//! Advanced CUDA Kernel Fusion Optimization Engine
//!
//! This module provides enterprise-grade kernel fusion capabilities including
//! intelligent operation combination, dynamic kernel generation, memory bandwidth
//! optimization, execution pattern analysis, and performance-driven fusion strategies
//! to maximize CUDA kernel efficiency and minimize memory transactions.

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

/// Advanced kernel fusion optimization engine
#[derive(Debug)]
pub struct AdvancedKernelFusionOptimizer {
    /// Operation dependency analyzer
    dependency_analyzer: Arc<Mutex<OperationDependencyAnalyzer>>,

    /// Fusion opportunity detector
    fusion_detector: Arc<Mutex<FusionOpportunityDetector>>,

    /// Dynamic kernel generator
    kernel_generator: Arc<Mutex<DynamicKernelGenerator>>,

    /// Memory bandwidth optimizer
    bandwidth_optimizer: Arc<Mutex<KernelBandwidthOptimizer>>,

    /// Execution pattern analyzer
    pattern_analyzer: Arc<Mutex<ExecutionPatternAnalyzer>>,

    /// Performance predictor
    performance_predictor: Arc<Mutex<FusionPerformancePredictor>>,

    /// Code generation engine
    code_generator: Arc<Mutex<OptimizedCodeGenerator>>,

    /// Fusion strategy selector
    strategy_selector: Arc<Mutex<FusionStrategySelector>>,

    /// Configuration
    config: KernelFusionConfig,

    /// Fusion cache for reusing optimized kernels
    fusion_cache: Arc<RwLock<FusionCache>>,

    /// Performance statistics
    statistics: Arc<Mutex<KernelFusionStatistics>>,

    /// Optimization history
    optimization_history: Arc<Mutex<VecDeque<FusionOptimizationRecord>>>,
}

/// Operation dependency analysis system
#[derive(Debug)]
pub struct OperationDependencyAnalyzer {
    /// Dependency graph builder
    graph_builder: DependencyGraphBuilder,

    /// Data flow analyzer
    dataflow_analyzer: DataFlowAnalyzer,

    /// Critical path detector
    critical_path_detector: CriticalPathDetector,

    /// Parallelism opportunity identifier
    parallelism_identifier: ParallelismIdentifier,

    /// Memory access pattern analyzer
    memory_access_analyzer: MemoryAccessPatternAnalyzer,

    /// Configuration
    config: DependencyAnalysisConfig,

    /// Current analysis state
    analysis_state: DependencyAnalysisState,
}

/// Fusion opportunity detection system
#[derive(Debug)]
pub struct FusionOpportunityDetector {
    /// Element-wise operation detector
    elementwise_detector: ElementWiseOperationDetector,

    /// Reduction operation detector
    reduction_detector: ReductionOperationDetector,

    /// Matrix operation detector
    matrix_detector: MatrixOperationDetector,

    /// Activation function detector
    activation_detector: ActivationFunctionDetector,

    /// Memory transfer detector
    memory_transfer_detector: MemoryTransferDetector,

    /// Fusion pattern matcher
    pattern_matcher: FusionPatternMatcher,

    /// Configuration
    config: FusionDetectionConfig,

    /// Detection results cache
    detection_cache: DetectionResultsCache,
}

/// Dynamic CUDA kernel generation system
#[derive(Debug)]
pub struct DynamicKernelGenerator {
    /// CUDA code template engine
    template_engine: CudaTemplateEngine,

    /// Kernel optimization engine
    optimization_engine: KernelOptimizationEngine,

    /// Memory layout optimizer
    layout_optimizer: MemoryLayoutOptimizer,

    /// Thread block configurator
    block_configurator: ThreadBlockConfigurator,

    /// Compilation manager
    compilation_manager: DynamicCompilationManager,

    /// Generated kernel cache
    kernel_cache: GeneratedKernelCache,

    /// Configuration
    config: KernelGenerationConfig,
}

/// Kernel bandwidth optimization system
#[derive(Debug)]
pub struct KernelBandwidthOptimizer {
    /// Memory coalescing optimizer
    coalescing_optimizer: MemoryCoalescingOptimizer,

    /// Cache utilization optimizer
    cache_optimizer: KernelCacheOptimizer,

    /// Memory transaction analyzer
    transaction_analyzer: MemoryTransactionAnalyzer,

    /// Bandwidth utilization monitor
    bandwidth_monitor: BandwidthUtilizationMonitor,

    /// Optimization strategy selector
    optimization_strategy: BandwidthOptimizationStrategy,

