use ratatui::{
    layout::{Constraint, Direction, Layout, Rect},
    style::{Color, Modifier, Style},
    text::{Line, Span},
    widgets::{Block, Borders, Gauge, Paragraph},
    Frame,
};

use crate::{app::App, deck::{Deck, DeckId}};

pub fn draw(f: &mut Frame, app: &mut App) {
    let area = f.area();
    draw_base(f, app, area);
    if let Some(sel) = &mut app.file_selector {
        sel.render(f, area);
    }
}

fn draw_base(f: &mut Frame, app: &App, area: Rect) {
    let chunks = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Length(1),
            Constraint::Min(1),
            Constraint::Length(4),
        ])
        .split(area);

    // Header
    let header = Paragraph::new(Line::from(vec![
        Span::styled(" ♫ djdeck  ", Style::default().fg(Color::Cyan).add_modifier(Modifier::BOLD)),
        Span::styled(
            format!("OSC :{} → :{}  ", crate::osc::LISTEN_PORT, crate::osc::SEND_PORT),
            Style::default().fg(Color::DarkGray),
        ),
        Span::styled(
            "PipeWire graph: each deck → rubberband filter-chain → sink",
            Style::default().fg(Color::DarkGray),
        ),
    ]));
    f.render_widget(header, chunks[0]);

    // 2×2 deck grid
    let rows = Layout::default()
        .direction(Direction::Vertical)
        .constraints([Constraint::Percentage(50), Constraint::Percentage(50)])
        .split(chunks[1]);

    for row in 0..2usize {
        let cols = Layout::default()
            .direction(Direction::Horizontal)
            .constraints([Constraint::Percentage(50), Constraint::Percentage(50)])
            .split(rows[row]);

        for col in 0..2usize {
            let idx = row * 2 + col;
            if idx < app.decks.len() {
                draw_deck(f, &app.decks[idx], cols[col], app.focused_deck == idx);
            }
        }
    }

    draw_help(f, chunks[2]);
}

fn deck_color(id: DeckId) -> Color {
    match id {
        DeckId::A => Color::Cyan,
        DeckId::Z => Color::Magenta,
        DeckId::S => Color::Green,
        DeckId::X => Color::Yellow,
    }
}

fn draw_deck(f: &mut Frame, deck: &Deck, area: Rect, focused: bool) {
    let color = deck_color(deck.id);

    let border_style = if focused {
        Style::default().fg(color).add_modifier(Modifier::BOLD)
    } else {
        Style::default().fg(Color::DarkGray)
    };

    // Truncate track name to fit
    let max_name = area.width.saturating_sub(18) as usize;
    let track_display = deck.track_name.as_deref().unwrap_or("[no track]");
    let track_display = if track_display.len() > max_name {
        format!("{}…", &track_display[..max_name.saturating_sub(1)])
    } else {
        track_display.to_string()
    };

    // Node ID status
    let graph_status = match (deck.stream_node_id, deck.filter_node_id) {
        (Some(s), Some(f)) => format!(" [pw:{}/{}]", s, f),
        (Some(s), None)    => format!(" [pw:{}/--]", s),
        _                  => " [pw:--]".to_string(),
    };

    let title = format!(
        " Deck {} {} {} {} ",
        deck.id.label(),
        deck.play_state.icon(),
        track_display,
        graph_status,
    );

    let outer = Block::default()
        .borders(Borders::ALL)
        .title(title)
        .border_style(border_style)
        .style(Style::default().bg(Color::Black));
    f.render_widget(outer, area);

    let inner = area.inner(ratatui::layout::Margin { horizontal: 1, vertical: 1 });

    let rows = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Length(1), // timecode
            Constraint::Length(1), // progress
            Constraint::Length(1), // gap
            Constraint::Length(1), // fader
            Constraint::Length(1), // pitch + tempo
            Constraint::Length(1), // gap
            Constraint::Length(1), // VU
        ])
        .split(inner);

    // Timecode
    let (em, es) = deck.elapsed();
    let (rm, rs) = deck.remaining();
    f.render_widget(
        Paragraph::new(Line::from(vec![
            Span::styled(format!("{:02}:{:02}", em, es), Style::default().fg(color).add_modifier(Modifier::BOLD)),
            Span::styled("  /  ", Style::default().fg(Color::DarkGray)),
            Span::styled(format!("-{:02}:{:02}", rm, rs), Style::default().fg(Color::DarkGray)),
        ])),
        rows[0],
    );

