use std::marker::PhantomData;

use musichoard::TrackFormat;
use ratatui::{
    backend::Backend,
    layout::{Alignment, Rect},
    style::{Color, Style},
    widgets::{Block, BorderType, Borders, List, ListItem, ListState, Paragraph},
    Frame,
};

use super::app::{App, Category};

struct ArtistArea {
    list: Rect,
}

struct AlbumArea {
    list: Rect,
    info: Rect,
}

struct TrackArea {
    list: Rect,
    info: Rect,
}

struct FrameAreas {
    artists: ArtistArea,
    albums: AlbumArea,
    tracks: TrackArea,
}

struct SelectionList<'a> {
    list: List<'a>,
    state: ListState,
}

struct ArtistState<'a> {
    list: SelectionList<'a>,
    active: bool,
}

struct AlbumState<'a> {
    list: SelectionList<'a>,
    info: Paragraph<'a>,
    active: bool,
}

struct TrackState<'a> {
    list: SelectionList<'a>,
    info: Paragraph<'a>,
    active: bool,
}

struct AppState<'a> {
    artists: ArtistState<'a>,
    albums: AlbumState<'a>,
    tracks: TrackState<'a>,
}

pub struct Ui<APP> {
    _phantom: PhantomData<APP>,
}

impl<APP: App> Ui<APP> {
    pub fn new() -> Self {
        Ui {
            _phantom: PhantomData,
        }
    }

    fn construct_areas(frame: Rect) -> FrameAreas {
        let width_one_third = frame.width / 3;
        let height_one_third = frame.height / 3;

        let panel_width = width_one_third;
        let panel_width_last = frame.width - 2 * panel_width;
        let panel_height_top = frame.height - height_one_third;
        let panel_height_bottom = height_one_third;

        let artist_list = Rect {
            x: frame.x,
            y: frame.y,
            width: panel_width,
            height: frame.height,
        };

        let album_list = Rect {
            x: artist_list.x + artist_list.width,
            y: frame.y,
            width: panel_width,
            height: panel_height_top,
        };

        let album_info = Rect {
            x: album_list.x,
            y: album_list.y + album_list.height,
            width: album_list.width,
            height: panel_height_bottom,
        };

        let track_list = Rect {
            x: album_list.x + album_list.width,
            y: frame.y,
            width: panel_width_last,
            height: panel_height_top,
        };

        let track_info = Rect {
            x: track_list.x,
            y: track_list.y + track_list.height,
            width: track_list.width,
            height: panel_height_bottom,
        };

        FrameAreas {
            artists: ArtistArea { list: artist_list },
            albums: AlbumArea {
                list: album_list,
                info: album_info,
            },
            tracks: TrackArea {
                list: track_list,
                info: track_info,
            },
        }
    }

    fn construct_artist_list(app: &APP) -> ArtistState {
        let artists = app.get_artist_ids();
        let list = List::new(
            artists
                .iter()
                .map(|id| ListItem::new(id.name.as_str()))
                .collect::<Vec<ListItem>>(),
        );

        let selected_artist = app.selected_artist();

        let mut state = ListState::default();
        state.select(selected_artist);

        let active = app.get_active_category() == Category::Artist;

        ArtistState {
            list: SelectionList { list, state },
            active,
        }
    }

    fn construct_album_list(app: &APP) -> AlbumState {
        let albums = app.get_album_ids();
        let list = List::new(
            albums
                .iter()
                .map(|id| ListItem::new(id.title.as_str()))
                .collect::<Vec<ListItem>>(),
        );

        let selected_album = app.selected_album();

        let mut state = ListState::default();
        state.select(selected_album);

        let active = app.get_active_category() == Category::Album;

        let album = selected_album.map(|i| albums[i]);
        let info = Paragraph::new(format!(
            "Title: {}\n\
             Year: {}",
            album.map(|a| a.title.as_str()).unwrap_or(""),
            album
                .map(|a| a.year.to_string())
                .unwrap_or_else(|| "".to_string()),
        ));