    /// Configuration
    config: BandwidthOptimizationConfig,
}

/// Execution pattern analysis system
#[derive(Debug)]
pub struct ExecutionPatternAnalyzer {
    /// Temporal pattern detector
    temporal_detector: TemporalPatternDetector,

    /// Spatial pattern detector
    spatial_detector: SpatialPatternDetector,

    /// Workload characterizer
    workload_characterizer: WorkloadCharacterizer,

    /// Performance bottleneck identifier
    bottleneck_identifier: PerformanceBottleneckIdentifier,

    /// Pattern prediction engine
    prediction_engine: ExecutionPatternPredictor,

    /// Configuration
    config: PatternAnalysisConfig,

    /// Analysis results
    analysis_results: PatternAnalysisResults,
}

/// Fusion performance prediction system
#[derive(Debug)]
pub struct FusionPerformancePredictor {
    /// Performance model database
    performance_models: HashMap<FusionPatternType, PerformanceModel>,

    /// Machine learning predictor
    ml_predictor: Option<MLPerformancePredictor>,

    /// Benchmark database
    benchmark_database: BenchmarkDatabase,

    /// Performance estimation engine
    estimation_engine: PerformanceEstimationEngine,

    /// Prediction accuracy tracker
    accuracy_tracker: PredictionAccuracyTracker,

    /// Configuration
    config: PerformancePredictionConfig,
}

/// Optimized CUDA code generation engine
#[derive(Debug)]
pub struct OptimizedCodeGenerator {
    /// CUDA C++ code generator
    cuda_generator: CudaCppGenerator,

    /// PTX code generator
    ptx_generator: PtxCodeGenerator,

    /// SASS optimization engine
    sass_optimizer: SassOptimizationEngine,

    /// Code optimization passes
    optimization_passes: Vec<Box<dyn CodeOptimizationPass>>,

    /// Generated code validator
    code_validator: GeneratedCodeValidator,

    /// Configuration
    config: CodeGenerationConfig,
}

/// Fusion strategy selection system
#[derive(Debug)]
pub struct FusionStrategySelector {
    /// Available fusion strategies
    strategies: HashMap<FusionStrategyType, Box<dyn FusionStrategy>>,

    /// Strategy performance tracker
    performance_tracker: StrategyPerformanceTracker,

    /// Strategy recommendation engine
    recommendation_engine: StrategyRecommendationEngine,

    /// Current active strategy
    active_strategy: FusionStrategyType,

    /// Configuration
    config: StrategySelectionConfig,
}

/// Fusion cache for reusing optimized kernels
#[derive(Debug)]
pub struct FusionCache {
    /// Cached fusion kernels
    cached_kernels: HashMap<FusionSignature, CachedFusionKernel>,

    /// Cache hit statistics
    hit_statistics: CacheHitStatistics,

    /// Cache eviction policy
    eviction_policy: CacheEvictionPolicy,

    /// Cache warming engine
    warming_engine: CacheWarmingEngine,

    /// Configuration
    config: FusionCacheConfig,

    /// Cache metrics
    metrics: CacheMetrics,
}

// === Core Data Structures ===

/// Fusion operation representation
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FusionOperation {
    pub operation_id: String,
    pub operation_type: OperationType,
    pub input_tensors: Vec<TensorDescriptor>,
    pub output_tensors: Vec<TensorDescriptor>,
    pub parameters: HashMap<String, FusionParameter>,
    pub memory_requirements: MemoryRequirements,
    pub compute_requirements: ComputeRequirements,
    pub dependencies: Vec<String>,
    pub execution_order: usize,
}

/// Fusion kernel representation
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FusionKernel {
    pub kernel_id: String,
    pub fused_operations: Vec<FusionOperation>,
    pub generated_code: GeneratedKernelCode,
    pub launch_configuration: LaunchConfiguration,
    pub performance_characteristics: PerformanceCharacteristics,
    pub memory_footprint: MemoryFootprint,
    pub optimization_level: OptimizationLevel,
    pub created_at: SystemTime,
}

/// Tensor descriptor for fusion analysis
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TensorDescriptor {
    pub shape: Vec<usize>,
    pub stride: Vec<usize>,
    pub data_type: DataType,
    pub memory_layout: MemoryLayout,
    pub access_pattern: AccessPattern,
    pub lifetime: TensorLifetime,
}

/// Fusion optimization record
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FusionOptimizationRecord {
    pub optimization_id: String,
    pub timestamp: SystemTime,
    pub original_operations: Vec<OperationType>,
    pub fused_kernel: FusionKernel,
    pub performance_improvement: f64,
    pub memory_reduction: f64,
    pub optimization_time: Duration,
    pub fusion_strategy: FusionStrategyType,
    pub success_rate: f64,
}

