#![allow(dead_code)]

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

use crate::data::{Album, AlbumStatus, Artist, MonitorState, Track};
use crate::theme;
use crate::ui::pane::{Pane, section_divider};
use crate::ui::progress_bar::progress_bar;

#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum LibraryFocus {
    #[default]
    Artists,
    Albums,
    Tracks,
}

pub struct LibraryState {
    pub artists: Vec<Artist>,
    pub focus: LibraryFocus,
    pub artist_state: ListState,
    pub album_state: ListState,
    pub track_state: ListState,
}

impl LibraryState {
    pub fn new(artists: Vec<Artist>) -> Self {
        let mut artist_state = ListState::default();
        let mut album_state = ListState::default();
        let mut track_state = ListState::default();

        if !artists.is_empty() {
            artist_state.select(Some(0));
            if !artists[0].albums.is_empty() {
                album_state.select(Some(0));
                track_state.select(Some(0));
            }
        }

        Self {
            artists,
            focus: LibraryFocus::Artists,
            artist_state,
            album_state,
            track_state,
        }
    }

    pub fn selected_artist(&self) -> Option<&Artist> {
        self.artist_state
            .selected()
            .and_then(|i| self.artists.get(i))
    }

    pub fn selected_album(&self) -> Option<&Album> {
        self.selected_artist()
            .and_then(|a| self.album_state.selected().and_then(|i| a.albums.get(i)))
    }

    pub fn move_up(&mut self) {
        match self.focus {
            LibraryFocus::Artists => {
                if let Some(i) = self.artist_state.selected() {
                    if i > 0 {
                        self.artist_state.select(Some(i - 1));
                        self.reset_album_selection();
                    }
                }
            }
            LibraryFocus::Albums => {
                if let Some(i) = self.album_state.selected() {
                    if i > 0 {
                        self.album_state.select(Some(i - 1));
                        self.reset_track_selection();
                    }
                }
            }
            LibraryFocus::Tracks => {
                if let Some(i) = self.track_state.selected() {
                    if i > 0 {
                        self.track_state.select(Some(i - 1));
                    }
                }
            }
        }
    }

    pub fn move_down(&mut self) {
        match self.focus {
            LibraryFocus::Artists => {
                let max = self.artists.len().saturating_sub(1);
                if let Some(i) = self.artist_state.selected() {
                    if i < max {
                        self.artist_state.select(Some(i + 1));
                        self.reset_album_selection();
                    }
                }
            }
            LibraryFocus::Albums => {
                let max = self
                    .selected_artist()
                    .map(|a| a.albums.len().saturating_sub(1))
                    .unwrap_or(0);
                if let Some(i) = self.album_state.selected() {
                    if i < max {
                        self.album_state.select(Some(i + 1));
                        self.reset_track_selection();
                    }
                }
            }
            LibraryFocus::Tracks => {
                let max = self.track_count().saturating_sub(1);
                if let Some(i) = self.track_state.selected() {
                    if i < max {
                        self.track_state.select(Some(i + 1));
                    }
                }
            }
        }
    }

    fn track_count(&self) -> usize {
        self.selected_album().map(|a| a.total as usize).unwrap_or(0)
    }

    pub fn focus_left(&mut self) {
        match self.focus {
            LibraryFocus::Artists => {}
            LibraryFocus::Albums => self.focus = LibraryFocus::Artists,
            LibraryFocus::Tracks => self.focus = LibraryFocus::Albums,
        }
    }

    pub fn focus_right(&mut self) {
        match self.focus {
            LibraryFocus::Artists => {
                if self.selected_artist().is_some() {
                    self.focus = LibraryFocus::Albums;
                }
            }
            LibraryFocus::Albums => {
                if self.selected_album().is_some() {
                    self.focus = LibraryFocus::Tracks;
                }
            }
            LibraryFocus::Tracks => {}
        }
    }

