#![allow(clippy::cast_possible_truncation, clippy::cast_sign_loss, clippy::cast_precision_loss, clippy::cast_possible_wrap)]
//! Chat transcript panel rendering — message cards with role badges.
//!
//! Flow: `draw_chat` turns `state.transcript_cache.messages` into a
//! visually rich transcript where each message is rendered as a "card"
//! with a role-colored left accent bar, a role badge pill, timestamp,
//! and markdown body. A streaming spinner line is appended when a turn
//! is in flight. The combined line list is sliced to the visible scroll
//! window before rendering.
//!
//! Design: messages are visually separated with vertical spacing, role
//! badges are colored pills on the left, and each message has a thin
//! role-colored border on its left side for quick visual scanning.

use ratatui::layout::Rect;
use ratatui::style::{Style, Modifier};
use ratatui::text::{Line, Span};
use ratatui::widgets::{Block, Borders, Paragraph, Wrap};
use ratatui::Frame;
use super::theme::Theme;

/// Break a flat run of styled spans into `Line`s at embedded `\n` boundaries.
fn split_spans_into_lines(spans: Vec<Span<'_>>) -> Vec<Line<'_>> {
    let mut lines = Vec::new();
    let mut current_spans = Vec::new();

    for span in spans {
        let text = span.content.as_ref();
        let mut parts = text.split('\n').peekable();
        while let Some(part) = parts.next() {
            if !part.is_empty() {
                current_spans.push(Span::styled(part.to_string(), span.style));
            }
            if parts.peek().is_some() {
                lines.push(Line::from(std::mem::take(&mut current_spans)));
            }
        }
    }
    if !current_spans.is_empty() {
        lines.push(Line::from(current_spans));
    }
    if lines.is_empty() {
        lines.push(Line::from(vec![]));
    }
    lines
}

fn role_badge(role: &crate::dto::chat::message::Role) -> &'static str {
    match role {
        crate::dto::chat::message::Role::User => " YOU ",
        crate::dto::chat::message::Role::Assistant => " AI ",
        crate::dto::chat::message::Role::System => " SYS ",
        crate::dto::chat::message::Role::Tool => " TOOL ",
    }
}

fn role_accent_color(role: &crate::dto::chat::message::Role) -> Color {
    match role {
        crate::dto::chat::message::Role::User => Theme::ROLE_USER,
        crate::dto::chat::message::Role::Assistant => Theme::ROLE_ASSISTANT,
        crate::dto::chat::message::Role::System => Theme::ROLE_SYSTEM,
        crate::dto::chat::message::Role::Tool => Theme::ROLE_TOOL,
    }
}

fn role_label(role: &crate::dto::chat::message::Role) -> &'static str {
    match role {
        crate::dto::chat::message::Role::User => "You",
        crate::dto::chat::message::Role::Assistant => "Assistant",
        crate::dto::chat::message::Role::System => "System",
        crate::dto::chat::message::Role::Tool => "Tool Call",
    }
}

fn format_timestamp(ts: i64) -> String {
    if ts <= 0 { return String::new(); }
    let secs = ts / 1000;
    let mins = (secs / 60) % 60;
    let hrs = (secs / 3600) % 24;
    format!("{hrs:02}:{mins:02}")
}

/// Render the scrollable chat transcript panel with message card styling.
#[allow(clippy::too_many_lines)]
pub fn draw_chat(frame: &mut Frame, area: Rect, state: &crate::app::state::rest::AppStateRest) {
    let messages = &state.transcript_cache.messages;
    let scroll_offset = state.scroll.offset;
    let max_visible = (area.height as usize).saturating_sub(3);

    let mut display_lines: Vec<Line> = Vec::new();

    // ── Header ───────────────────────────────────────────────────────────
    let title = if messages.is_empty() {
        String::from(" Chat ")
    } else {
        format!(" Chat  [{} msgs]", messages.len())
    };

    // ── Render messages as cards ─────────────────────────────────────────
    for msg in messages {
        let accent = role_accent_color(&msg.role);
        let badge = role_badge(&msg.role);
        let label = role_label(&msg.role);
        let ts_str = format_timestamp(msg.timestamp);

