use ratatui::prelude::*;
use ratatui::widgets::{
    Bar, BarChart, BarGroup, Block, Borders, Clear, List, ListItem, Paragraph, Wrap,
};

use crate::app::{App, InputMode, Panel};
use crate::library::{RightRow, SortMode};
use crate::state::RepeatMode;

pub fn draw(f: &mut Frame, app: &mut App) {
    let chunks = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Min(1),
            Constraint::Length(3),
        ])
        .split(f.area());

    let top = Layout::default()
        .direction(Direction::Horizontal)
        .constraints([Constraint::Percentage(30), Constraint::Percentage(70)])
        .split(chunks[0]);

    let left_col = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Min(1),
            Constraint::Length(8),
        ])
        .split(top[0]);

    draw_left_panel(f, app, left_col[0]);
    draw_equalizer(f, app, left_col[1]);
    draw_right_panel(f, app, top[1]);
    draw_status(f, app, chunks[1]);

    if app.show_help {
        draw_help(f, f.area());
    }
    if app.show_dirs {
        draw_dirs(f, app, f.area());
    }
}

fn draw_left_panel(f: &mut Frame, app: &mut App, area: Rect) {
    f.render_widget(Clear, area);

    let items: Vec<ListItem> = app
        .library
        .artists
        .iter()
        .map(|a| ListItem::new(a.name.clone()))
        .collect();

    let highlight = if app.active_panel == Panel::Left {
        Style::default().add_modifier(Modifier::REVERSED)
    } else {
        Style::default().add_modifier(Modifier::DIM)
    };

    let sel = if app.library.artists.is_empty() {
        None
    } else {
        Some(app.library.artist_selected)
    };
    app.library.left_state.select(sel);

    let title_text = match app.library.sort_mode {
        SortMode::ByArtist => " Исполнители ",
        SortMode::ByAlbum => " Альбомы ",
        SortMode::ByFilename => " Источник ",
    };
    let album_color = Color::Rgb(100, 149, 237);
    let title = Span::styled(title_text, Style::default().fg(album_color));

    let list = List::new(items)
        .block(Block::default().borders(Borders::ALL).title(title))
        .highlight_style(highlight)
        .highlight_symbol("> ");

    f.render_stateful_widget(list, area, &mut app.library.left_state);
}

fn fmt_dur(d: std::time::Duration) -> String {
    if d.is_zero() {
        "--:--".into()
    } else {
        format!("{}:{:02}", d.as_secs() / 60, d.as_secs() % 60)
    }
}

fn draw_right_panel(f: &mut Frame, app: &mut App, area: Rect) {
    f.render_widget(Clear, area);

    let rows = app.library.current_right_rows();

    let items: Vec<ListItem> = rows
        .iter()
        .enumerate()
        .map(|(idx, row)| match row {
            RightRow::AlbumHeader { name } => {
                let mut album_total = std::time::Duration::ZERO;
                let mut i = idx + 1;
                while i < rows.len() {
                    if let RightRow::Track { index_in_library } = rows[i] {
                        if let Some(t) = app.library.track(index_in_library) {
                            album_total += t.duration;
                        }
                        i += 1;
                    } else {
                        break;
                    }
                }
                let total_str = fmt_dur(album_total);

                let inner_width = area.width.saturating_sub(6) as usize;
                let pad = inner_width
                    .saturating_sub(name.len() + total_str.len() + 4)
                    .max(1);
                let line = format!("{} ] {} {}", name, "─".repeat(pad), total_str);

                let album_color = Color::Rgb(100, 149, 237);