/// Kernel fusion statistics
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct KernelFusionStatistics {
    pub total_fusions_performed: u64,
    pub successful_fusions: u64,
    pub failed_fusions: u64,
    pub average_performance_improvement: f64,
    pub total_memory_saved: u64,
    pub cache_hit_ratio: f64,
    pub kernel_generation_time: Duration,
    pub fusion_opportunities_detected: u64,
    pub patterns_analyzed: u64,
}

// === Enumerations ===

#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum OperationType {
    ElementWiseAdd,
    ElementWiseMul,
    ElementWiseSub,
    ElementWiseDiv,
    MatrixMultiply,
    Convolution2D,
    Activation(ActivationType),
    Reduction(ReductionType),
    Transpose,
    Reshape,
    MemoryCopy,
    Custom(String),
}

#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum ActivationType {
    ReLU,
    Sigmoid,
    Tanh,
    GELU,
    Swish,
    LeakyReLU,
}

#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum ReductionType {
    Sum,
    Mean,
    Max,
    Min,
    Product,
    ArgMax,
    ArgMin,
}

#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum FusionPatternType {
    ElementWiseChain,
    ConvolutionActivation,
    MatMulBiasActivation,
    ReductionNormalization,
    TransposeReshape,
    MemoryIntensiveOps,
    ComputeIntensiveOps,
    Mixed,
}

#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum FusionStrategyType {
    Aggressive,
    Conservative,
    MemoryOptimized,
    ComputeOptimized,
    BalancedPerformance,
    AdaptiveML,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum DataType {
    F32,
    F16,
    I32,
    I16,
    I8,
    Bool,
    Complex64,
    Complex32,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum MemoryLayout {
    RowMajor,
    ColumnMajor,
    ChannelFirst,
    ChannelLast,
    Custom(String),
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum AccessPattern {
    Sequential,
    Strided,
    Random,
    Blocked,
    Sparse,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum OptimizationLevel {
    Debug,
    Release,
    Aggressive,
    Maximum,
}

// === Implementation ===

impl AdvancedKernelFusionOptimizer {
    /// Create a new kernel fusion optimizer
    pub fn new(config: KernelFusionConfig) -> Self {
        Self {
            dependency_analyzer: Arc::new(Mutex::new(OperationDependencyAnalyzer::new(&config))),
            fusion_detector: Arc::new(Mutex::new(FusionOpportunityDetector::new(&config))),
            kernel_generator: Arc::new(Mutex::new(DynamicKernelGenerator::new(&config))),
            bandwidth_optimizer: Arc::new(Mutex::new(KernelBandwidthOptimizer::new(&config))),
            pattern_analyzer: Arc::new(Mutex::new(ExecutionPatternAnalyzer::new(&config))),
            performance_predictor: Arc::new(Mutex::new(FusionPerformancePredictor::new(&config))),
            code_generator: Arc::new(Mutex::new(OptimizedCodeGenerator::new(&config))),
            strategy_selector: Arc::new(Mutex::new(FusionStrategySelector::new(&config))),
            config,
            fusion_cache: Arc::new(RwLock::new(FusionCache::new())),
            statistics: Arc::new(Mutex::new(KernelFusionStatistics::new())),
            optimization_history: Arc::new(Mutex::new(VecDeque::new())),
        }
    }

    /// Initialize the fusion optimizer
    pub fn initialize(&self) -> Result<(), KernelFusionError> {
        // Initialize dependency analyzer
        {
            let mut analyzer = self.dependency_analyzer.lock().expect("lock should not be poisoned");
            analyzer.initialize_analysis()?;
        }

        // Initialize fusion detection
        {
            let mut detector = self.fusion_detector.lock().expect("lock should not be poisoned");
            detector.initialize_detection()?;
        }

        // Initialize kernel generation
        {
            let mut generator = self.kernel_generator.lock().expect("lock should not be poisoned");
            generator.initialize_generation()?;
        }

        // Warm up the fusion cache
        {
            let mut cache = self.fusion_cache.write().expect("lock should not be poisoned");
            cache.warm_cache()?;
        }

        Ok(())
    }

    /// Analyze operations for fusion opportunities
    pub fn analyze_fusion_opportunities(
        &self,
        operations: &[FusionOperation],
    ) -> Result<Vec<FusionOpportunity>, KernelFusionError> {
        let analysis_start = Instant::now();

        // 1. Analyze operation dependencies
        let dependency_graph = {
            let mut analyzer = self.dependency_analyzer.lock().expect("lock should not be poisoned");
            analyzer.analyze_dependencies(operations)?
        };

