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;

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

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

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();

    let _total_msgs = messages.len();

    for msg in messages.iter() {
        let role_color = match msg.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,
        };
        let prefix = match msg.role {
            crate::dto::chat::message::Role::User => ">",
            crate::dto::chat::message::Role::Assistant => "•",
            crate::dto::chat::message::Role::System => "#",
            crate::dto::chat::message::Role::Tool => "→",
        };

        let ts_str = format_timestamp(msg.timestamp);
        let badge = role_badge(&msg.role);
        let time_display = if ts_str.is_empty() { String::new() } else { format!(" [{}]", ts_str) };

        let header = Line::from(vec![
            Span::styled(
                format!(" {} ", badge),
                Style::default().fg(Theme::BG).bg(role_color).add_modifier(Modifier::BOLD),
            ),
            Span::styled(
                time_display,
                Style::default().fg(Theme::DIM),
            ),
        ]);

        let content_str = if msg.content.is_empty() {
            "(streaming...)".to_string()
        } else {
            msg.content.clone()
        };
        let mut content_spans = vec![Span::styled(format!("{} ", prefix), Style::default().fg(role_color))];
        content_spans.extend(super::markdown::render_markdown(&content_str, area.width));
        let content_line = Line::from(content_spans);

        display_lines.push(header);
        display_lines.push(content_line);
        display_lines.push(Line::from(Span::raw("")));
    }

    if state.turn_in_flight() {
        let spinner_frames = ["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"];
        let frame = spinner_frames[(state.misc.tick_count as usize / 2) % spinner_frames.len()];
        display_lines.push(Line::from(vec![
            Span::styled(" AI ", Style::default().fg(Theme::BG).bg(Theme::ROLE_ASSISTANT).add_modifier(Modifier::BOLD)),
            Span::styled(format!(" {} Generating...", frame), Style::default().fg(Theme::DIM)),
        ]));
        display_lines.push(Line::from(Span::raw("")));
    }

    let mut title = String::from(" Chat ");
    if !messages.is_empty() {
        title.push_str(&format!("[{} msgs]", messages.len()));
    }

    let block = Block::default()
        .borders(Borders::ALL)
        .border_style(Style::default().fg(Theme::BORDER))
        .title(title);

    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()
    };

    let paragraph = Paragraph::new(visible)
        .block(block)
        .wrap(Wrap { trim: false });

    frame.render_widget(paragraph, area);
}