//! Hardware Management Module
//!
//! This module provides comprehensive hardware management capabilities for the CUDA
//! optimization execution engine, including GPU device management, hardware resource
//! allocation, device monitoring, thermal management, power management, and
//! hardware abstraction to ensure optimal hardware utilization and system reliability.

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

/// Helper function for serde default SystemTime value
fn default_system_time() -> SystemTime {
    SystemTime::UNIX_EPOCH
}

use super::config::{GpuConfig, HardwareConfig, ThermalConfig};
use super::task_management::ResourceType;

/// Comprehensive hardware manager for CUDA execution
///
/// Manages all aspects of hardware including GPU device management, resource
/// allocation, hardware monitoring, thermal and power management, device
/// abstraction, and hardware optimization to ensure reliable and efficient
/// hardware utilization across the compute infrastructure.
#[derive(Debug)]
pub struct HardwareManager {
    /// GPU device manager
    gpu_manager: Arc<Mutex<GpuManager>>,

    /// Hardware resource allocator
    resource_allocator: Arc<Mutex<HardwareResourceAllocator>>,

    /// Device monitor for hardware health
    device_monitor: Arc<Mutex<DeviceMonitor>>,

    /// Thermal management system
    thermal_manager: Arc<Mutex<ThermalManager>>,

    /// Power management system
    power_manager: Arc<Mutex<PowerManager>>,

    /// Hardware abstraction layer
    hardware_abstraction: Arc<Mutex<HardwareAbstractionLayer>>,

    /// Device capability detector
    capability_detector: Arc<Mutex<DeviceCapabilityDetector>>,

    /// Hardware metrics collector
    metrics_collector: Arc<Mutex<HardwareMetricsCollector>>,

    /// Configuration
    config: HardwareConfig,

    /// Hardware state tracking
    hardware_state: Arc<RwLock<HardwareState>>,

    /// Hardware statistics
    statistics: Arc<Mutex<HardwareStatistics>>,

    /// Active hardware sessions
    active_sessions: Arc<Mutex<HashMap<u64, HardwareSession>>>,
}

/// GPU device manager for CUDA device control
#[derive(Debug)]
pub struct GpuManager {
    /// Available GPU devices
    gpu_devices: HashMap<GpuId, GpuDevice>,

    /// GPU device allocator
    device_allocator: GpuDeviceAllocator,

    /// GPU memory manager
    memory_manager: GpuMemoryManager,

    /// GPU context manager
    context_manager: GpuContextManager,

    /// GPU stream manager
    stream_manager: GpuStreamManager,

    /// GPU configuration
    config: GpuConfig,

    /// GPU performance tracker
    performance_tracker: GpuPerformanceTracker,

    /// GPU health monitor
    health_monitor: GpuHealthMonitor,
}

/// Hardware resource allocator for managing compute resources
#[derive(Debug)]
pub struct HardwareResourceAllocator {
    /// Resource pools by type
    resource_pools: HashMap<ResourceType, ResourcePool>,

    /// Allocation strategies
    allocation_strategies: HashMap<String, AllocationStrategy>,

    /// Resource scheduler
    resource_scheduler: ResourceScheduler,

    /// Allocation tracker
    allocation_tracker: AllocationTracker,

    /// Resource optimization engine
    optimization_engine: ResourceOptimizationEngine,

    /// Configuration
    config: ResourceAllocationConfig,

    /// Active allocations
    active_allocations: HashMap<String, ResourceAllocation>,
}

/// Device monitoring system for hardware health
#[derive(Debug)]
pub struct DeviceMonitor {
    /// Device health checkers
    health_checkers: HashMap<DeviceId, DeviceHealthChecker>,

    /// Hardware sensor reader
    sensor_reader: HardwareSensorReader,

    /// Device status tracker
    status_tracker: DeviceStatusTracker,

    /// Hardware event detector
    event_detector: HardwareEventDetector,

    /// Failure predictor
    failure_predictor: HardwareFailurePredictor,

    /// Monitoring configuration
    config: DeviceMonitoringConfig,

    /// Device health history
    health_history: HashMap<DeviceId, VecDeque<HealthRecord>>,
}

/// Thermal management system for temperature control
#[derive(Debug)]
pub struct ThermalManager {
    /// Temperature sensors
    temperature_sensors: HashMap<DeviceId, TemperatureSensor>,

    /// Thermal controllers
    thermal_controllers: HashMap<DeviceId, ThermalController>,

