'a> {
    version: u8,
    #[serde(rename = "type")]
    kind: &'static str,
    id: u64,
    command: &'a str,
    args: &'a str,
    context: &'a Context,
}

#[derive(Serialize)]
struct DocumentRequest<'a> {
    version: u8,
    #[serde(rename = "type")]
    kind: &'static str,
    #[serde(flatten)]
    event: &'a DocumentEvent,
}

fn diff_line_count<'de, D: serde::Deserializer<'de>>(
    deserializer: D,
    label: &str,
    minimum: usize,
) -> Result<usize, D::Error> {
    let value = serde_json::Value::deserialize(deserializer)?;
    value
        .as_u64()
        .and_then(|value| usize::try_from(value).ok())
        .filter(|value| *value >= minimum)
        .ok_or_else(|| {
            serde::de::Error::custom(format!(
                "{label} must be an Integer between {minimum} and {}",
                usize::MAX
            ))
        })
}

fn diff_context_lines<'de, D: serde::Deserializer<'de>>(
    deserializer: D,
) -> Result<usize, D::Error> {
    diff_line_count(deserializer, "diff_context_lines", 0)
}

fn diff_expand_lines<'de, D: serde::Deserializer<'de>>(deserializer: D) -> Result<usize, D::Error> {
    diff_line_count(deserializer, "diff_expand_lines", 1)
}

// Startup-only configuration does not inflate every queued plugin response.
#[derive(Deserialize)]
#[serde(deny_unknown_fields)]
struct ConfigFrame {
    version: u8,
    plugins: Vec<PluginConfig>,
    // Keep this wire field required; resolve its configuration after decoding.
    #[serde(deserialize_with = "serde_json::Value::deserialize")]
    lsp: serde_json::Value,
    bindings: Vec<Binding>,
    leader: String,
    file_explorer_side: String,
    file_picker_view: String,
    file_explorer_view: String,
    clipboard_mode: String,
    git_blame: bool,
    git_gutter: crate::gutter::GutterStyle,
    #[serde(deserialize_with = "crate::chrome::top")]
    top_bar: ChromeLine,
    #[serde(deserialize_with = "crate::chrome::bottom")]
    bottom_bar: ChromeLine,
    popup: PopupConfig,
    #[serde(deserialize_with = "crate::chrome::labels")]
    labels: BTreeMap<String, String>,
    #[serde(deserialize_with = "diff_context_lines")]
    diff_context_lines: usize,
    #[serde(deserialize_with = "diff_expand_lines")]
    diff_expand_lines: usize,
    diff_view_mode: crate::diff::ViewMode,
    diff_split_orientation: crate::panes::SplitAxis,
    diff_follow_working_copy: bool,
}

#[derive(Deserialize)]
#[serde(tag = "type", deny_unknown_fields)]
enum Response {
    #[serde(rename = "manifest")]
    Manifest {
        version: u8,
        name: String,
        requires: Vec<String>,
        commands: Vec<String>,
        #[serde(rename = "async")]
        asynchronous: bool,
    },
    #[serde(rename = "config")]
    Config(Box<ConfigFrame>),
    #[serde(rename = "result")]
    Result {
        version: u8,
        id: u64,
        effects: Vec<WireEffect>,
    },
    #[serde(rename = "update")]
    Update {
        version: u8,
        request_id: Option<u64>,
        effects: Vec<UpdateEffect>,
    },
    #[serde(rename = "error")]
    Error {
        version: u8,
        #[serde(default, deserialize_with = "optional_request_id")]
        id: Option<u64>,
        message: String,
    },
}

fn optional_request_id<'de, D: serde::Deserializer<'de>>(
    deserializer: D,
) -> Result<Option<u64>, D::Error> {
    u64::deserialize(deserializer).map(Some)
}

impl Response {
    fn version(&self) -> u8 {
        match self {
            Self::Manifest { version, .. }
            | Self::Result { version, .. }
            | Self::Update { version, .. }
            | Self::Error { version, .. } => *version,
            Self::Config(config) => config.version,
        }
    }
}

#[derive(Debug, Deserialize)]
#[serde(deny_unknown_fields)]
pub struct Binding {
    pub mode: String,
    pub key: String,
    pub command: Option<String>,
}

#[derive(Deserialize)]
#[serde(tag = "type", deny_unknown_fields)]
enum WireEffect {
    #[serde(rename = "insert")]
    Insert { text: String },
    #[serde(rename = "replace")]
    Replace { text: String },
    #[serde(rename = "message")]
    Message { text: String },
    #[serde(rename = "label")]
    Label { name: String, text: String },
}

struct OutboundFrame {
    bytes: Vec<u8>,
    acknowledge: bool,
}

struct Host {
    child: Option<Child>,
    requests: Option<SyncSender<OutboundFrame>>,
    writes: Receiver<Result<(), String>>,
    frames: Receiver<Response>,
    failure: Arc<OnceLock<String>>,
    reader: Option<JoinHandle<()>>,
    writer: Option<JoinHandle<()>>,
}

impl Host {
    fn spawn(mode: &str, path: &Path, options: &serde_json::Value) -> Result<Self, String> {
        #[derive(Serialize)]
        struct Startup<'a> {
            core_actions: crate::editor::CoreActionCatalog,
            command_aliases: crate::editor::CoreCommandAliases,
            options: &'a serde_json::Value,
        }
        let mut encoded_startup = FrameWriter(Vec::new());
        serde_json::to_writer(
            &mut encoded_startup,
            &Startup {
                core_actions: crate::editor::CoreActionCatalog,
                command_aliases: crate::editor::CoreCommandAliases,
                options,
            },
        )
        .map_err(|error| format!("Cannot encode bounded Ruby plugin options: {error}"))?;
        let executable = env::var_os("VAMP_RUBY").unwrap_or_else(|| "ruby".into());
        let mut command = Command::new(&executable);
        command
            .args(["-e", RUNNER, "--", mode])
            .arg(path)
            .arg(String::from_utf8(encoded_startup.0).expect("JSON is UTF-8"))
            .current_dir(path.parent().expect("absolute file has a parent"))
            .stdin(Stdio::piped())
            .stdout(Stdio::piped())
            .stderr(Stdio::null());
        #[cfg(unix)]
        {
            use std::os::unix::process::CommandExt;
            command.process_group(0);
        }
        let mut child = command.spawn().map_err(|error| {
            format!(
                "Ruby runtime {:?} unavailable or failed to start: {error}",
                executable
            )
        })?;
        let mut stdin = child.stdin.take().expect("piped child stdin");
        let stdout = child.stdout.take().expect("piped child stdout");
        let (request_tx, request_rx) = mpsc::sync_channel::<OutboundFrame>(MAX_QUEUE);
        let (write_tx, write_rx) = mpsc::sync_channel(1);
        let (frame_tx, frame_rx) = mpsc::sync_channel(MAX_QUEUE);
        let failure = Arc::new(OnceLock::new());
        let mut host = Self {
            child: Some(child),
            requests: Some(request_tx),
            writes: write_rx,
            frames: frame_rx,
            failure: Arc::clone(&failure),
            reader: None,
            writer: None,
        };
        let reader_failure = Arc::clone(&failure);
        host.reader = Some(
            thread::Builder::new()
                .name("vamp-ruby-reader".into())
                .spawn(move || {
                    let mut reader = BufReader::new(stdout);
                    loop {
                        let result = read_frame(&mut reader).and_then(|bytes| {
                            let response =
                                serde_json::from_slice::<Response>(&bytes).map_err(|error| {
                                    format!("Malformed Ruby protocol frame: {error}")
                                })?;
                            if response.version() != 1 {
                                return Err("Unsupported Ruby protocol version".into());
                            }
                            Ok(response)
                        });
                        match result {
                            Ok(response) => match frame_tx.try_send(response) {
                                Ok(()) => {}
                                Err(mpsc::TrySendError::Full(_)) => {
                                    record_failure(
                                        &reader_failure,
                                        "Ruby host update queue is full".into(),
                                    );
                                    break;
                                }
                                Err(mpsc::TrySendError::Disconnected(_)) => break,
                            },
                            Err(error) => {
                                record_failure(&reader_failure, error);
                                break;
                            }
                        }
                    }
                })
                .map_err(|error| format!("Cannot start Ruby reader: {error}"))?,
        );
        host.writer = Some(
            thread::Builder::new()
                .name("vamp-ruby-writer".into())
                .spawn(move || {
                    while let Ok(frame) = request_rx.recv() {
                        let result = stdin
                            .write_all(&frame.bytes)
                            .and_then(|_| stdin.flush())
                            .map_err(|error| format!("Ruby host write failed: {error}"));
                        if let Err(error) = &result {
                            record_failure(&failure, error.clone());
                        }
                        let failed = result.is_err();
                        if (frame.acknowledge && write_tx.try_send(result).is_err()) || failed {
                            break;
                        }
                    }
                })
                .map_err(|error| format!("Cannot start Ruby writer: {error}"))?,
        );
        Ok(host)
    }

    fn check(&self) -> Result<(), String> {
        if self.requests.is_none() {
            return Err("Ruby plugin is disabled".into());
        }
        if let Some(error) = self.failure.get() {
            return Err(error.clone());
        }
        Ok(())
    }

    fn enqueue(&mut self, request: &impl Serialize, acknowledge: bool) -> Result<(), String> {
        self.check()?;
        let mut frame = FrameWriter(Vec::new());
        serde_json::to_writer(&mut frame, request)
            .map_err(|error| format!("Cannot encode bounded Ruby request: {error}"))?;
        frame.0.push(b'\n');
        self.requests
            .as_ref()
            .expect("checked request channel")
            .try_send(OutboundFrame {
                bytes: frame.0,
                acknowledge,
            })
            .map_err(|error| match error {
                mpsc::TrySendError::Full(_) => "Ruby host request queue is full".into(),
                mpsc::TrySendError::Disconnected(_) => "Ruby host request channel failed".into(),
            })
    }

    fn queue(&mut self, request: &impl Serialize) -> Result<(), String> {
        self.enqueue(request, false)
    }

    fn send(&mut self, request: &Request<'_>, deadline: Instant) -> Result<(), String> {
        self.check()?;
        match self.frames.try_recv() {
            Ok(_) => return Err("Ruby host emitted an unsolicited protocol frame".into()),
            Err(mpsc::TryRecvError::Disconnected) => {
                return Err("Ruby host crashed or closed its output".into());
            }
            Err(mpsc::TryRecvError::Empty) => {}
        }
        self.enqueue(request, true)?;
        receive_until(&self.writes, deadline, "write")?
    }

