/**
 * Media Session Management
 *
 * Tracks high-level playback context (Audio/Movie/TvShow/Idle) that persists
 * beyond individual playback states. Enables persistent UI (miniplayer) and
 * proper transitions between content types.
 *
 * See SoftwareArchitecture.md Section 2.1 for state machine diagram.
 */

use log::info;
use serde::{Deserialize, Serialize};
use super::media::MediaItem;

/// Media session type tracking the high-level playback context
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum MediaSessionType {
    /// No active session - browsing library
    Idle,

    /// Audio playback session (music, audiobooks, podcasts)
    /// Persists until explicitly dismissed
    Audio {
        /// Last/current track being played
        last_item: Option<MediaItem>,
        /// True = playing/paused, False = stopped/ended
        is_active: bool,
    },

    /// Movie playback (single video, auto-dismiss on end)
    Movie {
        /// Currently loaded movie
        item: MediaItem,
        /// True = playing/paused, False = ended
        is_active: bool,
    },

    /// TV show playback (supports next episode auto-advance)
    TvShow {
        /// Currently loaded episode
        item: MediaItem,
        /// Series ID for fetching next episodes
        series_id: String,
        /// True = playing/paused, False = ended
        is_active: bool,
    },
}

impl MediaSessionType {
    /// Check if this is an active session (any type except Idle)
    #[allow(dead_code)]
    pub fn is_active_session(&self) -> bool {
        !matches!(self, MediaSessionType::Idle)
    }

    /// Check if playback is currently active within the session
    #[allow(dead_code)]
    pub fn is_playing_or_paused(&self) -> bool {
        match self {
            MediaSessionType::Audio { is_active, .. } => *is_active,
            MediaSessionType::Movie { is_active, .. } => *is_active,
            MediaSessionType::TvShow { is_active, .. } => *is_active,
            MediaSessionType::Idle => false,
        }
    }

    /// Get the current media item if any
    #[allow(dead_code)]
    pub fn current_item(&self) -> Option<&MediaItem> {
        match self {
            MediaSessionType::Audio { last_item, .. } => last_item.as_ref(),
            MediaSessionType::Movie { item, .. } => Some(item),
            MediaSessionType::TvShow { item, .. } => Some(item),
            MediaSessionType::Idle => None,
        }
    }
}

/// Manages media session state transitions
pub struct MediaSessionManager {
    current: MediaSessionType,
}

#[allow(dead_code)]
impl MediaSessionManager {
    pub fn new() -> Self {
        Self {
            current: MediaSessionType::Idle,
        }
    }

    /// Get the current session state
    pub fn current(&self) -> &MediaSessionType {
        &self.current
    }

    /// Start an audio session with a queue
    /// Transitions: Idle → Audio(active), Any → Audio(active)
    pub fn start_audio_session(&mut self, first_item: MediaItem) {
        info!("[MediaSession] Starting audio session: {}", first_item.title);
        self.current = MediaSessionType::Audio {
            last_item: Some(first_item),
            is_active: true,
        };
    }

    /// Update audio session with new track (during playback)
    pub fn update_audio_track(&mut self, item: MediaItem) {
        if let MediaSessionType::Audio { last_item, is_active } = &mut self.current {
            info!("[MediaSession] Updating audio track: {}", item.title);
            *last_item = Some(item);
            *is_active = true;
        }
    }

    /// Mark audio session as inactive (playback ended, queue finished)
    /// Session persists for resume
    pub fn audio_session_inactive(&mut self) {
        if let MediaSessionType::Audio { is_active, .. } = &mut self.current {
            info!("[MediaSession] Audio session now inactive (queue ended)");
            *is_active = false;
        }
    }

    /// Resume audio session
    pub fn resume_audio_session(&mut self) {
        if let MediaSessionType::Audio { is_active, .. } = &mut self.current {
            info!("[MediaSession] Resuming audio session");
            *is_active = true;
        }
    }

    /// Start a movie session
    /// Transitions: Any → Movie(active)
    pub fn start_movie_session(&mut self, item: MediaItem) {
        info!("[MediaSession] Starting movie session: {}", item.title);
        self.current = MediaSessionType::Movie {
            item,
            is_active: true,
        };
    }

    /// Mark movie session as inactive (playback ended)
    /// Movie sessions auto-dismiss to Idle
    pub fn movie_session_ended(&mut self) {
        if matches!(self.current, MediaSessionType::Movie { .. }) {
            info!("[MediaSession] Movie ended, transitioning to Idle");
            self.current = MediaSessionType::Idle;
        }
    }

    /// Start a TV show session
    /// Transitions: Any → TvShow(active)
    pub fn start_tv_session(&mut self, item: MediaItem, series_id: String) {
        info!("[MediaSession] Starting TV show session: {}", item.title);
        self.current = MediaSessionType::TvShow {
            item,
            series_id,
            is_active: true,
        };
    }

    /// Mark TV show session as inactive (episode ended, awaiting next)
    pub fn tv_session_episode_ended(&mut self) {
        if let MediaSessionType::TvShow { is_active, .. } = &mut self.current {
            info!("[MediaSession] Episode ended, awaiting next episode");
            *is_active = false;
        }
    }

