use std::time::{Duration, Instant};

use crate::audio::AudioPlayer;
use crate::library::{Library, SortMode};
use crate::state::{RepeatMode, SavedState};
use crate::track::{scan_dir, Track};

#[derive(Clone, Copy, PartialEq)]
pub enum Panel {
    Left,
    Right,
}

#[derive(Clone, Copy, PartialEq)]
pub enum InputMode {
    Normal,
    Search,
}

pub struct App {
    pub library: Library,
    pub player: AudioPlayer,
    pub status: String,
    pub playing_index: Option<usize>,
    pub active_panel: Panel,
    pub input_mode: InputMode,
    pub search_buffer: String,
    raw_tracks: Vec<Track>,
    music_dir: String,
    pub repeat: RepeatMode,
    pub shuffle: bool,
    pub show_help: bool,
    status_set_at: Instant,
}

const STATUS_RESET_AFTER: Duration = Duration::from_secs(2);

impl App {
    pub fn new(music_dir: &str) -> Result<Self, Box<dyn std::error::Error>> {
        let tracks = match crate::state::load_cache(music_dir) {
            Some(cached) => cached,
            None => {
                let scanned = scan_dir(music_dir);
                crate::state::save_cache(music_dir, &scanned);
                scanned
            }
        };

        let library = Library::build(tracks.clone(), SortMode::ByArtist);

        let mut app = Self {
            library,
            player: AudioPlayer::new()?,
            status: "F1 — помощь".into(),
            playing_index: None,
            active_panel: Panel::Left,
            input_mode: InputMode::Normal,
            search_buffer: String::new(),
            raw_tracks: tracks,
            music_dir: music_dir.to_string(),
            repeat: RepeatMode::Off,
            shuffle: false,
            show_help: false,
            status_set_at: Instant::now(),
        };

        let saved = crate::state::load();
        if let Some(vol) = saved.volume {
            app.player.set_volume(vol);
        }
        if let Some(rep) = saved.repeat {
            app.repeat = rep;
        }
        if let Some(sh) = saved.shuffle {
            app.shuffle = sh;
        }
        if let Some(mode) = saved.sort_mode {
            if mode != SortMode::ByArtist {
                app.library = Library::build(app.raw_tracks.clone(), mode);
            }
        }

        app.restore_playing(&saved);
        Ok(app)
    }

    fn set_status(&mut self, text: String) {
        self.status = text;
        self.status_set_at = Instant::now();
    }

    fn default_status(&self) -> String {
        match self.playing_index.and_then(|i| self.library.track(i)) {
            Some(t) => format!("▶ {} — {}", t.artist, t.title),
            None => "F1 — помощь".into(),
        }
    }

    pub fn tick_status(&mut self) {
        if self.input_mode == InputMode::Search {
            return;
        }
        if self.status_set_at.elapsed() < STATUS_RESET_AFTER {
            return;
        }
        let default = self.default_status();
        if self.status != default {
            self.status = default;
        }
    }

    fn restore_playing(&mut self, saved: &SavedState) {
        let Some(path_str) = &saved.last_playing_path else {
            return;
        };

        let target_path = std::path::PathBuf::from(path_str);
        let Some(idx) = self
            .library
            .all_tracks
            .iter()
            .position(|t| t.path == target_path)
        else {
            return;
        };

        let start_pos = saved.last_playing_pos_secs.map(Duration::from_secs);

        if let Some(track) = self.library.track(idx).cloned() {
            if self.player.play(&track.path, start_pos).is_ok() {
                self.playing_index = Some(idx);
                self.library.sync_with_playing(idx);
                self.player.toggle_pause();
                self.set_status(format!("Восстановлен: {} — {}", track.artist, track.title));
            }
        }
    }

    pub fn toggle_help(&mut self) {
        self.show_help = !self.show_help;
    }

    pub fn next_track(&mut self) {
        let total = self.library.all_tracks.len();
        if total == 0 {
            self.set_status("Библиотека пуста".into());
            return;
        }

        let next = match self.playing_index {
            Some(i) if i + 1 < total => i + 1,
            Some(_) => {
                if self.repeat == RepeatMode::Off {
                    self.set_status("Конец плейлиста".into());
                    return;
                }
                0
            }
            None => 0,
        };

        self.play_index(next);
        self.library.sync_with_playing(next);
    }

    pub fn prev_track(&mut self) {
        let total = self.library.all_tracks.len();
        if total == 0 {
            self.set_status("Библиотека пуста".into());
            return;
        }

        let prev = match self.playing_index {
            Some(0) => {
                if self.repeat == RepeatMode::Off {
                    self.set_status("Это первый трек".into());
                    return;
                }
                total - 1
            }
            Some(i) => i - 1,
            None => 0,
        };