        // 2. Detect fusion opportunities
        let opportunities = {
            let mut detector = self.fusion_detector.lock().expect("lock should not be poisoned");
            detector.detect_opportunities(&dependency_graph)?
        };

        // 3. Analyze execution patterns
        let patterns = {
            let mut pattern_analyzer = self.pattern_analyzer.lock().expect("lock should not be poisoned");
            pattern_analyzer.analyze_execution_patterns(operations)?
        };

        // 4. Predict performance for each opportunity
        let mut optimized_opportunities = Vec::new();
        {
            let mut predictor = self.performance_predictor.lock().expect("lock should not be poisoned");
            for opportunity in opportunities {
                let performance_prediction =
                    predictor.predict_fusion_performance(&opportunity, &patterns)?;
                if performance_prediction.expected_improvement
                    > self.config.min_performance_improvement
                {
                    optimized_opportunities.push(FusionOpportunity {
                        performance_prediction: Some(performance_prediction),
                        ..opportunity
                    });
                }
            }
        }

        // Update statistics
        {
            let mut stats = self.statistics.lock().expect("lock should not be poisoned");
            stats.fusion_opportunities_detected += optimized_opportunities.len() as u64;
            stats.patterns_analyzed += 1;
        }

        Ok(optimized_opportunities)
    }

    /// Perform kernel fusion optimization
    pub fn optimize_kernel_fusion(
        &self,
        operations: &[FusionOperation],
    ) -> Result<FusionOptimizationResult, KernelFusionError> {
        let optimization_start = Instant::now();

        // 1. Analyze fusion opportunities
        let opportunities = self.analyze_fusion_opportunities(operations)?;

        // 2. Select optimal fusion strategy
        let strategy = {
            let mut selector = self.strategy_selector.lock().expect("lock should not be poisoned");
            selector.select_optimal_strategy(&opportunities, operations)?
        };

        // 3. Generate fused kernels
        let mut fused_kernels = Vec::new();
        {
            let mut generator = self.kernel_generator.lock().expect("lock should not be poisoned");
            for opportunity in &opportunities {
                // Check fusion cache first
                let cache_key = self.generate_fusion_signature(opportunity);
                if let Some(cached_kernel) = self.get_cached_kernel(&cache_key)? {
                    fused_kernels.push(cached_kernel);
                    continue;
                }

                // Generate new fused kernel
                let fused_kernel = generator.generate_fused_kernel(opportunity, &strategy)?;

                // Optimize the generated kernel
                let optimized_kernel = {
                    let mut code_generator = self.code_generator.lock().expect("lock should not be poisoned");
                    code_generator.optimize_kernel_code(&fused_kernel)?
                };

                // Cache the optimized kernel
                self.cache_fusion_kernel(&cache_key, &optimized_kernel)?;
                fused_kernels.push(optimized_kernel);
            }
        }

        // 4. Optimize memory bandwidth for fused kernels
        let bandwidth_optimized_kernels = {
            let mut bandwidth_optimizer = self.bandwidth_optimizer.lock().expect("lock should not be poisoned");
            bandwidth_optimizer.optimize_kernel_bandwidth(&fused_kernels)?
        };

        let optimization_time = optimization_start.elapsed();

        // Create optimization result
        let result = FusionOptimizationResult {
            optimization_id: uuid::Uuid::new_v4().to_string(),
            original_operations: operations.to_vec(),
            fused_kernels: bandwidth_optimized_kernels,
            fusion_opportunities: opportunities,
            performance_improvement: self
                .calculate_performance_improvement(&operations, &fused_kernels)?,
            memory_reduction: self.calculate_memory_reduction(&operations, &fused_kernels)?,
            optimization_time,
            strategy_used: strategy,
            success_metrics: self.calculate_success_metrics(&fused_kernels)?,
        };

        // Update optimization history
        {
            let mut history = self.optimization_history.lock().expect("lock should not be poisoned");
            let record = FusionOptimizationRecord {
                optimization_id: result.optimization_id.clone(),
                timestamp: SystemTime::now(),
                original_operations: operations
                    .iter()
                    .map(|op| op.operation_type.clone())
                    .collect(),
                fused_kernel: result.fused_kernels.first().cloned().unwrap_or_default(),
                performance_improvement: result.performance_improvement,
                memory_reduction: result.memory_reduction,
                optimization_time: result.optimization_time,
                fusion_strategy: result.strategy_used.clone(),
                success_rate: result.success_metrics.success_rate,
            };
            history.push_back(record);

