feat: add full descriptions in a scrollable popup

src/main.rs

@@ -4,6 +4,9 @@
 //! Without a CLI query, start in insert mode; otherwise search and start in normal mode.
 //! Insert: Enter submits a changed query and returns to normal; Esc returns without searching.
 //! Normal: j/k selects, Enter streams, and i returns to insert mode to edit the query.
+//! Normal-mode d opens the full description; Up/Down scrolls lines and PgUp/PgDn scrolls pages.
+//! The centered popup uses up to 70% width and 60% height, capped at 96 by 20 cells.
+//! Esc closes the popup; j/k loads the selected video's description and i returns to editing.
 //! The player must read media from standard input when passed `-`.
 //! Audio and video are streamed through a pipe, never saved to a video file.
 //! See `--help` for controls; replacing playback or quitting cancels its processes.
@@ -16,9 +19,10 @@ use clap::Parser;
 use ratatui::{
     DefaultTerminal, Frame,
     crossterm::event::{self, Event, KeyCode, KeyEvent, KeyEventKind, KeyModifiers},
-    layout::{Constraint, Layout},
+    layout::{Constraint, Layout, Rect},
     style::{Color, Style, Stylize},
-    widgets::{Block, Paragraph, Row, Table, TableState, Wrap},
+    text::Line,
+    widgets::{Block, Clear, Paragraph, Row, Table, TableState, Wrap},
 };
 use youtube::{Job, Playback, Video};
 
@@ -26,7 +30,7 @@ use youtube::{Job, Playback, Video};
 #[command(
     version,
     about = "Search YouTube and stream videos to your chosen player",
-    after_help = "Requires yt-dlp, FFmpeg, and a player on PATH.\nThe player receives audio/video on standard input, with '-' as its last argument.\nWithout a CLI query, start in INSERT; a CLI query is searched automatically in NORMAL.\nINSERT: type to edit; Enter submits if changed and returns to NORMAL; Esc returns without submitting.\nNORMAL: j/k or arrows select; Enter streams; i edits the query; q quits.\nCtrl-U clears in INSERT; Ctrl-C quits in either mode.\nSelecting another video replaces playback. Quitting stops playback.\nExample: tubular --player mpv --player-arg=--volume=50 \"rust programming\""
+    after_help = "Requires yt-dlp, FFmpeg, and a player on PATH.\nThe player receives audio/video on standard input, with '-' as its last argument.\nWithout a CLI query, start in INSERT; a CLI query is searched automatically in NORMAL.\nINSERT: type to edit; Enter submits if changed and returns to NORMAL; Esc returns without submitting.\nNORMAL: j/k or arrows select; Enter streams; i edits the query; d toggles description; q quits.\nOpening the description fetches full video metadata, preserving paragraphs and caching it for these results.\nThe centered description window uses up to 70% width and 60% height, capped at 96 by 20 cells.\nWhile it is open, Up/Down scroll lines and PgUp/PgDn scroll pages; j/k still selects videos.\nEsc closes the description; i closes it to edit the query. Scrolling stays within the text.\nCtrl-U clears in INSERT; Ctrl-C quits in either mode.\nSelecting another video replaces playback. Quitting stops playback.\nExample: tubular --player mpv --player-arg=--volume=50 \"rust programming\""
 )]
 struct Options {
     /// Player executable (must support '-' for media on standard input).
@@ -54,6 +58,12 @@ struct App {
     submitted_query: String,
     videos: Vec<Video>,
     selection: TableState,
+    description_open: bool,
+    description_job: Option<(usize, Job)>,
+    description_error: Option<String>,
+    description_scroll: u16,
+    description_max_scroll: u16,
+    description_viewport: Option<(u16, u16)>,
     job: Option<Job>,
     playback: Option<Playback>,
     status: String,
@@ -74,6 +84,12 @@ impl App {
             submitted_query: String::new(),
             videos: Vec::new(),
             selection: TableState::default(),
+            description_open: false,
+            description_job: None,
+            description_error: None,
+            description_scroll: 0,
+            description_max_scroll: 0,
+            description_viewport: None,
             job: None,
             playback: None,
             status: "Type a query, then press Enter.".into(),
@@ -92,6 +108,8 @@ impl App {
         match Job::search(query) {
             Ok(job) => {
                 self.job = Some(job);
+                self.description_open = false;
+                self.description_job = None;
                 self.submitted_query = query.to_owned();
                 self.videos.clear();
                 self.selection = TableState::default();
@@ -101,6 +119,28 @@ impl App {
         }
     }
 