        AlbumState {
            list: SelectionList { list, state },
            info,
            active,
        }
    }

    fn construct_track_list(app: &APP) -> TrackState {
        let tracks = app.get_track_ids();
        let list = List::new(
            tracks
                .iter()
                .map(|id| ListItem::new(id.title.as_str()))
                .collect::<Vec<ListItem>>(),
        );

        let selected_track = app.selected_track();

        let mut state = ListState::default();
        state.select(selected_track);

        let active = app.get_active_category() == Category::Track;

        let track = selected_track.map(|i| tracks[i]);
        let info = Paragraph::new(format!(
            "Track: {}\n\
             Title: {}\n\
             Artist: {}\n\
             Format: {}",
            track
                .map(|t| t.number.to_string())
                .unwrap_or_else(|| "".to_string()),
            track.map(|t| t.title.as_str()).unwrap_or(""),
            track
                .map(|t| t.artist.join("; "))
                .unwrap_or_else(|| "".to_string()),
            track
                .map(|t| match t.format {
                    TrackFormat::Flac => "FLAC",
                    TrackFormat::Mp3 => "MP3",
                })
                .unwrap_or(""),
        ));

        TrackState {
            list: SelectionList { list, state },
            info,
            active,
        }
    }

    fn construct_app_state(app: &APP) -> AppState {
        AppState {
            artists: Self::construct_artist_list(app),
            albums: Self::construct_album_list(app),
            tracks: Self::construct_track_list(app),
        }
    }

    fn style(_active: bool) -> Style {
        Style::default().fg(Color::White).bg(Color::Black)
    }

    fn block_style(active: bool) -> Style {
        Self::style(active)
    }

    fn highlight_style(active: bool) -> Style {
        if active {
            Style::default().fg(Color::White).bg(Color::DarkGray)
        } else {
            Self::style(false)
        }
    }

    fn block<'a>(title: &str, active: bool) -> Block<'a> {
        Block::default()
            .title_alignment(Alignment::Center)
            .borders(Borders::ALL)
            .border_type(BorderType::Rounded)
            .style(Self::block_style(active))
            .title(format!(" {title} "))
    }

    fn render_list_widget<B: Backend>(
        title: &str,
        mut list: SelectionList,
        active: bool,
        area: Rect,
        frame: &mut Frame<'_, B>,
    ) {
        frame.render_stateful_widget(
            list.list
                .highlight_style(Self::highlight_style(active))
                .highlight_symbol(">> ")
                .style(Self::style(active))
                .block(Self::block(title, active)),
            area,
            &mut list.state,
        );
    }

    fn render_info_widget<B: Backend>(
        title: &str,
        paragraph: Paragraph,
        active: bool,
        area: Rect,
        frame: &mut Frame<'_, B>,
    ) {
        frame.render_widget(
            paragraph
                .style(Self::style(active))
                .block(Self::block(title, active)),
            area,
        );
    }

    fn render_artist_column<B: Backend>(
        state: ArtistState,
        area: ArtistArea,
        frame: &mut Frame<'_, B>,
    ) {
        Self::render_list_widget("Artists", state.list, state.active, area.list, frame);
    }

    fn render_album_column<B: Backend>(
        state: AlbumState,
        area: AlbumArea,
        frame: &mut Frame<'_, B>,
    ) {
        Self::render_list_widget("Albums", state.list, state.active, area.list, frame);
        Self::render_info_widget("Album info", state.info, state.active, area.info, frame);
    }

    fn render_track_column<B: Backend>(
        state: TrackState,
        area: TrackArea,
        frame: &mut Frame<'_, B>,
    ) {
        Self::render_list_widget("Tracks", state.list, state.active, area.list, frame);
        Self::render_info_widget("Track info", state.info, state.active, area.info, frame);
    }

    pub fn render<B: Backend>(&self, app: &APP, frame: &mut Frame<'_, B>) {
        let areas = Self::construct_areas(frame.size());
        let app_state = Self::construct_app_state(app);

        Self::render_artist_column(app_state.artists, areas.artists, frame);
        Self::render_album_column(app_state.albums, areas.albums, frame);
        Self::render_track_column(app_state.tracks, areas.tracks, frame);
    }
}

#[cfg(test)]
mod tests {
    // This is UI so the only sensible unit test is to run the code through various app states.

    use crate::{
        tests::COLLECTION,
        tui::{
            app::App,
            tests::{app, terminal},
        },
    };

    use super::Ui;

    #[test]
    fn empty() {
        let mut terminal = terminal();
        let app = app(vec![]);
        let ui = Ui::new();

        terminal.draw(|frame| ui.render(&app, frame)).unwrap();
    }

    #[test]
    fn collection() {
        let mut terminal = terminal();
        let mut app = app(COLLECTION.to_owned());
        let ui = Ui::new();

        terminal.draw(|frame| ui.render(&app, frame)).unwrap();

        // Change the track (which has a different track format).
        app.increment_category();
        app.increment_category();
        app.increment_selection();

        terminal.draw(|frame| ui.render(&app, frame)).unwrap();
    }
}