travelagent 1.11.1

use ratatui::{
    Frame,
    layout::Rect,
    style::{Modifier, Style},
    text::{Line, Span},
    widgets::Paragraph,
};

use crate::app::App;
use crate::theme::Theme;
use crate::ui::{markdown, styles};
use travelagent_core::forge::{RemoteComment, ReviewThread};

/// Default width used when the caller doesn't know the real panel width yet.
/// Wide enough to read comfortably without forcing pathological wrapping.
const DEFAULT_BODY_WIDTH: usize = 80;

/// Return the indices into the remote comments list of the top-level
/// threads, in the order they are rendered. Returns an empty vec in
/// local mode (no remote comments to enumerate).
pub fn top_level_thread_indices(app: &App) -> Vec<usize> {
    let Some(r) = app.remote() else {
        return Vec::new();
    };
    r.remote_comments
        .iter()
        .enumerate()
        .filter(|(_, c)| c.in_reply_to.is_none())
        .map(|(idx, _)| idx)
        .collect()
}

/// Look up the resolution state for a given top-level comment id.
/// Returns `None` if no matching review thread exists.
pub fn thread_is_resolved(threads: &[ReviewThread], root_comment_id: u64) -> Option<bool> {
    threads
        .iter()
        .find(|t| t.root_comment_id == root_comment_id)
        .map(|t| t.is_resolved)
}

/// Return the thread id for the currently selected top-level comment, if any.
pub fn selected_thread_id(app: &App) -> Option<String> {
    let r = app.remote()?;
    let tops = top_level_thread_indices(app);
    let idx = *tops.get(r.conversation_cursor)?;
    let root = r.remote_comments.get(idx)?;
    r.review_threads
        .iter()
        .find(|t| t.root_comment_id == root.id)
        .map(|t| t.id.clone())
}

/// Return the selected thread's root `RemoteComment` id, if any.
pub fn selected_root_comment_id(app: &App) -> Option<u64> {
    let r = app.remote()?;
    let tops = top_level_thread_indices(app);
    let idx = *tops.get(r.conversation_cursor)?;
    r.remote_comments.get(idx).map(|c| c.id)
}

/// Clamp the cursor to the available threads. No-op in local mode.
pub fn clamp_conversation_cursor(app: &mut App) {
    let tops = top_level_thread_indices(app);
    let Some(r) = app.remote_mut() else {
        return;
    };
    if tops.is_empty() {
        r.conversation_cursor = 0;
    } else if r.conversation_cursor >= tops.len() {
        r.conversation_cursor = tops.len() - 1;
    }
}

/// Build the lines for a single thread header, prefixing with the resolved
/// marker. Returns the styled line.
fn header_line(
    label: String,
    is_resolved: Option<bool>,
    theme_pending: ratatui::style::Color,
    theme_reviewed: ratatui::style::Color,
) -> Line<'static> {
    let (marker, marker_color) = match is_resolved {
        Some(true) => ("[\u{2713}] ", theme_reviewed),
        Some(false) => ("[ ] ", theme_pending),
        None => ("[ ] ", theme_pending),
    };
    Line::from(vec![
        Span::styled(marker.to_string(), Style::default().fg(marker_color)),
        Span::styled(label, Style::default().add_modifier(Modifier::BOLD)),
    ])
}

/// Result of laying out the conversation panel — used by rendering and tests.
#[derive(Debug, Clone)]
pub struct ConversationLayout {
    pub lines: Vec<Line<'static>>,
    /// For each top-level thread (in render order), the index of its header
    /// line within `lines`.
    pub thread_header_indices: Vec<usize>,
}

/// Build the lines that make up the conversation panel, and record the header
/// index for every top-level thread so the selected thread can be highlighted
/// and scrolled into view.
///
/// `width` is the available rendering width (in columns); the markdown
/// renderer wraps at this width after the 4/6-space reply indent is
/// accounted for.
pub fn layout(app: &App, width: usize) -> ConversationLayout {
    let theme = &app.theme;
    let mut lines: Vec<Line<'static>> = Vec::new();
    let mut thread_header_indices: Vec<usize> = Vec::new();