    fn receive(&mut self, deadline: Instant) -> Result<Response, String> {
        // Prefer an already queued startup/error response over the subsequent EOF.
        match receive_until(&self.frames, deadline, "response") {
            Ok(response) => Ok(response),
            Err(error) => self.check().and(Err(error)),
        }
    }

    fn poll(&mut self) -> Result<Vec<Response>, String> {
        if self.requests.is_none() {
            return Err("Ruby plugin is disabled".into());
        }
        let mut frames = Vec::new();
        let mut disconnected = false;
        for _ in 0..MAX_QUEUE {
            match self.frames.try_recv() {
                Ok(frame) => frames.push(frame),
                Err(mpsc::TryRecvError::Empty) => break,
                Err(mpsc::TryRecvError::Disconnected) => {
                    disconnected = true;
                    break;
                }
            }
        }
        // Ruby errors remain useful even when the host exits immediately afterward.
        if !frames
            .iter()
            .any(|frame| matches!(frame, Response::Error { .. }))
        {
            self.check()?;
            if disconnected {
                return Err("Ruby host crashed or closed its output".into());
            }
        }
        Ok(frames)
    }

    fn shutdown(&mut self) {
        if let Some(sender) = self.requests.as_ref() {
            let _ = sender.try_send(OutboundFrame {
                bytes: b"{\"version\":1,\"type\":\"shutdown\"}\n".to_vec(),
                acknowledge: false,
            });
        }
        self.requests.take();
        if let Some(mut child) = self.child.take() {
            // Descendants can inherit pipes; kill the host group before joining IO threads.
            #[cfg(unix)]
            unsafe {
                kill(-(child.id() as i32), 9);
            }
            let _ = child.kill();
            let _ = child.wait();
        }
        if let Some(writer) = self.writer.take() {
            let _ = writer.join();
        }
        if let Some(reader) = self.reader.take() {
            let _ = reader.join();
        }
    }
}

fn record_failure(failure: &OnceLock<String>, error: String) {
    let _ = failure.set(error);
}

impl Drop for Host {
    fn drop(&mut self) {
        self.shutdown();
    }
}

#[cfg(unix)]
unsafe extern "C" {
    fn kill(pid: i32, signal: i32) -> i32;
}

fn receive_until<T>(receiver: &Receiver<T>, deadline: Instant, phase: &str) -> Result<T, String> {
    let remaining = deadline.saturating_duration_since(Instant::now());
    if remaining.is_zero() {
        return Err(format!("Ruby host {phase} timeout"));
    }
    receiver
        .recv_timeout(remaining)
        .map_err(|error| match error {
            RecvTimeoutError::Timeout => format!("Ruby host {phase} timeout"),
            RecvTimeoutError::Disconnected => {
                format!("Ruby host crashed or closed its {phase} channel")
            }
        })
}

struct FrameWriter(Vec<u8>);

impl Write for FrameWriter {
    fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
        if bytes.len() > MAX_FRAME - self.0.len() {
            return Err(io::Error::new(
                io::ErrorKind::InvalidData,
                "protocol frame exceeds 4 MiB",
            ));
        }
        self.0.extend_from_slice(bytes);
        Ok(bytes.len())
    }

    fn flush(&mut self) -> io::Result<()> {
        Ok(())
    }
}

fn read_frame(reader: &mut impl BufRead) -> Result<Vec<u8>, String> {
    let mut frame = Vec::new();
    loop {
        let chunk = reader
            .fill_buf()
            .map_err(|error| format!("Ruby host read failed: {error}"))?;
        if chunk.is_empty() {
            return Err("Ruby host crashed or closed its output before a complete frame".into());
        }
        let newline = chunk.iter().position(|byte| *byte == b'\n');
        let length = newline.unwrap_or(chunk.len());
        if length > MAX_FRAME - frame.len() {
            return Err("Ruby protocol frame exceeds 4 MiB".into());
        }
        frame.extend_from_slice(&chunk[..length]);
        reader.consume(length + usize::from(newline.is_some()));
        if newline.is_some() {
            return Ok(frame);
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::{editor::Input, session::EditorSession};

    use super::*;
    use std::sync::atomic::{AtomicU64, Ordering};

    static NEXT_FIXTURE: AtomicU64 = AtomicU64::new(1);

    struct Fixture(PathBuf);

    impl Fixture {
        fn new() -> Self {
            let path = env::temp_dir().join(format!(
                "vamp-ruby-{}-{}",
                std::process::id(),
                NEXT_FIXTURE.fetch_add(1, Ordering::Relaxed)
            ));
            std::fs::create_dir(&path).unwrap();
            Self(path)
        }

        fn file(&self, name: &str, text: &str) -> PathBuf {
            let path = self.0.join(name);
            std::fs::write(&path, text).unwrap();
            path
        }

        fn plugin(&self, text: &str) -> (RubyPlugin, Feature) {
            self.plugin_with_options(text, &serde_json::json!({}))
        }

        fn plugin_with_options(
            &self,
            text: &str,
            options: &serde_json::Value,
        ) -> (RubyPlugin, Feature) {
            RubyPlugin::start(&self.file("plugin.rb", text), options).unwrap_or_else(|error| {
                panic!("Actual Ruby runtime required (VAMP_RUBY or ruby): {error}")
            })
        }
    }

    impl Drop for Fixture {
        fn drop(&mut self) {
            let _ = std::fs::remove_dir_all(&self.0);
        }
    }

    fn context() -> Context {
        Context {
            buffer_id: 7,
            revision: 11,
            root: "/project".into(),
            text: "α\nhello".into(),
            row: 2,
            column: 3,
            mode: "NORMAL".into(),
            path: Some("buffer.txt".into()),
        }
    }

    #[test]
    fn actual_ruby_dsl_context_queued_effects_and_output_isolation() {
        let fixture = Fixture::new();
        let (mut plugin, feature) = fixture.plugin(r#"
puts "startup noise"
STDOUT.write "direct startup noise\n"
warn "warning"
Vamp.plugin "greeting", requires: ["text"]
Vamp.command "greet" do |editor, args|
  puts "invocation noise"
  STDOUT.write "direct invocation noise\n"
  raise "bad context" unless editor.text == "α\nhello" && editor.row == 2 && editor.column == 3 && editor.mode == "NORMAL" && editor.path == "buffer.txt"
  raise "bad source" unless editor.buffer_id == 7 && editor.revision == 11 && editor.root == "/project" && editor.request_id > 0
  editor.insert "Hello #{args}!"
  editor.replace editor.text
  editor.message "Greeting inserted"
  editor.label :battery, "界 e\u0301 👩‍🚀\t\n\e"
  editor.label "battery", ""
end
"#);
        assert_eq!(feature.name, "greeting");
        assert_eq!(feature.required_capabilities, ["text"]);
        assert_eq!(feature.commands, ["greet"]);
        assert!(!feature.core);
        assert!(!plugin.is_async());
        for _ in 0..2 {
            let effects = plugin.invoke("greet", "friend", &context()).unwrap();
            assert!(
                matches!(&effects[..], [Effect::Insert(text), Effect::Replace(replacement), Effect::Message(message), Effect::Label { name, text: label }, Effect::Label { name: cleared_name, text: cleared }]
                if text == "Hello friend!" && replacement == "α\nhello" && message == "Greeting inserted"
                    && name == "battery" && cleared_name == "battery"
                    && label == "界 e\u{301} 👩‍🚀\t\n\u{1b}" && cleared.is_empty())
            );
        }
        plugin.disable();
        plugin.disable();
        assert!(
            plugin
                .invoke("greet", "", &context())
                .unwrap_err()
                .contains("disabled")
        );
        assert!(
            plugin.host.child.is_none()
                && plugin.host.reader.is_none()
                && plugin.host.writer.is_none()
        );
    }

    #[test]
    fn generated_core_actions_execute_through_ruby_configuration() {
        use crate::{
            editor::{Input, Mode},
            session::EditorSession,
        };

        let fixture = Fixture::new();
        let config = fixture.file(
            "config.rb",
            r#"Vamp.configure do |config|
  config.clipboard_mode = "separate"
  config.bind "Q", config.core.quit
  config.bind "F", config.core.force_quit
  config.bind "W", config.core.save
  config.bind "X", config.core.save_and_quit
  config.bind "E", config.core.edit
  config.bind "B", config.core.buffer
  config.bind "P", config.core.plugins
  config.bind "N", config.core.buffer_next
  config.bind "V", config.core.buffer_previous
  config.bind "D", config.core.buffer_delete
  config.bind "Z", config.core.buffer_force_delete
  config.bind "R", config.core.diff
  config.bind "ctrl+t", config.core.diff.close
  config.bind "H", config.core.word_wrap.toggle
  raise "mutable diff actions" unless config.core.frozen? && config.core.diff.frozen? &&
    config.core.diff.close.frozen? && config.core.diff.name.frozen? &&
    config.core.diff.close.name.frozen?
end"#,
        );
        let mut review = EditorSession::open(None, vec!["text".into()], Some(&config)).unwrap();
        assert!(!review.editor().word_wrap());
        review.handle(Input::Char('H'));
        assert!(review.editor().word_wrap());
        review.execute("word_wrap.toggle unexpected");
        assert!(review.editor().word_wrap());
        review.execute("word_wrap.toggle");
        assert!(!review.editor().word_wrap());
        review.handle(Input::Char('R'));
        review.handle(Input::Escape);
        assert!(review.editor().diff().is_none());
        review.handle(Input::Char('R'));
        assert!(review.editor().diff().is_some());
        review.handle(Input::Ctrl('t'));
        assert!(review.editor().diff().is_none());
        for (key, dirty, quit, saved) in [
            ('Q', false, true, false),
            ('Q', true, false, false),
            ('F', true, true, false),
            ('W', true, false, true),
            ('X', true, true, true),
        ] {
            let buffer = fixture.file("buffer.txt", "base");
            let mut session =
                EditorSession::open(Some(buffer.clone()), vec!["text".into()], Some(&config))
                    .unwrap();
            assert!(session.editor().startup_diagnostic().is_none());
            if dirty {
                for input in [Input::Char('i'), Input::Char('!'), Input::Escape] {
                    session.handle(input);
                }
            }
            session.handle(Input::Char(key));
            assert_eq!(session.editor().should_quit(), quit, "{key}");
            assert_eq!(
                std::fs::read_to_string(&buffer).unwrap(),
                if saved { "!base" } else { "base" },
                "{key}"
            );
            assert_eq!(session.editor().dirty(), dirty && !saved, "{key}");
        }

