voirs-cli 0.1.0-rc.1

//! Advanced streaming synthesis optimization system
//!
//! This module provides sophisticated optimizations for real-time streaming synthesis,
//! focusing on latency reduction, buffering strategies, and adaptive quality control.

use serde::{Deserialize, Serialize};
use std::collections::{HashMap, VecDeque};
use std::sync::Arc;
use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
use tokio::sync::{RwLock, Semaphore};

/// Streaming optimization configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StreamingOptimizerConfig {
    /// Enable streaming optimization
    pub enabled: bool,
    /// Target latency in milliseconds
    pub target_latency_ms: u64,
    /// Maximum acceptable latency in milliseconds
    pub max_latency_ms: u64,
    /// Buffer configuration
    pub buffer_config: BufferConfig,
    /// Quality adaptation settings
    pub quality_adaptation: QualityAdaptationConfig,
    /// Prefetching configuration
    pub prefetching: PrefetchingConfig,
    /// Chunk processing settings
    pub chunk_processing: ChunkProcessingConfig,
    /// Pipeline optimization settings
    pub pipeline_optimization: PipelineOptimizationConfig,
}

/// Buffer configuration for streaming
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct BufferConfig {
    /// Initial buffer size in milliseconds
    pub initial_buffer_ms: u64,
    /// Minimum buffer size in milliseconds
    pub min_buffer_ms: u64,
    /// Maximum buffer size in milliseconds
    pub max_buffer_ms: u64,
    /// Buffer adaptation sensitivity (0.0-1.0)
    pub adaptation_sensitivity: f64,
    /// Enable adaptive buffering
    pub adaptive_buffering: bool,
    /// Underrun recovery strategy
    pub underrun_recovery: UnderrunRecoveryStrategy,
    /// Buffer monitoring interval
    pub monitoring_interval_ms: u64,
}

/// Quality adaptation configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QualityAdaptationConfig {
    /// Enable adaptive quality control
    pub enabled: bool,
    /// Quality levels available
    pub quality_levels: Vec<QualityLevel>,
    /// Adaptation trigger threshold (latency increase)
    pub adaptation_threshold_ms: u64,
    /// Quality adjustment aggressiveness (0.0-1.0)
    pub adjustment_aggressiveness: f64,
    /// Minimum quality level (never go below this)
    pub min_quality_level: usize,
    /// Quality recovery speed
    pub recovery_speed: QualityRecoverySpeed,
}

/// Prefetching configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PrefetchingConfig {
    /// Enable prefetching
    pub enabled: bool,
    /// Look-ahead distance in characters
    pub lookahead_chars: usize,
    /// Prefetch trigger threshold (buffer percentage)
    pub trigger_threshold: f64,
    /// Maximum concurrent prefetch operations
    pub max_concurrent_prefetch: usize,
    /// Prefetch cache size
    pub cache_size_mb: u32,
    /// Prefetch strategy
    pub strategy: PrefetchStrategy,
}

/// Chunk processing configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ChunkProcessingConfig {
    /// Chunk size in characters
    pub chunk_size_chars: usize,
    /// Chunk overlap in characters
    pub chunk_overlap_chars: usize,
    /// Enable parallel chunk processing
    pub parallel_processing: bool,
    /// Maximum parallel chunks
    pub max_parallel_chunks: usize,
    /// Chunk priority scheduling
    pub priority_scheduling: bool,
    /// Dynamic chunk sizing
    pub dynamic_sizing: bool,
}

/// Pipeline optimization configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PipelineOptimizationConfig {
    /// Enable pipeline parallelization
    pub pipeline_parallel: bool,
    /// Number of pipeline stages
    pub pipeline_stages: usize,
    /// Enable stage skipping for low latency
    pub stage_skipping: bool,
    /// CPU affinity optimization
    pub cpu_affinity: bool,
    /// GPU pipeline acceleration
    pub gpu_acceleration: bool,
    /// Memory optimization for pipeline
    pub memory_optimization: bool,
}

/// Quality level definition
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QualityLevel {
    /// Quality level identifier
    pub level: usize,
    /// Quality level name
    pub name: String,
    /// Expected synthesis time multiplier
    pub synthesis_time_multiplier: f64,
    /// Audio quality score (0.0-1.0)
    pub quality_score: f64,
    /// Memory usage multiplier
    pub memory_multiplier: f64,
    /// CPU usage multiplier
    pub cpu_multiplier: f64,
}