    // Local mode has no remote comments — fall through to the "empty"
    // render below so the panel still paints.
    let remote_comments: &[RemoteComment] = app
        .remote()
        .map(|r| r.remote_comments.as_slice())
        .unwrap_or(&[]);
    let review_threads: &[ReviewThread] = app
        .remote()
        .map(|r| r.review_threads.as_slice())
        .unwrap_or(&[]);

    if remote_comments.is_empty() {
        lines.push(Line::from(Span::styled(
            "  No comments yet".to_string(),
            styles::dim_style(theme),
        )));
        return ConversationLayout {
            lines,
            thread_header_indices,
        };
    }

    let top_level: Vec<&RemoteComment> = remote_comments
        .iter()
        .filter(|c| c.in_reply_to.is_none())
        .collect();

    for comment in &top_level {
        let timestamp = comment.created_at.format("%Y-%m-%d %H:%M");
        let header_label = format!("  {} ({}):", comment.author, timestamp);
        let is_resolved = thread_is_resolved(review_threads, comment.id);
        let header_idx = lines.len();
        thread_header_indices.push(header_idx);
        lines.push(header_line(
            header_label,
            is_resolved,
            theme.pending,
            theme.reviewed,
        ));

        append_body_lines(
            &mut lines,
            &comment.body,
            theme,
            width,
            4,
            app.markdown_rendering_enabled,
        );

        if let Some(ref path) = comment.path {
            let loc = if let Some(line) = comment.line {
                format!("  [{path}:{line}]")
            } else {
                format!("  [{path}]")
            };
            lines.push(Line::from(Span::styled(loc, styles::dim_style(theme))));
        }

        let replies: Vec<&RemoteComment> = remote_comments
            .iter()
            .filter(|c| c.in_reply_to == Some(comment.id))
            .collect();

        for reply in &replies {
            let reply_ts = reply.created_at.format("%Y-%m-%d %H:%M");
            lines.push(Line::from(vec![Span::styled(
                format!("    \u{21b3} {} ({}):", reply.author, reply_ts),
                Style::default().add_modifier(Modifier::BOLD),
            )]));
            append_body_lines(
                &mut lines,
                &reply.body,
                theme,
                width,
                6,
                app.markdown_rendering_enabled,
            );
        }

        lines.push(Line::from(""));
    }

    ConversationLayout {
        lines,
        thread_header_indices,
    }
}

/// Append the body of a comment or reply, indenting each produced line by
/// `indent` columns. When `markdown_enabled` is true the body is rendered via
/// the markdown pipeline; otherwise each source line is pushed verbatim.
fn append_body_lines(
    lines: &mut Vec<Line<'static>>,
    body: &str,
    theme: &Theme,
    width: usize,
    indent: usize,
    markdown_enabled: bool,
) {
    let available = width.saturating_sub(indent);
    let prefix: String = " ".repeat(indent);
    let file_ref_style = Style::default().fg(theme.file_ref);
    if markdown_enabled {
        let rendered = markdown::render_markdown(body, theme, available);
        // Promote `@path/to/file` tokens to the theme's file-ref colour so
        // humans can visually trace code references within comment bodies.
        // Spans that already carry the markdown code colour are skipped to
        // avoid restyling tokens inside inline code or fenced blocks.
        let rendered = markdown::highlight_file_refs(rendered, file_ref_style, theme.markdown_code);
        for mut rendered_line in rendered {
            let mut spans = Vec::with_capacity(rendered_line.spans.len() + 1);
            spans.push(Span::raw(prefix.clone()));
            spans.append(&mut rendered_line.spans);
            lines.push(Line::from(spans));
        }
    } else {
        for body_line in body.lines() {
            let raw = Line::from(format!("{prefix}{body_line}"));
            let promoted =
                markdown::highlight_file_refs(vec![raw], file_ref_style, theme.markdown_code);
            lines.extend(promoted);
        }
    }
}