        let buffer = fixture.file("buffer.txt", "base");
        let second = fixture.file("second.txt", "second");
        let mut session =
            EditorSession::open(Some(buffer), vec!["text".into()], Some(&config)).unwrap();
        assert!(session.editor().startup_diagnostic().is_none());
        session.handle(Input::Char('E'));
        assert_eq!(session.editor().mode(), Mode::Command);
        assert_eq!(session.editor().command_line(), "edit ");
        for ch in second.to_string_lossy().chars() {
            session.handle(Input::Char(ch));
        }
        session.handle(Input::Enter);
        assert_eq!(session.editor().lines(), &["second"]);
        session.handle(Input::Char('B'));
        assert_eq!(session.editor().mode(), Mode::Command);
        assert_eq!(session.editor().command_line(), "buffer ");
        session.handle(Input::Char('1'));
        session.handle(Input::Enter);
        assert_eq!(session.editor().buffer_id(), 1);
        assert_eq!(session.editor().lines(), &["base"]);
        session.handle(Input::Char('P'));
        assert!(session.editor().message().contains("text"));
        session.handle(Input::Char('N'));
        assert_eq!(session.editor().buffer_id(), 2);
        session.handle(Input::Char('V'));
        assert_eq!(session.editor().buffer_id(), 1);
        session.handle(Input::Char('D'));
        assert!(!session.editor().has_buffer(1));
        assert_eq!(session.editor().buffer_id(), 2);
        for input in [Input::Char('i'), Input::Char('!'), Input::Escape] {
            session.handle(input);
        }
        session.handle(Input::Char('D'));
        assert!(session.editor().has_buffer(2));
        session.handle(Input::Char('Z'));
        assert!(!session.editor().has_buffer(2));
        assert_eq!(std::fs::read_to_string(second).unwrap(), "second");
    }

    #[test]
    fn raw_builtin_aliases_are_not_external_binding_commands() {
        let fixture = Fixture::new();
        for name in [
            "quit",
            "save",
            "buffer_next",
            "q",
            "w",
            "bnext",
            "q!",
            "wq",
            "bprev",
            "bdelete",
            "bdelete!",
            "core.quit",
        ] {
            let config = fixture.file(
                "config.rb",
                &format!("Vamp.configure {{ |config| config.bind 'K', '{name}' }}"),
            );
            assert!(load_config(&config).is_err(), "{name}");
        }
    }

    #[test]
    fn plugin_commands_cannot_shadow_canonical_commands_or_aliases() {
        let fixture = Fixture::new();
        for name in [
            "quit",
            "save",
            "buffer_next",
            "q",
            "w",
            "bnext",
            "q!",
            "wq",
            "bprev",
            "bdelete",
            "bdelete!",
        ] {
            let path = fixture.file(
                "plugin.rb",
                &format!("Vamp.plugin 'shadow'\nVamp.command '{name}' do |editor, args|\nend"),
            );
            assert!(
                RubyPlugin::start(&path, &serde_json::json!({})).is_err(),
                "plugin shadowed built-in command {name}"
            );
        }
    }

    #[test]
    fn config_resolves_relative_paths_and_rejects_invalid_types_and_core() {
        let fixture = Fixture::new();
        let config = fixture.file(
            "config.rb",
            r#"
puts "configuration noise"
Vamp.configure do |config|
  config.plugin "plugins/greeting.rb"
  config.bind "g", "greet"
end
"#,
        );
        let loaded = load_config(&config).unwrap();
        assert_eq!(
            loaded.plugins[0].path,
            fixture.0.join("plugins/greeting.rb")
        );
        assert_eq!(loaded.plugins[0].options, serde_json::json!({}));
        let invalid = fixture.file("invalid.rb", "Vamp.configure { |config| config.plugin 7 }");
        assert!(
            load_config(&invalid)
                .unwrap_err()
                .contains("must be a String")
        );
        for target in [
            "7",
            "{}",
            "config.core.lsp",
            "config.core.lsp.hover.tap { |action| action.name = 'core.delete' }",
            "config.core.lsp.tap { |namespace| namespace.define_singleton_method(:bogus) { namespace.hover } }.bogus",
            "config.core.diff.tap { |action| action.name = 'core.delete' }",
            "config.core.diff.tap { |action| action.define_singleton_method(:bogus) { action.close } }.bogus",
            "config.core.diff.close.tap { |action| action.name = 'core.delete' }",
        ] {
            let invalid = fixture.file(
                "invalid_action.rb",
                &format!("Vamp.configure {{ |config| config.bind 'K', {target} }}"),
            );
            assert!(load_config(&invalid).is_err(), "{target}");
        }
        let invalid = fixture.file("core.rb", "Vamp.plugin 'evil', core: true");
        assert!(RubyPlugin::start(&invalid, &serde_json::json!({})).is_err());
        let invalid = fixture.file("syntax.rb", "this is not valid ruby (");
        assert!(RubyPlugin::start(&invalid, &serde_json::json!({})).is_err());
    }

    #[test]
    fn config_leader_defaults_custom_keys_validation_and_required_wire_field() {
        let fixture = Fixture::new();
        let defaults = Config::default();
        assert_eq!(defaults.leader, "space");
        assert!(defaults.plugins.is_empty() && defaults.bindings.is_empty());
        assert!(defaults.lsp.is_empty());
        let path = fixture.file("config.rb", "Vamp.configure { |_| }");
        assert_eq!(load_config(&path).unwrap().leader, "space");
        for (source, key) in [
            (r#"Vamp.configure { |config| config.leader = "," }"#, ","),
            (r#"Vamp.configure { |config| config.leader = "\\" }"#, "\\"),
        ] {
            let path = fixture.file("config.rb", source);
            assert_eq!(load_config(&path).unwrap().leader, key);
        }
        for (value, error) in [
            ("7", "leader key must be a String"),
            ("nil", "leader key must be a String"),
            (r#""""#, "leader key must not be empty"),
        ] {
            let path = fixture.file(
                "config.rb",
                &format!("Vamp.configure {{ |config| config.leader = {value} }}"),
            );
            assert!(load_config(&path).unwrap_err().contains(error), "{value}");
        }
        for frame in [
            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"leader":null,"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
            r#"{"type":"config","version":1,"plugins":[],"lsp":{},"bindings":[],"leader":7,"file_explorer_side":"right","file_picker_view":"list","file_explorer_view":"tree","clipboard_mode":"system","git_blame":true,"git_gutter":"bar","top_bar":{},"bottom_bar":{},"popup":{"command":{},"search":{}},"labels":{},"diff_context_lines":10,"diff_expand_lines":15,"diff_view_mode":"split","diff_split_orientation":"vertical","diff_follow_working_copy":true}"#,
        ] {
            assert!(serde_json::from_str::<Response>(frame).is_err(), "{frame}");
        }
    }

    #[test]
    fn git_gutter_config_modes_default_and_rejection() {
        use crate::gutter::GutterStyle;
        let fixture = Fixture::new();
        let path = fixture.file("config.rb", "Vamp.configure { |_config| }");
        assert_eq!(load_config(&path).unwrap().git_gutter, GutterStyle::Bar);
        for (name, expected) in [
            ("bar", GutterStyle::Bar),
            ("symbols", GutterStyle::Symbols),
            ("line_numbers", GutterStyle::LineNumbers),
            ("none", GutterStyle::None),
        ] {
            let path = fixture.file(
                "config.rb",
                &format!("Vamp.configure {{ |config| config.git_gutter = {name:?} }}"),
            );
            assert_eq!(load_config(&path).unwrap().git_gutter, expected);
        }
        for value in ["\"unsupported\"", "\"\"", "false", "7", ":bar"] {
            let path = fixture.file(
                "config.rb",
                &format!("Vamp.configure {{ |config| config.git_gutter = {value} }}"),
            );
            assert!(load_config(&path).is_err(), "{value}");
        }
    }

    #[test]
    fn git_blame_boolean_config_typed_toggle_palette_and_wire_validation() {
        let fixture = Fixture::new();
        let config = fixture.file("config.rb", "Vamp.configure { |_config| }");
        assert!(load_config(&config).unwrap().git_blame);
        let config = fixture.file("config.rb", r#"
Vamp.configure do |config|
  config.git_blame = false
  config.bind "G", config.core.git_blame.toggle
  raise "mutable blame action" unless config.core.git_blame.frozen? && config.core.git_blame.toggle.frozen?
end
"#);
        let mut session = EditorSession::open(None, vec![], Some(&config)).unwrap();
        assert!(!session.editor().git_blame());
        session.handle(Input::Char('G'));
        assert!(session.editor().git_blame());
        session.execute("git_blame.toggle extra");
        assert!(session.editor().git_blame());
        session.execute("git_blame.toggle");
        assert!(!session.editor().git_blame());
        session.handle(Input::Ctrl('p'));
        for ch in "git blame".chars() {
            session.handle(Input::Char(ch));
        }
        assert_eq!(session.editor().palette().unwrap().entries.len(), 1);
        session.handle(Input::Enter);
        assert!(session.editor().git_blame());
        for value in ["nil", "0", r#""false""#, "[]", "{}"] {
            let config = fixture.file(
                "config.rb",
                &format!("Vamp.configure {{ |config| config.git_blame = {value} }}"),
            );
            assert!(
                load_config(&config)
                    .unwrap_err()
                    .contains("git_blame must be true or false")
            );
        }
        let mut frame = serde_json::json!({
            "type": "config", "version": 1, "plugins": [], "lsp": {}, "bindings": [],
            "leader": "space", "file_explorer_side": "right", "file_picker_view": "tree",
            "file_explorer_view": "tree", "clipboard_mode": "system", "git_blame": true,
            "git_gutter": "bar",
            "top_bar": {}, "bottom_bar": {}, "popup": {"command": {}, "search": {}},
            "labels": {}, "diff_context_lines": 10, "diff_expand_lines": 15,
            "diff_view_mode": "split", "diff_split_orientation": "vertical",
            "diff_follow_working_copy": true
        });
        assert!(serde_json::from_value::<Response>(frame.clone()).is_ok());
        for value in [
            serde_json::Value::Null,
            serde_json::json!(0),
            serde_json::json!("false"),
        ] {
            frame["git_blame"] = value;
            assert!(serde_json::from_value::<Response>(frame.clone()).is_err());
        }
        frame.as_object_mut().unwrap().remove("git_blame");
        assert!(serde_json::from_value::<Response>(frame).is_err());
    }

