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

use crate::app::App;
use crate::engine::SequencerSnapshot;
use crate::state::PatternsViewLevel;

pub fn render(frame: &mut Frame, app: &App, snapshot: &SequencerSnapshot, area: Rect) {
    match app.patterns_view_level {
        PatternsViewLevel::Banks => render_banks(frame, app, snapshot, area),
        PatternsViewLevel::Patterns { bank } => render_patterns(frame, app, snapshot, area, bank),
    }
}

fn render_banks(frame: &mut Frame, app: &App, snapshot: &SequencerSnapshot, area: Rect) {
    let block = Block::default()
        .borders(Borders::ALL)
        .border_style(Style::new().fg(Color::Rgb(100, 160, 180)))
        .title("Banks");

    let inner = block.inner(area);
    frame.render_widget(block, area);

    if inner.width < 50 {
        let msg = Paragraph::new("Terminal too narrow")
            .alignment(Alignment::Center)
            .style(Style::new().fg(Color::Rgb(120, 125, 135)));
        frame.render_widget(msg, inner);
        return;
    }

    let banks_with_playback: Vec<usize> = snapshot
        .slot_data
        .iter()
        .filter(|s| s.active)
        .map(|s| s.bank)
        .collect();

    let bank_names: Vec<Option<&str>> = app
        .project_state
        .project
        .banks
        .iter()
        .map(|b| b.name.as_deref())
        .collect();

    render_grid(
        frame,
        inner,
        app.patterns_cursor,
        app.editor_ctx.bank,
        &banks_with_playback,
        &bank_names,
    );
}

fn render_patterns(
    frame: &mut Frame,
    app: &App,
    snapshot: &SequencerSnapshot,
    area: Rect,
    bank: usize,
) {
    let bank_name = app.project_state.project.banks[bank].name.as_deref();
    let title_text = match bank_name {
        Some(name) => format!("{name} › Patterns"),
        None => format!("Bank {:02} › Patterns", bank + 1),
    };
    let title = Line::from(vec![
        Span::raw(title_text),
        Span::styled("  [Esc]←", Style::new().fg(Color::Rgb(120, 125, 135))),
    ]);

    let block = Block::default()
        .borders(Borders::ALL)
        .border_style(Style::new().fg(Color::Rgb(100, 160, 180)))
        .title(title);

    let inner = block.inner(area);
    frame.render_widget(block, area);

    if inner.width < 50 {
        let msg = Paragraph::new("Terminal too narrow")
            .alignment(Alignment::Center)
            .style(Style::new().fg(Color::Rgb(120, 125, 135)));
        frame.render_widget(msg, inner);
        return;
    }

    let playing_patterns: Vec<usize> = snapshot
        .slot_data
        .iter()
        .filter(|s| s.active && s.bank == bank)
        .map(|s| s.pattern)
        .collect();

    let edit_pattern = if app.editor_ctx.bank == bank {
        app.editor_ctx.pattern
    } else {
        usize::MAX
    };

    let pattern_names: Vec<Option<&str>> = app.project_state.project.banks[bank]
        .patterns
        .iter()
        .map(|p| p.name.as_deref())
        .collect();

    render_pattern_grid(
        frame,
        app,
        snapshot,
        inner,
        bank,
        app.patterns_cursor,
        edit_pattern,
        &playing_patterns,
        &pattern_names,
    );
}

fn render_grid(
    frame: &mut Frame,
    area: Rect,
    cursor: usize,
    edit_pos: usize,
    playing_positions: &[usize],
    names: &[Option<&str>],
) {
    let rows = Layout::vertical([
        Constraint::Fill(1),
        Constraint::Fill(1),
        Constraint::Fill(1),
        Constraint::Fill(1),
    ])
    .split(area);

    for row in 0..4 {
        let cols = Layout::horizontal(vec![Constraint::Fill(1); 4]).split(rows[row]);
        for col in 0..4 {
            let idx = row * 4 + col;
            let is_cursor = idx == cursor;
            let is_edit = idx == edit_pos;
            let is_playing = playing_positions.contains(&idx);

            let (bg, fg) = match (is_cursor, is_edit, is_playing) {
                (true, _, _) => (Color::Cyan, Color::Black),
                (false, true, _) => (Color::Rgb(45, 106, 95), Color::White),
                (false, false, true) => (Color::Rgb(45, 80, 45), Color::Green),
                (false, false, false) => (Color::Rgb(45, 48, 55), Color::Rgb(120, 125, 135)),
            };

            let name = names.get(idx).and_then(|n| *n).unwrap_or("");
            let number = format!("{:02}", idx + 1);
            let cell = cols[col];