/// Auto-scroll so the header of the selected thread (at `thread_header_indices[cursor]`)
/// is visible within `viewport_height` rows starting at `current_scroll`.
pub fn auto_scroll_for_cursor(
    current_scroll: usize,
    total_lines: usize,
    viewport_height: usize,
    thread_header_indices: &[usize],
    cursor: usize,
) -> usize {
    let max_scroll = total_lines.saturating_sub(viewport_height);
    let header = match thread_header_indices.get(cursor) {
        Some(&h) => h,
        None => return current_scroll.min(max_scroll),
    };

    let mut scroll = current_scroll.min(max_scroll);
    // If header is above the viewport, scroll up to it.
    if header < scroll {
        scroll = header;
    } else if viewport_height > 0 && header >= scroll + viewport_height {
        // If header is below the viewport, scroll down so header is the last row.
        scroll = header + 1 - viewport_height;
    }
    scroll.min(max_scroll)
}

pub fn render(frame: &mut Frame, app: &mut App, area: Rect) {
    let width = (area.width as usize).max(DEFAULT_BODY_WIDTH.min(20));
    let layout = layout(app, width);

    let total_lines = layout.lines.len();
    let viewport_height = area.height as usize;

    // Precompute styles here — we can't borrow both &app.theme and
    // &mut app.mode at once (both live on `App`).
    let panel_style = styles::panel_style(&app.theme);
    let selected = styles::selected_style(&app.theme);

    // Auto-scroll so the selected thread is visible. No-op in local
    // mode (no conversation state to adjust).
    let selected_header = if let Some(r) = app.remote_mut() {
        r.conversation_scroll = auto_scroll_for_cursor(
            r.conversation_scroll,
            total_lines,
            viewport_height,
            &layout.thread_header_indices,
            r.conversation_cursor,
        );
        let scroll = r.conversation_scroll;
        let sel = layout
            .thread_header_indices
            .get(r.conversation_cursor)
            .copied();
        (scroll, sel)
    } else {
        (0, None)
    };
    let (scroll, sel_header) = selected_header;

    let visible: Vec<Line> = layout
        .lines
        .into_iter()
        .enumerate()
        .skip(scroll)
        .take(viewport_height)
        .map(|(idx, line)| {
            if Some(idx) == sel_header {
                line.style(selected)
            } else {
                line
            }
        })
        .collect();

    let paragraph = Paragraph::new(visible).style(panel_style);
    frame.render_widget(paragraph, area);
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::app::App;
    use crate::theme::Theme;
    use chrono::Utc;
    use travelagent_core::forge::{PrId, RemoteComment, ReviewThread};

    /// Build a remote-mode App for conversation tests. Uses `new_remote`
    /// with `forge = None` so the app is in `AppMode::Remote(_)` without
    /// requiring a mock forge backend.
    fn build_test_app() -> App {
        App::new_remote(
            Theme::dark(),
            None,
            false,
            Vec::new(),
            "Test PR".to_string(),
            1,
            "owner",
            "repo",
            crate::test_support::runtime_handle(),
            None,
            PrId {
                owner: "owner".to_string(),
                repo: "repo".to_string(),
                number: 1,
            },
        )
        .expect("new_remote builds in tests")
    }

    fn top_comment(id: u64, body: &str) -> RemoteComment {
        RemoteComment {
            id,
            author: "alice".to_string(),
            body: body.to_string(),
            path: None,
            line: None,
            side: None,
            created_at: Utc::now(),
            in_reply_to: None,
        }
    }

    fn reply(id: u64, parent: u64, body: &str) -> RemoteComment {
        RemoteComment {
            id,
            author: "bob".to_string(),
            body: body.to_string(),
            path: None,
            line: None,
            side: None,
            created_at: Utc::now(),
            in_reply_to: Some(parent),
        }
    }

    fn thread(id: &str, root: u64, resolved: bool) -> ReviewThread {
        ReviewThread {
            id: id.to_string(),
            is_resolved: resolved,
            root_comment_id: root,
        }
    }

    #[test]
    fn top_level_thread_indices_filters_replies() {
        let mut app = build_test_app();
        app.remote_mut().unwrap().remote_comments = vec![
            top_comment(1, "first"),
            reply(2, 1, "reply to first"),
            top_comment(3, "second"),
        ];
        let tops = top_level_thread_indices(&app);
        assert_eq!(tops, vec![0, 2]);
    }

    #[test]
    fn selected_thread_id_returns_matching_thread() {
        let mut app = build_test_app();
        {
            let r = app.remote_mut().unwrap();
            r.remote_comments = vec![top_comment(10, "hi"), top_comment(20, "there")];
            r.review_threads = vec![thread("t10", 10, false), thread("t20", 20, true)];
            r.conversation_cursor = 1;
        }
        assert_eq!(selected_thread_id(&app), Some("t20".to_string()));

        app.remote_mut().unwrap().conversation_cursor = 0;
        assert_eq!(selected_thread_id(&app), Some("t10".to_string()));
    }