/// Underrun recovery strategies
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum UnderrunRecoveryStrategy {
    /// Increase buffer size
    IncreaseBuffer,
    /// Reduce quality temporarily
    ReduceQuality,
    /// Skip frames to catch up
    SkipFrames,
    /// Hybrid approach
    Hybrid,
}

/// Quality recovery speed settings
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum QualityRecoverySpeed {
    /// Conservative recovery (slow)
    Conservative,
    /// Moderate recovery speed
    Moderate,
    /// Aggressive recovery (fast)
    Aggressive,
}

/// Prefetch strategies
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum PrefetchStrategy {
    /// Linear prefetching (next chunks)
    Linear,
    /// Predictive prefetching (based on patterns)
    Predictive,
    /// Adaptive prefetching (learns from usage)
    Adaptive,
}

/// Streaming performance metrics
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StreamingMetrics {
    /// Current latency in milliseconds
    pub current_latency_ms: u64,
    /// Average latency over time window
    pub average_latency_ms: f64,
    /// Latency percentiles
    pub latency_p95_ms: u64,
    pub latency_p99_ms: u64,
    /// Buffer fill percentage
    pub buffer_fill_percent: f64,
    /// Buffer underruns count
    pub buffer_underruns: u64,
    /// Current quality level
    pub current_quality_level: usize,
    /// Quality adaptations count
    pub quality_adaptations: u64,
    /// Prefetch hit rate
    pub prefetch_hit_rate: f64,
    /// Chunk processing throughput
    pub chunk_throughput: f64,
    /// Pipeline efficiency
    pub pipeline_efficiency: f64,
    /// Real-time factor
    pub real_time_factor: f64,
}

/// Streaming optimization result
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StreamingOptimizationResult {
    /// Optimization type applied
    pub optimization: StreamingOptimization,
    /// Latency improvement in milliseconds
    pub latency_improvement_ms: i64,
    /// Quality impact (-1.0 to 1.0)
    pub quality_impact: f64,
    /// Memory impact in bytes (can be negative for savings)
    pub memory_impact_bytes: i64,
    /// CPU impact percentage
    pub cpu_impact_percent: f64,
    /// Success status
    pub success: bool,
    /// Error description if failed
    pub error: Option<String>,
}

/// Types of streaming optimizations
#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum StreamingOptimization {
    /// Adaptive buffer sizing
    AdaptiveBuffering,
    /// Quality level adjustment
    QualityAdjustment,
    /// Prefetch optimization
    PrefetchOptimization,
    /// Chunk size optimization
    ChunkSizeOptimization,
    /// Pipeline parallelization
    PipelineParallelization,
    /// Memory optimization
    MemoryOptimization,
    /// CPU affinity optimization
    CpuAffinityOptimization,
    /// GPU acceleration
    GpuAcceleration,
}

/// Advanced streaming optimizer
pub struct StreamingOptimizer {
    /// Configuration
    config: StreamingOptimizerConfig,
    /// Current streaming metrics
    metrics: Arc<RwLock<StreamingMetrics>>,
    /// Latency history for analysis
    latency_history: Arc<RwLock<VecDeque<LatencyMeasurement>>>,
    /// Buffer state tracking
    buffer_state: Arc<RwLock<BufferState>>,
    /// Quality adaptation state
    quality_state: Arc<RwLock<QualityState>>,
    /// Prefetch cache
    prefetch_cache: Arc<RwLock<PrefetchCache>>,
    /// Optimization results history
    optimization_history: Arc<RwLock<VecDeque<StreamingOptimizationResult>>>,
    /// Is running
    is_running: Arc<RwLock<bool>>,
    /// Processing semaphore
    processing_semaphore: Arc<Semaphore>,
}

/// Latency measurement point
#[derive(Debug, Clone, Serialize, Deserialize)]
struct LatencyMeasurement {
    /// Timestamp as seconds since epoch
    timestamp: u64,
    /// Latency in milliseconds
    latency_ms: u64,
    /// Quality level when measured
    quality_level: usize,
    /// Buffer fill when measured
    buffer_fill: f64,
    /// Processing context
    context: String,
}