            // Fill background
            frame.render_widget(Block::default().style(Style::new().bg(bg)), cell);

            let top_area = Rect::new(cell.x, cell.y, cell.width, 1);
            let center_y = cell.y + cell.height / 2;
            let center_area = Rect::new(cell.x, center_y, cell.width, 1);

            if name.is_empty() {
                // Number centered
                frame.render_widget(
                    Paragraph::new(number)
                        .alignment(Alignment::Center)
                        .style(Style::new().fg(fg).add_modifier(Modifier::BOLD)),
                    center_area,
                );
            } else {
                // Number centered at top
                frame.render_widget(
                    Paragraph::new(number)
                        .alignment(Alignment::Center)
                        .style(Style::new().fg(fg).add_modifier(Modifier::DIM)),
                    top_area,
                );
                // Name centered in middle
                frame.render_widget(
                    Paragraph::new(name)
                        .alignment(Alignment::Center)
                        .style(Style::new().fg(fg).add_modifier(Modifier::BOLD)),
                    center_area,
                );
            }
        }
    }
}

fn render_pattern_grid(
    frame: &mut Frame,
    app: &App,
    snapshot: &SequencerSnapshot,
    area: Rect,
    bank: usize,
    cursor: usize,
    edit_pos: usize,
    playing_positions: &[usize],
    names: &[Option<&str>],
) {
    let rows = Layout::vertical([
        Constraint::Fill(1),
        Constraint::Fill(1),
        Constraint::Fill(1),
        Constraint::Fill(1),
    ])
    .split(area);

    for row in 0..4 {
        let cols = Layout::horizontal(vec![Constraint::Fill(1); 4]).split(rows[row]);
        for col in 0..4 {
            let idx = row * 4 + col;
            let is_cursor = idx == cursor;
            let is_edit = idx == edit_pos;
            let is_playing = playing_positions.contains(&idx);
            let queued = app.is_pattern_queued(bank, idx, snapshot);

            let (bg, fg, prefix) = match (is_cursor, is_playing, queued) {
                (true, _, _) => (Color::Cyan, Color::Black, ""),
                (false, true, Some(false)) => (Color::Rgb(120, 90, 30), Color::Yellow, "×"),
                (false, true, _) => (Color::Rgb(45, 80, 45), Color::Green, "▶"),
                (false, false, Some(true)) => (Color::Rgb(80, 80, 45), Color::Yellow, "?"),
                (false, false, _) if is_edit => (Color::Rgb(45, 106, 95), Color::White, ""),
                (false, false, _) => (Color::Rgb(45, 48, 55), Color::Rgb(120, 125, 135), ""),
            };

            let name = names.get(idx).and_then(|n| *n).unwrap_or("");
            let number = format!("{}{:02}", prefix, idx + 1);
            let cell = cols[col];

            // Fill background
            frame.render_widget(Block::default().style(Style::new().bg(bg)), cell);

            let top_area = Rect::new(cell.x, cell.y, cell.width, 1);
            let center_y = cell.y + cell.height / 2;
            let center_area = Rect::new(cell.x, center_y, cell.width, 1);

            if name.is_empty() {
                // Number centered
                frame.render_widget(
                    Paragraph::new(number)
                        .alignment(Alignment::Center)
                        .style(Style::new().fg(fg).add_modifier(Modifier::BOLD)),
                    center_area,
                );
            } else {
                // Number centered at top
                frame.render_widget(
                    Paragraph::new(number)
                        .alignment(Alignment::Center)
                        .style(Style::new().fg(fg).add_modifier(Modifier::DIM)),
                    top_area,
                );
                // Name centered in middle
                frame.render_widget(
                    Paragraph::new(name)
                        .alignment(Alignment::Center)
                        .style(Style::new().fg(fg).add_modifier(Modifier::BOLD)),
                    center_area,
                );
            }
        }
    }
}