    pub fn cycle_focus(&mut self) {
        self.focus = match self.focus {
            LibraryFocus::Artists => LibraryFocus::Albums,
            LibraryFocus::Albums => LibraryFocus::Tracks,
            LibraryFocus::Tracks => LibraryFocus::Artists,
        };
    }

    fn reset_album_selection(&mut self) {
        if let Some(artist) = self.selected_artist() {
            if !artist.albums.is_empty() {
                self.album_state.select(Some(0));
            } else {
                self.album_state.select(None);
            }
        }
        self.reset_track_selection();
    }

    fn reset_track_selection(&mut self) {
        if self.selected_album().is_some() {
            self.track_state.select(Some(0));
        } else {
            self.track_state.select(None);
        }
    }

    pub fn artist_count(&self) -> usize {
        self.artists.len()
    }

    pub fn selected_artist_index(&self) -> Option<usize> {
        self.artist_state.selected()
    }
}

fn status_icon(status: AlbumStatus, monitored: bool) -> (char, Style) {
    if !monitored {
        return ('◌', Style::default().fg(theme::GRAY));
    }
    match status {
        AlbumStatus::Complete => ('●', Style::default().fg(theme::GREEN)),
        AlbumStatus::Partial => ('◐', Style::default().fg(theme::YELLOW)),
        AlbumStatus::Wanted => ('○', Style::default().fg(theme::RED)),
        AlbumStatus::Unmonitored => ('◌', Style::default().fg(theme::GRAY)),
    }
}

fn monitor_state_icon(state: MonitorState, status: AlbumStatus) -> (char, Style) {
    match state {
        MonitorState::Monitored => match status {
            AlbumStatus::Complete => ('✓', Style::default().fg(theme::GREEN)),
            AlbumStatus::Partial => ('◐', Style::default().fg(theme::YELLOW)),
            AlbumStatus::Wanted => ('!', Style::default().fg(theme::RED)),
            AlbumStatus::Unmonitored => ('-', Style::default().fg(theme::GRAY)),
        },
        MonitorState::Unmonitored => ('-', Style::default().fg(theme::GRAY)),
        MonitorState::Excluded => ('x', Style::default().fg(theme::RED)),
        MonitorState::Unspecified => ('?', Style::default().fg(theme::GRAY)),
    }
}

fn track_icon(have: bool) -> (char, Style) {
    if have {
        ('✓', Style::default().fg(theme::GREEN))
    } else {
        ('✗', Style::default().fg(theme::RED))
    }
}

fn artist_status(artist: &Artist) -> AlbumStatus {
    let total: u16 = artist.albums.iter().map(|a| a.total).sum();
    let have: u16 = artist.albums.iter().map(|a| a.have).sum();
    if have == total {
        AlbumStatus::Complete
    } else if have == 0 {
        AlbumStatus::Wanted
    } else {
        AlbumStatus::Partial
    }
}

fn fmt_size(gb: f64) -> String {
    if gb >= 1.0 {
        format!("{:.1} GB", gb)
    } else {
        format!("{} MB", (gb * 1024.0).round() as u32)
    }
}

pub fn render_library(frame: &mut Frame, area: Rect, state: &mut LibraryState) {
    let chunks = Layout::horizontal([Constraint::Length(32), Constraint::Fill(1)]).split(area);

    render_artists_pane(frame, chunks[0], state);
    render_detail_pane(frame, chunks[1], state);
}

fn render_artists_pane(frame: &mut Frame, area: Rect, state: &mut LibraryState) {
    let focused = state.focus == LibraryFocus::Artists;
    let artist_count = state.artists.len();

    let total_albums: usize = state.artists.iter().map(|a| a.albums.len()).sum();
    let total_size: f64 = state.artists.iter().map(|a| a.size_gb).sum();

    let footer = Line::from(vec![
        Span::styled(
            format!("{} artists · {} alb", artist_count, total_albums),
            Style::default().fg(theme::GRAY),
        ),
        Span::raw("  "),
        Span::styled(fmt_size(total_size), Style::default().fg(theme::GRAY)),
    ]);

    let artist_count_str = artist_count.to_string();
    let pane = Pane::new("Artists")
        .meta(&artist_count_str)
        .focused(focused)
        .footer(footer);

