//! ReadHandle : consommation individuelle d'une playlist

use crate::playlist::Playlist;
use crate::track::PlaylistTrack;
use crate::Result;
use pmocache::cache_trait::FileCache;
use pmodidl::{Container, Item, Resource};
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;

/// Handle de lecture sur une playlist (peut avoir plusieurs instances)
pub struct ReadHandle {
    playlist: Arc<Playlist>,
    cursor: AtomicUsize,
}

impl ReadHandle {
    /// Crée un nouveau handle de lecture
    pub(crate) fn new(playlist: Arc<Playlist>) -> Self {
        Self {
            playlist,
            cursor: AtomicUsize::new(0),
        }
    }
    
    /// Pop le prochain morceau (avance le curseur)
    ///
    /// Skip automatiquement les entrées invalides dans le cache.
    pub async fn pop(&self) -> Result<Option<PlaylistTrack>> {
        loop {
            if !self.playlist.is_alive() {
                return Err(crate::Error::PlaylistDeleted(self.playlist.id.clone()));
            }
            
            let pos = self.cursor.load(Ordering::SeqCst);
            
            let core = self.playlist.core.read().await;
            
            // Fin de playlist ?
            if pos >= core.len() {
                return Ok(None);
            }
            
            let record = match core.get(pos) {
                Some(r) => r,
                None => return Ok(None),
            };
            
            let cache_pk = record.cache_pk.clone();
            drop(core);
            
            // Vérifier validité dans le cache
            let cache = crate::manager::audio_cache()?;
            if cache.is_valid_pk(&cache_pk) {
                // Valide, avancer le curseur et retourner
                self.cursor.fetch_add(1, Ordering::SeqCst);
                return Ok(Some(PlaylistTrack::new(cache_pk)));
            } else {
                // Invalide, supprimer de la playlist et continuer
                tracing::warn!("Cache entry {} missing, removing from playlist", cache_pk);
                let mut core = self.playlist.core.write().await;
                core.remove_by_cache_pk(&cache_pk);
                drop(core);
                
                // Sauvegarder si persistante
                if self.playlist.persistent {
                    if let Some(persistence) = crate::manager::PlaylistManager().persistence() {
                        let title = self.playlist.title().await;
                        let core = self.playlist.core.read().await;
                        let _ = persistence.save_playlist(&self.playlist.id, &title, &core.config, &core.tracks).await;
                    }
                }
                
                // Ne pas avancer le curseur, continuer avec la position actuelle
                continue;
            }
        }
    }
    
    /// Peek le prochain morceau sans avancer le curseur
    pub async fn peek(&self) -> Result<Option<PlaylistTrack>> {
        if !self.playlist.is_alive() {
            return Err(crate::Error::PlaylistDeleted(self.playlist.id.clone()));
        }
        
        let pos = self.cursor.load(Ordering::SeqCst);
        let core = self.playlist.core.read().await;
        
        match core.get(pos) {
            Some(record) => {
                // Vérifier validité
                let cache = crate::manager::audio_cache()?;
                if cache.is_valid_pk(&record.cache_pk) {
                    Ok(Some(PlaylistTrack::new(record.cache_pk.clone())))
                } else {
                    Ok(None)
                }
            }
            None => Ok(None),
        }
    }
    
    /// Position actuelle du curseur
    pub fn position(&self) -> usize {
        self.cursor.load(Ordering::SeqCst)
    }
    
    /// Nombre de morceaux restants (compte uniquement les valides)
    pub async fn remaining(&self) -> Result<usize> {
        if !self.playlist.is_alive() {
            return Err(crate::Error::PlaylistDeleted(self.playlist.id.clone()));
        }
        
        let pos = self.cursor.load(Ordering::SeqCst);
        let core = self.playlist.core.read().await;
        
        if pos >= core.len() {
            return Ok(0);
        }
        
        let cache = crate::manager::audio_cache()?;
        let mut count = 0;
        
        for i in pos..core.len() {
            if let Some(record) = core.get(i) {
                if cache.is_valid_pk(&record.cache_pk) {
                    count += 1;
                }
            }
        }
        
        Ok(count)
    }
    
    /// Crée un nouveau handle avec cursor à 0
    pub fn get_new_handle(&self) -> Result<ReadHandle> {
        if !self.playlist.is_alive() {
            return Err(crate::Error::PlaylistDeleted(self.playlist.id.clone()));
        }
        
        Ok(ReadHandle::new(self.playlist.clone()))
    }
    
    /// Vérifie si la playlist est vivante
    pub fn is_alive(&self) -> bool {
        self.playlist.is_alive()
    }
    
    /// ID de la playlist
    pub fn id(&self) -> &str {
        &self.playlist.id
    }
    
    /// Génère un Container DIDL-Lite
    pub async fn to_container(&self) -> Result<Container> {
        if !self.playlist.is_alive() {
            return Err(crate::Error::PlaylistDeleted(self.playlist.id.clone()));
        }
        
        let title = self.playlist.title().await;
        let remaining = self.remaining().await?;
        
        Ok(Container {
            id: self.playlist.id.clone(),
            parent_id: "0".to_string(),
            restricted: Some("1".to_string()),
            child_count: Some(remaining.to_string()),
            searchable: Some("0".to_string()),
            title,
            class: "object.container.playlistContainer".to_string(),
            containers: vec![],
            items: vec![],
        })
    }
    
    /// Génère des Items DIDL-Lite depuis la position actuelle
    pub async fn to_items(&self, limit: usize) -> Result<Vec<Item>> {
        if !self.playlist.is_alive() {
            return Err(crate::Error::PlaylistDeleted(self.playlist.id.clone()));
        }
        
        let pos = self.cursor.load(Ordering::SeqCst);
        let core = self.playlist.core.read().await;
        let cache = crate::manager::audio_cache()?;
        
        // Récupérer base_url depuis le cache (via route_for)
        let mut items = Vec::new();
        let mut idx = 0;
        
        for i in pos..core.len() {
            if items.len() >= limit {
                break;
            }
            
            let record = match core.get(i) {
                Some(r) => r,
                None => continue,
            };
            
            // Vérifier validité
            if !cache.is_valid_pk(&record.cache_pk) {
                continue;
            }
            
            // Charger métadonnées
            let metadata = match pmoaudiocache::get_metadata(&*cache, &record.cache_pk) {
                Ok(m) => m,
                Err(_) => continue,
            };
            
            // Construire l'URL via route_for
            let url = cache.route_for(&record.cache_pk, None);
            
            // Créer le Resource DIDL
            let resource = metadata.to_didl_resource(url);
            
            // Créer l'Item
            let item = Item {
                id: format!("{}:{}", self.playlist.id, pos + idx),
                parent_id: self.playlist.id.clone(),
                restricted: Some("1".to_string()),
                title: metadata.title.unwrap_or_else(|| "Unknown".to_string()),
                creator: metadata.artist.clone(),
                class: "object.item.audioItem.musicTrack".to_string(),
                artist: metadata.artist,
                album: metadata.album,
                genre: metadata.genre,
                album_art: None, // TODO: intégrer pmocovers
                album_art_pk: None,
                date: metadata.year.map(|y| y.to_string()),
                original_track_number: metadata.track_number.map(|n| n.to_string()),
                resources: vec![resource],
                descriptions: vec![],
            };
            
            items.push(item);
            idx += 1;
        }
        
        Ok(items)
    }
}