    #[test]
    fn selected_thread_id_none_when_empty() {
        let app = build_test_app();
        assert!(selected_thread_id(&app).is_none());
    }

    #[test]
    fn thread_is_resolved_handles_missing() {
        let threads = vec![thread("t1", 1, true), thread("t2", 2, false)];
        assert_eq!(thread_is_resolved(&threads, 1), Some(true));
        assert_eq!(thread_is_resolved(&threads, 2), Some(false));
        assert_eq!(thread_is_resolved(&threads, 3), None);
    }

    #[test]
    fn clamp_conversation_cursor_keeps_in_bounds() {
        let mut app = build_test_app();
        {
            let r = app.remote_mut().unwrap();
            r.remote_comments = vec![top_comment(1, "a"), top_comment(2, "b")];
            r.conversation_cursor = 99;
        }
        clamp_conversation_cursor(&mut app);
        assert_eq!(app.remote().unwrap().conversation_cursor, 1);

        {
            let r = app.remote_mut().unwrap();
            r.remote_comments.clear();
            r.conversation_cursor = 99;
        }
        clamp_conversation_cursor(&mut app);
        assert_eq!(app.remote().unwrap().conversation_cursor, 0);
    }

    #[test]
    fn layout_produces_header_for_each_top_level_thread() {
        let mut app = build_test_app();
        app.remote_mut().unwrap().remote_comments = vec![
            top_comment(1, "first"),
            reply(2, 1, "reply"),
            top_comment(3, "second"),
        ];
        let layout = layout(&app, 80);
        assert_eq!(layout.thread_header_indices.len(), 2);
        // First header is at index 0
        assert_eq!(layout.thread_header_indices[0], 0);
        // Second header should be after the first header, its body, and the reply lines.
        assert!(layout.thread_header_indices[1] > layout.thread_header_indices[0]);
    }

    #[test]
    fn layout_empty_when_no_comments() {
        let app = build_test_app();
        let layout = layout(&app, 80);
        assert_eq!(layout.thread_header_indices.len(), 0);
        assert_eq!(layout.lines.len(), 1); // "No comments yet"
    }

    #[test]
    fn layout_renders_resolved_marker() {
        let mut app = build_test_app();
        {
            let r = app.remote_mut().unwrap();
            r.remote_comments = vec![top_comment(1, "first"), top_comment(2, "second")];
            r.review_threads = vec![thread("t1", 1, true), thread("t2", 2, false)];
        }
        let layout = layout(&app, 80);
        // The resolved thread header should contain the check mark.
        let first_header = &layout.lines[layout.thread_header_indices[0]];
        let first_text: String = first_header
            .spans
            .iter()
            .map(|s| s.content.as_ref())
            .collect();
        assert!(first_text.starts_with("[\u{2713}] "));

        let second_header = &layout.lines[layout.thread_header_indices[1]];
        let second_text: String = second_header
            .spans
            .iter()
            .map(|s| s.content.as_ref())
            .collect();
        assert!(second_text.starts_with("[ ] "));
    }

    #[test]
    fn auto_scroll_keeps_header_in_viewport() {
        let headers = vec![0, 10, 20];
        // Cursor 2 (header at line 20), viewport 5, total 30
        let scroll = auto_scroll_for_cursor(0, 30, 5, &headers, 2);
        // Header 20 must be visible: scroll = 20 + 1 - 5 = 16
        assert_eq!(scroll, 16);

        // Cursor 0 when scrolled down: scroll back up so header 0 is visible.
        let scroll = auto_scroll_for_cursor(18, 30, 5, &headers, 0);
        assert_eq!(scroll, 0);

        // Already visible: scroll stays.
        let scroll = auto_scroll_for_cursor(8, 30, 5, &headers, 1);
        assert_eq!(scroll, 8);
    }

    #[test]
    fn auto_scroll_clamps_at_max() {
        let headers = vec![0];
        let scroll = auto_scroll_for_cursor(100, 10, 5, &headers, 0);
        assert_eq!(scroll, 0);
    }
}