    #[test]
    fn working_diff_tracking_rejects_non_boolean_configuration() {
        let fixture = Fixture::new();
        for value in ["nil", "0", r#""false""#, "[]", "{}"] {
            let path = fixture.file(
                "config.rb",
                &format!("Vamp.configure {{ |config| config.diff_follow_working_copy = {value} }}"),
            );
            assert!(
                load_config(&path)
                    .unwrap_err()
                    .contains("diff_follow_working_copy must be true or false")
            );
        }
    }

    #[test]
    fn chrome_configuration_normalizes_ruby_values_and_retains_unspecified_defaults() {
        let fixture = Fixture::new();
        let path = fixture.file(
            "config.rb",
            r#"
Vamp.configure do |config|
  config.bar.top = {left: [:tabs], center: ["workspace"], right: [:battery],
    tabs: {title: "T{index}:{path}{modified}", padding: 0, first_leading_edge: ""},
    battery: {leading_edge: "界", trailing_edge: ""}}
  config.bar.bottom = {"left" => [], center: [:workspace]}
  config.labels = {battery: "bat 38%", "workspace" => "界 e\u0301 👩‍🚀\t\n\e"}
end
"#,
        );
        let loaded = load_config(&path).unwrap();
        assert_eq!(loaded.top_bar.left, ["tabs"]);
        assert_eq!(loaded.top_bar.center, ["workspace"]);
        assert_eq!(loaded.top_bar.right, ["battery"]);
        assert_eq!(
            loaded.top_bar.segment("tabs").title,
            "T{index}:{path}{modified}"
        );
        assert_eq!(loaded.top_bar.segment("tabs").padding, 0);
        assert_eq!(loaded.top_bar.segment("battery").leading_edge, "界");
        assert_eq!(
            loaded.top_bar.segment("workspace"),
            &crate::chrome::SegmentConfig::default()
        );
        assert!(loaded.bottom_bar.left.is_empty());
        assert_eq!(loaded.labels["battery"], "bat 38%");
        assert_eq!(loaded.labels["workspace"], "界 e\u{301} 👩‍🚀\t\n\u{1b}");
    }

    #[test]
    fn popup_configuration_accepts_ruby_symbol_and_string_anchors_independently() {
        use crate::chrome::PopupAnchor;

        let fixture = Fixture::new();
        let anchors = [
            ("top_left", PopupAnchor::TopLeft),
            ("top_center", PopupAnchor::TopCenter),
            ("top_right", PopupAnchor::TopRight),
            ("center_left", PopupAnchor::CenterLeft),
            ("center", PopupAnchor::Center),
            ("center_right", PopupAnchor::CenterRight),
            ("bottom_left", PopupAnchor::BottomLeft),
            ("bottom_center", PopupAnchor::BottomCenter),
            ("bottom_right", PopupAnchor::BottomRight),
        ];
        for (index, (command_name, command_anchor)) in anchors.iter().enumerate() {
            let (search_name, search_anchor) = anchors[(index + 1) % anchors.len()];
            let path = fixture.file(
                "config.rb",
                &format!(
                    "Vamp.configure do |config|\n\
                       config.popup.command = {{anchor: :{command_name}}}\n\
                       config.popup.search = {{'anchor' => '{search_name}'}}\n\
                     end"
                ),
            );
            let loaded = load_config(&path).unwrap();
            assert_eq!(loaded.popup.command.anchor, *command_anchor);
            assert_eq!(loaded.popup.search.anchor, search_anchor);
        }
    }

    #[test]
    fn popup_configuration_rejects_unknown_options_anchors_callbacks_and_types() {
        let fixture = Fixture::new();
        for (value, expected) in [
            ("[]", "must be a Hash"),
            ("nil", "must be a Hash"),
            ("7", "must be a Hash"),
            ("{width: 72}", "unknown popup option"),
            ("{callback: -> { 'center' }}", "unknown popup option"),
            ("{anchor: :middle}", "unknown popup anchor"),
            ("{anchor: 'TopLeft'}", "unknown popup anchor"),
            ("{anchor: nil}", "must be a String"),
            ("{anchor: 7}", "must be a String"),
            ("{anchor: true}", "must be a String"),
            ("{anchor: []}", "must be a String"),
            ("{anchor: {}}", "must be a String"),
            ("{anchor: -> { :center }}", "must be a String"),
            (
                "{anchor: :center, 'anchor' => :top_left}",
                "duplicate chrome key",
            ),
            ("{7 => :center}", "chrome key must be a String"),
        ] {
            for mode in ["command", "search"] {
                let path = fixture.file(
                    "config.rb",
                    &format!("Vamp.configure {{ |config| config.popup.{mode} = {value} }}"),
                );
                let error = load_config(&path).unwrap_err();
                assert!(error.contains(expected), "{mode}={value}: {error}");
            }
        }
        let path = fixture.file("config.rb", "Vamp.configure { |config| config.popup = {} }");
        assert!(load_config(&path).unwrap_err().contains("undefined method"));
    }

    #[test]
    fn bar_namespace_is_stable_and_accepts_swapped_builtins() {
        let fixture = Fixture::new();
        let path = fixture.file(
            "config.rb",
            r#"
Vamp.configure do |config|
  bar = config.bar
  raise "bar namespace must be stable" unless bar.equal?(config.bar)
  bar.top = {left: [:mode, :language], right: [], mode: {padding: 0}}
  config.bar.bottom = {left: [:tabs], right: [], tabs: {title: "{name}{modified}"}}
end
"#,
        );
        let loaded = load_config(&path).unwrap();
        assert_eq!(loaded.top_bar.left, ["mode", "language"]);
        assert_eq!(loaded.top_bar.segment("mode").padding, 0);
        assert_eq!(loaded.top_bar.segment("language").padding, 1);
        assert_eq!(loaded.bottom_bar.left, ["tabs"]);
        assert_eq!(loaded.bottom_bar.segment("tabs").title, "{name}{modified}");

        for setter in ["bar", "tabline", "statusline"] {
            let path = fixture.file(
                "config.rb",
                &format!("Vamp.configure {{ |config| config.{setter} = {{}} }}"),
            );
            let error = load_config(&path).unwrap_err();
            assert!(error.contains("undefined method"), "{setter}: {error}");
        }
    }

    #[test]
    fn chrome_configuration_rejects_invalid_types_names_and_templates() {
        let fixture = Fixture::new();
        for (setting, value, expected) in [
            ("bar.top", "[]", "must be a Hash"),
            ("bar.bottom", "[]", "must be a Hash"),
            ("bar.top", "{left: :tabs}", "must be an Array"),
            ("bar.top", "{left: [7]}", "must be a String"),
            ("bar.top", "{left: [:bad_name!]}", "must match"),
            (
                "bar.bottom",
                "{tabs: {title: '{unknown}'}}",
                "unknown title placeholder",
            ),
            ("bar.top", r#"{mode: {leading_edge: "\n"}}"#, "single-line"),
            ("bar.top", "{language: {padding: 65}}", "between 0 and 64"),
            ("bar.bottom", "{tabs: {padding: '1'}}", "must be an Integer"),
            ("bar.top", "{lsp: {margin: 65}}", "between 0 and 64"),
            ("bar.bottom", "{lsp: {margin: -1}}", "between 0 and 64"),
            ("bar.top", "{lsp: {margin: '1'}}", "must be an Integer"),
            ("bar.bottom", "{lsp: {margin: 1.5}}", "must be an Integer"),
            ("bar.top", "{lsp: {margin: nil}}", "must be an Integer"),
            ("bar.top", "{mode: {title: nil}}", "must be a String"),
            (
                "bar.bottom",
                "{tabs: {color: 'red'}}",
                "unknown chrome style option",
            ),
            (
                "bar.top",
                "{left: [], 'left' => []}",
                "duplicate chrome key",
            ),
            ("labels", "[]", "must be a Hash"),
            ("labels", "{battery: 7}", "label text must be a String"),
            ("labels", "{'bad-name' => ''}", "must match"),
        ] {
            let path = fixture.file(
                "config.rb",
                &format!("Vamp.configure {{ |config| config.{setting} = {value} }}"),
            );
            let error = load_config(&path).unwrap_err();
            assert!(error.contains(expected), "{setting}={value}: {error}");
        }
    }

    #[test]
    fn label_wire_effects_require_name_and_string_text() {
        for frame in [
            serde_json::json!({"type": "label", "text": ""}),
            serde_json::json!({"type": "label", "name": 7, "text": ""}),
            serde_json::json!({"type": "label", "name": "battery"}),
            serde_json::json!({"type": "label", "name": "battery", "text": null}),
            serde_json::json!({"type": "label", "name": "battery", "text": 7}),
            serde_json::json!({"type": "label", "name": "battery", "text": "", "extra": true}),
        ] {
            assert!(serde_json::from_value::<WireEffect>(frame.clone()).is_err());
            assert!(serde_json::from_value::<UpdateEffect>(frame).is_err());
        }
    }