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

    let items: Vec<ListItem> = state
        .artists
        .iter()
        .map(|artist| {
            let status = artist_status(artist);
            let (icon_char, icon_style) = monitor_state_icon(artist.monitor_state, status);

            let total: u16 = artist.albums.iter().map(|a| a.total).sum();
            let have: u16 = artist.albums.iter().map(|a| a.have).sum();

            let mut name_text = artist.name.clone();

            let count_str = format!("{}/{}", have, total);
            let name_width = inner.width as usize - 2 - count_str.len() - 2;
            if name_text.len() > name_width {
                name_text.truncate(name_width.saturating_sub(1));
                name_text.push('…');
            }

            let padding = name_width.saturating_sub(name_text.len());

            Line::from(vec![
                Span::styled(format!("{} ", icon_char), icon_style),
                Span::styled(name_text, Style::default().fg(theme::FG1)),
                Span::raw(" ".repeat(padding)),
                Span::styled(count_str, Style::default().fg(theme::GRAY)),
            ])
            .into()
        })
        .collect();

    let highlight_style = if focused {
        Style::default().bg(theme::YELLOW).fg(theme::BG0)
    } else {
        Style::default().bg(theme::SELECT_BG).fg(theme::FG1)
    };

    let list = List::new(items).highlight_style(highlight_style);
    frame.render_stateful_widget(list, inner, &mut state.artist_state);
}

fn render_detail_pane(frame: &mut Frame, area: Rect, state: &mut LibraryState) {
    let focused = state.focus == LibraryFocus::Albums || state.focus == LibraryFocus::Tracks;

    let artist = state.selected_artist();

    let meta = artist
        .map(|a| {
            format!(
                "{} · {}",
                a.country,
                a.genres.first().map(|s| s.as_str()).unwrap_or("")
            )
        })
        .unwrap_or_default();

    let have_tracks: u16 = artist
        .map(|a| a.albums.iter().map(|al| al.have).sum())
        .unwrap_or(0);
    let total_tracks: u16 = artist
        .map(|a| a.albums.iter().map(|al| al.total).sum())
        .unwrap_or(0);

    let footer = if artist.is_some() {
        Line::from(vec![Span::styled(
            format!("{}/{} tracks", have_tracks, total_tracks),
            Style::default().fg(theme::GRAY),
        )])
    } else {
        Line::from("")
    };

    let pane = Pane::new("Detail")
        .meta(&meta)
        .focused(focused)
        .footer(footer);

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

    let Some(artist) = artist else {
        let msg = Paragraph::new(Span::styled(
            "No artist selected",
            Style::default().fg(theme::GRAY),
        ));
        frame.render_widget(msg, inner);
        return;
    };

    let chunks = Layout::vertical([
        Constraint::Length(6),
        Constraint::Length(1),
        Constraint::Percentage(40),
        Constraint::Length(1),
        Constraint::Fill(1),
    ])
    .split(inner);

    render_artist_header(frame, chunks[0], artist);

    let albums_count = artist.albums.len();
    let albums_label = format!("{} releases", albums_count);
    let album_divider = section_divider("albums", Some(&albums_label));
    frame.render_widget(Paragraph::new(album_divider), chunks[1]);

    let selected_artist_idx = state.artist_state.selected();
    if let Some(idx) = selected_artist_idx {
        if let Some(artist) = state.artists.get(idx) {
            let albums = artist.albums.clone();
            let focus = state.focus;
            render_albums_list(frame, chunks[2], &albums, focus, &mut state.album_state);
        }
    }

    let album_title = state
        .selected_album()
        .map(|a| a.title.clone())
        .unwrap_or_default();
    let track_counts = state
        .selected_album()
        .map(|a| format!("{}/{}", a.have, a.total))
        .unwrap_or_default();
    let track_label = format!("tracks · {}", album_title);
    let track_divider = section_divider(&track_label, Some(&track_counts));
    frame.render_widget(Paragraph::new(track_divider), chunks[3]);