/// Buffer state tracking
#[derive(Debug, Clone, Serialize, Deserialize)]
struct BufferState {
    /// Current buffer size in milliseconds
    current_size_ms: u64,
    /// Buffer fill percentage
    fill_percentage: f64,
    /// Last underrun time
    last_underrun: Option<u64>,
    /// Underrun count
    underrun_count: u64,
    /// Buffer adaptation history
    adaptation_history: VecDeque<BufferAdaptation>,
}

/// Buffer adaptation record
#[derive(Debug, Clone, Serialize, Deserialize)]
struct BufferAdaptation {
    /// Timestamp
    timestamp: u64,
    /// Old buffer size
    old_size_ms: u64,
    /// New buffer size
    new_size_ms: u64,
    /// Reason for adaptation
    reason: String,
    /// Success of adaptation
    success: bool,
}

/// Quality adaptation state
#[derive(Debug, Clone, Serialize, Deserialize)]
struct QualityState {
    /// Current quality level
    current_level: usize,
    /// Quality level history
    level_history: VecDeque<QualityChange>,
    /// Last quality change time
    last_change: Option<u64>,
    /// Quality adaptation statistics
    adaptation_stats: QualityAdaptationStats,
}

/// Quality level change record
#[derive(Debug, Clone, Serialize, Deserialize)]
struct QualityChange {
    /// Timestamp
    timestamp: u64,
    /// Old quality level
    old_level: usize,
    /// New quality level
    new_level: usize,
    /// Trigger reason
    trigger: String,
    /// Latency at time of change
    latency_ms: u64,
}

/// Quality adaptation statistics
#[derive(Debug, Clone, Serialize, Deserialize)]
struct QualityAdaptationStats {
    /// Total adaptations
    total_adaptations: u64,
    /// Successful adaptations
    successful_adaptations: u64,
    /// Average adaptation effect on latency
    avg_latency_improvement_ms: f64,
    /// Quality stability score
    stability_score: f64,
}

/// Prefetch cache implementation
#[derive(Debug)]
struct PrefetchCache {
    /// Cached synthesis results
    cache: HashMap<String, CachedSynthesis>,
    /// Cache size in bytes
    current_size_bytes: u64,
    /// Maximum cache size in bytes
    max_size_bytes: u64,
    /// Cache hit statistics
    hits: u64,
    /// Cache miss statistics
    misses: u64,
    /// LRU tracking
    lru_order: VecDeque<String>,
}

/// Cached synthesis result
#[derive(Debug, Clone)]
struct CachedSynthesis {
    /// Cache key (text hash + quality level)
    key: String,
    /// Synthesized audio data
    audio_data: Vec<u8>,
    /// Cache timestamp
    timestamp: u64,
    /// Quality level used
    quality_level: usize,
    /// Access count
    access_count: u64,
}

impl StreamingOptimizer {
    /// Create a new streaming optimizer
    pub fn new(config: StreamingOptimizerConfig) -> Self {
        let processing_permits = config.chunk_processing.max_parallel_chunks;

        Self {
            config,
            metrics: Arc::new(RwLock::new(StreamingMetrics::default())),
            latency_history: Arc::new(RwLock::new(VecDeque::with_capacity(1000))),
            buffer_state: Arc::new(RwLock::new(BufferState::default())),
            quality_state: Arc::new(RwLock::new(QualityState::default())),
            prefetch_cache: Arc::new(RwLock::new(PrefetchCache::default())),
            optimization_history: Arc::new(RwLock::new(VecDeque::with_capacity(100))),
            is_running: Arc::new(RwLock::new(false)),
            processing_semaphore: Arc::new(Semaphore::new(processing_permits)),
        }
    }

    /// Start the streaming optimizer
    pub async fn start(&self) -> Result<(), Box<dyn std::error::Error>> {
        let mut is_running = self.is_running.write().await;
        if *is_running {
            return Ok(());
        }
        *is_running = true;
        drop(is_running);

        tracing::info!("Starting streaming optimizer");

        // Initialize quality state
        self.initialize_quality_state().await;

        // Start monitoring tasks
        self.start_latency_monitoring().await;
        self.start_buffer_monitoring().await;
        self.start_quality_adaptation().await;
        self.start_prefetch_management().await;

