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

use crate::app::App;
use crate::engine::SequencerSnapshot;
use crate::model::{MAX_BANKS, MAX_PATTERNS};
use crate::state::PatternsColumn;

pub fn render(frame: &mut Frame, app: &App, snapshot: &SequencerSnapshot, area: Rect) {
    let [banks_area, gap, patterns_area] = Layout::horizontal([
        Constraint::Fill(1),
        Constraint::Length(1),
        Constraint::Fill(1),
    ])
    .areas(area);

    render_banks(frame, app, snapshot, banks_area);
    // gap is just empty space
    let _ = gap;
    render_patterns(frame, app, snapshot, patterns_area);
}

fn render_banks(frame: &mut Frame, app: &App, snapshot: &SequencerSnapshot, area: Rect) {
    let is_focused = matches!(app.patterns_nav.column, PatternsColumn::Banks);

    let [title_area, inner] =
        Layout::vertical([Constraint::Length(1), Constraint::Fill(1)]).areas(area);

    let title_color = if is_focused {
        Color::Rgb(100, 160, 180)
    } else {
        Color::Rgb(70, 75, 85)
    };
    let title = Paragraph::new("Banks")
        .style(Style::new().fg(title_color))
        .alignment(ratatui::layout::Alignment::Center);
    frame.render_widget(title, title_area);

    let banks_with_playback: Vec<usize> = snapshot
        .active_patterns
        .iter()
        .map(|p| p.bank)
        .collect();

    let banks_with_staged: Vec<usize> = app
        .playback
        .staged_changes
        .iter()
        .filter_map(|c| match &c.change {
            crate::engine::PatternChange::Start { bank, .. } => Some(*bank),
            _ => None,
        })
        .collect();

    let row_height = (inner.height / MAX_BANKS as u16).max(1);
    let total_needed = row_height * MAX_BANKS as u16;
    let top_padding = if inner.height > total_needed {
        (inner.height - total_needed) / 2
    } else {
        0
    };

    for idx in 0..MAX_BANKS {
        let y = inner.y + top_padding + (idx as u16) * row_height;
        if y >= inner.y + inner.height {
            break;
        }

        let row_area = Rect {
            x: inner.x,
            y,
            width: inner.width,
            height: row_height.min(inner.y + inner.height - y),
        };

        let is_cursor = is_focused && idx == app.patterns_nav.bank_cursor;
        let is_selected = idx == app.patterns_nav.bank_cursor;
        let is_edit = idx == app.editor_ctx.bank;
        let is_playing = banks_with_playback.contains(&idx);
        let is_staged = banks_with_staged.contains(&idx);

        let (bg, fg, prefix) = match (is_cursor, is_playing, is_staged) {
            (true, _, _) => (Color::Cyan, Color::Black, ""),
            (false, true, _) => (Color::Rgb(45, 80, 45), Color::Green, "> "),
            (false, false, true) => (Color::Rgb(80, 60, 100), Color::Magenta, "+ "),
            (false, false, false) if is_selected => (Color::Rgb(60, 65, 75), Color::White, ""),
            (false, false, false) if is_edit => (Color::Rgb(45, 106, 95), Color::White, ""),
            (false, false, false) => (Color::Reset, Color::Rgb(120, 125, 135), ""),
        };

        let name = app.project_state.project.banks[idx]
            .name
            .as_deref()
            .unwrap_or("");
        let label = if name.is_empty() {
            format!("{}{:02}", prefix, idx + 1)
        } else {
            format!("{}{:02} {}", prefix, idx + 1, name)
        };

        let style = Style::new().bg(bg).fg(fg);
        let style = if is_playing || is_staged {
            style.add_modifier(Modifier::BOLD)
        } else {
            style
        };

        // Fill the entire row with background color
        let bg_block = Block::default().style(Style::new().bg(bg));
        frame.render_widget(bg_block, row_area);

        let text_y = if row_height > 1 {
            row_area.y + (row_height - 1) / 2
        } else {
            row_area.y
        };
        let text_area = Rect {
            x: row_area.x,
            y: text_y,
            width: row_area.width,
            height: 1,
        };
        let para = Paragraph::new(label).style(style);
        frame.render_widget(para, text_area);
    }
}

fn render_patterns(frame: &mut Frame, app: &App, snapshot: &SequencerSnapshot, area: Rect) {
    use crate::model::PatternSpeed;

    let is_focused = matches!(app.patterns_nav.column, PatternsColumn::Patterns);

    let [title_area, inner] =
        Layout::vertical([Constraint::Length(1), Constraint::Fill(1)]).areas(area);

    let title_color = if is_focused {
        Color::Rgb(100, 160, 180)
    } else {
        Color::Rgb(70, 75, 85)
    };

    let bank = app.patterns_nav.bank_cursor;
    let bank_name = app.project_state.project.banks[bank].name.as_deref();
    let title_text = match bank_name {
        Some(name) => format!("Patterns ({name})"),
        None => format!("Patterns (Bank {:02})", bank + 1),
    };
    let title = Paragraph::new(title_text)
        .style(Style::new().fg(title_color))
        .alignment(ratatui::layout::Alignment::Center);
    frame.render_widget(title, title_area);