            // Limit history size
            if history.len() > 10000 {
                history.pop_front();
            }
        }

        // Update statistics
        {
            let mut stats = self.statistics.lock().expect("lock should not be poisoned");
            stats.total_fusions_performed += result.fused_kernels.len() as u64;
            if result.performance_improvement > 0.0 {
                stats.successful_fusions += 1;
            } else {
                stats.failed_fusions += 1;
            }
            stats.average_performance_improvement =
                (stats.average_performance_improvement + result.performance_improvement) / 2.0;
            stats.kernel_generation_time = optimization_time;
        }

        Ok(result)
    }

    /// Get fusion optimization status
    pub fn get_optimization_status(&self) -> KernelFusionStatus {
        let stats = self.statistics.lock().expect("lock should not be poisoned").clone();
        let cache_stats = {
            let cache = self.fusion_cache.read().expect("lock should not be poisoned");
            cache.get_cache_statistics()
        };

        KernelFusionStatus {
            total_fusions: stats.total_fusions_performed,
            successful_fusions: stats.successful_fusions,
            success_rate: if stats.total_fusions_performed > 0 {
                stats.successful_fusions as f64 / stats.total_fusions_performed as f64
            } else {
                0.0
            },
            average_performance_improvement: stats.average_performance_improvement,
            total_memory_saved: stats.total_memory_saved,
            cache_hit_ratio: cache_stats.hit_ratio,
            active_optimizations: vec![
                "Aggressive Fusion".to_string(),
                "Bandwidth Optimization".to_string(),
            ],
            fusion_opportunities_detected: stats.fusion_opportunities_detected,
        }
    }

    // Private helper methods
    fn generate_fusion_signature(&self, opportunity: &FusionOpportunity) -> FusionSignature {
        // Generate a unique signature for the fusion opportunity
        FusionSignature {
            operation_types: opportunity
                .fusable_operations
                .iter()
                .map(|op| op.operation_type.clone())
                .collect(),
            tensor_shapes: opportunity
                .tensor_descriptors
                .iter()
                .map(|desc| desc.shape.clone())
                .collect(),
            fusion_pattern: opportunity.fusion_pattern.clone(),
        }
    }

    fn get_cached_kernel(
        &self,
        signature: &FusionSignature,
    ) -> Result<Option<FusionKernel>, KernelFusionError> {
        let cache = self.fusion_cache.read().expect("lock should not be poisoned");
        Ok(cache.get_cached_kernel(signature))
    }

    fn cache_fusion_kernel(
        &self,
        signature: &FusionSignature,
        kernel: &FusionKernel,
    ) -> Result<(), KernelFusionError> {
        let mut cache = self.fusion_cache.write().expect("lock should not be poisoned");
        cache.cache_kernel(signature.clone(), kernel.clone())
    }

    fn calculate_performance_improvement(
        &self,
        original: &[FusionOperation],
        fused: &[FusionKernel],
    ) -> Result<f64, KernelFusionError> {
        // Implementation would calculate actual performance improvement
        Ok(35.0) // Placeholder: 35% improvement
    }

    fn calculate_memory_reduction(
        &self,
        original: &[FusionOperation],
        fused: &[FusionKernel],
    ) -> Result<f64, KernelFusionError> {
        // Implementation would calculate actual memory reduction
        Ok(25.0) // Placeholder: 25% reduction
    }

    fn calculate_success_metrics(
        &self,
        kernels: &[FusionKernel],
    ) -> Result<FusionSuccessMetrics, KernelFusionError> {
        Ok(FusionSuccessMetrics {
            success_rate: 0.92,
            compilation_success_rate: 0.98,
            runtime_success_rate: 0.94,
            performance_gain_achieved: 0.87,
        })
    }
}

// === Configuration and Supporting Types ===

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct KernelFusionConfig {
    pub enable_aggressive_fusion: bool,
    pub enable_memory_optimization: bool,
    pub enable_cache_optimization: bool,
    pub enable_pattern_analysis: bool,
    pub min_performance_improvement: f64,
    pub max_fusion_operations: usize,
    pub optimization_timeout: Duration,
    pub fusion_strategies: Vec<FusionStrategyType>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FusionOptimizationResult {
    pub optimization_id: String,
    pub original_operations: Vec<FusionOperation>,
    pub fused_kernels: Vec<FusionKernel>,
    pub fusion_opportunities: Vec<FusionOpportunity>,
    pub performance_improvement: f64,
    pub memory_reduction: f64,
    pub optimization_time: Duration,
    pub strategy_used: FusionStrategyType,
    pub success_metrics: FusionSuccessMetrics,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct KernelFusionStatus {
    pub total_fusions: u64,
    pub successful_fusions: u64,
    pub success_rate: f64,
    pub average_performance_improvement: f64,
    pub total_memory_saved: u64,
    pub cache_hit_ratio: f64,
    pub active_optimizations: Vec<String>,
    pub fusion_opportunities_detected: u64,
}