    #[test]
    fn config_diff_excerpt_counts_accept_custom_values_and_reject_invalid_values() {
        let fixture = Fixture::new();
        for (context, expand) in [(0, 7), (3, 1), (usize::MAX, usize::MAX)] {
            let path = fixture.file(
                "config.rb",
                &format!(
                    "Vamp.configure {{ |config| config.diff_context_lines = {context}; config.diff_expand_lines = {expand} }}"
                ),
            );
            let loaded = load_config(&path).unwrap();
            assert_eq!(
                (loaded.diff_context_lines, loaded.diff_expand_lines),
                (context, expand)
            );
        }
        let frame = serde_json::json!({
            "version": 1, "type": "config", "plugins": [], "lsp": {},
            "bindings": [], "leader": "space", "file_explorer_side": "right",
            "file_picker_view": "tree", "file_explorer_view": "tree",
            "top_bar": {}, "bottom_bar": {}, "labels": {},
            "popup": {"command": {}, "search": {}},
            "clipboard_mode": "system", "diff_context_lines": 0, "diff_expand_lines": 7,
            "diff_view_mode": "split", "diff_split_orientation": "vertical",
            "diff_follow_working_copy": true
        });
        for setting in ["diff_context_lines", "diff_expand_lines"] {
            for value in [
                "-1",
                "1.5",
                "\"3\"",
                "true",
                "false",
                "nil",
                "18446744073709551616",
                "0",
            ] {
                if setting == "diff_context_lines" && value == "0" {
                    continue;
                }
                let path = fixture.file(
                    "config.rb",
                    &format!("Vamp.configure {{ |config| config.{setting} = {value} }}"),
                );
                let error = load_config(&path).unwrap_err();
                assert!(
                    error.contains(setting) && error.contains("must be"),
                    "{value}: {error}"
                );

                let mut invalid_frame = frame.clone();
                invalid_frame[setting] =
                    serde_json::from_str(if value == "nil" { "null" } else { value }).unwrap();
                let error = serde_json::from_value::<Response>(invalid_frame)
                    .err()
                    .unwrap();
                assert!(error.to_string().contains(setting), "{value}: {error}");
            }
        }
    }

    #[test]
    fn lsp_configuration_is_disabled_unless_explicitly_enabled() {
        let fixture = Fixture::new();
        for source in [
            "Vamp.configure { |_| }",
            r#"Vamp.configure do |config|
  config.lsp["rust"] = false
  config.lsp["python"] = false
  config.lsp["not-a-preset"] = false
end"#,
        ] {
            let path = fixture.file("config.rb", source);
            let config = load_config(&path).unwrap();
            assert!(config.lsp.is_empty());
            assert!(config.plugins.is_empty());
        }
    }

    #[test]
    fn lsp_presets_custom_languages_and_overrides_reach_native_configuration() {
        let fixture = Fixture::new();
        let path = fixture.file(
            "config.rb",
            r#"Vamp.configure do |config|
  config.lsp["rust"] = true
  config.lsp["python"] = true
  config.lsp["ruby"] = true
end"#,
        );
        let config = load_config(&path).unwrap();
        assert_eq!(config.lsp.len(), 4);
        for (language, command, extension) in [
            ("rust", &["rust-analyzer"][..], "rs"),
            ("ruby", &["solargraph", "stdio"][..], "rb"),
        ] {
            let server = config
                .lsp
                .iter()
                .find(|server| server.language_id == language)
                .unwrap();
            assert_eq!(server.command, command);
            assert_eq!(server.extensions, [extension]);
            assert_eq!(server.initialization_options, serde_json::json!({}));
            assert_eq!(server.settings, serde_json::json!({}));
        }
        let python: Vec<_> = config
            .lsp
            .iter()
            .filter(|server| server.language_id == "python")
            .collect();
        assert_eq!(python.len(), 2);
        for (server, command, initialization_options) in [
            (
                python[0],
                ["ty", "server"],
                serde_json::json!({"experimental": {"useUv": "off"}}),
            ),
            (python[1], ["ruff", "server"], serde_json::json!({})),
        ] {
            assert_eq!(server.command, command);
            assert_eq!(server.extensions, ["py"]);
            assert_eq!(server.initialization_options, initialization_options);
            assert_eq!(server.settings, serde_json::json!({}));
        }

        let path = fixture.file(
            "config.rb",
            r#"Vamp.configure do |config|
  config.lsp["rust"] = {
    extensions: ["rs", "ron"],
    initialization_options: {cargo: {features: ["α"]}},
    settings: {"rust-analyzer" => {check: {command: "clippy"}}}
  }
  config.lsp["python"] = {command: ["custom-python-server", "--stdio"]}
  config.lsp["ruby"] = {command: ["bundle", "exec", "solargraph", "stdio"]}
  config.lsp["my-language.c++"] = {
    command: ["custom server", "--flag", ""],
    extensions: ["custom", "لغة"],
    settings: {nested: {enabled: true, limit: 3, unset: nil}}
  }
end"#,
        );
        let config = load_config(&path).unwrap();
        let rust = config
            .lsp
            .iter()
            .find(|server| server.language_id == "rust")
            .unwrap();
        assert_eq!(rust.command, ["rust-analyzer"]);
        assert_eq!(rust.extensions, ["rs", "ron"]);
        assert_eq!(
            rust.initialization_options,
            serde_json::json!({"cargo": {"features": ["α"]}})
        );
        assert_eq!(
            rust.settings,
            serde_json::json!({"rust-analyzer": {"check": {"command": "clippy"}}})
        );
        let python = config
            .lsp
            .iter()
            .find(|server| server.language_id == "python")
            .unwrap();
        assert_eq!(python.command, ["custom-python-server", "--stdio"]);
        assert_eq!(python.extensions, ["py"]);
        assert_eq!(python.initialization_options, serde_json::json!({}));
        assert_eq!(python.settings, serde_json::json!({}));
        assert_eq!(
            config
                .lsp
                .iter()
                .filter(|server| server.language_id == "python")
                .count(),
            1
        );
        let ruby = config
            .lsp
            .iter()
            .find(|server| server.language_id == "ruby")
            .unwrap();
        assert_eq!(ruby.command, ["bundle", "exec", "solargraph", "stdio"]);
        assert_eq!(ruby.extensions, ["rb"]);
        let custom = config
            .lsp
            .iter()
            .find(|server| server.language_id == "my-language.c++")
            .unwrap();
        assert_eq!(custom.command, ["custom server", "--flag", ""]);
        assert_eq!(custom.extensions, ["custom", "لغة"]);
        assert_eq!(custom.initialization_options, serde_json::json!({}));
        assert_eq!(
            custom.settings,
            serde_json::json!({"nested": {"enabled": true, "limit": 3, "unset": null}})
        );
    }

    #[test]
    fn lsp_python_common_options_and_ordered_server_overrides() {
        let fixture = Fixture::new();
        let path = fixture.file(
            "config.rb",
            r#"Vamp.configure do |config|
  config.lsp["python"] = {
    extensions: ["py", "pyi"],
    initialization_options: {diagnosticMode: "workspace"},
    settings: {shared: true}
  }
end"#,
        );
        let config = load_config(&path).unwrap();
        assert_eq!(config.lsp.len(), 2);
        for (server, command) in config
            .lsp
            .iter()
            .zip([["ty", "server"], ["ruff", "server"]])
        {
            assert_eq!(server.language_id, "python");
            assert_eq!(server.command, command);
            assert_eq!(server.extensions, ["py", "pyi"]);
            assert_eq!(
                server.initialization_options,
                serde_json::json!({"diagnosticMode": "workspace"})
            );
            assert_eq!(server.settings, serde_json::json!({"shared": true}));
        }
        let path = fixture.file(
            "config.rb",
            r#"Vamp.configure do |config|
  config.lsp["python"] = {servers: [
    {command: ["type-server", "--stdio"], initialization_options: {experimental: {useUv: "off"}}, settings: {first: true}},
    {command: ["lint-server"], initialization_options: {settings: {lint: {enable: true}}}}
  ]}
  config.lsp["custom"] = {extensions: ["custom"], servers: [
    {command: ["custom-first"]}, {command: ["custom-second"], settings: {second: true}}
  ]}
end"#,
        );
        let config = load_config(&path).unwrap();
        for (language, commands, extensions) in [
            (
                "python",
                [&["type-server", "--stdio"][..], &["lint-server"][..]],
                ["py"],
            ),
            (
                "custom",
                [&["custom-first"][..], &["custom-second"][..]],
                ["custom"],
            ),
        ] {
            let servers: Vec<_> = config
                .lsp
                .iter()
                .filter(|server| server.language_id == language)
                .collect();
            assert_eq!(servers.len(), 2);
            for (server, command) in servers.iter().zip(commands) {
                assert_eq!(server.command, command);
                assert_eq!(server.extensions, extensions);
            }
        }
        let python: Vec<_> = config
            .lsp
            .iter()
            .filter(|server| server.language_id == "python")
            .collect();
        assert_eq!(
            python[0].initialization_options,
            serde_json::json!({"experimental": {"useUv": "off"}})
        );
        assert_eq!(python[0].settings, serde_json::json!({"first": true}));
        assert_eq!(
            python[1].initialization_options,
            serde_json::json!({"settings": {"lint": {"enable": true}}})
        );
        assert_eq!(python[1].settings, serde_json::json!({}));
        let custom: Vec<_> = config
            .lsp
            .iter()
            .filter(|server| server.language_id == "custom")
            .collect();
        assert_eq!(custom[0].initialization_options, serde_json::json!({}));
        assert_eq!(custom[1].settings, serde_json::json!({"second": true}));
        let path = fixture.file(
            "config.rb",
            r#"Vamp.configure { |config| config.lsp["python"] = {settings: {shared: true}} }"#,
        );
        let config = load_config(&path).unwrap();
        assert_eq!(
            config.lsp[0].initialization_options,
            serde_json::json!({"experimental": {"useUv": "off"}})
        );
        assert_eq!(config.lsp[1].initialization_options, serde_json::json!({}));
    }

    #[test]
    fn lsp_server_lists_reject_invalid_shapes_and_ambiguous_options_locally() {
        let fixture = Fixture::new();
        for (options, error) in [
            ("{servers: nil}", "nonempty array"),
            ("{servers: {command: ['server']}}", "nonempty array"),
            ("{servers: []}", "nonempty array"),
            (
                "{servers: [true]}",
                "servers[0] must be a configuration object",
            ),
            ("{servers: [{}]}", "servers[0] requires command argv"),
            ("{servers: [{command: []}]}", "servers[0] command must be"),
            (
                "{servers: [{command: ['server'], extensions: ['py']}]}",
                "servers[0] has unknown option",
            ),
            (
                "{servers: [{command: ['server'], servers: []}]}",
                "servers[0] has unknown option",
            ),
            (
                "{servers: [{command: ['server'], initialization_options: []}]}",
                "servers[0] initialization_options must be",
            ),
            (
                "{servers: [{command: ['server']}, {command: ['other'], settings: nil}]}",
                "servers[1] settings must be",
            ),
            (
                "{servers: [{command: ['server']}], command: ['other']}",
                "cannot be combined",
            ),
            (
                "{servers: [{command: ['server']}], initialization_options: {}}",
                "cannot be combined",
            ),
            (
                "{servers: [{command: ['server']}], settings: {}}",
                "cannot be combined",
            ),
        ] {
            let path = fixture.file(
                "config.rb",
                &format!("Vamp.configure {{ |config| config.lsp[\"python\"] = {options} }}"),
            );
            let actual = load_config(&path).unwrap_err();
            assert!(
                actual.starts_with("Ruby config: LSP language \"python\""),
                "{actual}"
            );
            assert!(actual.contains(error), "{options}: {actual}");
        }
    }