    let playing_patterns: Vec<usize> = snapshot
        .active_patterns
        .iter()
        .filter(|p| p.bank == bank)
        .map(|p| p.pattern)
        .collect();

    let staged_to_play: Vec<usize> = app
        .playback
        .staged_changes
        .iter()
        .filter_map(|c| match &c.change {
            crate::engine::PatternChange::Start {
                bank: b, pattern, ..
            } if *b == bank => Some(*pattern),
            _ => None,
        })
        .collect();

    let staged_to_stop: Vec<usize> = app
        .playback
        .staged_changes
        .iter()
        .filter_map(|c| match &c.change {
            crate::engine::PatternChange::Stop {
                bank: b,
                pattern,
            } if *b == bank => Some(*pattern),
            _ => None,
        })
        .collect();

    let edit_pattern = if app.editor_ctx.bank == bank {
        Some(app.editor_ctx.pattern)
    } else {
        None
    };

    let row_height = (inner.height / MAX_PATTERNS as u16).max(1);
    let total_needed = row_height * MAX_PATTERNS as u16;
    let top_padding = if inner.height > total_needed {
        (inner.height - total_needed) / 2
    } else {
        0
    };

    for idx in 0..MAX_PATTERNS {
        let y = inner.y + top_padding + (idx as u16) * row_height;
        if y >= inner.y + inner.height {
            break;
        }

        let row_area = Rect {
            x: inner.x,
            y,
            width: inner.width,
            height: row_height.min(inner.y + inner.height - y),
        };

        let is_cursor = is_focused && idx == app.patterns_nav.pattern_cursor;
        let is_selected = idx == app.patterns_nav.pattern_cursor;
        let is_edit = edit_pattern == Some(idx);
        let is_playing = playing_patterns.contains(&idx);
        let is_staged_play = staged_to_play.contains(&idx);
        let is_staged_stop = staged_to_stop.contains(&idx);

        let (bg, fg, prefix) = match (is_cursor, is_playing, is_staged_play, is_staged_stop) {
            (true, _, _, _) => (Color::Cyan, Color::Black, ""),
            (false, true, _, true) => (Color::Rgb(120, 60, 80), Color::Magenta, "- "),
            (false, true, _, false) => (Color::Rgb(45, 80, 45), Color::Green, "> "),
            (false, false, true, _) => (Color::Rgb(80, 60, 100), Color::Magenta, "+ "),
            (false, false, false, _) if is_selected => (Color::Rgb(60, 65, 75), Color::White, ""),
            (false, false, false, _) if is_edit => (Color::Rgb(45, 106, 95), Color::White, ""),
            (false, false, false, _) => (Color::Reset, Color::Rgb(120, 125, 135), ""),
        };

        let pattern = &app.project_state.project.banks[bank].patterns[idx];
        let name = pattern.name.as_deref().unwrap_or("");
        let length = pattern.length;
        let speed = pattern.speed;

        let base_style = Style::new().bg(bg).fg(fg);
        let bold_style = base_style.add_modifier(Modifier::BOLD);

        // Fill the entire row with background color
        let bg_block = Block::default().style(Style::new().bg(bg));
        frame.render_widget(bg_block, row_area);

        let text_y = if row_height > 1 {
            row_area.y + (row_height - 1) / 2
        } else {
            row_area.y
        };

        // Split row into columns: [index+name] [length] [speed]
        let speed_width: u16 = 14; // "Speed: 1/4x "
        let length_width: u16 = 13; // "Length: 16 "
        let name_width = row_area
            .width
            .saturating_sub(speed_width + length_width + 2);

        let [name_area, length_area, speed_area] = Layout::horizontal([
            Constraint::Length(name_width),
            Constraint::Length(length_width),
            Constraint::Length(speed_width),
        ])
        .areas(Rect {
            x: row_area.x,
            y: text_y,
            width: row_area.width,
            height: 1,
        });

        // Column 1: prefix + index + name (left-aligned)
        let name_text = if name.is_empty() {
            format!("{}{:02}", prefix, idx + 1)
        } else {
            format!("{}{:02} {}", prefix, idx + 1, name)
        };
        let name_style = if is_playing || is_staged_play {
            bold_style
        } else {
            base_style
        };
        frame.render_widget(Paragraph::new(name_text).style(name_style), name_area);

        // Column 2: length
        let length_line = Line::from(vec![
            Span::styled("Length: ", bold_style),
            Span::styled(format!("{length}"), base_style),
        ]);
        frame.render_widget(Paragraph::new(length_line), length_area);

        // Column 3: speed (only if non-default)
        if speed != PatternSpeed::NORMAL {
            let speed_line = Line::from(vec![
                Span::styled("Speed: ", bold_style),
                Span::styled(speed.label(), base_style),
            ]);
            frame.render_widget(Paragraph::new(speed_line), speed_area);
        }
    }
}