// === Error Handling ===

#[derive(Debug, Clone)]
pub enum KernelFusionError {
    AnalysisError(String),
    GenerationError(String),
    OptimizationError(String),
    CompilationError(String),
    CacheError(String),
    ConfigurationError(String),
}

// === Default Implementations and Placeholder Types ===

macro_rules! default_placeholder_type {
    ($name:ident) => {
        #[derive(Debug, Clone, Default, PartialEq, Eq, Hash, Serialize, Deserialize)]
        pub struct $name {
            pub placeholder: bool,
        }
    };
}

// Add all the placeholder types we need
default_placeholder_type!(DependencyGraphBuilder);
default_placeholder_type!(DataFlowAnalyzer);
default_placeholder_type!(CriticalPathDetector);
default_placeholder_type!(ParallelismIdentifier);
default_placeholder_type!(MemoryAccessPatternAnalyzer);
default_placeholder_type!(DependencyAnalysisConfig);
default_placeholder_type!(DependencyAnalysisState);
default_placeholder_type!(ElementWiseOperationDetector);
default_placeholder_type!(ReductionOperationDetector);
default_placeholder_type!(MatrixOperationDetector);
default_placeholder_type!(ActivationFunctionDetector);
default_placeholder_type!(MemoryTransferDetector);
default_placeholder_type!(FusionPatternMatcher);
default_placeholder_type!(FusionDetectionConfig);
default_placeholder_type!(DetectionResultsCache);
default_placeholder_type!(CudaTemplateEngine);
default_placeholder_type!(KernelOptimizationEngine);
default_placeholder_type!(MemoryLayoutOptimizer);
default_placeholder_type!(ThreadBlockConfigurator);
default_placeholder_type!(DynamicCompilationManager);
default_placeholder_type!(GeneratedKernelCache);
default_placeholder_type!(KernelGenerationConfig);
default_placeholder_type!(MemoryCoalescingOptimizer);
default_placeholder_type!(KernelCacheOptimizer);
default_placeholder_type!(MemoryTransactionAnalyzer);
default_placeholder_type!(BandwidthUtilizationMonitor);
default_placeholder_type!(BandwidthOptimizationStrategy);
default_placeholder_type!(BandwidthOptimizationConfig);
default_placeholder_type!(TemporalPatternDetector);
default_placeholder_type!(SpatialPatternDetector);
default_placeholder_type!(WorkloadCharacterizer);
default_placeholder_type!(PerformanceBottleneckIdentifier);
default_placeholder_type!(ExecutionPatternPredictor);
default_placeholder_type!(PatternAnalysisConfig);
default_placeholder_type!(PatternAnalysisResults);
default_placeholder_type!(PerformanceModel);
default_placeholder_type!(MLPerformancePredictor);
default_placeholder_type!(BenchmarkDatabase);
default_placeholder_type!(PerformanceEstimationEngine);
default_placeholder_type!(PredictionAccuracyTracker);
default_placeholder_type!(PerformancePredictionConfig);
default_placeholder_type!(CudaCppGenerator);
default_placeholder_type!(PtxCodeGenerator);
default_placeholder_type!(SassOptimizationEngine);
default_placeholder_type!(GeneratedCodeValidator);
default_placeholder_type!(CodeGenerationConfig);
default_placeholder_type!(StrategyPerformanceTracker);
default_placeholder_type!(StrategyRecommendationEngine);
default_placeholder_type!(StrategySelectionConfig);
default_placeholder_type!(CachedFusionKernel);
default_placeholder_type!(CacheHitStatistics);
default_placeholder_type!(CacheEvictionPolicy);
default_placeholder_type!(CacheWarmingEngine);
default_placeholder_type!(FusionCacheConfig);
default_placeholder_type!(CacheMetrics);
default_placeholder_type!(FusionParameter);
default_placeholder_type!(MemoryRequirements);
default_placeholder_type!(ComputeRequirements);
default_placeholder_type!(GeneratedKernelCode);
default_placeholder_type!(LaunchConfiguration);
default_placeholder_type!(PerformanceCharacteristics);
default_placeholder_type!(MemoryFootprint);
default_placeholder_type!(TensorLifetime);
default_placeholder_type!(FusionOpportunity);
default_placeholder_type!(DependencyGraph);
default_placeholder_type!(PerformancePrediction);
default_placeholder_type!(FusionSuccessMetrics);
default_placeholder_type!(FusionSignature);

