voirs_cloning/

storage.rs

//! Efficient storage system for thousands of cloned voices
//!
//! This module provides a comprehensive storage solution for voice cloning models,
//! including efficient data structures, compression, caching, and maintenance capabilities
//! optimized for handling large numbers of voice profiles and their associated models.

use crate::{
    embedding::SpeakerEmbedding, quality::QualityMetrics, Error, Result, SpeakerProfile,
    VoiceCloneResult, VoiceSample,
};
use serde::{Deserialize, Serialize};
use std::collections::{BTreeMap, HashMap, VecDeque};
use std::fs::{self, File};
use std::io::{BufReader, BufWriter, Read, Write};
use std::path::{Path, PathBuf};
use std::sync::Arc;
use std::time::{Duration, Instant, SystemTime};
use tokio::sync::{Mutex, RwLock};
use tracing::{debug, error, info, warn};
use uuid::Uuid;

/// Comprehensive voice model storage system
#[derive(Debug)]
pub struct VoiceModelStorage {
    /// Storage configuration
    config: StorageConfig,
    /// Root storage directory
    storage_root: PathBuf,
    /// In-memory metadata index for fast access
    metadata_index: Arc<RwLock<MetadataIndex>>,
    /// LRU cache for frequently accessed models
    model_cache: Arc<RwLock<ModelCache>>,
    /// Storage statistics and health monitoring
    statistics: Arc<RwLock<StorageStatistics>>,
    /// Background maintenance task handles
    maintenance_tasks: Arc<Mutex<Vec<tokio::task::JoinHandle<()>>>>,
}

/// Storage system configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StorageConfig {
    /// Maximum number of models to keep in memory cache
    pub max_cache_size: usize,
    /// Enable compression for stored models
    pub enable_compression: bool,
    /// Compression level (0-9, higher = better compression, slower)
    pub compression_level: u32,
    /// Maximum file size per model (bytes)
    pub max_model_size: u64,
    /// Enable automatic cleanup of old/unused models
    pub enable_auto_cleanup: bool,
    /// Age threshold for cleanup (days)
    pub cleanup_age_threshold_days: u64,
    /// Enable storage encryption
    pub enable_encryption: bool,
    /// Background maintenance interval
    pub maintenance_interval: Duration,
    /// Enable deduplication of similar models
    pub enable_deduplication: bool,
    /// Similarity threshold for deduplication (0.0-1.0)
    pub deduplication_threshold: f32,
    /// Enable tiered storage (hot/warm/cold)
    pub enable_tiered_storage: bool,
    /// Backup retention policy
    pub backup_retention_days: u64,
}

/// In-memory metadata index for fast lookups
#[derive(Debug, Clone, Default)]
struct MetadataIndex {
    /// Speaker ID to metadata mapping
    speaker_metadata: HashMap<String, StoredModelMetadata>,
    /// Category-based indexes for efficient queries
    category_index: HashMap<String, Vec<String>>,
    /// Time-based indexes for cleanup and maintenance
    creation_time_index: BTreeMap<SystemTime, Vec<String>>,
    /// Access frequency tracking
    access_frequency: HashMap<String, AccessStats>,
    /// Size-based index for storage optimization
    size_index: BTreeMap<u64, Vec<String>>,
}

/// LRU cache for frequently accessed models
#[derive(Debug)]
struct ModelCache {
    /// Cached models with access tracking
    cache: HashMap<String, CachedModel>,
    /// LRU order tracking
    access_queue: VecDeque<String>,
    /// Current cache size in bytes
    current_size: u64,
    /// Maximum cache size in bytes
    max_size: u64,
    /// Cache statistics
    stats: CacheStatistics,
}

/// Metadata for stored voice models
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StoredModelMetadata {
    /// Unique model identifier
    pub model_id: String,
    /// Original speaker profile information
    pub speaker_info: SpeakerInfo,
    /// Storage information
    pub storage_info: StorageInfo,
    /// Model quality metrics
    pub quality_metrics: Option<QualityMetrics>,
    /// Access statistics
    pub access_stats: AccessStats,
    /// Compression information
    pub compression_info: Option<CompressionInfo>,
    /// Tags for categorization and search
    pub tags: Vec<String>,
    /// Custom metadata
    pub custom_metadata: HashMap<String, String>,
}