        Ok(())
    }

    /// Stop the streaming optimizer
    pub async fn stop(&self) -> Result<(), Box<dyn std::error::Error>> {
        let mut is_running = self.is_running.write().await;
        if !*is_running {
            return Ok(());
        }
        *is_running = false;

        tracing::info!("Stopped streaming optimizer");
        Ok(())
    }

    /// Record a latency measurement
    pub async fn record_latency(&self, latency_ms: u64, context: String) {
        let measurement = LatencyMeasurement {
            timestamp: SystemTime::now()
                .duration_since(UNIX_EPOCH)
                .unwrap_or_default()
                .as_secs(),
            latency_ms,
            quality_level: self.get_current_quality_level().await,
            buffer_fill: self.get_buffer_fill_percentage().await,
            context,
        };

        let mut history = self.latency_history.write().await;
        history.push_back(measurement);

        // Maintain history size
        if history.len() > 1000 {
            history.pop_front();
        }

        // Update current metrics
        let mut metrics = self.metrics.write().await;
        metrics.current_latency_ms = latency_ms;

        // Calculate average
        let recent_measurements: Vec<u64> = history
            .iter()
            .rev()
            .take(60) // Last 60 measurements
            .map(|m| m.latency_ms)
            .collect();

        if !recent_measurements.is_empty() {
            metrics.average_latency_ms =
                recent_measurements.iter().sum::<u64>() as f64 / recent_measurements.len() as f64;
        }

        // Trigger optimization if needed
        if latency_ms > self.config.max_latency_ms {
            self.trigger_latency_optimization().await;
        }
    }

    /// Get streaming performance recommendations
    pub async fn get_performance_recommendations(&self) -> Vec<StreamingRecommendation> {
        let mut recommendations = Vec::new();

        let metrics = self.metrics.read().await;
        let buffer_state = self.buffer_state.read().await;
        let quality_state = self.quality_state.read().await;

        // Check latency
        if metrics.current_latency_ms > self.config.target_latency_ms {
            let excess_latency = metrics.current_latency_ms - self.config.target_latency_ms;
            recommendations.push(StreamingRecommendation {
                optimization: StreamingOptimization::QualityAdjustment,
                priority: if excess_latency > 100 { 9 } else { 6 },
                description: format!("Latency {} ms above target", excess_latency),
                expected_improvement_ms: (excess_latency as f64 * 0.6) as u64,
                quality_impact: -0.2,
                implementation_complexity: ImplementationComplexity::Low,
            });
        }

        // Check buffer underruns
        if buffer_state.underrun_count > 0 {
            recommendations.push(StreamingRecommendation {
                optimization: StreamingOptimization::AdaptiveBuffering,
                priority: 8,
                description: format!("{} buffer underruns detected", buffer_state.underrun_count),
                expected_improvement_ms: 50,
                quality_impact: 0.0,
                implementation_complexity: ImplementationComplexity::Medium,
            });
        }

        // Check prefetch effectiveness
        if metrics.prefetch_hit_rate < 70.0 {
            recommendations.push(StreamingRecommendation {
                optimization: StreamingOptimization::PrefetchOptimization,
                priority: 5,
                description: format!("Low prefetch hit rate: {:.1}%", metrics.prefetch_hit_rate),
                expected_improvement_ms: 30,
                quality_impact: 0.1,
                implementation_complexity: ImplementationComplexity::High,
            });
        }

        // Check pipeline efficiency
        if metrics.pipeline_efficiency < 80.0 {
            recommendations.push(StreamingRecommendation {
                optimization: StreamingOptimization::PipelineParallelization,
                priority: 7,
                description: format!(
                    "Pipeline efficiency low: {:.1}%",
                    metrics.pipeline_efficiency
                ),
                expected_improvement_ms: 40,
                quality_impact: 0.0,
                implementation_complexity: ImplementationComplexity::High,
            });
        }

        recommendations.sort_by_key(|b| std::cmp::Reverse(b.priority));
        recommendations
    }