        self.play_index(prev);
        self.library.sync_with_playing(prev);
    }

    fn persist(&self) {
        let playing_path = self
            .playing_index
            .and_then(|i| self.library.track(i))
            .map(|t| t.path.to_string_lossy().to_string());

        let playing_pos = if self.playing_index.is_some() {
            Some(self.player.position().as_secs())
        } else {
            None
        };

        let state = SavedState {
            last_path: Some(self.music_dir.clone()),
            volume: Some(self.player.volume()),
            sort_mode: Some(self.library.sort_mode),
            repeat: Some(self.repeat),
            shuffle: Some(self.shuffle),
            last_playing_path: playing_path,
            last_playing_pos_secs: playing_pos,
        };
        crate::state::save(&state);
    }

    pub fn on_exit(&self) {
        self.persist();
    }

    pub fn start_search(&mut self) {
        self.input_mode = InputMode::Search;
        self.search_buffer.clear();
        self.status_set_at = Instant::now();
    }

    pub fn cancel_search(&mut self) {
        self.input_mode = InputMode::Normal;
        self.search_buffer.clear();
        self.rebuild_library();
        self.set_status("Поиск отменён".into());
    }

    pub fn commit_search(&mut self) {
        self.input_mode = InputMode::Normal;
        let msg = if self.search_buffer.is_empty() {
            "Фильтр сброшен".to_string()
        } else {
            format!("Фильтр: {}", self.search_buffer)
        };
        self.set_status(msg);
    }

    pub fn search_push(&mut self, c: char) {
        self.search_buffer.push(c);
        self.rebuild_library();
        self.status_set_at = Instant::now();
    }

    pub fn search_pop(&mut self) {
        self.search_buffer.pop();
        self.rebuild_library();
        self.status_set_at = Instant::now();
    }

    fn rebuild_library(&mut self) {
        let mode = self.library.sort_mode;
        self.library = Library::build_with_filter(
            self.raw_tracks.clone(),
            mode,
            self.search_buffer.clone(),
        );
        if let Some(i) = self.playing_index {
            self.library.sync_with_playing(i);
        }
    }

    pub fn up(&mut self) {
        match self.active_panel {
            Panel::Left => self.library.artist_move(-1),
            Panel::Right => self.library.right_move(-1),
        }
    }

    pub fn down(&mut self) {
        match self.active_panel {
            Panel::Left => self.library.artist_move(1),
            Panel::Right => self.library.right_move(1),
        }
    }

    pub fn toggle_panel(&mut self) {
        self.active_panel = match self.active_panel {
            Panel::Left => Panel::Right,
            Panel::Right => Panel::Left,
        };
        let msg = match self.active_panel {
            Panel::Left => "Активна: левая панель".to_string(),
            Panel::Right => "Активна: правая панель".to_string(),
        };
        self.set_status(msg);
    }

    pub fn jump_to_playing(&mut self) {
        if let Some(i) = self.playing_index {
            self.library.sync_with_playing(i);
            self.active_panel = Panel::Right;
            self.set_status("→ к играющему треку".into());
        } else {
            self.set_status("Ничего не играет".into());
        }
    }

    pub fn goto_start(&mut self) {
        match self.active_panel {
            Panel::Left => {
                self.library.artist_selected = 0;
                self.library.left_state.select(Some(0));
            }
            Panel::Right => self.library.right_goto_start(),
        }
    }

    pub fn goto_end(&mut self) {
        match self.active_panel {
            Panel::Left => {
                if !self.library.artists.is_empty() {
                    self.library.artist_selected = self.library.artists.len() - 1;
                    self.library
                        .left_state
                        .select(Some(self.library.artist_selected));
                }
            }
            Panel::Right => self.library.right_goto_end(),
        }
    }

    pub fn play_index(&mut self, index_in_library: usize) {
        let Some(track) = self.library.track(index_in_library).cloned() else {
            return;
        };
        match self.player.play(&track.path, None) {
            Ok(_) => {
                self.playing_index = Some(index_in_library);
                self.set_status(format!("▶ {} — {}", track.artist, track.title));
            }
            Err(e) => self.set_status(format!("Ошибка: {}", e)),
        }
    }

    pub fn play_selected(&mut self) {
        if let Some(idx) = self.library.right_track_index() {
            self.play_index(idx);
        } else {
            self.set_status("Выделен заголовок группы".into());
        }
    }

    pub fn stop(&mut self) {
        self.player.stop();
        self.playing_index = None;
        self.set_status("Остановлено".into());
    }

    pub fn toggle_pause(&mut self) {
        self.player.toggle_pause();
    }

    pub fn maybe_advance(&mut self) {
        if self.playing_index.is_none() || !self.player.is_finished() {
            return;
        }

        if self.repeat == RepeatMode::One {
            if let Some(i) = self.playing_index {
                self.play_index(i);
            }
            return;
        }