    /// Cooling system manager
    cooling_manager: CoolingSystemManager,

    /// Thermal policy enforcer
    policy_enforcer: ThermalPolicyEnforcer,

    /// Thermal throttling controller
    throttling_controller: ThermalThrottlingController,

    /// Configuration
    config: ThermalConfig,

    /// Thermal history
    thermal_history: HashMap<DeviceId, VecDeque<ThermalRecord>>,
}

/// Power management system for energy optimization
#[derive(Debug)]
pub struct PowerManager {
    /// Power monitors by device
    power_monitors: HashMap<DeviceId, PowerMonitor>,

    /// Power allocation controller
    allocation_controller: PowerAllocationController,

    /// Dynamic voltage and frequency scaling
    dvfs_controller: DvfsController,

    /// Power state manager
    state_manager: PowerStateManager,

    /// Energy optimizer
    energy_optimizer: EnergyOptimizer,

    /// Configuration
    config: PowerManagementConfig,

    /// Power consumption history
    power_history: HashMap<DeviceId, VecDeque<PowerRecord>>,
}

/// Hardware abstraction layer for unified device access
#[derive(Debug)]
pub struct HardwareAbstractionLayer {
    /// Device drivers
    device_drivers: HashMap<DeviceType, DeviceDriver>,

    /// Hardware interface adapters
    interface_adapters: HashMap<String, InterfaceAdapter>,

    /// Device capability registry
    capability_registry: DeviceCapabilityRegistry,

    /// Hardware command executor
    command_executor: HardwareCommandExecutor,

    /// Device abstraction cache
    abstraction_cache: DeviceAbstractionCache,

    /// Configuration
    config: AbstractionLayerConfig,
}

/// Device capability detector for hardware feature discovery
#[derive(Debug)]
pub struct DeviceCapabilityDetector {
    /// Capability scanners by device type
    capability_scanners: HashMap<DeviceType, CapabilityScanner>,

    /// Feature detector
    feature_detector: HardwareFeatureDetector,

    /// Benchmark suite for capability testing
    benchmark_suite: HardwareBenchmarkSuite,

    /// Capability database
    capability_database: CapabilityDatabase,

    /// Detection configuration
    config: CapabilityDetectionConfig,
}

// === Core Types and Structures ===

/// GPU device representation
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct GpuDevice {
    /// GPU identifier
    pub gpu_id: GpuId,

    /// Device name
    pub name: String,

    /// Device architecture
    pub architecture: GpuArchitecture,

    /// Compute capability
    pub compute_capability: ComputeCapability,

    /// Total memory
    pub total_memory: u64,

    /// Available memory (simplified for serialization)
    pub available_memory: u64,

    /// Number of streaming multiprocessors
    pub sm_count: u32,

    /// Number of CUDA cores
    pub cuda_cores: u32,

    /// Memory bandwidth
    pub memory_bandwidth: u64,

    /// Base clock frequency
    pub base_clock: u32,

    /// Memory clock frequency
    pub memory_clock: u32,

    /// Device capabilities
    pub capabilities: DeviceCapabilities,

    /// Current device state
    pub state: GpuDeviceState,

    /// Device utilization
    pub utilization: GpuUtilization,

    /// Temperature readings (simplified for serialization)
    pub temperature: u64,

    /// Power consumption (simplified for serialization)
    pub power_consumption: u64,
}

/// Resource pool for managing hardware resources
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ResourcePool {
    /// Pool identifier
    pub pool_id: String,

    /// Resource type
    pub resource_type: ResourceType,

    /// Total capacity
    pub total_capacity: u64,

    /// Available capacity (simplified for serialization)
    pub available_capacity: u64,

    /// Reserved capacity (simplified for serialization)
    pub reserved_capacity: u64,

    /// Pool resources
    pub resources: Vec<PoolResource>,

    /// Pool configuration
    pub config: ResourcePoolConfig,

    /// Pool status
    pub status: PoolStatus,

    /// Allocation policy
    pub allocation_policy: AllocationPolicy,
}

/// Resource allocation record
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ResourceAllocation {
    /// Allocation identifier
    pub allocation_id: String,

    /// Allocated resources
    pub allocated_resources: Vec<AllocatedResource>,

    /// Allocation timestamp
    #[serde(skip, default = "default_system_time")]
    pub allocation_time: SystemTime,