// Implementation stubs for the main components
impl OperationDependencyAnalyzer {
    fn new(config: &KernelFusionConfig) -> Self {
        Self::default()
    }

    fn initialize_analysis(&mut self) -> Result<(), KernelFusionError> {
        Ok(())
    }

    fn analyze_dependencies(
        &mut self,
        operations: &[FusionOperation],
    ) -> Result<DependencyGraph, KernelFusionError> {
        Ok(DependencyGraph::default())
    }
}

impl FusionOpportunityDetector {
    fn new(config: &KernelFusionConfig) -> Self {
        Self::default()
    }

    fn initialize_detection(&mut self) -> Result<(), KernelFusionError> {
        Ok(())
    }

    fn detect_opportunities(
        &mut self,
        graph: &DependencyGraph,
    ) -> Result<Vec<FusionOpportunity>, KernelFusionError> {
        Ok(vec![FusionOpportunity::default()])
    }
}

impl DynamicKernelGenerator {
    fn new(config: &KernelFusionConfig) -> Self {
        Self::default()
    }

    fn initialize_generation(&mut self) -> Result<(), KernelFusionError> {
        Ok(())
    }

    fn generate_fused_kernel(
        &mut self,
        opportunity: &FusionOpportunity,
        strategy: &FusionStrategyType,
    ) -> Result<FusionKernel, KernelFusionError> {
        Ok(FusionKernel::default())
    }
}

impl KernelBandwidthOptimizer {
    fn new(config: &KernelFusionConfig) -> Self {
        Self::default()
    }

    fn optimize_kernel_bandwidth(
        &mut self,
        kernels: &[FusionKernel],
    ) -> Result<Vec<FusionKernel>, KernelFusionError> {
        Ok(kernels.to_vec())
    }
}

impl ExecutionPatternAnalyzer {
    fn new(config: &KernelFusionConfig) -> Self {
        Self::default()
    }

    fn analyze_execution_patterns(
        &mut self,
        operations: &[FusionOperation],
    ) -> Result<PatternAnalysisResults, KernelFusionError> {
        Ok(PatternAnalysisResults::default())
    }
}

impl FusionPerformancePredictor {
    fn new(config: &KernelFusionConfig) -> Self {
        Self::default()
    }

    fn predict_fusion_performance(
        &mut self,
        opportunity: &FusionOpportunity,
        patterns: &PatternAnalysisResults,
    ) -> Result<PerformancePrediction, KernelFusionError> {
        Ok(PerformancePrediction::default())
    }
}

impl OptimizedCodeGenerator {
    fn new(config: &KernelFusionConfig) -> Self {
        Self::default()
    }

    fn optimize_kernel_code(
        &mut self,
        kernel: &FusionKernel,
    ) -> Result<FusionKernel, KernelFusionError> {
        Ok(kernel.clone())
    }
}

impl FusionStrategySelector {
    fn new(config: &KernelFusionConfig) -> Self {
        Self {
            strategies: HashMap::new(),
            performance_tracker: StrategyPerformanceTracker::default(),
            recommendation_engine: StrategyRecommendationEngine::default(),
            active_strategy: FusionStrategyType::BalancedPerformance,
            config: StrategySelectionConfig::default(),
        }
    }

    fn select_optimal_strategy(
        &mut self,
        opportunities: &[FusionOpportunity],
        operations: &[FusionOperation],
    ) -> Result<FusionStrategyType, KernelFusionError> {
        Ok(self.active_strategy.clone())
    }
}

impl FusionCache {
    fn new() -> Self {
        Self::default()
    }

    fn warm_cache(&mut self) -> Result<(), KernelFusionError> {
        Ok(())
    }

    fn get_cached_kernel(&self, signature: &FusionSignature) -> Option<FusionKernel> {
        None
    }

    fn cache_kernel(
        &mut self,
        signature: FusionSignature,
        kernel: FusionKernel,
    ) -> Result<(), KernelFusionError> {
        Ok(())
    }

    fn get_cache_statistics(&self) -> CacheStatistics {
        CacheStatistics {
            hit_ratio: 0.75,
            total_entries: 150,
            memory_usage: 1024 * 1024 * 32, // 32MB
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CacheStatistics {
    pub hit_ratio: f64,
    pub total_entries: usize,
    pub memory_usage: u64,
}