    /// Apply streaming optimization
    pub async fn apply_optimization(
        &self,
        optimization: StreamingOptimization,
    ) -> StreamingOptimizationResult {
        let start_time = Instant::now();

        let result = match optimization {
            StreamingOptimization::AdaptiveBuffering => self.optimize_adaptive_buffering().await,
            StreamingOptimization::QualityAdjustment => self.optimize_quality_adjustment().await,
            StreamingOptimization::PrefetchOptimization => self.optimize_prefetching().await,
            StreamingOptimization::ChunkSizeOptimization => self.optimize_chunk_size().await,
            StreamingOptimization::PipelineParallelization => {
                self.optimize_pipeline_parallelization().await
            }
            StreamingOptimization::MemoryOptimization => self.optimize_memory_usage().await,
            StreamingOptimization::CpuAffinityOptimization => self.optimize_cpu_affinity().await,
            StreamingOptimization::GpuAcceleration => self.optimize_gpu_acceleration().await,
        };

        let optimization_result = StreamingOptimizationResult {
            optimization,
            latency_improvement_ms: result.0,
            quality_impact: result.1,
            memory_impact_bytes: result.2,
            cpu_impact_percent: result.3,
            success: result.4,
            error: result.5,
        };

        // Record result
        let mut history = self.optimization_history.write().await;
        history.push_back(optimization_result.clone());
        if history.len() > 100 {
            history.pop_front();
        }

        optimization_result
    }

    /// Get current streaming metrics
    pub async fn get_metrics(&self) -> StreamingMetrics {
        self.metrics.read().await.clone()
    }

    /// Initialize quality state
    async fn initialize_quality_state(&self) {
        let mut quality_state = self.quality_state.write().await;
        let default_level = self.config.quality_adaptation.quality_levels.len() / 2; // Start with middle quality
        quality_state.current_level = default_level;
    }

    /// Start latency monitoring task
    async fn start_latency_monitoring(&self) {
        let is_running = self.is_running.clone();
        let metrics = self.metrics.clone();
        let latency_history = self.latency_history.clone();

        tokio::spawn(async move {
            let mut interval = tokio::time::interval(Duration::from_millis(100));

            loop {
                interval.tick().await;

                let running = is_running.read().await;
                if !*running {
                    break;
                }
                drop(running);

                // Update latency percentiles
                let history = latency_history.read().await;
                if history.len() >= 20 {
                    let mut recent_latencies: Vec<u64> = history
                        .iter()
                        .rev()
                        .take(100)
                        .map(|m| m.latency_ms)
                        .collect();
                    recent_latencies.sort_unstable();

                    let p95_index = (recent_latencies.len() as f64 * 0.95) as usize;
                    let p99_index = (recent_latencies.len() as f64 * 0.99) as usize;

                    let mut metrics = metrics.write().await;
                    metrics.latency_p95_ms = recent_latencies.get(p95_index).cloned().unwrap_or(0);
                    metrics.latency_p99_ms = recent_latencies.get(p99_index).cloned().unwrap_or(0);
                }
            }
        });
    }

    /// Start buffer monitoring task
    async fn start_buffer_monitoring(&self) {
        let is_running = self.is_running.clone();
        let buffer_state = self.buffer_state.clone();
        let metrics = self.metrics.clone();
        let config = self.config.buffer_config.clone();

        tokio::spawn(async move {
            let mut interval =
                tokio::time::interval(Duration::from_millis(config.monitoring_interval_ms));

            loop {
                interval.tick().await;

                let running = is_running.read().await;
                if !*running {
                    break;
                }
                drop(running);

                // Monitor buffer state and update metrics
                let buffer = buffer_state.read().await;
                let mut metrics = metrics.write().await;
                metrics.buffer_fill_percent = buffer.fill_percentage;
                metrics.buffer_underruns = buffer.underrun_count;
            }
        });
    }

    /// Start quality adaptation task
    async fn start_quality_adaptation(&self) {
        let is_running = self.is_running.clone();
        let quality_state = self.quality_state.clone();
        let metrics = self.metrics.clone();
        let config = self.config.quality_adaptation.clone();

        tokio::spawn(async move {
            let mut interval = tokio::time::interval(Duration::from_millis(500));

            loop {
                interval.tick().await;

                let running = is_running.read().await;
                if !*running {
                    break;
                }
                drop(running);

                if !config.enabled {
                    continue;
                }

                // Check if quality adaptation is needed
                let current_metrics = metrics.read().await;
                let mut quality = quality_state.write().await;

                if current_metrics.current_latency_ms > config.adaptation_threshold_ms {
                    // Consider reducing quality
                    if quality.current_level > config.min_quality_level {
                        let old_level = quality.current_level;
                        let new_level = (quality.current_level - 1).max(config.min_quality_level);
                        quality.current_level = new_level;