    /// Allocation duration
    pub duration: Option<Duration>,

    /// Allocation priority
    pub priority: AllocationPriority,

    /// Allocation status
    pub status: AllocationStatus,

    /// Resource requirements
    pub requirements: ResourceRequirements,

    /// Allocation metadata
    pub metadata: HashMap<String, String>,
}

/// Device health record for monitoring
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct HealthRecord {
    /// Record timestamp
    pub timestamp: SystemTime,

    /// Device identifier
    pub device_id: DeviceId,

    /// Health status
    pub health_status: HealthStatus,

    /// Health metrics
    pub health_metrics: HealthMetrics,

    /// Warning indicators
    pub warnings: Vec<HealthWarning>,

    /// Error conditions
    pub errors: Vec<HealthError>,

    /// Diagnostic information
    pub diagnostics: DiagnosticInfo,
}

/// Thermal record for temperature tracking
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ThermalRecord {
    /// Record timestamp
    pub timestamp: SystemTime,

    /// Device identifier
    pub device_id: DeviceId,

    /// Temperature readings
    pub temperatures: HashMap<String, f64>,

    /// Thermal state
    pub thermal_state: ThermalState,

    /// Cooling activity
    pub cooling_activity: CoolingActivity,

    /// Thermal events
    pub thermal_events: Vec<ThermalEvent>,
}

/// Power consumption record
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PowerRecord {
    /// Record timestamp
    pub timestamp: SystemTime,

    /// Device identifier
    pub device_id: DeviceId,

    /// Power consumption in watts
    pub power_consumption: f64,

    /// Voltage levels
    pub voltage_levels: HashMap<String, f64>,

    /// Current levels
    pub current_levels: HashMap<String, f64>,

    /// Power state
    pub power_state: PowerState,

    /// Energy efficiency metrics
    pub efficiency_metrics: EnergyEfficiencyMetrics,
}

// === Enumerations and Configuration Types ===

/// GPU identifier type
pub type GpuId = u32;

/// Device identifier type
pub type DeviceId = String;

/// GPU architectures
#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum GpuArchitecture {
    /// Maxwell architecture
    Maxwell,
    /// Pascal architecture
    Pascal,
    /// Volta architecture
    Volta,
    /// Turing architecture
    Turing,
    /// Ampere architecture
    Ampere,
    /// Ada Lovelace architecture
    AdaLovelace,
    /// Hopper architecture
    Hopper,
    /// Custom architecture
    Custom(String),
}

/// Compute capability versions
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
pub struct ComputeCapability {
    pub major: u32,
    pub minor: u32,
}

/// GPU device states
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum GpuDeviceState {
    /// Device is active and available
    Active,
    /// Device is idle
    Idle,
    /// Device is busy processing
    Busy,
    /// Device is in error state
    Error,
    /// Device is disabled
    Disabled,
    /// Device is in maintenance mode
    Maintenance,
}

/// Device types for hardware abstraction
#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum DeviceType {
    /// CUDA GPU device
    CudaGpu,
    /// CPU device
    Cpu,
    /// Memory device
    Memory,
    /// Storage device
    Storage,
    /// Network device
    Network,
    /// Custom device type
    Custom(String),
}

/// Health status levels
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
pub enum HealthStatus {
    Excellent = 0,
    Good = 1,
    Fair = 2,
    Poor = 3,
    Critical = 4,
    Failed = 5,
}

/// Thermal states
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum ThermalState {
    /// Temperature within normal range
    Normal,
    /// Temperature elevated but acceptable
    Elevated,
    /// Temperature approaching warning threshold
    Warning,
    /// Temperature at critical threshold
    Critical,
    /// Thermal emergency state
    Emergency,
}

/// Power states for energy management
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum PowerState {
    /// Full power operation
    Active,
    /// Reduced power operation
    Reduced,
    /// Low power standby
    Standby,
    /// Suspend to RAM
    Suspend,
    /// Device powered off
    Off,
}

/// Pool status enumeration
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum PoolStatus {
    Active,
    Inactive,
    Maintenance,
    Error,
}

/// Allocation status
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum AllocationStatus {
    Pending,
    Active,
    Released,
    Failed,
    Expired,
}

/// Allocation priorities
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
pub enum AllocationPriority {
    Critical = 0,
    High = 1,
    Medium = 2,
    Low = 3,
}

// === Configuration Structures ===

/// Device monitoring configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DeviceMonitoringConfig {
    /// Monitoring interval
    pub monitoring_interval: Duration,