    #[test]
    fn lsp_server_limit_is_enforced_at_configuration_startup() {
        let fixture = Fixture::new();
        for count in [16, 17] {
            let path = fixture.file(
                "config.rb",
                &format!(
                    "Vamp.configure {{ |config| config.lsp[\"python\"] = {{servers: Array.new({count}) {{ {{command: [\"server\"]}} }} }} }}"
                ),
            );
            let result = load_config(&path);
            if count == 16 {
                assert_eq!(result.unwrap().lsp.len(), 16);
            } else {
                assert_eq!(
                    result.unwrap_err(),
                    "Ruby config: LSP configuration supports at most 16 configured servers"
                );
            }
        }
    }

    #[test]
    fn lsp_configuration_rejects_invalid_keys_values_and_json_options() {
        let fixture = Fixture::new();
        for assignment in [
            r#"config.lsp[:rust] = true"#,
            r#"config.lsp[7] = false"#,
            r#"config.lsp[""] = false"#,
            r#"config.lsp["bad\nkey"] = false"#,
            r#"config.lsp["\xFF".b] = false"#,
            r#"config.lsp["rust"] = nil"#,
            r#"config.lsp["rust"] = []"#,
            r#"config.lsp["rust"] = "yes""#,
            r#"config.lsp["custom"] = {}"#,
            r#"config.lsp["custom"] = {command: ["server"]}"#,
            r#"config.lsp["custom"] = {servers: [{command: ["server"]}]}"#,
            r#"config.lsp["custom"] = {extensions: ["custom"]}"#,
            r#"config.lsp["rust"] = {command: "server"}"#,
            r#"config.lsp["rust"] = {command: []}"#,
            r#"config.lsp["rust"] = {command: [""]}"#,
            r#"config.lsp["rust"] = {command: ["server", 7]}"#,
            r#"config.lsp["rust"] = {command: ["server", "bad\0argument"]}"#,
            r#"config.lsp["rust"] = {extensions: "rs"}"#,
            r#"config.lsp["rust"] = {extensions: []}"#,
            r#"config.lsp["rust"] = {extensions: [""]}"#,
            r#"config.lsp["rust"] = {extensions: [7]}"#,
            r#"config.lsp["rust"] = {extensions: [".rs"]}"#,
            r#"config.lsp["rust"] = {extensions: ["path/rs"]}"#,
            r#"config.lsp["rust"] = {extensions: ["path\\rs"]}"#,
            r#"config.lsp["rust"] = {extensions: ["r s"]}"#,
            r#"config.lsp["rust"] = {extensions: ["r\u0001s"]}"#,
            r#"config.lsp["rust"] = {initialization_options: []}"#,
            r#"config.lsp["rust"] = {settings: nil}"#,
            r#"config.lsp["rust"] = {settings: {bad: Object.new}}"#,
            r#"config.lsp["rust"] = {settings: {bad: Float::NAN}}"#,
            r#"config.lsp["rust"] = {settings: {7 => true}}"#,
            r#"config.lsp["rust"] = {unknown: true}"#,
        ] {
            let path = fixture.file(
                "invalid.rb",
                &format!("Vamp.configure {{ |config| {assignment} }}"),
            );
            assert!(load_config(&path).is_err(), "{assignment}");
        }
        let path = fixture.file(
            "invalid.rb",
            r#"Vamp.configure { |config| config.lsp["unsupported-language"] = true }"#,
        );
        let error = load_config(&path).unwrap_err();
        assert!(!error.contains("Malformed Ruby protocol frame"), "{error}");
        assert!(
            error.contains("\"unsupported-language\"")
                && error.contains("command")
                && error.contains("extensions"),
            "{error}"
        );
    }

    #[test]
    fn lsp_wire_configuration_is_resolved_after_decoding() {
        let mut frame = serde_json::json!({
            "version": 1, "type": "config", "plugins": [], "lsp": {},
            "bindings": [], "leader": "space", "file_explorer_side": "right",
            "file_picker_view": "tree", "file_explorer_view": "tree",
            "git_blame": true,
            "git_gutter": "bar",
            "top_bar": {}, "bottom_bar": {}, "labels": {},
            "popup": {"command": {}, "search": {}},
            "clipboard_mode": "system", "diff_context_lines": 10, "diff_expand_lines": 15,
            "diff_view_mode": "split", "diff_split_orientation": "vertical",
            "diff_follow_working_copy": true
        });
        let Response::Config(config) = serde_json::from_value::<Response>(frame.clone()).unwrap()
        else {
            panic!("expected config frame");
        };
        assert!(crate::lsp_config::resolve(config.lsp).unwrap().is_empty());
        frame["lsp"] = serde_json::json!({"rust": true});
        let Response::Config(config) = serde_json::from_value::<Response>(frame.clone()).unwrap()
        else {
            panic!("expected config frame");
        };
        assert_eq!(
            crate::lsp_config::resolve(config.lsp).unwrap()[0].command,
            ["rust-analyzer"]
        );
        for value in [
            serde_json::json!(null),
            serde_json::json!([]),
            serde_json::json!({"": false}),
            serde_json::json!({"bad\u{0085}key": false}),
            serde_json::json!({"rust": null}),
            serde_json::json!({"python": []}),
            serde_json::json!({"unknown": true}),
            serde_json::json!({"custom": {}}),
            serde_json::json!({"rust": {"command": ["tool", "bad\0argument"]}}),
            serde_json::json!({"rust": {"extensions": ["bad\nextension"]}}),
            serde_json::json!({"rust": {"initialization_options": []}}),
            serde_json::json!({"rust": {"settings": "not-an-object"}}),
            serde_json::json!({"rust": {"unexpected": true}}),
            serde_json::json!({"python": {"servers": []}}),
            serde_json::json!({"python": {"servers": [null]}}),
            serde_json::json!({"python": {"servers": [{}]}}),
            serde_json::json!({"python": {"servers": [{"command": ["server"], "extensions": ["py"]}]}}),
            serde_json::json!({"python": {"servers": [{"command": ["server"]}], "settings": {}}}),
        ] {
            frame["lsp"] = value;
            let Response::Config(config) =
                serde_json::from_value::<Response>(frame.clone()).unwrap()
            else {
                panic!("expected config frame");
            };
            assert!(crate::lsp_config::resolve(config.lsp).is_err(), "{frame}");
        }
        let mut languages: serde_json::Map<String, serde_json::Value> = (0..14)
            .map(|index| {
                (
                    format!("custom-{index}"),
                    serde_json::json!({"command": ["server"], "extensions": ["custom"]}),
                )
            })
            .collect();
        languages.insert("python".into(), serde_json::json!(true));
        frame["lsp"] = serde_json::Value::Object(languages);
        let Response::Config(config) = serde_json::from_value::<Response>(frame.clone()).unwrap()
        else {
            panic!("expected config frame");
        };
        assert_eq!(crate::lsp_config::resolve(config.lsp).unwrap().len(), 16);
        frame["lsp"]["ruby"] = serde_json::json!(true);
        let Response::Config(config) = serde_json::from_value::<Response>(frame.clone()).unwrap()
        else {
            panic!("expected config frame");
        };
        assert_eq!(
            crate::lsp_config::resolve(config.lsp).unwrap_err(),
            "LSP configuration supports at most 16 configured servers"
        );
        frame.as_object_mut().unwrap().remove("lsp");
        assert!(serde_json::from_value::<Response>(frame).is_err());
    }

    #[test]
    fn malformed_config_wire_remains_a_protocol_error() {
        let fixture = Fixture::new();
        for mutation in [
            "return '['",
            "frame.delete('lsp')",
            "frame.delete('top_bar')",
            "frame.delete('bottom_bar')",
            "frame.delete('labels')",
            "frame.delete('popup')",
            "frame['popup'] = nil",
            "frame['popup'] = []",
            "frame['popup'] = {'selector' => {}}",
            "frame['popup'] = {'command' => nil}",
            "frame['popup'] = {'search' => 7}",
            "frame['popup'] = {'command' => {'anchor' => nil}}",
            "frame['popup'] = {'search' => {'anchor' => 'middle'}}",
            "frame['popup'] = {'command' => {'width' => 72}}",
            "frame['top_bar'] = 7",
            "frame['bottom_bar'] = []",
            "frame['labels'] = {'battery' => 7}",
            "frame['bottom_bar'] = {'tabs' => {'title' => '{unknown}'}}",
            "frame['top_bar'] = {'mode' => {'leading_edge' => \"\\n\"}}",
            "frame['top_bar'] = {'left' => nil}",
            "frame['bottom_bar'] = {'left' => ['bad-name']}",
            "frame['bottom_bar'] = {'tabs' => {'padding' => '1'}}",
            "frame['top_bar'] = {'language' => {'color' => 'red'}}",
            "frame['labels'] = {'bad-name' => ''}",
            "frame['leader'] = 7",
            "frame['unexpected'] = true",
        ] {
            let source = format!(
                r#"
Vamp.configure {{ |config| config.lsp["ruby"] = true }}
module JSON
  class << self
    alias_method :original_generate, :generate
    def generate(frame)
      if frame['type'] == 'config'
        {mutation}
      end
      original_generate(frame)
    end
  end
end
"#
            );
            let path = fixture.file("config.rb", &source);
            let error = load_config(&path).unwrap_err();
            assert!(
                error.starts_with("Malformed Ruby protocol frame: "),
                "{mutation}: {error}"
            );
        }
    }