+    fn load_description(&mut self) {
+        self.description_job = None;
+        self.description_error = None;
+        self.description_scroll = 0;
+        self.description_viewport = None;
+        let Some(index) = self
+            .selection
+            .selected()
+            .filter(|&index| index < self.videos.len())
+        else {
+            return;
+        };
+        let video = &self.videos[index];
+        if video.description.is_some() {
+            return;
+        }
+        match Job::description(&video.id) {
+            Ok(job) => self.description_job = Some((index, job)),
+            Err(error) => self.description_error = Some(error.to_string()),
+        }
+    }
+
     fn play(&mut self) {
         if self.job.is_some() {
             return;
@@ -139,6 +179,23 @@ impl App {
                 Err(error) => error,
             };
         }
+        if let Some(result) = self
+            .description_job
+            .as_mut()
+            .and_then(|(_, job)| job.poll())
+        {
+            let (index, _) = self
+                .description_job
+                .take()
+                .expect("completed description job exists");
+            if let Some(video) = self.videos.get_mut(index) {
+                match result.and_then(|output| youtube::full_description(&output, &video.id)) {
+                    Ok(description) => video.description = Some(description),
+                    Err(error) => self.description_error = Some(error),
+                }
+            }
+            self.description_viewport = None;
+        }
         if let Some(result) = self.playback.as_mut().and_then(Playback::poll) {
             self.playback = None;
             self.status = match result {
@@ -152,6 +209,8 @@ impl App {
         if key.code == KeyCode::Char('c') && key.modifiers.contains(KeyModifiers::CONTROL) {
             return true;
         }
+        let selected_before = self.selection.selected();
+        let description_was_open = self.description_open;
         if self.mode == Mode::Insert {
             match key.code {
                 KeyCode::Esc => self.mode = Mode::Normal,
@@ -177,7 +236,46 @@ impl App {
         } else {
             match key.code {
                 KeyCode::Char('q') => return true,
-                KeyCode::Char('i') => self.mode = Mode::Insert,
+                KeyCode::Char('i') => {
+                    self.description_open = false;
+                    self.mode = Mode::Insert;
+                }
+                KeyCode::Char('d') => {
+                    self.description_open = !self.description_open
+                        && self
+                            .selection
+                            .selected()
+                            .is_some_and(|index| index < self.videos.len());
+                }
+                KeyCode::Esc => self.description_open = false,
+                KeyCode::Down if self.description_open => {
+                    self.description_scroll = self
+                        .description_scroll
+                        .saturating_add(1)
+                        .min(self.description_max_scroll);
+                }
+                KeyCode::Up if self.description_open => {
+                    self.description_scroll = self.description_scroll.saturating_sub(1);
+                }
+                KeyCode::PageDown if self.description_open => {
+                    let page = self
+                        .description_viewport
+                        .map(|(_, height)| height)
+                        .unwrap_or(1)
+                        .max(1);
+                    self.description_scroll = self
+                        .description_scroll
+                        .saturating_add(page)
+                        .min(self.description_max_scroll);
+                }
+                KeyCode::PageUp if self.description_open => {
+                    let page = self
+                        .description_viewport
+                        .map(|(_, height)| height)
+                        .unwrap_or(1)
+                        .max(1);
+                    self.description_scroll = self.description_scroll.saturating_sub(page);
+                }
                 KeyCode::Enter => self.play(),
                 KeyCode::Down | KeyCode::Char('j') => self.selection.select_next(),
                 KeyCode::Up | KeyCode::Char('k') => self.selection.select_previous(),
@@ -194,6 +292,11 @@ impl App {
             self.selection
                 .select(Some(index.min(self.videos.len() - 1)));
         }
+        if !self.description_open {
+            self.description_job = None;
+        } else if !description_was_open || self.selection.selected() != selected_before {
+            self.load_description();
+        }
         false
     }
 
@@ -249,9 +352,74 @@ impl App {
             Mode::Insert => {
                 "INSERT · Enter search → normal · Esc normal · Ctrl-U clear · Ctrl-C quit"
             }
-            Mode::Normal => "NORMAL · j/k or ↑/↓ select · Enter stream · i insert · q quit",
+            Mode::Normal if self.description_open => {
+                "NORMAL · ↑/↓ PgUp/PgDn scroll · j/k video · d/Esc close · i insert · q quit"
+            }
+            Mode::Normal => {
+                "NORMAL · j/k select · Enter stream · i insert · d description · q quit"
+            }
         };
         frame.render_widget(Paragraph::new(help_text).dim(), help);
+        if self.description_open
+            && let Some(video) = self
+                .selection
+                .selected()
+                .and_then(|index| self.videos.get(index))
+        {
+            let area = frame.area();
+            let width = area
+                .width
+                .saturating_sub(4)
+                .min((u32::from(area.width) * 70 / 100) as u16)
+                .min(96);
+            let height = area
+                .height
+                .saturating_sub(4)
+                .min((u32::from(area.height) * 60 / 100) as u16)
+                .min(20);
+            let popup = Rect::new(
+                area.x + (area.width - width) / 2,
+                area.y + (area.height - height) / 2,
+                width,
+                height,
+            );
+            frame.render_widget(Clear, popup);
+            let text = match video.description.as_deref() {
+                Some("") => "This video has no description.",
+                Some(description) => description,
+                None => self
+                    .description_error
+                    .as_deref()
+                    .unwrap_or("Loading full description..."),
+            };
+            let paragraph = Paragraph::new(text).wrap(Wrap { trim: false });
+            let viewport = (width.saturating_sub(2), height.saturating_sub(2));
+            if self.description_viewport != Some(viewport) {
+                self.description_max_scroll = if viewport.0 == 0 || viewport.1 == 0 {
+                    0
+                } else {
+                    paragraph
+                        .line_count(viewport.0)
+                        .saturating_sub(viewport.1 as usize)
+                        .min(u16::MAX as usize) as u16
+                };
+                self.description_viewport = Some(viewport);
+            }
+            self.description_scroll = self.description_scroll.min(self.description_max_scroll);
+            frame.render_widget(
+                paragraph.scroll((self.description_scroll, 0)).block(
+                    Block::bordered()
+                        .title(" Description · ↑/↓ PgUp/PgDn · d/Esc close ")
+                        .title_bottom(Line::from(vec![
+                            " ".into(),
+                            video.title.as_str().into(),
+                            " ".into(),
+                        ]))
+                        .border_style(Style::new().fg(Color::Cyan)),
+                ),
+                popup,
+            );
+        }
     }
 