    /// Health check frequency
    pub health_check_frequency: Duration,

    /// Enable failure prediction
    pub enable_failure_prediction: bool,

    /// Health history retention
    pub health_history_retention: Duration,

    /// Alert thresholds
    pub alert_thresholds: HashMap<String, f64>,
}

/// Power management configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PowerManagementConfig {
    /// Enable dynamic power management
    pub enable_dynamic_power_management: bool,

    /// Power budget limits
    pub power_budget_limits: HashMap<DeviceId, f64>,

    /// Energy optimization targets
    pub energy_optimization_targets: EnergyOptimizationTargets,

    /// DVFS configuration
    pub dvfs_config: DvfsConfig,

    /// Power state transition rules
    pub state_transition_rules: PowerStateTransitionRules,
}

/// Resource allocation configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ResourceAllocationConfig {
    /// Default allocation strategy
    pub default_allocation_strategy: String,

    /// Resource reservation policies
    pub reservation_policies: HashMap<ResourceType, ReservationPolicy>,

    /// Allocation timeout settings
    pub allocation_timeouts: AllocationTimeouts,

    /// Enable resource oversubscription
    pub enable_oversubscription: bool,

    /// Oversubscription limits
    pub oversubscription_limits: OversubscriptionLimits,
}

/// Abstraction layer configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AbstractionLayerConfig {
    /// Enable hardware abstraction caching
    pub enable_caching: bool,

    /// Cache timeout
    pub cache_timeout: Duration,

    /// Driver auto-detection
    pub auto_detect_drivers: bool,

    /// Interface adapter settings
    pub adapter_settings: HashMap<String, AdapterSettings>,
}

/// Capability detection configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CapabilityDetectionConfig {
    /// Enable capability benchmarking
    pub enable_benchmarking: bool,

    /// Benchmark timeout
    pub benchmark_timeout: Duration,

    /// Capability cache duration
    pub capability_cache_duration: Duration,

    /// Enable capability validation
    pub enable_validation: bool,
}

// === Implementation ===

impl HardwareManager {
    /// Create a new hardware manager
    pub fn new(config: HardwareConfig) -> Self {
        Self {
            gpu_manager: Arc::new(Mutex::new(GpuManager::new(&config.gpu))),
            resource_allocator: Arc::new(Mutex::new(HardwareResourceAllocator::new(&config))),
            device_monitor: Arc::new(Mutex::new(DeviceMonitor::new(&config))),
            thermal_manager: Arc::new(Mutex::new(ThermalManager::new(&config.thermal))),
            power_manager: Arc::new(Mutex::new(PowerManager::new(&config))),
            hardware_abstraction: Arc::new(Mutex::new(HardwareAbstractionLayer::new(&config))),
            capability_detector: Arc::new(Mutex::new(DeviceCapabilityDetector::new(&config))),
            metrics_collector: Arc::new(Mutex::new(HardwareMetricsCollector::new())),
            config,
            hardware_state: Arc::new(RwLock::new(HardwareState::new())),
            statistics: Arc::new(Mutex::new(HardwareStatistics::new())),
            active_sessions: Arc::new(Mutex::new(HashMap::new())),
        }
    }

    /// Initialize hardware system
    pub fn initialize_hardware(&self) -> Result<(), HardwareError> {
        // Initialize GPU devices
        {
            let mut gpu_manager = self.gpu_manager.lock().expect("lock should not be poisoned");
            gpu_manager.initialize_devices()?;
        }

        // Start device monitoring
        {
            let mut monitor = self.device_monitor.lock().expect("lock should not be poisoned");
            monitor.start_monitoring()?;
        }

        // Initialize thermal management
        {
            let mut thermal_manager = self.thermal_manager.lock().expect("lock should not be poisoned");
            thermal_manager.initialize_thermal_systems()?;
        }

        // Initialize power management
        {
            let mut power_manager = self.power_manager.lock().expect("lock should not be poisoned");
            power_manager.initialize_power_systems()?;
        }

        // Update statistics
        {
            let mut stats = self.statistics.lock().expect("lock should not be poisoned");
            stats.initialization_count += 1;
            stats.last_initialization = Some(SystemTime::now());
        }

        Ok(())
    }

    /// Discover available hardware devices
    pub fn discover_devices(&self) -> Result<Vec<DeviceInfo>, HardwareError> {
        let mut capability_detector = self.capability_detector.lock().expect("lock should not be poisoned");
        let devices = capability_detector.discover_devices()?;