    #[test]
    fn crash_hang_callback_failure_and_fresh_host_recovery() {
        let fixture = Fixture::new();
        for callback in [
            "exit! 19",
            "sleep 10",
            "editor.insert 'must not escape'; raise 'callback failed'",
            "editor.insert 7",
        ] {
            let (mut plugin, _) = fixture.plugin(&format!(
                "Vamp.plugin 'failure'\nVamp.command('fail') {{ |editor, args| {callback} }}"
            ));
            let error = plugin.invoke("fail", "", &context()).unwrap_err();
            if callback == "sleep 10" {
                assert!(error.contains("timeout"), "{error}");
            }
            assert!(
                plugin.host.child.is_none()
                    && plugin.host.reader.is_none()
                    && plugin.host.writer.is_none()
            );
            assert!(
                plugin
                    .invoke("fail", "", &context())
                    .unwrap_err()
                    .contains("disabled")
            );
            let (mut recovered, _) = fixture.plugin(
                "Vamp.plugin 'recovered'\nVamp.command('ok') { |editor, args| editor.message 'alive' }");
            assert!(
                matches!(&recovered.invoke("ok", "", &context()).unwrap()[..],
                [Effect::Message(message)] if message == "alive")
            );
        }
    }

    #[test]
    fn nonstandard_callback_exceptions_are_reported_without_effects() {
        let fixture = Fixture::new();
        for (callback, expected) in [
            ("exit 19", "SystemExit: exit"),
            ("raise Interrupt, 'interrupted'", "Interrupt: interrupted"),
        ] {
            let (mut plugin, _) = fixture.plugin(&format!(
                "Vamp.plugin 'failure'\nVamp.command('fail') {{ |editor, _| editor.insert 'must not escape'; {callback} }}"
            ));
            let error = plugin.invoke("fail", "", &context()).unwrap_err();
            assert!(error.contains(expected), "{error}");
            assert!(
                plugin
                    .invoke("fail", "", &context())
                    .unwrap_err()
                    .contains("disabled")
            );
        }
    }

    #[test]
    fn startup_and_config_hangs_are_bounded() {
        let fixture = Fixture::new();
        let path = fixture.file("hang.rb", "sleep 10");
        assert!(
            RubyPlugin::start(&path, &serde_json::json!({}))
                .err()
                .unwrap()
                .contains("timeout")
        );
        assert!(load_config(&path).unwrap_err().contains("timeout"));
    }

    #[test]
    fn invalid_protocol_version_shape_effect_and_request_id_shutdown() {
        let fixture = Fixture::new();
        for mutation in [
            "frame['version'] = 2",
            "frame['id'] += 1",
            "frame['effects'] = [{'type' => 'delete', 'text' => 'x'}]",
            "frame['effects'] = [{'type' => 'insert', 'text' => 7}]",
            "frame['unexpected'] = true",
        ] {
            let source = format!(
                r#"
Vamp.plugin 'protocol'
Vamp.command('ok') {{ |editor, args| editor.insert 'x' }}
module JSON
  class << self
    alias_method :original_generate, :generate
    def generate(frame)
      if frame['type'] == 'result'
        {mutation}
      end
      original_generate(frame)
    end
  end
end
"#
            );
            let (mut plugin, _) = fixture.plugin(&source);
            assert!(plugin.invoke("ok", "", &context()).is_err(), "{mutation}");
            assert!(plugin.host.child.is_none());
        }
    }

    #[test]
    fn bounded_frames_and_stalled_writes_shutdown() {
        let fixture = Fixture::new();
        let (mut plugin, _) = fixture.plugin(
            "Vamp.plugin 'large'\nVamp.command('large') { |editor, args| editor.insert 'x' * (4 * 1024 * 1024 + 1) }");
        assert!(plugin.invoke("large", "", &context()).is_err());
        assert!(plugin.host.child.is_none());

        // Stop Ruby reading the request pipe after it sends the manifest.
        let (mut plugin, _) = fixture.plugin(
            r#"
Vamp.plugin 'blocked'
Vamp.command('ok') { |editor, args| editor.message 'ok' }
class IO
  def gets(*args)
    sleep 10
  end
end
"#,
        );
        let mut big_context = context();
        big_context.text = "x".repeat(2 * 1024 * 1024);
        assert!(
            plugin
                .invoke("ok", "", &big_context)
                .unwrap_err()
                .contains("timeout")
        );
        assert!(plugin.host.child.is_none());

        let (mut plugin, _) = fixture.plugin(
            "Vamp.plugin 'request'\nVamp.command('ok') { |editor, args| editor.message 'ok' }",
        );
        big_context.text = "x".repeat(MAX_FRAME + 1);
        assert!(
            plugin
                .invoke("ok", "", &big_context)
                .unwrap_err()
                .contains("4 MiB")
        );
        assert!(plugin.host.child.is_none());

        for payload in ["'not json'", "'x' * (4 * 1024 * 1024 + 1)"] {
            let source = format!(
                r#"
Vamp.plugin 'bad_frame'
Vamp.command('ok') {{ |editor, args| editor.message 'ok' }}
class IO
  alias_method :original_write, :write
  def write(payload)
    if payload.include?('"type":"result"')
      original_write({payload})
    else
      original_write(payload)
    end
  end
end
"#
            );
            let (mut plugin, _) = fixture.plugin(&source);
            assert!(plugin.invoke("ok", "", &context()).is_err());
            assert!(plugin.host.child.is_none());
        }
    }

    #[cfg(unix)]
    #[test]
    fn inherited_pipes_do_not_prevent_drop_or_timeout_cleanup() {
        let fixture = Fixture::new();
        let (mut plugin, _) = fixture.plugin(
            r#"
Vamp.plugin 'forked'
Vamp.command('hang') do |editor, args|
  fork { sleep 10 }
  sleep 10
end
"#,
        );
        assert!(
            plugin
                .invoke("hang", "", &context())
                .unwrap_err()
                .contains("timeout")
        );
        assert!(plugin.host.reader.is_none() && plugin.host.writer.is_none());
        let (plugin, _) = fixture.plugin("Vamp.plugin 'drop'\nfork { sleep 10 }");
        drop(plugin);
    }

    fn document(event: crate::plugin::DocumentEventKind) -> DocumentEvent {
        DocumentEvent {
            event,
            document: crate::plugin::DocumentSnapshot {
                id: 7,
                revision: 11,
                path: Some("buffer.txt".into()),
                root: "/project".into(),
                text: "α\nhello".into(),
            },
        }
    }

    fn collect_until(
        plugin: &mut RubyPlugin,
        ready: impl Fn(&[PluginEvent]) -> bool,
    ) -> Vec<PluginEvent> {
        let deadline = Instant::now() + STARTUP_TIMEOUT;
        let mut events = Vec::new();
        loop {
            events.extend(plugin.poll().unwrap());
            if ready(&events) {
                return events;
            }
            assert!(
                Instant::now() < deadline,
                "Ruby event fixture did not respond"
            );
            thread::sleep(Duration::from_millis(1));
        }
    }

    #[test]
    fn asynchronous_documents_background_updates_and_results_share_framed_transport() {
        use crate::plugin::{DiagnosticSeverity, DocumentEventKind};
        let fixture = Fixture::new();
        let (mut plugin, feature) = fixture.plugin_with_options(
            r##"
Vamp.plugin "async", requires: ["text", "diagnostics"], async: true
raise "options" unless Vamp.options["nested"]["items"] == ["α", 3, true]
raise "mutable options" unless Vamp.options.frozen? && Vamp.options["nested"].frozen? &&
  Vamp.options["nested"]["items"].frozen? && Vamp.options["nested"]["items"][0].frozen?
begin
  Vamp.options["nested"]["items"] << "bad"
  raise "mutation escaped"
rescue FrozenError
end
events = []
Vamp.on_document do |event|
  doc = event["document"]
  raise "bad snapshot" unless doc["id"] == 7 && doc["revision"] == 11 &&
    doc["root"] == "/project" && doc["text"] == "α\nhello" && doc["path"] == "buffer.txt"
  raise "mutable document" unless event.frozen? && doc.frozen? && doc["text"].frozen?
  events << event["event"]
end
Vamp.command "ask" do |editor, _|
  raise "document ordering" unless events == %w[open change save close]
  raise "wrong request" unless editor.request_id > 0
  Thread.new do
    puts "background output is not protocol"
    Vamp.publish [
      {type: "diagnostics", buffer_id: editor.buffer_id, revision: editor.revision,
       items: [{start: {row: 1, column: 0}, end: {row: 1, column: 2},
                severity: "warning", message: "actual background diagnostic"}]},
      {type: "navigate", buffer_id: editor.buffer_id, revision: editor.revision,
       path: "/project/target α.txt", row: 1, column: 2}
    ], request_id: editor.request_id
  end
  workers = 4.times.map do |worker|
    Thread.new { 3.times { |item| Vamp.publish [{type: "message", text: "#{worker}:#{item}:α"}] } }
  end
  workers.each(&:join)
  editor.message "queued result"
end
"##,
            &serde_json::json!({"nested": {"items": ["α", 3, true]}}),
        );
        assert!(plugin.is_async());
        assert_eq!(feature.required_capabilities, ["text", "diagnostics"]);
        for event in [
            DocumentEventKind::Open,
            DocumentEventKind::Change,
            DocumentEventKind::Save,
            DocumentEventKind::Close,
        ] {
            plugin.notify_document(&document(event)).unwrap();
        }
        let id = plugin.queue_invoke("ask", "", &context()).unwrap();
        let events = collect_until(&mut plugin, |events| {
            events.iter().any(|event| matches!(event, PluginEvent::Response { id: response_id, .. } if *response_id == id)) &&
            events.iter().filter(|event| matches!(event, PluginEvent::Update(_))).count() == 13
        });
        assert!(events.iter().any(|event| matches!(event,
            PluginEvent::Response { id: response_id, effects } if *response_id == id &&
                matches!(&effects[..], [Effect::Message(text)] if text == "queued result"))));
        let update = events
            .iter()
            .find_map(|event| match event {
                PluginEvent::Update(update) if update.request_id == Some(id) => Some(update),
                _ => None,
            })
            .unwrap();
        assert!(matches!(&update.effects[..],
            [UpdateEffect::Diagnostics { buffer_id: 7, revision: 11, items },
             UpdateEffect::Navigate { buffer_id: 7, revision: 11, path, row: 1, column: 2 }]
            if items.len() == 1 && items[0].severity == DiagnosticSeverity::Warning &&
                items[0].message == "actual background diagnostic" &&
                path == Path::new("/project/target α.txt")));
        assert!(plugin.pending.is_empty());
    }