    render_tracks_list(frame, chunks[4], state);
}

fn render_artist_header(frame: &mut Frame, area: Rect, artist: &Artist) {
    let have: u16 = artist.albums.iter().map(|a| a.have).sum();
    let total: u16 = artist.albums.iter().map(|a| a.total).sum();

    let (status_icon, status_text, status_style) = match artist.monitor_state {
        MonitorState::Monitored => (
            Span::styled("● ", Style::default().fg(theme::GREEN)),
            "Monitored",
            Style::default().fg(theme::FG2),
        ),
        MonitorState::Unmonitored => (
            Span::styled("◌ ", Style::default().fg(theme::GRAY)),
            "Unmonitored",
            Style::default().fg(theme::GRAY),
        ),
        MonitorState::Excluded => (
            Span::styled("⊘ ", Style::default().fg(theme::RED)),
            "Excluded",
            Style::default().fg(theme::RED),
        ),
        MonitorState::Unspecified => (
            Span::styled("? ", Style::default().fg(theme::GRAY)),
            "Unknown",
            Style::default().fg(theme::GRAY),
        ),
    };

    let lines = vec![
        Line::from(Span::styled(
            &artist.name,
            Style::default()
                .fg(theme::YELLOW)
                .add_modifier(Modifier::BOLD),
        )),
        Line::from(""),
        Line::from(vec![
            Span::styled("status  ", Style::default().fg(theme::GRAY)),
            status_icon,
            Span::styled(status_text, status_style),
            Span::raw("   "),
            Span::styled("path  ", Style::default().fg(theme::GRAY)),
            Span::styled(&artist.path, Style::default().fg(theme::AQUA)),
        ]),
        Line::from(vec![
            Span::styled("quality ", Style::default().fg(theme::GRAY)),
            Span::styled(&artist.quality, Style::default().fg(theme::FG1)),
            Span::raw("   "),
            Span::styled("size  ", Style::default().fg(theme::GRAY)),
            Span::styled(fmt_size(artist.size_gb), Style::default().fg(theme::FG1)),
        ]),
        Line::from(vec![
            Span::styled("albums  ", Style::default().fg(theme::GRAY)),
            Span::styled(
                artist.albums.len().to_string(),
                Style::default().fg(theme::FG1),
            ),
            Span::raw("   "),
            Span::styled("tracks ", Style::default().fg(theme::GRAY)),
            Span::styled(have.to_string(), Style::default().fg(theme::FG1)),
            Span::styled(format!(" / {}", total), Style::default().fg(theme::GRAY)),
        ]),
    ];

    let paragraph = Paragraph::new(lines).style(Style::default().bg(theme::BG0));
    frame.render_widget(paragraph, area);
}

fn render_albums_list(
    frame: &mut Frame,
    area: Rect,
    albums: &[Album],
    focus: LibraryFocus,
    album_state: &mut ListState,
) {
    let focused = focus == LibraryFocus::Albums;

    let items: Vec<ListItem> = albums
        .iter()
        .map(|album| {
            let (icon_char, icon_style) = status_icon(album.status, album.monitored);
            let type_str = format!("[{}]", album.album_type);
            let year_str = album.year.to_string();
            let progress = progress_bar(album.have, album.total, 10, album.status);
            let count_str = format!("{}/{}", album.have, album.total);

            let quality_style = if album.quality == "—" {
                Style::default().fg(theme::GRAY)
            } else {
                Style::default().fg(theme::AQUA)
            };

            let title_width =
                area.width as usize - 2 - type_str.len() - 1 - 4 - 1 - 10 - 1 - 5 - 1 - 8;
            let mut title = album.title.clone();
            if title.len() > title_width {
                title.truncate(title_width.saturating_sub(1));
                title.push('…');
            }

            let mut spans = vec![
                Span::styled(format!("{} ", icon_char), icon_style),
                Span::styled(title, Style::default().fg(theme::FG1)),
                Span::raw(" "),
                Span::styled(type_str, Style::default().fg(theme::GRAY)),
                Span::raw(" "),
                Span::styled(year_str, Style::default().fg(theme::GRAY)),
                Span::raw(" "),
            ];
            spans.extend(progress.spans);
            spans.push(Span::raw(" "));
            spans.push(Span::styled(count_str, Style::default().fg(theme::GRAY)));
            spans.push(Span::raw(" "));
            spans.push(Span::styled(&album.quality, quality_style));