        // Update statistics
        {
            let mut stats = self.statistics.lock().expect("lock should not be poisoned");
            stats.devices_discovered = devices.len() as u64;
        }

        Ok(devices)
    }

    /// Allocate hardware resources
    pub fn allocate_resources(
        &self,
        requirements: ResourceRequirements,
    ) -> Result<String, HardwareError> {
        let mut allocator = self.resource_allocator.lock().expect("lock should not be poisoned");
        let allocation_id = allocator.allocate_resources(requirements)?;

        // Update statistics
        {
            let mut stats = self.statistics.lock().expect("lock should not be poisoned");
            stats.resource_allocations += 1;
        }

        Ok(allocation_id)
    }

    /// Release allocated resources
    pub fn release_resources(&self, allocation_id: &str) -> Result<(), HardwareError> {
        let mut allocator = self.resource_allocator.lock().expect("lock should not be poisoned");
        allocator.release_allocation(allocation_id)?;

        // Update statistics
        {
            let mut stats = self.statistics.lock().expect("lock should not be poisoned");
            stats.resource_releases += 1;
        }

        Ok(())
    }

    /// Get device health status
    pub fn get_device_health(&self, device_id: &DeviceId) -> Result<HealthStatus, HardwareError> {
        let monitor = self.device_monitor.lock().expect("lock should not be poisoned");
        monitor.get_device_health(device_id)
    }

    /// Get thermal status
    pub fn get_thermal_status(&self) -> Result<ThermalStatusReport, HardwareError> {
        let thermal_manager = self.thermal_manager.lock().expect("lock should not be poisoned");
        thermal_manager.get_thermal_status()
    }

    /// Get power consumption status
    pub fn get_power_status(&self) -> Result<PowerStatusReport, HardwareError> {
        let power_manager = self.power_manager.lock().expect("lock should not be poisoned");
        power_manager.get_power_status()
    }

    /// Get hardware statistics
    pub fn get_hardware_statistics(&self) -> HardwareStatistics {
        let stats = self.statistics.lock().expect("lock should not be poisoned");
        stats.clone()
    }

    /// Execute hardware command
    pub fn execute_hardware_command(
        &self,
        command: HardwareCommand,
    ) -> Result<CommandResult, HardwareError> {
        let mut hal = self.hardware_abstraction.lock().expect("lock should not be poisoned");
        let result = hal.execute_command(command)?;

        // Update statistics
        {
            let mut stats = self.statistics.lock().expect("lock should not be poisoned");
            stats.commands_executed += 1;
        }

        Ok(result)
    }
}

impl GpuManager {
    fn new(config: &GpuConfig) -> Self {
        Self {
            gpu_devices: HashMap::new(),
            device_allocator: GpuDeviceAllocator::new(),
            memory_manager: GpuMemoryManager::new(),
            context_manager: GpuContextManager::new(),
            stream_manager: GpuStreamManager::new(),
            config: config.clone(),
            performance_tracker: GpuPerformanceTracker::new(),
            health_monitor: GpuHealthMonitor::new(),
        }
    }

    fn initialize_devices(&mut self) -> Result<(), HardwareError> {
        // Discover and initialize GPU devices
        let device_count = self.get_device_count()?;

        for device_id in 0..device_count {
            let device = self.create_gpu_device(device_id)?;
            self.gpu_devices.insert(device_id, device);
        }

        Ok(())
    }

    fn get_device_count(&self) -> Result<u32, HardwareError> {
        // Implementation would query actual CUDA device count
        Ok(1) // Placeholder
    }

    fn create_gpu_device(&self, device_id: GpuId) -> Result<GpuDevice, HardwareError> {
        // Implementation would query actual device properties
        Ok(GpuDevice {
            gpu_id: device_id,
            name: format!("GPU Device {}", device_id),
            architecture: GpuArchitecture::Ampere,
            compute_capability: ComputeCapability { major: 8, minor: 6 },
            total_memory: 12 * 1024 * 1024 * 1024, // 12GB
            available_memory: 12 * 1024 * 1024 * 1024,
            sm_count: 108,
            cuda_cores: 6912,
            memory_bandwidth: 900 * 1024 * 1024 * 1024, // 900 GB/s
            base_clock: 1410,
            memory_clock: 9001,
            capabilities: DeviceCapabilities::default(),
            state: GpuDeviceState::Active,
            utilization: GpuUtilization::default(),
            temperature: 45,
            power_consumption: 250,
        })
    }
}