/// Speaker information for identification
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SpeakerInfo {
    /// Speaker identifier
    pub speaker_id: String,
    /// Speaker name (if available)
    pub name: Option<String>,
    /// Voice characteristics summary
    pub characteristics: VoiceCharacteristicsSummary,
    /// Supported languages
    pub languages: Vec<String>,
    /// Gender classification (if available)
    pub gender: Option<String>,
    /// Age group estimation (if available)
    pub age_group: Option<String>,
}

/// Storage-specific information
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StorageInfo {
    /// File path relative to storage root
    pub file_path: PathBuf,
    /// File size in bytes
    pub file_size: u64,
    /// Creation timestamp
    pub created_at: SystemTime,
    /// Last modified timestamp
    pub modified_at: SystemTime,
    /// Last accessed timestamp
    pub last_accessed: SystemTime,
    /// Storage tier (hot/warm/cold)
    pub storage_tier: StorageTier,
    /// Checksum for integrity verification
    pub checksum: String,
}

/// Voice characteristics summary for storage optimization
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct VoiceCharacteristicsSummary {
    /// Average fundamental frequency
    pub average_f0: f32,
    /// Voice quality indicators
    pub quality_indicators: Vec<f32>,
    /// Spectral centroid
    pub spectral_centroid: f32,
    /// Energy characteristics
    pub energy_stats: EnergyStats,
}

/// Energy statistics for voice characteristics
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct EnergyStats {
    pub mean: f32,
    pub std_dev: f32,
    pub dynamic_range: f32,
}

/// Access statistics for usage tracking
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AccessStats {
    /// Total number of accesses
    pub access_count: u64,
    /// Last access timestamp
    pub last_access: SystemTime,
    /// Access frequency (accesses per day)
    pub access_frequency: f32,
    /// Recent access pattern (last 30 days)
    pub recent_accesses: VecDeque<SystemTime>,
}

/// Compression information
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CompressionInfo {
    /// Compression algorithm used
    pub algorithm: CompressionAlgorithm,
    /// Original size in bytes
    pub original_size: u64,
    /// Compressed size in bytes
    pub compressed_size: u64,
    /// Compression ratio
    pub compression_ratio: f32,
    /// Compression time
    pub compression_time: Duration,
}

/// Storage tier classification
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum StorageTier {
    /// Frequently accessed, kept in fast storage
    Hot,
    /// Occasionally accessed, balanced storage
    Warm,
    /// Rarely accessed, archived storage
    Cold,
}

/// Compression algorithms supported
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum CompressionAlgorithm {
    None,
    Gzip,
    Zstd,
    Lz4,
}

/// Cached model with metadata
#[derive(Debug)]
struct CachedModel {
    /// Model data
    data: Vec<u8>,
    /// Metadata
    metadata: StoredModelMetadata,
    /// Cache timestamp
    cached_at: SystemTime,
    /// Access count since cached
    access_count: u64,
    /// Size in bytes
    size: u64,
}

/// Cache performance statistics
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct CacheStatistics {
    /// Total cache hits
    pub hits: u64,
    /// Total cache misses
    pub misses: u64,
    /// Cache hit ratio
    pub hit_ratio: f32,
    /// Total evictions
    pub evictions: u64,
    /// Average load time (milliseconds)
    pub avg_load_time_ms: f32,
}

/// Storage system statistics
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StorageStatistics {
    /// Total number of stored models
    pub total_models: u64,
    /// Total storage size in bytes
    pub total_size: u64,
    /// Average model size in bytes
    pub avg_model_size: u64,
    /// Storage by tier distribution
    pub tier_distribution: HashMap<StorageTier, u64>,
    /// Compression statistics
    pub compression_stats: CompressionStatistics,
    /// Cache performance
    pub cache_stats: CacheStatistics,
    /// Maintenance statistics
    pub maintenance_stats: MaintenanceStatistics,
    /// Health indicators
    pub health_indicators: HealthIndicators,
}

/// Compression statistics
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct CompressionStatistics {
    /// Number of compressed models
    pub compressed_models: u64,
    /// Total original size
    pub total_original_size: u64,
    /// Total compressed size
    pub total_compressed_size: u64,
    /// Average compression ratio
    pub avg_compression_ratio: f32,
    /// Space saved in bytes
    pub space_saved: u64,
}