        let total = self.library.all_tracks.len();
        if total == 0 {
            return;
        }

        let next = if self.shuffle {
            let seed = std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .map(|d| d.as_nanos() as usize)
                .unwrap_or(0);
            seed % total
        } else {
            match self.playing_index {
                Some(i) if i + 1 < total => i + 1,
                _ => {
                    if self.repeat == RepeatMode::All {
                        0
                    } else {
                        self.set_status("Конец плейлиста".into());
                        self.playing_index = None;
                        return;
                    }
                }
            }
        };

        self.play_index(next);
        self.library.sync_with_playing(next);
    }

    pub fn cycle_repeat(&mut self) {
        self.repeat = match self.repeat {
            RepeatMode::Off => RepeatMode::All,
            RepeatMode::All => RepeatMode::One,
            RepeatMode::One => RepeatMode::Off,
        };
        let msg = match self.repeat {
            RepeatMode::Off => "Repeat: off".to_string(),
            RepeatMode::All => "Repeat: all".to_string(),
            RepeatMode::One => "Repeat: one".to_string(),
        };
        self.set_status(msg);
    }

    pub fn toggle_shuffle(&mut self) {
        self.shuffle = !self.shuffle;
        let msg = if self.shuffle {
            "Shuffle: on".to_string()
        } else {
            "Shuffle: off".to_string()
        };
        self.set_status(msg);
    }

    pub fn volume_up(&mut self) {
        self.player.change_volume(0.05);
        let msg = format!("Громкость: {}%", (self.player.volume() * 100.0) as u32);
        self.set_status(msg);
    }

    pub fn volume_down(&mut self) {
        self.player.change_volume(-0.05);
        let msg = format!("Громкость: {}%", (self.player.volume() * 100.0) as u32);
        self.set_status(msg);
    }

    pub fn seek(&mut self, delta_secs: i64) {
        if self.playing_index.is_none() {
            self.set_status("Ничего не воспроизводится".into());
            return;
        }
        let total = self
            .playing_index
            .and_then(|i| self.library.track(i))
            .map(|t| t.duration)
            .unwrap_or(Duration::ZERO);

        match self.player.seek_by(delta_secs, total) {
            Ok(new_pos) => {
                let sign = if delta_secs >= 0 { "+" } else { "" };
                let msg = format!(
                    "Перемотка {}{}с → {:02}:{:02}",
                    sign,
                    delta_secs,
                    new_pos.as_secs() / 60,
                    new_pos.as_secs() % 60,
                );
                self.set_status(msg);
            }
            Err(_) => self.set_status("Перемотка недоступна".into()),
        }
    }

    pub fn seek_percent(&mut self, percent: u8) {
        if self.playing_index.is_none() {
            self.set_status("Ничего не воспроизводится".into());
            return;
        }
        let total = match self
            .playing_index
            .and_then(|i| self.library.track(i))
            .map(|t| t.duration)
        {
            Some(d) if !d.is_zero() => d,
            _ => {
                self.set_status("Длительность неизвестна".into());
                return;
            }
        };
        let target = total.mul_f32(percent as f32 / 100.0);
        match self.player.seek_to(target) {
            Ok(_) => {
                let msg = format!(
                    "→ {}% ({:02}:{:02})",
                    percent,
                    target.as_secs() / 60,
                    target.as_secs() % 60,
                );
                self.set_status(msg);
            }
            Err(_) => self.set_status("Перемотка недоступна".into()),
        }
    }

    pub fn progress(&self) -> (Duration, Duration) {
        match self.playing_index.and_then(|i| self.library.track(i)) {
            Some(t) => (self.player.position(), t.duration),
            None => (Duration::ZERO, Duration::ZERO),
        }
    }

    pub fn toggle_sort(&mut self) {
        let new_mode = match self.library.sort_mode {
            SortMode::ByArtist => SortMode::ByAlbum,
            SortMode::ByAlbum => SortMode::ByFilename,
            SortMode::ByFilename => SortMode::ByArtist,
        };

        let playing_path = self
            .playing_index
            .and_then(|i| self.library.track(i))
            .map(|t| t.path.clone());

        self.library = Library::build_with_filter(
            self.raw_tracks.clone(),
            new_mode,
            self.search_buffer.clone(),
        );

        self.playing_index = playing_path
            .and_then(|p| self.library.all_tracks.iter().position(|t| t.path == p));

        if let Some(i) = self.playing_index {
            self.library.sync_with_playing(i);
        }

        let msg = match new_mode {
            SortMode::ByArtist => "Сортировка: по артисту/альбому".to_string(),
            SortMode::ByAlbum => "Сортировка: по альбому/артисту".to_string(),
            SortMode::ByFilename => "Сортировка: по имени файла".to_string(),
        };
        self.set_status(msg);
    }
}