impl HardwareResourceAllocator {
    fn new(config: &HardwareConfig) -> Self {
        Self {
            resource_pools: HashMap::new(),
            allocation_strategies: HashMap::new(),
            resource_scheduler: ResourceScheduler::new(),
            allocation_tracker: AllocationTracker::new(),
            optimization_engine: ResourceOptimizationEngine::new(),
            config: config.resource_allocation.clone().unwrap_or_default(),
            active_allocations: HashMap::new(),
        }
    }

    fn allocate_resources(
        &mut self,
        requirements: ResourceRequirements,
    ) -> Result<String, HardwareError> {
        let allocation_id = uuid::Uuid::new_v4().to_string();

        // Find suitable resources
        let allocated_resources = self.find_suitable_resources(&requirements)?;

        let allocation = ResourceAllocation {
            allocation_id: allocation_id.clone(),
            allocated_resources,
            allocation_time: SystemTime::now(),
            duration: requirements.duration,
            priority: requirements.priority.unwrap_or(AllocationPriority::Medium),
            status: AllocationStatus::Active,
            requirements,
            metadata: HashMap::new(),
        };

        self.active_allocations
            .insert(allocation_id.clone(), allocation);

        Ok(allocation_id)
    }

    fn release_allocation(&mut self, allocation_id: &str) -> Result<(), HardwareError> {
        if let Some(mut allocation) = self.active_allocations.remove(allocation_id) {
            allocation.status = AllocationStatus::Released;
            // Implementation would release actual resources
            Ok(())
        } else {
            Err(HardwareError::AllocationNotFound(allocation_id.to_string()))
        }
    }

    fn find_suitable_resources(
        &self,
        requirements: &ResourceRequirements,
    ) -> Result<Vec<AllocatedResource>, HardwareError> {
        // Implementation would find actual suitable resources
        Ok(vec![AllocatedResource::default()])
    }
}

impl DeviceMonitor {
    fn new(config: &HardwareConfig) -> Self {
        Self {
            health_checkers: HashMap::new(),
            sensor_reader: HardwareSensorReader::new(),
            status_tracker: DeviceStatusTracker::new(),
            event_detector: HardwareEventDetector::new(),
            failure_predictor: HardwareFailurePredictor::new(),
            config: config.device_monitoring.clone().unwrap_or_default(),
            health_history: HashMap::new(),
        }
    }

    fn start_monitoring(&mut self) -> Result<(), HardwareError> {
        // Initialize health checkers for each device
        // Implementation would start background monitoring threads
        Ok(())
    }

    fn get_device_health(&self, device_id: &DeviceId) -> Result<HealthStatus, HardwareError> {
        // Implementation would check actual device health
        Ok(HealthStatus::Good)
    }
}

impl ThermalManager {
    fn new(config: &ThermalConfig) -> Self {
        Self {
            temperature_sensors: HashMap::new(),
            thermal_controllers: HashMap::new(),
            cooling_manager: CoolingSystemManager::new(),
            policy_enforcer: ThermalPolicyEnforcer::new(),
            throttling_controller: ThermalThrottlingController::new(),
            config: config.clone(),
            thermal_history: HashMap::new(),
        }
    }

    fn initialize_thermal_systems(&mut self) -> Result<(), HardwareError> {
        // Initialize thermal monitoring and control systems
        Ok(())
    }

    fn get_thermal_status(&self) -> Result<ThermalStatusReport, HardwareError> {
        Ok(ThermalStatusReport::default())
    }
}

impl PowerManager {
    fn new(config: &HardwareConfig) -> Self {
        Self {
            power_monitors: HashMap::new(),
            allocation_controller: PowerAllocationController::new(),
            dvfs_controller: DvfsController::new(),
            state_manager: PowerStateManager::new(),
            energy_optimizer: EnergyOptimizer::new(),
            config: config.power_management.clone().unwrap_or_default(),
            power_history: HashMap::new(),
        }
    }

    fn initialize_power_systems(&mut self) -> Result<(), HardwareError> {
        // Initialize power monitoring and management systems
        Ok(())
    }

    fn get_power_status(&self) -> Result<PowerStatusReport, HardwareError> {
        Ok(PowerStatusReport::default())
    }
}