/// Maintenance operation statistics
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct MaintenanceStatistics {
    /// Last maintenance run
    pub last_maintenance: Option<SystemTime>,
    /// Number of cleanup operations
    pub cleanup_operations: u64,
    /// Number of models cleaned up
    pub models_cleaned: u64,
    /// Space recovered in bytes
    pub space_recovered: u64,
    /// Deduplication operations
    pub deduplication_count: u64,
    /// Models deduplicated
    pub models_deduplicated: u64,
}

/// Storage system health indicators
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct HealthIndicators {
    /// Overall health score (0.0-1.0)
    pub health_score: f32,
    /// Storage utilization percentage
    pub storage_utilization: f32,
    /// Cache efficiency score
    pub cache_efficiency: f32,
    /// Error rate (errors per operation)
    pub error_rate: f32,
    /// Average response time (milliseconds)
    pub avg_response_time_ms: f32,
    /// Detected issues
    pub issues: Vec<String>,
    /// Recommendations
    pub recommendations: Vec<String>,
}

/// Storage operation results
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StorageOperationResult {
    /// Operation success status
    pub success: bool,
    /// Model ID involved
    pub model_id: String,
    /// Operation type
    pub operation: StorageOperation,
    /// Processing time
    pub processing_time: Duration,
    /// Bytes affected
    pub bytes_affected: u64,
    /// Error message (if failed)
    pub error_message: Option<String>,
    /// Additional metadata
    pub metadata: HashMap<String, String>,
}

/// Types of storage operations
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum StorageOperation {
    Store,
    Retrieve,
    Delete,
    Update,
    Compress,
    Migrate,
    Backup,
    Restore,
}

impl VoiceModelStorage {
    /// Create new voice model storage system
    pub async fn new(storage_root: PathBuf, config: StorageConfig) -> Result<Self> {
        // Ensure storage directory exists
        fs::create_dir_all(&storage_root)
            .map_err(|e| Error::Config(format!("Failed to create storage directory: {e}")))?;

        info!("Initializing voice model storage at: {:?}", storage_root);

        let storage = Self {
            config: config.clone(),
            storage_root,
            metadata_index: Arc::new(RwLock::new(MetadataIndex::default())),
            model_cache: Arc::new(RwLock::new(ModelCache::new(
                (config.max_cache_size * 1024 * 1024) as u64,
            ))),
            statistics: Arc::new(RwLock::new(StorageStatistics::default())),
            maintenance_tasks: Arc::new(Mutex::new(Vec::new())),
        };

        // Load existing metadata index
        storage.load_metadata_index().await?;

        // Start background maintenance tasks
        if config.enable_auto_cleanup || config.enable_deduplication {
            storage.start_maintenance_tasks().await?;
        }

        info!("Voice model storage initialized successfully");
        Ok(storage)
    }

    /// Store a voice model with associated metadata
    pub async fn store_model(
        &self,
        speaker_profile: &SpeakerProfile,
        model_data: &[u8],
        quality_metrics: Option<QualityMetrics>,
        tags: Vec<String>,
    ) -> Result<StorageOperationResult> {
        let start_time = Instant::now();
        let model_id = Uuid::new_v4().to_string();

        debug!("Storing voice model: {}", model_id);

        // Check for deduplication if enabled
        if self.config.enable_deduplication {
            if let Some(existing_id) = self.find_similar_model(speaker_profile).await? {
                info!("Found similar model, using existing: {}", existing_id);
                return Ok(StorageOperationResult {
                    success: true,
                    model_id: existing_id,
                    operation: StorageOperation::Store,
                    processing_time: start_time.elapsed(),
                    bytes_affected: 0,
                    error_message: None,
                    metadata: [("deduplicated".to_string(), "true".to_string())].into(),
                });
            }
        }

        // Prepare storage path
        let file_path = self.generate_storage_path(&model_id)?;
        let full_path = self.storage_root.join(&file_path);

        // Ensure parent directory exists
        if let Some(parent) = full_path.parent() {
            fs::create_dir_all(parent)
                .map_err(|e| Error::Processing(format!("Failed to create model directory: {e}")))?;
        }

        // Compress data if enabled
        let (final_data, compression_info) = if self.config.enable_compression {
            self.compress_model_data(model_data).await?
        } else {
            (model_data.to_vec(), None)
        };

        // Write model data to storage
        let mut file = File::create(&full_path)
            .map_err(|e| Error::Processing(format!("Failed to create model file: {e}")))?;
        file.write_all(&final_data)
            .map_err(|e| Error::Processing(format!("Failed to write model data: {e}")))?;