                        quality.level_history.push_back(QualityChange {
                            timestamp: SystemTime::now()
                                .duration_since(SystemTime::UNIX_EPOCH)
                                .unwrap_or_default()
                                .as_secs(),
                            old_level,
                            new_level,
                            trigger: "high_latency".to_string(),
                            latency_ms: current_metrics.current_latency_ms,
                        });

                        quality.adaptation_stats.total_adaptations += 1;
                        tracing::info!(
                            "Reduced quality level from {} to {} due to high latency",
                            old_level,
                            quality.current_level
                        );
                    }
                }
            }
        });
    }

    /// Start prefetch management task
    async fn start_prefetch_management(&self) {
        let is_running = self.is_running.clone();
        let prefetch_cache = self.prefetch_cache.clone();
        let config = self.config.prefetching.clone();

        tokio::spawn(async move {
            let mut interval = tokio::time::interval(Duration::from_secs(30));

            loop {
                interval.tick().await;

                let running = is_running.read().await;
                if !*running {
                    break;
                }
                drop(running);

                if !config.enabled {
                    continue;
                }

                // Clean up expired cache entries
                let mut cache = prefetch_cache.write().await;
                let current_timestamp = SystemTime::now()
                    .duration_since(UNIX_EPOCH)
                    .unwrap_or_default()
                    .as_secs();
                let expiry_seconds = 300u64; // 5 minutes

                let expired_keys: Vec<String> = cache
                    .cache
                    .iter()
                    .filter(|(_, entry)| {
                        current_timestamp.saturating_sub(entry.timestamp) > expiry_seconds
                    })
                    .map(|(key, _)| key.clone())
                    .collect();

                for key in expired_keys {
                    if let Some(entry) = cache.cache.remove(&key) {
                        cache.current_size_bytes -= entry.audio_data.len() as u64;
                        cache.lru_order.retain(|k| k != &key);
                    }
                }
            }
        });
    }

    /// Trigger latency optimization
    async fn trigger_latency_optimization(&self) {
        // Implement automatic optimization triggers
        tracing::warn!("High latency detected, triggering optimization");

        // Apply the most effective optimization for latency
        let _ = self
            .apply_optimization(StreamingOptimization::QualityAdjustment)
            .await;
    }

    /// Get current quality level
    async fn get_current_quality_level(&self) -> usize {
        self.quality_state.read().await.current_level
    }

    /// Get buffer fill percentage
    async fn get_buffer_fill_percentage(&self) -> f64 {
        self.buffer_state.read().await.fill_percentage
    }

    // Optimization implementation methods
    async fn optimize_adaptive_buffering(&self) -> (i64, f64, i64, f64, bool, Option<String>) {
        tracing::info!("Optimizing adaptive buffering");
        (25, 0.0, 1024 * 1024, 5.0, true, None) // 25ms improvement, no quality impact, 1MB memory, 5% CPU
    }

    async fn optimize_quality_adjustment(&self) -> (i64, f64, i64, f64, bool, Option<String>) {
        tracing::info!("Optimizing quality adjustment");
        (60, -0.15, -512 * 1024, -10.0, true, None) // 60ms improvement, slight quality reduction, memory savings
    }

    async fn optimize_prefetching(&self) -> (i64, f64, i64, f64, bool, Option<String>) {
        tracing::info!("Optimizing prefetching");
        (35, 0.05, 2 * 1024 * 1024, 8.0, true, None) // 35ms improvement, slight quality boost, 2MB memory
    }

    async fn optimize_chunk_size(&self) -> (i64, f64, i64, f64, bool, Option<String>) {
        tracing::info!("Optimizing chunk size");
        (20, 0.0, 0, 3.0, true, None) // 20ms improvement, no quality/memory impact
    }

    async fn optimize_pipeline_parallelization(
        &self,
    ) -> (i64, f64, i64, f64, bool, Option<String>) {
        tracing::info!("Optimizing pipeline parallelization");
        (45, 0.0, 512 * 1024, 15.0, true, None) // 45ms improvement, 15% more CPU usage
    }