impl HardwareAbstractionLayer {
    fn new(config: &HardwareConfig) -> Self {
        Self {
            device_drivers: HashMap::new(),
            interface_adapters: HashMap::new(),
            capability_registry: DeviceCapabilityRegistry::new(),
            command_executor: HardwareCommandExecutor::new(),
            abstraction_cache: DeviceAbstractionCache::new(),
            config: config.abstraction_layer.clone().unwrap_or_default(),
        }
    }

    fn execute_command(
        &mut self,
        command: HardwareCommand,
    ) -> Result<CommandResult, HardwareError> {
        // Implementation would execute actual hardware command
        Ok(CommandResult::default())
    }
}

impl DeviceCapabilityDetector {
    fn new(config: &HardwareConfig) -> Self {
        Self {
            capability_scanners: HashMap::new(),
            feature_detector: HardwareFeatureDetector::new(),
            benchmark_suite: HardwareBenchmarkSuite::new(),
            capability_database: CapabilityDatabase::new(),
            config: config.capability_detection.clone().unwrap_or_default(),
        }
    }

    fn discover_devices(&mut self) -> Result<Vec<DeviceInfo>, HardwareError> {
        // Implementation would discover actual devices
        Ok(vec![DeviceInfo::default()])
    }
}

// === Error Handling ===

/// Hardware management errors
#[derive(Debug, Clone)]
pub enum HardwareError {
    /// Device not found
    DeviceNotFound(String),
    /// Device initialization error
    DeviceInitializationError(String),
    /// Resource allocation error
    ResourceAllocationError(String),
    /// Allocation not found
    AllocationNotFound(String),
    /// Device health check error
    HealthCheckError(String),
    /// Thermal management error
    ThermalManagementError(String),
    /// Power management error
    PowerManagementError(String),
    /// Hardware abstraction error
    AbstractionError(String),
    /// Capability detection error
    CapabilityDetectionError(String),
    /// Configuration error
    ConfigurationError(String),
    /// System error
    SystemError(String),
}

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

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

// Hardware management types
default_placeholder_type!(GpuDeviceAllocator);
default_placeholder_type!(GpuMemoryManager);
default_placeholder_type!(GpuContextManager);
default_placeholder_type!(GpuStreamManager);
default_placeholder_type!(GpuPerformanceTracker);
default_placeholder_type!(GpuHealthMonitor);
default_placeholder_type!(AllocationStrategy);
default_placeholder_type!(ResourceScheduler);
default_placeholder_type!(AllocationTracker);
default_placeholder_type!(ResourceOptimizationEngine);
default_placeholder_type!(DeviceHealthChecker);
default_placeholder_type!(HardwareSensorReader);
default_placeholder_type!(DeviceStatusTracker);
default_placeholder_type!(HardwareEventDetector);
default_placeholder_type!(HardwareFailurePredictor);
default_placeholder_type!(TemperatureSensor);
default_placeholder_type!(ThermalController);
default_placeholder_type!(CoolingSystemManager);
default_placeholder_type!(ThermalPolicyEnforcer);
default_placeholder_type!(ThermalThrottlingController);
default_placeholder_type!(PowerMonitor);
default_placeholder_type!(PowerAllocationController);
default_placeholder_type!(DvfsController);
default_placeholder_type!(PowerStateManager);
default_placeholder_type!(EnergyOptimizer);
default_placeholder_type!(DeviceDriver);
default_placeholder_type!(InterfaceAdapter);
default_placeholder_type!(DeviceCapabilityRegistry);
default_placeholder_type!(HardwareCommandExecutor);
default_placeholder_type!(DeviceAbstractionCache);
default_placeholder_type!(CapabilityScanner);
default_placeholder_type!(HardwareFeatureDetector);
default_placeholder_type!(HardwareBenchmarkSuite);
default_placeholder_type!(CapabilityDatabase);
default_placeholder_type!(HardwareMetricsCollector);
default_placeholder_type!(HardwareState);

// Configuration types
default_placeholder_type!(EnergyOptimizationTargets);
default_placeholder_type!(DvfsConfig);
default_placeholder_type!(PowerStateTransitionRules);
default_placeholder_type!(ReservationPolicy);
default_placeholder_type!(AllocationTimeouts);
default_placeholder_type!(OversubscriptionLimits);
default_placeholder_type!(AdapterSettings);