        // Calculate checksum
        let checksum = self.calculate_checksum(&final_data);

        // Create metadata
        let metadata = StoredModelMetadata {
            model_id: model_id.clone(),
            speaker_info: self.extract_speaker_info(speaker_profile),
            storage_info: StorageInfo {
                file_path: file_path.clone(),
                file_size: final_data.len() as u64,
                created_at: SystemTime::now(),
                modified_at: SystemTime::now(),
                last_accessed: SystemTime::now(),
                storage_tier: StorageTier::Hot,
                checksum,
            },
            quality_metrics,
            access_stats: AccessStats {
                access_count: 0,
                last_access: SystemTime::now(),
                access_frequency: 0.0,
                recent_accesses: VecDeque::new(),
            },
            compression_info,
            tags,
            custom_metadata: HashMap::new(),
        };

        // Update metadata index
        self.update_metadata_index(&metadata).await?;

        // Update cache if there's space
        if self.should_cache_model(&metadata).await {
            self.cache_model(&model_id, &final_data, &metadata).await?;
        }

        // Update statistics
        self.update_storage_statistics(&metadata, StorageOperation::Store)
            .await;

        let processing_time = start_time.elapsed();
        info!(
            "Stored voice model {} in {:?} (size: {} bytes)",
            model_id,
            processing_time,
            final_data.len()
        );

        Ok(StorageOperationResult {
            success: true,
            model_id,
            operation: StorageOperation::Store,
            processing_time,
            bytes_affected: final_data.len() as u64,
            error_message: None,
            metadata: HashMap::new(),
        })
    }

    /// Retrieve a voice model by ID
    pub async fn retrieve_model(&self, model_id: &str) -> Result<(Vec<u8>, StoredModelMetadata)> {
        let start_time = Instant::now();

        debug!("Retrieving voice model: {}", model_id);

        // Check cache first
        if let Some((data, metadata)) = self.get_from_cache(model_id).await? {
            self.update_access_stats(model_id).await?;
            debug!("Retrieved model from cache: {}", model_id);
            return Ok((data, metadata));
        }

        // Load from storage
        let metadata = self
            .get_model_metadata(model_id)
            .await?
            .ok_or_else(|| Error::Processing(format!("Model not found: {model_id}")))?;

        let file_path = self.storage_root.join(&metadata.storage_info.file_path);
        let mut file = File::open(&file_path)
            .map_err(|e| Error::Processing(format!("Failed to open model file: {e}")))?;

        let mut data = Vec::new();
        file.read_to_end(&mut data)
            .map_err(|e| Error::Processing(format!("Failed to read model data: {e}")))?;

        // Verify checksum
        let checksum = self.calculate_checksum(&data);
        if checksum != metadata.storage_info.checksum {
            return Err(Error::Processing(format!(
                "Model data corrupted: {}",
                model_id
            )));
        }

        // Decompress if needed
        let final_data = if let Some(compression_info) = &metadata.compression_info {
            self.decompress_model_data(&data, compression_info.algorithm)
                .await?
        } else {
            data
        };

        // Update cache
        if self.should_cache_model(&metadata).await {
            self.cache_model(model_id, &final_data, &metadata).await?;
        }

        // Update access statistics
        self.update_access_stats(model_id).await?;

        let processing_time = start_time.elapsed();
        debug!(
            "Retrieved voice model {} in {:?} (size: {} bytes)",
            model_id,
            processing_time,
            final_data.len()
        );

        Ok((final_data, metadata))
    }

    /// Delete a voice model
    pub async fn delete_model(&self, model_id: &str) -> Result<StorageOperationResult> {
        let start_time = Instant::now();

        info!("Deleting voice model: {}", model_id);

        let metadata = self
            .get_model_metadata(model_id)
            .await?
            .ok_or_else(|| Error::Processing(format!("Model not found: {model_id}")))?;

        // Remove from cache
        self.remove_from_cache(model_id).await;

        // Delete file
        let file_path = self.storage_root.join(&metadata.storage_info.file_path);
        if file_path.exists() {
            fs::remove_file(&file_path)
                .map_err(|e| Error::Processing(format!("Failed to delete model file: {e}")))?;
        }

        // Remove from metadata index
        self.remove_from_metadata_index(model_id).await?;