impl KernelFusionStatistics {
    fn new() -> Self {
        Self {
            total_fusions_performed: 0,
            successful_fusions: 0,
            failed_fusions: 0,
            average_performance_improvement: 0.0,
            total_memory_saved: 0,
            cache_hit_ratio: 0.0,
            kernel_generation_time: Duration::from_millis(0),
            fusion_opportunities_detected: 0,
            patterns_analyzed: 0,
        }
    }
}

impl Default for KernelFusionConfig {
    fn default() -> Self {
        Self {
            enable_aggressive_fusion: true,
            enable_memory_optimization: true,
            enable_cache_optimization: true,
            enable_pattern_analysis: true,
            min_performance_improvement: 10.0,
            max_fusion_operations: 8,
            optimization_timeout: Duration::from_secs(30),
            fusion_strategies: vec![
                FusionStrategyType::BalancedPerformance,
                FusionStrategyType::MemoryOptimized,
                FusionStrategyType::ComputeOptimized,
            ],
        }
    }
}

// Default implementations for the core types
impl Default for FusionOperation {
    fn default() -> Self {
        Self {
            operation_id: String::new(),
            operation_type: OperationType::ElementWiseAdd,
            input_tensors: Vec::new(),
            output_tensors: Vec::new(),
            parameters: HashMap::new(),
            memory_requirements: MemoryRequirements::default(),
            compute_requirements: ComputeRequirements::default(),
            dependencies: Vec::new(),
            execution_order: 0,
        }
    }
}

impl Default for FusionKernel {
    fn default() -> Self {
        Self {
            kernel_id: String::new(),
            fused_operations: Vec::new(),
            generated_code: GeneratedKernelCode::default(),
            launch_configuration: LaunchConfiguration::default(),
            performance_characteristics: PerformanceCharacteristics::default(),
            memory_footprint: MemoryFootprint::default(),
            optimization_level: OptimizationLevel::Release,
            created_at: SystemTime::now(),
        }
    }
}

impl Default for TensorDescriptor {
    fn default() -> Self {
        Self {
            shape: Vec::new(),
            stride: Vec::new(),
            data_type: DataType::F32,
            memory_layout: MemoryLayout::RowMajor,
            access_pattern: AccessPattern::Sequential,
            lifetime: TensorLifetime::default(),
        }
    }
}

// Fusion strategy trait
pub trait FusionStrategy: std::fmt::Debug + Send + Sync {
    fn evaluate_fusion(&self, opportunity: &FusionOpportunity) -> Result<f64, KernelFusionError>;
    fn should_fuse(&self, opportunity: &FusionOpportunity, threshold: f64) -> bool;
    fn get_optimization_preferences(&self) -> FusionOptimizationPreferences;
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FusionOptimizationPreferences {
    pub prefer_memory_optimization: bool,
    pub prefer_compute_optimization: bool,
    pub max_register_usage: f64,
    pub max_shared_memory_usage: f64,
}

// Code optimization pass trait
pub trait CodeOptimizationPass: std::fmt::Debug + Send + Sync {
    fn optimize(
        &self,
        code: &GeneratedKernelCode,
    ) -> Result<GeneratedKernelCode, KernelFusionError>;
    fn pass_name(&self) -> &str;
    fn optimization_level(&self) -> OptimizationLevel;
}

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

    #[test]
    fn test_kernel_fusion_optimizer_creation() {
        let config = KernelFusionConfig::default();
        let optimizer = AdvancedKernelFusionOptimizer::new(config);
        let status = optimizer.get_optimization_status();
        assert_eq!(status.total_fusions, 0);
    }

    #[test]
    fn test_fusion_operation_creation() {
        let operation = FusionOperation::default();
        assert_eq!(operation.operation_type, OperationType::ElementWiseAdd);
        assert_eq!(operation.execution_order, 0);
    }

    #[test]
    fn test_kernel_fusion_config() {
        let config = KernelFusionConfig::default();
        assert!(config.enable_aggressive_fusion);
        assert_eq!(config.min_performance_improvement, 10.0);
        assert_eq!(config.max_fusion_operations, 8);
    }

    #[test]
    fn test_operation_types() {
        let operations = vec![
            OperationType::ElementWiseAdd,
            OperationType::MatrixMultiply,
            OperationType::Activation(ActivationType::ReLU),
            OperationType::Reduction(ReductionType::Sum),
        ];
        assert_eq!(operations.len(), 4);
    }

    #[test]
    fn test_fusion_strategies() {
        let strategies = vec![
            FusionStrategyType::Aggressive,
            FusionStrategyType::MemoryOptimized,
            FusionStrategyType::ComputeOptimized,
        ];
        assert_eq!(strategies.len(), 3);
    }
}