                ListItem::new(Line::from(vec![
                    Span::styled("[ ", Style::default().fg(album_color)),
                    Span::styled(
                        line,
                        Style::default()
                            .fg(album_color)
                            .add_modifier(Modifier::BOLD),
                    ),
                ]))
            }
            RightRow::Track { index_in_library } => {
                let is_playing = Some(*index_in_library) == app.playing_index;
                let marker = if is_playing { "♪ " } else { "  " };

                let (title, num, dur) = match app.library.track(*index_in_library) {
                    Some(t) => (
                        t.title.clone(),
                        t.track_number
                            .map(|n| format!("{:02}. ", n))
                            .unwrap_or_default(),
                        fmt_dur(t.duration),
                    ),
                    None => ("<unknown>".into(), String::new(), "--:--".into()),
                };

                let style = if is_playing {
                    Style::default().fg(Color::Green)
                } else {
                    Style::default()
                };

                let left = format!("  {}{}{}", marker, num, title);
                let inner_width = area.width.saturating_sub(4) as usize;

                let left_len = left.chars().count();
                let dur_len = dur.chars().count();
                let pad = inner_width
                    .saturating_sub(left_len + dur_len)
                    .max(1);

                ListItem::new(Line::from(vec![
                    Span::styled(left, style),
                    Span::raw(" ".repeat(pad)),
                    Span::styled(dur, style),
                ]))
            }
        })
        .collect();

    let selected_name = app
        .library
        .artists
        .get(app.library.artist_selected)
        .map(|a| a.name.as_str())
        .unwrap_or("—");

    let title_text = match app.library.sort_mode {
        SortMode::ByArtist => {
            if app.library.filter.is_empty() {
                format!(" Альбомы и треки - {} ", selected_name)
            } else {
                format!(
                    " Альбомы и треки - {} [{}] ",
                    selected_name, app.library.filter
                )
            }
        }
        SortMode::ByAlbum => {
            if app.library.filter.is_empty() {
                format!(" Исполнители и треки - {} ", selected_name)
            } else {
                format!(
                    " Исполнители и треки - {} [{}] ",
                    selected_name, app.library.filter
                )
            }
        }
        SortMode::ByFilename => {
            if app.library.filter.is_empty() {
                " Альбомы и треки ".into()
            } else {
                format!(" Альбомы и треки [{}] ", app.library.filter)
            }
        }
    };
    let album_color = Color::Rgb(100, 149, 237);
    let title = Span::styled(title_text, Style::default().fg(album_color));

    let highlight = if app.active_panel == Panel::Right {
        Style::default().add_modifier(Modifier::REVERSED)
    } else {
        Style::default().add_modifier(Modifier::DIM)
    };

    let sel = if rows.is_empty() {
        None
    } else {
        Some(app.library.right_selected)
    };
    app.library.right_state.select(sel);

    let list = List::new(items)
        .block(Block::default().borders(Borders::ALL).title(title))
        .highlight_style(highlight)
        .highlight_symbol("> ");

    f.render_stateful_widget(list, area, &mut app.library.right_state);
}

fn draw_equalizer(f: &mut Frame, app: &App, area: Rect) {
    let inner_width = area.width.saturating_sub(1) as usize;
    if inner_width == 0 {
        return;
    }

    let num_bars = (inner_width / 2).max(4);

    let bars_data = app.player.spectrum.bars();
    let step = (bars_data.len() / num_bars).max(1);

    let mut display: Vec<f32> = Vec::with_capacity(num_bars);
    for i in 0..num_bars {
        let start = i * step;
        let end = (start + step).min(bars_data.len());
        if start >= bars_data.len() {
            display.push(0.0);
            continue;
        }
        let sum: f32 = bars_data[start..end].iter().sum();
        display.push(sum / (end - start).max(1) as f32);
    }

    let bars: Vec<Bar> = display
        .iter()
        .map(|&v| {
            Bar::default()
                .value((v * 100.0) as u64)
                .style(Style::default().fg(Color::Rgb(100, 149, 237)))
        })
        .collect();

    let chart = BarChart::default()
        .data(BarGroup::default().bars(&bars))
        .bar_width(1)
        .bar_gap(1)
        .max(100)
        .bar_set(ratatui::symbols::bar::NINE_LEVELS)
        .block(
            Block::default()
                .borders(Borders::ALL)
                .title(" Эквалайзер ")
                .title_style(Style::default().fg(Color::Rgb(100, 149, 237))),
        );