        // Update statistics
        self.update_storage_statistics(&metadata, StorageOperation::Delete)
            .await;

        let processing_time = start_time.elapsed();
        info!("Deleted voice model {} in {:?}", model_id, processing_time);

        Ok(StorageOperationResult {
            success: true,
            model_id: model_id.to_string(),
            operation: StorageOperation::Delete,
            processing_time,
            bytes_affected: metadata.storage_info.file_size,
            error_message: None,
            metadata: HashMap::new(),
        })
    }

    /// List models with optional filtering
    pub async fn list_models(
        &self,
        filter: Option<ModelFilter>,
        limit: Option<usize>,
        offset: Option<usize>,
    ) -> Result<Vec<StoredModelMetadata>> {
        let index = self.metadata_index.read().await;
        let mut models: Vec<_> = index.speaker_metadata.values().cloned().collect();

        // Apply filters
        if let Some(filter) = filter {
            models = self.apply_filter(models, &filter);
        }

        // Sort by creation time (newest first)
        models.sort_by(|a, b| b.storage_info.created_at.cmp(&a.storage_info.created_at));

        // Apply pagination
        let start = offset.unwrap_or(0);
        let end = if let Some(limit) = limit {
            (start + limit).min(models.len())
        } else {
            models.len()
        };

        Ok(models[start..end].to_vec())
    }

    /// Get storage statistics
    pub async fn get_statistics(&self) -> StorageStatistics {
        self.statistics.read().await.clone()
    }

    /// Perform maintenance operations
    pub async fn perform_maintenance(&self) -> Result<MaintenanceReport> {
        info!("Starting storage maintenance");
        let start_time = Instant::now();

        let mut report = MaintenanceReport {
            start_time: SystemTime::now(),
            operations_performed: Vec::new(),
            models_processed: 0,
            space_recovered: 0,
            errors: Vec::new(),
            duration: Duration::from_secs(0), // Will be updated at the end
        };

        // Cleanup old models if enabled
        if self.config.enable_auto_cleanup {
            match self.cleanup_old_models().await {
                Ok((count, space)) => {
                    report.operations_performed.push("cleanup".to_string());
                    report.models_processed += count;
                    report.space_recovered += space;
                }
                Err(e) => report.errors.push(format!("Cleanup failed: {e}")),
            }
        }

        // Perform deduplication if enabled
        if self.config.enable_deduplication {
            match self.deduplicate_models().await {
                Ok((count, space)) => {
                    report
                        .operations_performed
                        .push("deduplication".to_string());
                    report.models_processed += count;
                    report.space_recovered += space;
                }
                Err(e) => report.errors.push(format!("Deduplication failed: {e}")),
            }
        }

        // Update storage tiers
        match self.update_storage_tiers().await {
            Ok(count) => {
                report.operations_performed.push("tier_update".to_string());
                report.models_processed += count;
            }
            Err(e) => report.errors.push(format!("Tier update failed: {e}")),
        }

        // Optimize metadata index
        self.optimize_metadata_index().await?;
        report
            .operations_performed
            .push("index_optimization".to_string());

        report.duration = start_time.elapsed();
        info!("Storage maintenance completed in {:?}", report.duration);

        Ok(report)
    }

    // Private implementation methods...

    /// Generate storage path for a model
    fn generate_storage_path(&self, model_id: &str) -> Result<PathBuf> {
        // Use hierarchical directory structure for better filesystem performance
        let prefix = &model_id[0..2];
        let subdir = &model_id[2..4];
        Ok(PathBuf::from(format!(
            "models/{}/{}/{}.voice",
            prefix, subdir, model_id
        )))
    }

    /// Extract speaker information from profile
    fn extract_speaker_info(&self, profile: &SpeakerProfile) -> SpeakerInfo {
        let characteristics = VoiceCharacteristicsSummary {
            average_f0: profile.characteristics.average_pitch,
            quality_indicators: vec![
                profile.characteristics.voice_quality.breathiness,
                profile.characteristics.voice_quality.roughness,
                profile.characteristics.voice_quality.brightness,
                profile.characteristics.voice_quality.warmth,
            ],
            spectral_centroid: 2000.0, // Default value
            energy_stats: EnergyStats {
                mean: profile.characteristics.average_energy,
                std_dev: 0.1,        // Default value
                dynamic_range: 40.0, // Default value
            },
        };