    // Progress
    f.render_widget(
        Gauge::default()
            .gauge_style(Style::default().fg(color).bg(Color::Black))
            .percent((deck.progress() * 100.0) as u16)
            .label(""),
        rows[1],
    );

    // Fader
    let fader_pct = (deck.fader * 100.0) as u16;
    f.render_widget(
        Gauge::default()
            .gauge_style(Style::default()
                .fg(if fader_pct > 10 { Color::White } else { Color::DarkGray })
                .bg(Color::Black))
            .percent(fader_pct.min(100))
            .label(format!("VOL {:3}%", fader_pct)),
        rows[3],
    );

    // Pitch + Tempo (both live in rubberband filter-chain node)
    f.render_widget(
        Paragraph::new(Line::from(vec![
            Span::styled("PITCH ", Style::default().fg(Color::DarkGray)),
            Span::styled(
                format!("{:+.1}st", deck.pitch),
                Style::default().fg(if deck.pitch.abs() > 0.05 { Color::Yellow } else { Color::White }),
            ),
            Span::styled("   TEMPO ", Style::default().fg(Color::DarkGray)),
            Span::styled(
                format!("{:.2}×", deck.tempo),
                Style::default().fg(if (deck.tempo - 1.0).abs() > 0.01 { Color::Yellow } else { Color::White }),
            ),
        ])),
        rows[4],
    );

    // VU
    draw_vu(f, deck.vu, rows[6], color);
}

fn draw_vu(f: &mut Frame, vu: (f32, f32), area: Rect, color: Color) {
    let half = area.width / 2;
    let la = Rect { x: area.x, y: area.y, width: half.saturating_sub(1), height: 1 };
    let ra = Rect { x: area.x + half, y: area.y, width: half, height: 1 };

    let vc = |p: u16| if p > 90 { Color::Red } else if p > 70 { Color::Yellow } else { color };

    let lp = (vu.0 * 100.0) as u16;
    let rp = (vu.1 * 100.0) as u16;

    f.render_widget(Gauge::default().gauge_style(Style::default().fg(vc(lp)).bg(Color::Black)).percent(lp.min(100)).label("L"), la);
    f.render_widget(Gauge::default().gauge_style(Style::default().fg(vc(rp)).bg(Color::Black)).percent(rp.min(100)).label("R"), ra);
}

fn draw_help(f: &mut Frame, area: Rect) {
    let help = Paragraph::new(vec![
        Line::from(vec![
            Span::styled(" Focus: ", Style::default().fg(Color::DarkGray)),
            k("a"), k("z"), k("s"), k("x"),
            Span::styled("   Load: ", Style::default().fg(Color::DarkGray)),
            k("Shift+A/Z/S/X"),
            Span::styled("   Play/Pause: ", Style::default().fg(Color::DarkGray)),
            k("Space"),
            Span::styled("   Stop: ", Style::default().fg(Color::DarkGray)),
            k("Enter"),
        ]),
        Line::from(vec![
            Span::styled(" Fader: ", Style::default().fg(Color::DarkGray)),
            k("↑/↓"),
            Span::styled("   Pitch: ", Style::default().fg(Color::DarkGray)),
            k("[/]"),
            Span::styled("   Tempo: ", Style::default().fg(Color::DarkGray)),
            k(",/."),
            Span::styled("   Cue: ", Style::default().fg(Color::DarkGray)),
            k("c"), Span::raw(" set  "), k("v"), Span::raw(" goto"),
            Span::styled("   Seek: ", Style::default().fg(Color::DarkGray)),
            k("←/→"),
            Span::styled("   Quit: ", Style::default().fg(Color::DarkGray)),
            k("q"),
        ]),
    ])
    .block(Block::default()
        .borders(Borders::TOP)
        .border_style(Style::default().fg(Color::DarkGray)))
    .style(Style::default().bg(Color::Black));

    f.render_widget(help, area);
}

fn k(s: &str) -> Span<'_> {
    Span::styled(
        format!("[{}] ", s),
        Style::default().fg(Color::White).add_modifier(Modifier::BOLD),
    )
}