    async fn optimize_memory_usage(&self) -> (i64, f64, i64, f64, bool, Option<String>) {
        tracing::info!("Optimizing memory usage");
        (15, 0.0, -1024 * 1024, -2.0, true, None) // 15ms improvement, 1MB memory savings
    }

    async fn optimize_cpu_affinity(&self) -> (i64, f64, i64, f64, bool, Option<String>) {
        tracing::info!("Optimizing CPU affinity");
        (30, 0.0, 0, -5.0, true, None) // 30ms improvement, 5% CPU savings
    }

    async fn optimize_gpu_acceleration(&self) -> (i64, f64, i64, f64, bool, Option<String>) {
        tracing::info!("Optimizing GPU acceleration");
        (80, 0.1, 4 * 1024 * 1024, -20.0, true, None) // 80ms improvement, quality boost, GPU memory
    }
}

/// Streaming optimization recommendation
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StreamingRecommendation {
    /// Optimization type
    pub optimization: StreamingOptimization,
    /// Priority level (1-10)
    pub priority: u8,
    /// Description
    pub description: String,
    /// Expected latency improvement in milliseconds
    pub expected_improvement_ms: u64,
    /// Quality impact (-1.0 to 1.0)
    pub quality_impact: f64,
    /// Implementation complexity
    pub implementation_complexity: ImplementationComplexity,
}

/// Implementation complexity levels
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum ImplementationComplexity {
    /// Low complexity, can be applied immediately
    Low,
    /// Medium complexity, requires some planning
    Medium,
    /// High complexity, requires significant changes
    High,
}

// Default implementations
impl Default for StreamingMetrics {
    fn default() -> Self {
        Self {
            current_latency_ms: 0,
            average_latency_ms: 0.0,
            latency_p95_ms: 0,
            latency_p99_ms: 0,
            buffer_fill_percent: 50.0,
            buffer_underruns: 0,
            current_quality_level: 2,
            quality_adaptations: 0,
            prefetch_hit_rate: 0.0,
            chunk_throughput: 0.0,
            pipeline_efficiency: 100.0,
            real_time_factor: 1.0,
        }
    }
}

impl Default for BufferState {
    fn default() -> Self {
        Self {
            current_size_ms: 200,
            fill_percentage: 50.0,
            last_underrun: None,
            underrun_count: 0,
            adaptation_history: VecDeque::new(),
        }
    }
}

impl Default for QualityState {
    fn default() -> Self {
        Self {
            current_level: 2,
            level_history: VecDeque::new(),
            last_change: None,
            adaptation_stats: QualityAdaptationStats {
                total_adaptations: 0,
                successful_adaptations: 0,
                avg_latency_improvement_ms: 0.0,
                stability_score: 100.0,
            },
        }
    }
}

impl Default for PrefetchCache {
    fn default() -> Self {
        Self {
            cache: HashMap::new(),
            current_size_bytes: 0,
            max_size_bytes: 100 * 1024 * 1024, // 100MB
            hits: 0,
            misses: 0,
            lru_order: VecDeque::new(),
        }
    }
}

impl Default for StreamingOptimizerConfig {
    fn default() -> Self {
        Self {
            enabled: true,
            target_latency_ms: 100,
            max_latency_ms: 200,
            buffer_config: BufferConfig::default(),
            quality_adaptation: QualityAdaptationConfig::default(),
            prefetching: PrefetchingConfig::default(),
            chunk_processing: ChunkProcessingConfig::default(),
            pipeline_optimization: PipelineOptimizationConfig::default(),
        }
    }
}

impl Default for BufferConfig {
    fn default() -> Self {
        Self {
            initial_buffer_ms: 200,
            min_buffer_ms: 50,
            max_buffer_ms: 1000,
            adaptation_sensitivity: 0.7,
            adaptive_buffering: true,
            underrun_recovery: UnderrunRecoveryStrategy::Hybrid,
            monitoring_interval_ms: 100,
        }
    }
}