     fn run(mut self, terminal: &mut DefaultTerminal) -> io::Result<()> {
@@ -290,11 +458,13 @@ mod tests {
                 id: "jNQXAC9IVRw".into(),
                 title: "Me at the zoo".into(),
                 channel: None,
+                description: None,
             },
             Video {
                 id: "rQ_J9WH6CGk".into(),
                 title: "Rust course".into(),
                 channel: None,
+                description: None,
             },
         ];
         app.selection.select(Some(0));

src/youtube.rs

@@ -13,6 +13,9 @@ pub struct Video {
     pub id: String,
     pub title: String,
     pub channel: Option<String>,
+    // Search descriptions are truncated; only full video metadata populates this cache.
+    #[serde(skip)]
+    pub description: Option<String>,
 }
 
 #[derive(Deserialize)]
@@ -42,6 +45,22 @@ pub fn search_results(output: &str) -> Result<Vec<Video>, String> {
     Ok(videos)
 }
 
+pub fn full_description(output: &str, expected_id: &str) -> Result<String, String> {
+    #[derive(Deserialize)]
+    struct Details {
+        id: String,
+        description: Option<String>,
+    }
+    let details: Details =
+        serde_json::from_str(output).map_err(|error| format!("Invalid video metadata: {error}"))?;
+    if details.id != expected_id {
+        return Err("Video metadata did not match the requested video".into());
+    }
+    let mut description = details.description.unwrap_or_default();
+    description.retain(|c| !c.is_control() || c == '\n' || c == '\t');
+    Ok(description)
+}
+
 // Own the extractor so replacing a request or quitting also cancels its process.
 pub struct Job {
     child: Child,
@@ -50,9 +69,25 @@ pub struct Job {
 
 impl Job {
     pub fn search(query: &str) -> io::Result<Self> {
+        Self::spawn(&[
+            "--flat-playlist",
+            "--dump-single-json",
+            &format!("ytsearch20:{query}"),
+        ])
+    }
+
+    pub fn description(id: &str) -> io::Result<Self> {
+        Self::spawn(&[
+            "--no-playlist",
+            "--skip-download",
+            "--dump-single-json",
+            &format!("https://www.youtube.com/watch?v={id}"),
+        ])
+    }
+
+    fn spawn(args: &[&str]) -> io::Result<Self> {
         let mut child = extractor()
-            .args(["--flat-playlist", "--dump-single-json"])
-            .arg(format!("ytsearch20:{query}"))
+            .args(args)
             .stdin(Stdio::null())
             .stdout(Stdio::piped())
             .stderr(Stdio::piped())
@@ -265,4 +300,19 @@ mod tests {
         assert!(search_results(r#"{"entries":[{"id":"--bad","title":"Bad"}]}"#).is_err());
         assert!(search_results("not JSON").is_err());
     }
+
+    #[test]
+    fn full_descriptions_preserve_paragraphs_and_reject_mismatched_videos() {
+        let metadata = r#"{"id":"jNQXAC9IVRw","description":"First paragraph.\n\n日本語\tsecond paragraph.\u001b\nLast line."}"#;
+        assert_eq!(
+            full_description(metadata, "jNQXAC9IVRw").unwrap(),
+            "First paragraph.\n\n日本語\tsecond paragraph.\nLast line."
+        );
+        assert!(full_description(metadata, "rQ_J9WH6CGk").is_err());
+        assert!(full_description("not JSON", "jNQXAC9IVRw").is_err());
+        assert_eq!(
+            full_description(r#"{"id":"jNQXAC9IVRw","description":null}"#, "jNQXAC9IVRw").unwrap(),
+            ""
+        );
+    }
 }