    f.render_widget(chart, area);
}

fn draw_status(f: &mut Frame, app: &App, area: Rect) {
    let inner = Layout::default()
        .direction(Direction::Horizontal)
        .constraints([
            Constraint::Min(1),
            Constraint::Length(18),
            Constraint::Length(16),
            Constraint::Length(12),
        ])
        .split(area);

    let (status_text, status_title) = match app.input_mode {
        InputMode::Search => (format!(">{}", app.search_buffer), " Поиск "),
        InputMode::Command => (format!(":{}", app.command_buffer), " Команда "),
        InputMode::Normal => {
            let prefix = if app.player.is_paused() { "|| " } else { "   " };
            (format!("{}{}", prefix, app.status), " Статус ")
        }
    };

    let status = Paragraph::new(status_text)
        .block(
            Block::default()
                .borders(Borders::ALL)
                .title(status_title)
                .title_style(Style::default().fg(Color::Rgb(100, 149, 237)))
        );
    f.render_widget(status, inner[0]);

    let (pos, total) = app.progress();
    let time_text = format!(
        "{:02}:{:02} / {:02}:{:02}",
        pos.as_secs() / 60,
        pos.as_secs() % 60,
        total.as_secs() / 60,
        total.as_secs() % 60,
    );
    let time = Paragraph::new(time_text)
        .alignment(Alignment::Center)
        .block(
            Block::default()
                .borders(Borders::ALL)
                .title(" Время ")
                .title_style(Style::default().fg(Color::Rgb(100, 149, 237)))
        );
    f.render_widget(time, inner[1]);

    let mode_str = match (app.repeat, app.shuffle) {
        (RepeatMode::Off, false) => "".to_string(),
        (RepeatMode::Off, true) => "SHUF".to_string(),
        (RepeatMode::All, false) => "RPT ALL".to_string(),
        (RepeatMode::One, false) => "RPT ONE".to_string(),
        (RepeatMode::All, true) => "RPT+SHUF".to_string(),
        (RepeatMode::One, true) => "ONE+SHUF".to_string(),
    };
    let mode = Paragraph::new(mode_str)
        .alignment(Alignment::Center)
        .block(
           Block::default()
           .borders(Borders::ALL)
           .title(" Режим ")
           .title_style(Style::default().fg(Color::Rgb(100, 149, 237)))
        );
    f.render_widget(mode, inner[2]);

    let vol_text = format!("Vol: {}%", (app.player.volume() * 100.0) as u32);
    let vol = Paragraph::new(vol_text)
        .alignment(Alignment::Center)
        .block(
           Block::default()
           .borders(Borders::ALL)
           .title(" Звук ")
           .title_style(Style::default().fg(Color::Rgb(100, 149, 237)))
        );
    f.render_widget(vol, inner[3]);
}

fn draw_dirs(f: &mut Frame, app: &App, screen: Rect) {
    let count = app.sources().len();

    // Строки: заголовок (1) + пустая (1) + "Список" (1) + N + пустая (1) + подсказка (1)
    let content_lines = 5 + count;
    let desired_height = (content_lines + 2) as u16;

    let width = 70u16.min(screen.width.saturating_sub(4));
    let max_h = screen.height.saturating_sub(4);
    let height = desired_height.min(max_h).max(5);

    let x = (screen.width.saturating_sub(width)) / 2;
    let y = (screen.height.saturating_sub(height)) / 2;
    let area = Rect::new(x, y, width, height);

    f.render_widget(Clear, area);

    let title_color = Style::default().fg(Color::Rgb(100, 149, 237));
    let header = Style::default()
        .fg(Color::Yellow)
        .add_modifier(Modifier::BOLD);
    let dim = Style::default().fg(Color::DarkGray);