    #[test]
    fn asynchronous_invocation_does_not_wait_for_callback_or_result() {
        let fixture = Fixture::new();
        let (mut plugin, _) = fixture.plugin(
            r#"
Vamp.plugin "blocked", async: true
Vamp.command "block" do |editor, _|
  Vamp.publish [{type: "message", text: "callback entered"}], request_id: editor.request_id
  sleep 10
end
"#,
        );
        let id = plugin.queue_invoke("block", "", &context()).unwrap();
        let events = collect_until(&mut plugin, |events| !events.is_empty());
        assert!(matches!(&events[..], [PluginEvent::Update(update)]
            if update.request_id == Some(id)));
        assert!(plugin.pending.contains(&id));
        assert!(plugin.poll().unwrap().is_empty());
        plugin.disable();
        assert!(
            plugin.host.child.is_none()
                && plugin.host.reader.is_none()
                && plugin.host.writer.is_none()
        );
    }

    #[test]
    fn plugin_options_config_transport_validation_and_required_wire_fields() {
        let fixture = Fixture::new();
        let path = fixture.file("config.rb",
            r#"Vamp.configure { |config| config.plugin "plugin.rb", options: {nested: {argv: ["tool", "α space"]}} }"#);
        let config = load_config(&path).unwrap();
        assert_eq!(
            config.plugins[0].options,
            serde_json::json!({"nested": {"argv": ["tool", "α space"]}})
        );
        for value in [
            "[]",
            "nil",
            "{bad: Object.new}",
            "{bad: Float::NAN}",
            "{7 => 'bad'}",
        ] {
            let path = fixture.file(
                "invalid.rb",
                &format!(
                    "Vamp.configure {{ |config| config.plugin 'plugin.rb', options: {value} }}"
                ),
            );
            assert!(load_config(&path).is_err(), "{value}");
        }
        let plugin_path = fixture.file("plugin.rb", "Vamp.plugin 'options'");
        assert!(RubyPlugin::start(&plugin_path, &serde_json::json!([])).is_err());
        for frame in [
            r#"{"path":"p.rb"}"#,
            r#"{"path":"p.rb","options":null}"#,
            r#"{"path":"p.rb","options":[]}"#,
            r#"{"path":7,"options":{}}"#,
            r#"{"path":"p.rb","options":{},"extra":true}"#,
        ] {
            assert!(
                serde_json::from_str::<PluginConfig>(frame).is_err(),
                "{frame}"
            );
        }
        for frame in [
            r#"{"type":"manifest","version":1,"name":"p","requires":[],"commands":[]}"#,
            r#"{"type":"manifest","version":1,"name":"p","requires":[],"commands":[],"async":"yes"}"#,
        ] {
            assert!(serde_json::from_str::<Response>(frame).is_err(), "{frame}");
        }
    }

    #[test]
    fn malformed_async_updates_and_unknown_response_ids_retire_host() {
        let fixture = Fixture::new();
        for mutation in [
            "frame['version'] = 2",
            "frame['request_id'] = 'bad'",
            "frame['request_id'] = 0",
            "frame['request_id'] = 999",
            "frame['effects'] = [{'type' => 'message', 'text' => 7}]",
            "frame['effects'] = [{'type' => 'navigate', 'buffer_id' => 7, 'revision' => 11, 'path' => '/x', 'row' => -1, 'column' => 0}]",
            "frame['effects'] = [{'type' => 'diagnostics', 'buffer_id' => 7, 'revision' => 11, 'items' => [{'start' => {'row' => 0, 'column' => 0}, 'end' => {'row' => 0, 'column' => 1}, 'severity' => 'fatal', 'message' => 'x'}]}]",
            "frame['unexpected'] = true",
            "frame.replace({'type' => 'result', 'version' => 1, 'id' => 999, 'effects' => []})",
        ] {
            let (mut plugin, _) = fixture.plugin(&format!(r#"
Vamp.plugin 'protocol', async: true
Vamp.command('ask') {{ |editor, _| Vamp.publish [{{type: 'message', text: 'valid'}}], request_id: editor.request_id }}
module JSON
  class << self
    alias_method :original_generate, :generate
    def generate(frame)
      {mutation} if frame['type'] == 'update'
      original_generate(frame)
    end
  end
end
"#));
            plugin.queue_invoke("ask", "", &context()).unwrap();
            let deadline = Instant::now() + STARTUP_TIMEOUT;
            loop {
                if plugin.poll().is_err() {
                    break;
                }
                assert!(Instant::now() < deadline, "{mutation}");
                thread::sleep(Duration::from_millis(1));
            }
            assert!(
                plugin.host.child.is_none()
                    && plugin.host.reader.is_none()
                    && plugin.host.writer.is_none(),
                "{mutation}"
            );
        }
    }

    #[test]
    fn asynchronous_queue_overflow_and_crash_are_explicit_and_cleaned_up() {
        let fixture = Fixture::new();
        let (mut plugin, _) = fixture.plugin(
            r#"
Vamp.plugin 'blocked', async: true
class IO
  def gets(*args)
    sleep 10
  end
end
"#,
        );
        let mut event = document(crate::plugin::DocumentEventKind::Open);
        event.document.text = "x".repeat(128 * 1024);
        let error = (0..MAX_QUEUE + 2)
            .find_map(|_| plugin.notify_document(&event).err())
            .unwrap();
        assert!(error.contains("queue is full"), "{error}");
        assert!(
            plugin.host.child.is_none()
                && plugin.host.reader.is_none()
                && plugin.host.writer.is_none()
        );

        let (mut plugin, _) = fixture.plugin(
            r#"
Vamp.plugin 'flood', async: true
Vamp.command('flood') { |_, _| 256.times { Vamp.publish [{type: 'message', text: 'flood'}] } }
"#,
        );
        plugin.queue_invoke("flood", "", &context()).unwrap();
        let deadline = Instant::now() + STARTUP_TIMEOUT;
        while plugin.host.failure.get().is_none() {
            assert!(
                Instant::now() < deadline,
                "flood did not overflow bounded reader"
            );
            thread::sleep(Duration::from_millis(1));
        }
        assert!(plugin.poll().unwrap_err().contains("queue is full"));
        assert!(plugin.host.child.is_none());

        let (mut plugin, _) = fixture
            .plugin("Vamp.plugin 'crash', async: true\nVamp.command('crash') { |_, _| exit! 19 }");
        plugin.queue_invoke("crash", "", &context()).unwrap();
        let deadline = Instant::now() + STARTUP_TIMEOUT;
        loop {
            if plugin.poll().is_err() {
                break;
            }
            assert!(Instant::now() < deadline);
            thread::sleep(Duration::from_millis(1));
        }
        assert!(
            plugin.host.child.is_none()
                && plugin.host.reader.is_none()
                && plugin.host.writer.is_none()
        );
    }

    #[test]
    fn shutdown_hook_runs_for_shutdown_frame_without_protocol_corruption() {
        let fixture = Fixture::new();
        let marker = fixture.0.join("shutdown");
        let (mut plugin, _) = fixture.plugin_with_options(
            "Vamp.plugin 'shutdown', async: true\nVamp.on_shutdown { File.write(Vamp.options['marker'], 'stopped') }",
            &serde_json::json!({"marker": marker}),
        );
        plugin
            .host
            .queue(&serde_json::json!({"type": "shutdown", "version": 1}))
            .unwrap();
        let deadline = Instant::now() + STARTUP_TIMEOUT;
        while plugin
            .host
            .child
            .as_mut()
            .unwrap()
            .try_wait()
            .unwrap()
            .is_none()
        {
            assert!(Instant::now() < deadline);
            thread::sleep(Duration::from_millis(1));
        }
        assert_eq!(std::fs::read_to_string(marker).unwrap(), "stopped");
        plugin.disable();
        assert!(
            plugin.host.child.is_none()
                && plugin.host.reader.is_none()
                && plugin.host.writer.is_none()
        );
    }

    #[test]
    fn ruby_rejects_invalid_document_context_and_sync_async_dsl_usage() {
        let fixture = Fixture::new();
        for declaration in [
            "Vamp.plugin 'bad', async: 'yes'",
            "Vamp.plugin 'bad'\nVamp.on_document { |_| }",
            "Vamp.plugin 'bad'\nVamp.publish []",
        ] {
            let path = fixture.file("bad.rb", declaration);
            assert!(RubyPlugin::start(&path, &serde_json::json!({})).is_err());
        }
        for (field, value) in [
            ("root", serde_json::json!(7)),
            ("buffer_id", serde_json::json!(-1)),
            ("revision", serde_json::json!("old")),
        ] {
            let (mut plugin, _) = fixture.plugin(
                "Vamp.plugin 'context', async: true\nVamp.command('ask') { |editor, _| editor.message 'must not escape' }");
            let mut frame = serde_json::json!({
                "version": 1, "type": "invoke", "id": 1, "command": "ask", "args": "",
                "context": context(),
            });
            frame["context"][field] = value;
            plugin.pending.insert(1);
            plugin.next_id = 2;
            plugin.host.queue(&frame).unwrap();
            let deadline = Instant::now() + STARTUP_TIMEOUT;
            loop {
                match plugin.poll() {
                    Err(error) => {
                        assert!(error.contains("context"), "{error}");
                        break;
                    }
                    Ok(events) => assert!(events.is_empty()),
                }
                assert!(Instant::now() < deadline);
                thread::sleep(Duration::from_millis(1));
            }
            assert!(plugin.host.child.is_none());
        }
        let (mut plugin, _) = fixture.plugin(
            "Vamp.plugin 'document', async: true\nVamp.on_document { |_| raise 'must not invoke invalid snapshot' }");
        plugin.host.queue(&serde_json::json!({
            "version": 1, "type": "document", "event": "open",
            "document": {"id": 7, "revision": "old", "path": null, "root": "/project", "text": "text"},
        })).unwrap();
        let deadline = Instant::now() + STARTUP_TIMEOUT;
        loop {
            match plugin.poll() {
                Err(error) => {
                    assert!(error.contains("invalid document snapshot"), "{error}");
                    break;
                }
                Ok(events) => assert!(events.is_empty()),
            }
            assert!(Instant::now() < deadline);
            thread::sleep(Duration::from_millis(1));
        }
        assert!(
            plugin.host.child.is_none()
                && plugin.host.reader.is_none()
                && plugin.host.writer.is_none()
        );
    }
}