    /// Advance to next episode in TV session
    pub fn tv_session_next_episode(&mut self, next_item: MediaItem) {
        if let MediaSessionType::TvShow { item, is_active, .. } = &mut self.current {
            info!("[MediaSession] Advancing to next episode: {}", next_item.title);
            *item = next_item;
            *is_active = true;
        }
    }

    /// End TV show session (series complete or user dismissed)
    pub fn tv_session_ended(&mut self) {
        if matches!(self.current, MediaSessionType::TvShow { .. }) {
            info!("[MediaSession] TV show session ended, transitioning to Idle");
            self.current = MediaSessionType::Idle;
        }
    }

    /// Dismiss/clear current session (user action)
    /// Transitions: Any → Idle
    pub fn dismiss(&mut self) {
        info!("[MediaSession] Dismissing session: {:?}", self.current);
        self.current = MediaSessionType::Idle;
    }

    /// Check if we should show miniplayer
    pub fn should_show_miniplayer(&self) -> bool {
        matches!(self.current, MediaSessionType::Audio { .. })
    }

    /// Check if we should show video player
    pub fn should_show_video_player(&self) -> bool {
        matches!(
            self.current,
            MediaSessionType::Movie { .. } | MediaSessionType::TvShow { .. }
        )
    }
}

impl Default for MediaSessionManager {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::player::media::MediaSource;

    fn create_test_audio_item(title: &str) -> MediaItem {
        MediaItem {
            id: title.to_string(),
            title: title.to_string(),
            name: Some(title.to_string()),
            artist: Some("Test Artist".to_string()),
            album: Some("Test Album".to_string()),
            album_name: Some("Test Album".to_string()),
            album_id: None,
            artist_items: None,
            artists: Some(vec!["Test Artist".to_string()]),
            primary_image_tag: None,
            item_type: Some("Audio".to_string()),
            playlist_id: None,
            duration: Some(180.0),
            artwork_url: None,
            media_type: crate::player::media::MediaType::Audio,
            source: MediaSource::DirectUrl {
                url: "http://example.com/audio.mp3".to_string(),
            },
            video_codec: None,
            needs_transcoding: false,
            video_width: None,
            video_height: None,
            subtitles: vec![],
            series_id: None,
            server_id: None,
        }
    }

    fn create_test_movie_item(title: &str) -> MediaItem {
        MediaItem {
            id: title.to_string(),
            title: title.to_string(),
            name: Some(title.to_string()),
            artist: None,
            album: None,
            album_name: None,
            album_id: None,
            artist_items: None,
            artists: None,
            primary_image_tag: None,
            item_type: Some("Movie".to_string()),
            playlist_id: None,
            duration: Some(7200.0),
            artwork_url: None,
            media_type: crate::player::media::MediaType::Video,
            source: MediaSource::DirectUrl {
                url: "http://example.com/movie.mp4".to_string(),
            },
            video_codec: None,
            needs_transcoding: false,
            video_width: None,
            video_height: None,
            subtitles: vec![],
            series_id: None,
            server_id: None,
        }
    }

    #[test]
    fn test_initial_state_is_idle() {
        let manager = MediaSessionManager::new();
        assert_eq!(manager.current(), &MediaSessionType::Idle);
    }

    #[test]
    fn test_audio_session_lifecycle() {
        let mut manager = MediaSessionManager::new();

        // Start audio session
        let track = create_test_audio_item("Track 1");
        manager.start_audio_session(track.clone());

        assert!(matches!(
            manager.current(),
            MediaSessionType::Audio { is_active: true, .. }
        ));
        assert!(manager.should_show_miniplayer());

        // Update to next track
        let track2 = create_test_audio_item("Track 2");
        manager.update_audio_track(track2);
        assert!(manager.current().is_playing_or_paused());

        // Queue ends, session goes inactive
        manager.audio_session_inactive();
        assert!(matches!(
            manager.current(),
            MediaSessionType::Audio { is_active: false, .. }
        ));
        assert!(manager.should_show_miniplayer()); // Still shows!

        // Resume
        manager.resume_audio_session();
        assert!(manager.current().is_playing_or_paused());

        // Dismiss
        manager.dismiss();
        assert_eq!(manager.current(), &MediaSessionType::Idle);
        assert!(!manager.should_show_miniplayer());
    }

    #[test]
    fn test_movie_session_auto_dismiss() {
        let mut manager = MediaSessionManager::new();

        let movie = create_test_movie_item("Test Movie");
        manager.start_movie_session(movie);

        assert!(matches!(
            manager.current(),
            MediaSessionType::Movie { is_active: true, .. }
        ));
        assert!(manager.should_show_video_player());

        // Movie ends, auto-dismiss to Idle
        manager.movie_session_ended();
        assert_eq!(manager.current(), &MediaSessionType::Idle);
    }

    #[test]
    fn test_session_replacement() {
        let mut manager = MediaSessionManager::new();

        // Start with audio
        let track = create_test_audio_item("Track 1");
        manager.start_audio_session(track);
        assert!(manager.should_show_miniplayer());

        // Switch to movie (replaces audio session)
        let movie = create_test_movie_item("Test Movie");
        manager.start_movie_session(movie);
        assert!(!manager.should_show_miniplayer());
        assert!(manager.should_show_video_player());
    }
}