            Line::from(spans).into()
        })
        .collect();

    let highlight_style = if focused {
        Style::default().bg(theme::YELLOW).fg(theme::BG0)
    } else {
        Style::default().bg(theme::SELECT_BG).fg(theme::FG1)
    };

    let list = List::new(items).highlight_style(highlight_style);
    frame.render_stateful_widget(list, area, album_state);
}

fn render_tracks_list(frame: &mut Frame, area: Rect, state: &mut LibraryState) {
    let focused = state.focus == LibraryFocus::Tracks;
    let tracks = state.get_tracks();

    if tracks.is_empty() {
        let msg = Paragraph::new(Span::styled(
            "(no album selected)",
            Style::default().fg(theme::GRAY),
        ));
        frame.render_widget(msg, area);
        return;
    }

    let items: Vec<ListItem> = tracks
        .iter()
        .map(|track| {
            let (icon_char, icon_style) = track_icon(track.have);
            let num_str = format!("{:02}", track.number);

            let title_style = if track.have {
                Style::default().fg(theme::FG1)
            } else {
                Style::default().fg(theme::GRAY)
            };

            let quality_style = if track.have {
                Style::default().fg(theme::AQUA)
            } else {
                Style::default().fg(theme::RED)
            };

            Line::from(vec![
                Span::styled(format!("{} ", icon_char), icon_style),
                Span::styled(num_str, Style::default().fg(theme::GRAY)),
                Span::raw(" "),
                Span::styled(&track.title, title_style),
                Span::raw(" "),
                Span::styled(&track.duration, Style::default().fg(theme::GRAY)),
                Span::raw(" "),
                Span::styled(&track.quality, quality_style),
            ])
            .into()
        })
        .collect();

    let highlight_style = if focused {
        Style::default().bg(theme::YELLOW).fg(theme::BG0)
    } else {
        Style::default().bg(theme::SELECT_BG).fg(theme::FG1)
    };

    let list = List::new(items).highlight_style(highlight_style);
    frame.render_stateful_widget(list, area, &mut state.track_state);
}

impl LibraryState {
    pub fn get_tracks(&self) -> Vec<Track> {
        let Some(album) = self.selected_album() else {
            return Vec::new();
        };

        tracks_for(album)
    }
}

fn tracks_for(album: &Album) -> Vec<Track> {
    let titles = [
        "Opening",
        "Curtain Call",
        "Half-Light",
        "Polaroid",
        "Switchback",
        "Slow Dancer",
        "The Inheritance",
        "Glassworks",
        "Interlude",
        "Aftermath",
        "Static",
        "Returner",
        "Dust Bowl",
        "Postcard",
        "Late Reply",
        "Honeymoon",
        "Northern Lights",
        "Cold Open",
        "Coda",
        "Reprise",
    ];

    (0..album.total)
        .map(|i| {
            let idx = i as usize;
            let m = 2 + ((idx * 7) % 5);
            let s = (idx * 13) % 60;
            let title_idx = idx % titles.len();
            let title = if idx >= titles.len() {
                format!("{} II", titles[title_idx])
            } else {
                titles[title_idx].to_string()
            };
            let have = i < album.have;
            let quality = if have {
                album.quality.clone()
            } else {
                "—".to_string()
            };

            Track {
                number: i + 1,
                title,
                duration: format!("{}:{:02}", m, s),
                have,
                quality,
            }
        })
        .collect()
}