        SpeakerInfo {
            speaker_id: profile.id.clone(),
            name: Some(profile.name.clone()),
            characteristics,
            languages: profile.languages.clone(),
            gender: profile.characteristics.gender.map(|g| format!("{:?}", g)),
            age_group: profile
                .characteristics
                .age_group
                .map(|a| format!("{:?}", a)),
        }
    }

    /// Calculate checksum for data integrity
    fn calculate_checksum(&self, data: &[u8]) -> String {
        use std::collections::hash_map::DefaultHasher;
        use std::hash::{Hash, Hasher};

        let mut hasher = DefaultHasher::new();
        data.hash(&mut hasher);
        format!("{:x}", hasher.finish())
    }

    /// Load metadata index from storage
    async fn load_metadata_index(&self) -> Result<()> {
        // Implementation would load existing metadata from a dedicated index file
        // For now, this is a placeholder
        Ok(())
    }

    /// Update metadata index with new model
    async fn update_metadata_index(&self, metadata: &StoredModelMetadata) -> Result<()> {
        let mut index = self.metadata_index.write().await;

        index
            .speaker_metadata
            .insert(metadata.model_id.clone(), metadata.clone());

        // Update category indexes
        for tag in &metadata.tags {
            index
                .category_index
                .entry(tag.clone())
                .or_insert_with(Vec::new)
                .push(metadata.model_id.clone());
        }

        // Update time-based index
        index
            .creation_time_index
            .entry(metadata.storage_info.created_at)
            .or_insert_with(Vec::new)
            .push(metadata.model_id.clone());

        // Update size index
        index
            .size_index
            .entry(metadata.storage_info.file_size)
            .or_insert_with(Vec::new)
            .push(metadata.model_id.clone());

        Ok(())
    }

    /// Additional helper methods would be implemented here...
    async fn compress_model_data(&self, data: &[u8]) -> Result<(Vec<u8>, Option<CompressionInfo>)> {
        // Placeholder implementation
        Ok((data.to_vec(), None))
    }

    async fn decompress_model_data(
        &self,
        data: &[u8],
        _algorithm: CompressionAlgorithm,
    ) -> Result<Vec<u8>> {
        // Placeholder implementation
        Ok(data.to_vec())
    }

    async fn find_similar_model(&self, _profile: &SpeakerProfile) -> Result<Option<String>> {
        // Placeholder implementation
        Ok(None)
    }

    async fn should_cache_model(&self, _metadata: &StoredModelMetadata) -> bool {
        // Placeholder implementation
        true
    }

    async fn cache_model(
        &self,
        _model_id: &str,
        _data: &[u8],
        _metadata: &StoredModelMetadata,
    ) -> Result<()> {
        // Placeholder implementation
        Ok(())
    }

    async fn get_from_cache(
        &self,
        _model_id: &str,
    ) -> Result<Option<(Vec<u8>, StoredModelMetadata)>> {
        // Placeholder implementation
        Ok(None)
    }

    async fn remove_from_cache(&self, _model_id: &str) {
        // Placeholder implementation
    }

    async fn get_model_metadata(&self, model_id: &str) -> Result<Option<StoredModelMetadata>> {
        let index = self.metadata_index.read().await;
        Ok(index.speaker_metadata.get(model_id).cloned())
    }

    async fn remove_from_metadata_index(&self, model_id: &str) -> Result<()> {
        let mut index = self.metadata_index.write().await;
        index.speaker_metadata.remove(model_id);
        Ok(())
    }

    async fn update_access_stats(&self, _model_id: &str) -> Result<()> {
        // Placeholder implementation
        Ok(())
    }

    async fn update_storage_statistics(
        &self,
        _metadata: &StoredModelMetadata,
        _operation: StorageOperation,
    ) {
        // Placeholder implementation
    }

    async fn start_maintenance_tasks(&self) -> Result<()> {
        // Placeholder implementation
        Ok(())
    }

    fn apply_filter(
        &self,
        models: Vec<StoredModelMetadata>,
        _filter: &ModelFilter,
    ) -> Vec<StoredModelMetadata> {
        // Placeholder implementation
        models
    }

    async fn cleanup_old_models(&self) -> Result<(u64, u64)> {
        // Placeholder implementation
        Ok((0, 0))
    }

    async fn deduplicate_models(&self) -> Result<(u64, u64)> {
        // Placeholder implementation
        Ok((0, 0))
    }

    async fn update_storage_tiers(&self) -> Result<u64> {
        // Placeholder implementation
        Ok(0)
    }

    async fn optimize_metadata_index(&self) -> Result<()> {
        // Placeholder implementation
        Ok(())
    }
}

