//! Module d'optimisation pour ressources limitées
//! Stratégie: Single-threaded, streaming, minimal memory footprint

use std::path::{Path, PathBuf};
use crate::error::Result;

/// Configuration pour optimisation mémoire
#[derive(Debug, Clone, Copy)]
pub struct MemoryOptimization {
    /// Vider le cache après chaque image (vs garder en mémoire)
    pub aggressive_cleanup: bool,
    /// Taille max du cache d'images (0 = aucun cache)
    pub max_cache_mb: usize,
    /// Réduire la qualité si pas assez de RAM
    pub adaptive_quality: bool,
    /// Utiliser les fichiers temporaires plutôt que la RAM
    pub use_temp_files: bool,
}

impl Default for MemoryOptimization {
    fn default() -> Self {
        Self {
            aggressive_cleanup: true,
            max_cache_mb: 100,
            adaptive_quality: true,
            use_temp_files: true,
        }
    }
}

/// Détecteur de ressources disponibles
pub struct ResourceMonitor {
    pub optimization: MemoryOptimization,
}

impl ResourceMonitor {
    pub fn new() -> Self {
        Self {
            optimization: MemoryOptimization::default(),
        }
    }

    /// Vérifier la RAM disponible (estimation)
    pub fn get_available_memory_mb() -> usize {
        // Estimation simple: on suppose ~500MB dispo pour l'app
        // En production, utiliser sysinfo crate
        500
    }

    /// Ajuster les paramètres selon les ressources
    pub fn auto_configure() -> MemoryOptimization {
        let available = Self::get_available_memory_mb();

        MemoryOptimization {
            aggressive_cleanup: available < 1000,
            max_cache_mb: (available / 5).min(200),
            adaptive_quality: available < 2000,
            use_temp_files: available < 1500,
        }
    }

    /// Nettoyer les ressources
    pub fn cleanup(temp_dir: &Path) -> std::io::Result<()> {
        if temp_dir.exists() {
            std::fs::remove_dir_all(temp_dir)?;
        }
        Ok(())
    }
}

/// Cache avec limite de taille
pub struct LimitedCache {
    max_size_mb: usize,
    current_size_mb: usize,
}

impl LimitedCache {
    pub fn new(max_size_mb: usize) -> Self {
        Self {
            max_size_mb,
            current_size_mb: 0,
        }
    }

    pub fn can_cache(&self, size_mb: usize) -> bool {
        self.current_size_mb + size_mb <= self.max_size_mb
    }

    pub fn add(&mut self, size_mb: usize) {
        self.current_size_mb += size_mb;
    }

    pub fn clear(&mut self) {
        self.current_size_mb = 0;
    }
}

/// Gestionnaire de génération en streaming pour traiter images une à une
pub struct StreamingGenerator {
    pub temp_dir: PathBuf,
    pub use_temp: bool,
}

impl StreamingGenerator {
    pub fn new(work_dir: &Path, use_temp: bool) -> Result<Self> {
        let temp_dir = work_dir.join(".temp");
        if use_temp && !temp_dir.exists() {
            std::fs::create_dir_all(&temp_dir)?;
        }
        Ok(Self { temp_dir, use_temp })
    }

    /// Traiter une image en streaming (charge -> traite -> décharge)
    pub async fn process_image_streaming<F>(
        &self,
        input: &Path,
        output: &Path,
        processor: F,
    ) -> Result<()>
    where
        F: Fn(image::DynamicImage) -> Result<image::DynamicImage>,
    {
        // 1. Charger
        let img = image::open(input).map_err(|e| {
            crate::error::GeneratorError::ImageGenerationFailed(format!("Load failed: {}", e))
        })?;

        // 2. Traiter (reste en mémoire)
        let processed = processor(img)?;

        // 3. Sauvegarder
        processed.save(output).map_err(|e| {
            crate::error::GeneratorError::ImageGenerationFailed(format!("Save failed: {}", e))
        })?;

        // 4. Nettoyer explicitement
        drop(processed);

        Ok(())
    }

    /// Cleanup
    pub fn cleanup(&self) -> std::io::Result<()> {
        if self.use_temp && self.temp_dir.exists() {
            std::fs::remove_dir_all(&self.temp_dir)?;
        }
        Ok(())
    }
}

/// Checkpointing pour reprendre depuis le dernier succès
pub struct CheckpointManager {
    pub checkpoint_file: PathBuf,
}

impl CheckpointManager {
    pub fn new(work_dir: &Path) -> Self {
        Self {
            checkpoint_file: work_dir.join(".generation_checkpoint.json"),
        }
    }

    /// Sauvegarder le progrès
    pub fn save_checkpoint(&self, story_id: &str, scene_id: usize) -> Result<()> {
        #[derive(serde::Serialize)]
        struct Checkpoint {
            story_id: String,
            last_scene: usize,
        }

        let checkpoint = Checkpoint {
            story_id: story_id.to_string(),
            last_scene: scene_id,
        };

        let json = serde_json::to_string(&checkpoint)?;
        std::fs::write(&self.checkpoint_file, json)?;
        Ok(())
    }

    /// Charger le dernier checkpoint
    pub fn load_checkpoint(&self) -> Result<Option<(String, usize)>> {
        if !self.checkpoint_file.exists() {
            return Ok(None);
        }

        #[derive(serde::Deserialize)]
        struct Checkpoint {
            story_id: String,
            last_scene: usize,
        }

        let json = std::fs::read_to_string(&self.checkpoint_file)?;
        let checkpoint: Checkpoint = serde_json::from_str(&json)?;
        Ok(Some((checkpoint.story_id, checkpoint.last_scene)))
    }

    /// Nettoyer après succès
    pub fn clear(&self) -> std::io::Result<()> {
        if self.checkpoint_file.exists() {
            std::fs::remove_file(&self.checkpoint_file)?;
        }
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_limited_cache() {
        let mut cache = LimitedCache::new(100);
        assert!(cache.can_cache(50));
        cache.add(50);
        assert!(cache.can_cache(49));
        assert!(!cache.can_cache(51));
        cache.clear();
        assert!(cache.can_cache(100));
    }
}