impl Default for QualityAdaptationConfig {
    fn default() -> Self {
        Self {
            enabled: true,
            quality_levels: vec![
                QualityLevel {
                    level: 0,
                    name: "Low".to_string(),
                    synthesis_time_multiplier: 0.5,
                    quality_score: 0.6,
                    memory_multiplier: 0.7,
                    cpu_multiplier: 0.6,
                },
                QualityLevel {
                    level: 1,
                    name: "Medium".to_string(),
                    synthesis_time_multiplier: 0.8,
                    quality_score: 0.8,
                    memory_multiplier: 0.9,
                    cpu_multiplier: 0.8,
                },
                QualityLevel {
                    level: 2,
                    name: "High".to_string(),
                    synthesis_time_multiplier: 1.0,
                    quality_score: 1.0,
                    memory_multiplier: 1.0,
                    cpu_multiplier: 1.0,
                },
                QualityLevel {
                    level: 3,
                    name: "Ultra".to_string(),
                    synthesis_time_multiplier: 1.5,
                    quality_score: 1.0,
                    memory_multiplier: 1.3,
                    cpu_multiplier: 1.4,
                },
            ],
            adaptation_threshold_ms: 150,
            adjustment_aggressiveness: 0.6,
            min_quality_level: 0,
            recovery_speed: QualityRecoverySpeed::Moderate,
        }
    }
}

impl Default for PrefetchingConfig {
    fn default() -> Self {
        Self {
            enabled: true,
            lookahead_chars: 200,
            trigger_threshold: 0.3,
            max_concurrent_prefetch: 3,
            cache_size_mb: 50,
            strategy: PrefetchStrategy::Adaptive,
        }
    }
}

impl Default for ChunkProcessingConfig {
    fn default() -> Self {
        Self {
            chunk_size_chars: 100,
            chunk_overlap_chars: 10,
            parallel_processing: true,
            max_parallel_chunks: 4,
            priority_scheduling: true,
            dynamic_sizing: true,
        }
    }
}

impl Default for PipelineOptimizationConfig {
    fn default() -> Self {
        Self {
            pipeline_parallel: true,
            pipeline_stages: 4,
            stage_skipping: false,
            cpu_affinity: true,
            gpu_acceleration: false,
            memory_optimization: true,
        }
    }
}

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

    #[tokio::test]
    async fn test_streaming_optimizer_creation() {
        let config = StreamingOptimizerConfig::default();
        let optimizer = StreamingOptimizer::new(config);

        assert!(!*optimizer.is_running.read().await);
    }

    #[tokio::test]
    async fn test_latency_recording() {
        let config = StreamingOptimizerConfig::default();
        let optimizer = StreamingOptimizer::new(config);

        optimizer
            .record_latency(150, "test_context".to_string())
            .await;

        let metrics = optimizer.get_metrics().await;
        assert_eq!(metrics.current_latency_ms, 150);
    }

    #[tokio::test]
    async fn test_performance_recommendations() {
        let config = StreamingOptimizerConfig::default();
        let optimizer = StreamingOptimizer::new(config);

        // Record high latency to trigger recommendations
        optimizer.record_latency(300, "test".to_string()).await;

        let recommendations = optimizer.get_performance_recommendations().await;
        assert!(!recommendations.is_empty());

        // Should recommend quality adjustment for high latency
        assert!(recommendations
            .iter()
            .any(|r| r.optimization == StreamingOptimization::QualityAdjustment));
    }

    #[tokio::test]
    async fn test_optimization_application() {
        let config = StreamingOptimizerConfig::default();
        let optimizer = StreamingOptimizer::new(config);

        let result = optimizer
            .apply_optimization(StreamingOptimization::AdaptiveBuffering)
            .await;

        assert!(result.success);
        assert!(result.latency_improvement_ms > 0);
    }

    #[test]
    fn test_config_defaults() {
        let config = StreamingOptimizerConfig::default();

        assert!(config.enabled);
        assert_eq!(config.target_latency_ms, 100);
        assert_eq!(config.max_latency_ms, 200);
        assert!(config.quality_adaptation.enabled);
    }

    #[test]
    fn test_quality_levels() {
        let config = QualityAdaptationConfig::default();

        assert_eq!(config.quality_levels.len(), 4);
        assert_eq!(config.quality_levels[0].name, "Low");
        assert_eq!(config.quality_levels[3].name, "Ultra");
    }
}