    let mut lines = vec![
        Line::from(Span::styled(
            "  Источники библиотеки  ",
            title_color.add_modifier(Modifier::BOLD),
        )),
        Line::from(""),
        Line::from(Span::styled("  Список", header)),
    ];

    for (i, src) in app.sources().iter().enumerate() {
        lines.push(Line::from(vec![
            Span::styled(format!("  [{}] ", i), dim),
            Span::raw(src.clone()),
        ]));
    }

    lines.push(Line::from(""));
    lines.push(Line::from(Span::styled(
        "  :rm <N> — удалить, Esc — закрыть",
        dim,
    )));

    let para = Paragraph::new(lines)
        .block(
            Block::default()
                .borders(Borders::ALL)
                .border_style(title_color)
                .title(" Библиотека "),
        )
        .wrap(Wrap { trim: false });

    f.render_widget(para, area);
}

fn draw_help(f: &mut Frame, screen: Rect) {
    let width = 62u16.min(screen.width.saturating_sub(4));
    let height = 44u16.min(screen.height.saturating_sub(4));

    let x = (screen.width.saturating_sub(width)) / 2;
    let y = (screen.height.saturating_sub(height)) / 2;
    let area = Rect::new(x, y, width, height);

    f.render_widget(Clear, area);

    let header = Style::default()
        .fg(Color::Yellow)
        .add_modifier(Modifier::BOLD);
    let title_color = Style::default().fg(Color::Rgb(100, 149, 237));

    let help_text = vec![
        Line::from(Span::styled(
            "  Управление плеером  ",
            title_color.add_modifier(Modifier::BOLD),
        )),
        Line::from(""),
        Line::from(Span::styled("  Навигация", header)),
        Line::from("  w / ↑          вверх по списку"),
        Line::from("  s / ↓          вниз по списку"),
        Line::from("  Tab            переключить панель"),
        Line::from("  g / G          в начало / в конец списка"),
        Line::from("  f              к играющему треку"),
        Line::from(""),
        Line::from(Span::styled("  Воспроизведение", header)),
        Line::from("  Enter          играть выделенный трек"),
        Line::from("  Space          пауза / продолжить"),
        Line::from("  z              стоп"),
        Line::from("  Ctrl+→ / Ctrl+d   следующий трек"),
        Line::from("  Ctrl+← / Ctrl+a   предыдущий трек"),
        Line::from("  r              repeat: off → all → one"),
        Line::from("  x              shuffle вкл/выкл"),
        Line::from(""),
        Line::from(Span::styled("  Перемотка", header)),
        Line::from("  a / ←          −5 секунд"),
        Line::from("  d / →          +5 секунд"),
        Line::from("  1..9           перейти к 10%..90% трека"),
        Line::from(""),
        Line::from(Span::styled("  Команды", header)),
        Line::from("  :add <путь>    добавить в сессию"),
        Line::from("  :load <путь>   заменить сессию"),
        Line::from("  :reload        пересканировать всё"),
        Line::from("  :save          сохранить библиотеку"),
        Line::from("  :savepl <файл> экспорт в M3U/PLS"),
        Line::from("  :dirs          список источников"),
        Line::from("  :rm <N>        удалить источник"),
        Line::from("  :clear         очистить источники"),
        Line::from("  :help          эта справка"),
        Line::from("  :q             выход"),
        Line::from(""),
        Line::from(Span::styled("  Звук и прочее", header)),
        Line::from("  + / -          громкость"),
        Line::from("  /              поиск"),
        Line::from("  Del            удалить из списка"),
        Line::from("  t              сортировка: артист → альбом → файл"),
        Line::from("  F1             эта справка"),
        Line::from("  q / Esc        выход"),
        Line::from(""),
        Line::from(Span::styled(
            "  F1 или Esc - закрыть  ",
            Style::default().fg(Color::DarkGray),
        )),
    ];

    let help = Paragraph::new(help_text).block(
        Block::default()
            .borders(Borders::ALL)
            .border_style(title_color)
            .title(" Помощь "),
    );

    f.render_widget(help, area);
}