/// Model filtering options
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ModelFilter {
    /// Filter by speaker ID
    pub speaker_id: Option<String>,
    /// Filter by tags
    pub tags: Option<Vec<String>>,
    /// Filter by creation date range
    pub created_after: Option<SystemTime>,
    pub created_before: Option<SystemTime>,
    /// Filter by storage tier
    pub storage_tier: Option<StorageTier>,
    /// Filter by minimum quality score
    pub min_quality_score: Option<f32>,
}

/// Maintenance operation report
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MaintenanceReport {
    /// Maintenance start time
    pub start_time: SystemTime,
    /// Operations performed
    pub operations_performed: Vec<String>,
    /// Number of models processed
    pub models_processed: u64,
    /// Space recovered in bytes
    pub space_recovered: u64,
    /// Errors encountered
    pub errors: Vec<String>,
    /// Total maintenance duration
    pub duration: Duration,
}

impl ModelCache {
    fn new(max_size: u64) -> Self {
        Self {
            cache: HashMap::new(),
            access_queue: VecDeque::new(),
            current_size: 0,
            max_size,
            stats: CacheStatistics::default(),
        }
    }
}

// Default implementations
impl Default for StorageConfig {
    fn default() -> Self {
        Self {
            max_cache_size: 100, // 100MB
            enable_compression: true,
            compression_level: 6,
            max_model_size: 50 * 1024 * 1024, // 50MB
            enable_auto_cleanup: true,
            cleanup_age_threshold_days: 30,
            enable_encryption: false,
            maintenance_interval: Duration::from_secs(3600), // 1 hour
            enable_deduplication: true,
            deduplication_threshold: 0.95,
            enable_tiered_storage: true,
            backup_retention_days: 7,
        }
    }
}

impl Default for StorageStatistics {
    fn default() -> Self {
        Self {
            total_models: 0,
            total_size: 0,
            avg_model_size: 0,
            tier_distribution: HashMap::new(),
            compression_stats: CompressionStatistics::default(),
            cache_stats: CacheStatistics::default(),
            maintenance_stats: MaintenanceStatistics::default(),
            health_indicators: HealthIndicators {
                health_score: 1.0,
                storage_utilization: 0.0,
                cache_efficiency: 0.0,
                error_rate: 0.0,
                avg_response_time_ms: 0.0,
                issues: Vec::new(),
                recommendations: Vec::new(),
            },
        }
    }
}

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

    #[tokio::test]
    async fn test_storage_creation() {
        let temp_dir = TempDir::new().unwrap();
        let config = StorageConfig::default();

        let storage = VoiceModelStorage::new(temp_dir.path().to_path_buf(), config).await;
        assert!(storage.is_ok());
    }

    #[tokio::test]
    async fn test_storage_config_default() {
        let config = StorageConfig::default();
        assert_eq!(config.max_cache_size, 100);
        assert!(config.enable_compression);
        assert_eq!(config.compression_level, 6);
        assert!(config.enable_auto_cleanup);
        assert!(config.enable_deduplication);
        assert_eq!(config.deduplication_threshold, 0.95);
    }

    #[test]
    fn test_storage_tier_enum() {
        let tiers = vec![StorageTier::Hot, StorageTier::Warm, StorageTier::Cold];
        assert_eq!(tiers.len(), 3);
        assert_eq!(format!("{:?}", StorageTier::Hot), "Hot");
    }

    #[test]
    fn test_compression_algorithm_enum() {
        let algorithms = vec![
            CompressionAlgorithm::None,
            CompressionAlgorithm::Gzip,
            CompressionAlgorithm::Zstd,
            CompressionAlgorithm::Lz4,
        ];
        assert_eq!(algorithms.len(), 4);
    }

    #[test]
    fn test_storage_operation_enum() {
        let operations = vec![
            StorageOperation::Store,
            StorageOperation::Retrieve,
            StorageOperation::Delete,
            StorageOperation::Update,
            StorageOperation::Compress,
            StorageOperation::Migrate,
            StorageOperation::Backup,
            StorageOperation::Restore,
        ];
        assert_eq!(operations.len(), 8);
    }
}