        // ── Role header line ─────────────────────────────────────────────
        // Left accent bar + badge pill + role name + timestamp
        let header = Line::from(vec![
            // Thin accent bar on the left
            Span::styled(
                "▎",
                Style::default().fg(accent),
            ),
            // Role badge pill
            Span::styled(
                badge,
                Style::default()
                    .fg(Theme::BG)
                    .bg(accent)
                    .add_modifier(Modifier::BOLD),
            ),
            // Role name
            Span::styled(
                format!(" {label}"),
                Style::default().fg(accent).add_modifier(Modifier::BOLD),
            ),
            // Timestamp
            Span::styled(
                if ts_str.is_empty() { String::new() } else { format!("  {ts_str}") },
                Style::default().fg(Theme::TEXT_DIM),
            ),
        ]);
        display_lines.push(header);

        // ── Message content ──────────────────────────────────────────────
        let is_last = std::ptr::eq(msg, messages.last().unwrap());
        let content_str = if msg.content.trim().is_empty() {
            if is_last && state.turn_in_flight() {
                "(streaming...)".to_string()
            } else {
                "(tool execution)".to_string()
            }
        } else {
            msg.content.clone()
        };

        // Render markdown content with accent-colored prefix
        let mut content_spans = vec![
            Span::styled("  ", Style::default().fg(accent)),
        ];
        content_spans.extend(super::markdown::render_markdown(&content_str, area.width));
        let message_lines = split_spans_into_lines(content_spans);

        for line in message_lines {
            display_lines.push(line);
        }

        // ── Message separator ────────────────────────────────────────────
        display_lines.push(Line::from(Span::raw("")));
    }

    // ── Streaming indicator ──────────────────────────────────────────────
    if state.turn_in_flight() {
        let spinner_frames = ["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"];
        let frame_idx = (state.misc.tick_count as usize / 2) % spinner_frames.len();
        let spinner = spinner_frames[frame_idx];

        display_lines.push(Line::from(vec![
            Span::styled(
                "▎",
                Style::default().fg(Theme::ROLE_ASSISTANT),
            ),
            Span::styled(
                " AI ",
                Style::default()
                    .fg(Theme::BG)
                    .bg(Theme::ROLE_ASSISTANT)
                    .add_modifier(Modifier::BOLD),
            ),
            Span::styled(
                format!(" {spinner} "),
                Style::default().fg(Theme::ROLE_ASSISTANT).add_modifier(Modifier::BOLD),
            ),
            Span::styled(
                "Generating...",
                Style::default().fg(Theme::TEXT_MUTED).add_modifier(Modifier::ITALIC),
            ),
        ]));
        display_lines.push(Line::from(Span::raw("")));
    }

    // ── Scrolling ────────────────────────────────────────────────────────
    let block = Block::default()
        .borders(Borders::ALL)
        .border_style(Style::default().fg(Theme::BORDER))
        .title(Span::styled(
            title,
            Style::default().fg(Theme::TEXT_MUTED),
        ));

    let total = display_lines.len();
    let max_offset = total.saturating_sub(max_visible);
    let offset = scroll_offset.min(max_offset);

    let end_idx = total.saturating_sub(offset);
    let start_idx = end_idx.saturating_sub(max_visible);
    let visible: Vec<Line> = if start_idx < end_idx && start_idx < total {
        display_lines[start_idx..end_idx].to_vec()
    } else {
        display_lines[total.saturating_sub(max_visible)..total].to_vec()
    };

    // ── Scroll position indicator ────────────────────────────────────────
    // Show a small percentage indicator in the title if scrolled
    let scroll_pct = if total > max_visible {
        ((offset as f64 / max_offset as f64) * 100.0) as u8
    } else {
        0
    };

    let block = if scroll_pct > 0 {
        let scroll_title = format!(" Chat  [{} msgs]  ── {}% ↑ ", messages.len(), scroll_pct);
        Block::default()
            .borders(Borders::ALL)
            .border_style(Style::default().fg(Theme::BORDER))
            .title(Span::styled(
                scroll_title,
                Style::default().fg(Theme::TEXT_MUTED),
            ))
    } else {
        block
    };

    let paragraph = Paragraph::new(visible)
        .block(block)
        .style(Style::default().bg(Theme::BG))
        .wrap(Wrap { trim: false });

    frame.render_widget(paragraph, area);
}

// Need to import Color for role_accent_color
use ratatui::style::Color;