use std::{
    fs,
    path::PathBuf,
    sync::atomic::{AtomicU64, Ordering},
};

use vamp::editor::{Editor, Feature, Input};

static NEXT: AtomicU64 = AtomicU64::new(0);

struct Fixture(PathBuf);

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

    fn editor(&self, name: &str, text: &str) -> Editor {
        let path = self.0.join(name);
        fs::write(&path, text).unwrap();
        Editor::open(Some(path), vec!["text".into()]).unwrap()
    }
}

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

fn insert(editor: &mut Editor, text: &str) {
    for input in [Input::Char('i'), Input::Paste(text.into()), Input::Escape] {
        editor.handle(input);
    }
}

#[test]
fn save_and_w_preserve_spaced_path_arguments_and_write_current_contents() {
    for command in ["save", "w"] {
        let fixture = Fixture::new();
        let mut editor = fixture.editor("original file.txt", "original\n");
        insert(&mut editor, "changed ");
        let destination = fixture.0.join("saved file with spaces.txt");

        editor.execute(&format!(":{command} {}", destination.display()));

        assert_eq!(editor.path(), Some(destination.as_path()), "{command}");
        assert_eq!(
            fs::read_to_string(&destination).unwrap(),
            "changed original\n"
        );
        assert_eq!(
            fs::read_to_string(fixture.0.join("original file.txt")).unwrap(),
            "original\n"
        );
        assert!(!editor.dirty(), "{command}");
        assert!(!editor.should_quit(), "{command}");
    }
}

#[test]
fn quit_and_q_refuse_dirty_buffers_then_exit_when_clean() {
    for command in ["quit", "q"] {
        let fixture = Fixture::new();
        let mut editor = fixture.editor("file.txt", "original\n");
        insert(&mut editor, "changed ");

        editor.execute(command);

        assert!(!editor.should_quit(), "{command}");
        assert!(editor.dirty(), "{command}");
        assert_eq!(editor.context().text, "changed original\n");
        assert_eq!(
            fs::read_to_string(fixture.0.join("file.txt")).unwrap(),
            "original\n"
        );

        editor.handle(Input::Char('u'));
        assert!(!editor.dirty(), "{command}");
        editor.execute(command);
        assert!(editor.should_quit(), "{command}");
    }
}

#[test]
fn force_quit_and_q_bang_validate_arguments_before_discarding_changes() {
    for command in ["force_quit", "q!"] {
        let fixture = Fixture::new();
        let mut editor = fixture.editor("file.txt", "original\n");
        insert(&mut editor, "changed ");

        editor.execute(&format!("{command} unexpected argument"));

        assert!(!editor.should_quit(), "{command}");
        assert!(editor.dirty(), "{command}");
        assert_eq!(editor.context().text, "changed original\n");

        editor.execute(command);
        assert!(editor.should_quit(), "{command}");
        assert_eq!(
            fs::read_to_string(fixture.0.join("file.txt")).unwrap(),
            "original\n"
        );
    }
}

#[test]
fn buffer_next_and_bnext_preserve_each_buffers_dirty_text_and_undo() {
    for command in ["buffer_next", "bnext"] {
        let fixture = Fixture::new();
        let mut editor = fixture.editor("first.txt", "first\n");
        let first_id = editor.buffer_id();
        insert(&mut editor, "changed ");
        let second_path = fixture.0.join("second file.txt");
        fs::write(&second_path, "second\n").unwrap();
        editor.execute(&format!("edit {}", second_path.display()));
        let second_id = editor.buffer_id();
        assert_ne!(first_id, second_id);
        insert(&mut editor, "edited ");

        editor.execute(command);

        assert_eq!(editor.buffer_id(), first_id, "{command}");
        assert_eq!(editor.context().text, "changed first\n");
        assert!(editor.dirty(), "{command}");
        editor.handle(Input::Char('u'));
        assert_eq!(editor.context().text, "first\n");
        assert!(!editor.dirty(), "{command}");

        editor.execute(command);

        assert_eq!(editor.buffer_id(), second_id, "{command}");
        assert_eq!(editor.context().text, "edited second\n");
        assert!(editor.dirty(), "{command}");
        editor.handle(Input::Char('u'));
        assert_eq!(editor.context().text, "second\n");
        assert!(!editor.dirty(), "{command}");
        assert_eq!(editor.buffer_count(), 2);
        assert_eq!(
            fs::read_to_string(fixture.0.join("first.txt")).unwrap(),
            "first\n"
        );
        assert_eq!(fs::read_to_string(&second_path).unwrap(), "second\n");
    }
}

#[test]
fn builtin_canonical_and_alias_collisions_reject_the_entire_feature() {
    for reserved in ["save", "w", "quit", "q"] {
        let mut editor = Editor::open(None, vec!["text".into()]).unwrap();
        let feature = |commands: Vec<String>| Feature {
            name: "example".into(),
            required_capabilities: vec!["text".into()],
            commands,
            core: false,
        };

        assert!(
            editor
                .register(feature(vec!["example.run".into(), reserved.into()]))
                .is_err(),
            "{reserved}"
        );
        assert!(editor.execute("example.run").is_none(), "{reserved}");

        editor
            .register(feature(vec!["example.run".into()]))
            .unwrap();
        let invocation = editor.execute("example.run remaining args").unwrap();
        assert_eq!(invocation.plugin, "example");
    }
}