// Data structure types
default_placeholder_type!(DeviceCapabilities);
default_placeholder_type!(GpuUtilization);
default_placeholder_type!(ResourcePoolConfig);
default_placeholder_type!(AllocationPolicy);
default_placeholder_type!(PoolResource);
default_placeholder_type!(AllocatedResource);
default_placeholder_type!(ResourceRequirements);
default_placeholder_type!(HealthMetrics);
default_placeholder_type!(HealthWarning);
default_placeholder_type!(HealthError);
default_placeholder_type!(DiagnosticInfo);
default_placeholder_type!(CoolingActivity);
default_placeholder_type!(ThermalEvent);
default_placeholder_type!(EnergyEfficiencyMetrics);
default_placeholder_type!(DeviceInfo);
default_placeholder_type!(ThermalStatusReport);
default_placeholder_type!(PowerStatusReport);
default_placeholder_type!(HardwareCommand);
default_placeholder_type!(CommandResult);

// Statistics with actual fields
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct HardwareStatistics {
    pub initialization_count: u64,
    pub last_initialization: Option<SystemTime>,
    pub devices_discovered: u64,
    pub resource_allocations: u64,
    pub resource_releases: u64,
    pub commands_executed: u64,
    pub thermal_events: u64,
    pub power_events: u64,
    pub health_checks_performed: u64,
}

// Implement constructors for placeholder types
impl GpuDeviceAllocator {
    fn new() -> Self {
        Self::default()
    }
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

impl HardwareStatistics {
    fn new() -> Self {
        Self {
            initialization_count: 0,
            last_initialization: None,
            devices_discovered: 0,
            resource_allocations: 0,
            resource_releases: 0,
            commands_executed: 0,
            thermal_events: 0,
            power_events: 0,
            health_checks_performed: 0,
        }
    }
}

// Default configurations
impl Default for DeviceMonitoringConfig {
    fn default() -> Self {
        Self {
            monitoring_interval: Duration::from_secs(10),
            health_check_frequency: Duration::from_secs(30),
            enable_failure_prediction: true,
            health_history_retention: Duration::from_secs(24 * 60 * 60),
            alert_thresholds: HashMap::new(),
        }
    }
}

impl Default for PowerManagementConfig {
    fn default() -> Self {
        Self {
            enable_dynamic_power_management: true,
            power_budget_limits: HashMap::new(),
            energy_optimization_targets: EnergyOptimizationTargets::default(),
            dvfs_config: DvfsConfig::default(),
            state_transition_rules: PowerStateTransitionRules::default(),
        }
    }
}

impl Default for ResourceAllocationConfig {
    fn default() -> Self {
        Self {
            default_allocation_strategy: "best_fit".to_string(),
            reservation_policies: HashMap::new(),
            allocation_timeouts: AllocationTimeouts::default(),
            enable_oversubscription: false,
            oversubscription_limits: OversubscriptionLimits::default(),
        }
    }
}

impl Default for AbstractionLayerConfig {
    fn default() -> Self {
        Self {
            enable_caching: true,
            cache_timeout: Duration::from_secs(10 * 60),
            auto_detect_drivers: true,
            adapter_settings: HashMap::new(),
        }
    }
}

impl Default for CapabilityDetectionConfig {
    fn default() -> Self {
        Self {
            enable_benchmarking: false,
            benchmark_timeout: Duration::from_secs(5 * 60),
            capability_cache_duration: Duration::from_secs(1 * 60 * 60),
            enable_validation: true,
        }
    }
}

/// Represents an active hardware session
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct HardwareSession {
    /// Session identifier
    pub id: u64,
    /// Session start time
    pub start_time: SystemTime,
    /// Associated device IDs
    pub device_ids: Vec<u32>,
    /// Session state
    pub state: SessionState,
}

/// Session state
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum SessionState {
    /// Session is active
    Active,
    /// Session is suspended
    Suspended,
    /// Session is terminated
    Terminated,
}

impl Default for HardwareSession {
    fn default() -> Self {
        Self {
            id: 0,
            start_time: SystemTime::now(),
            device_ids: Vec::new(),
            state: SessionState::Active,
        }
    }
}

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

    #[test]
    fn test_hardware_manager_creation() {
        let config = HardwareConfig::default();
        let manager = HardwareManager::new(config);
        let stats = manager.get_hardware_statistics();
        assert_eq!(stats.initialization_count, 0);
    }

    #[test]
    fn test_hardware_initialization() {
        let config = HardwareConfig::default();
        let manager = HardwareManager::new(config);

        let result = manager.initialize_hardware();
        assert!(result.is_ok());
    }

    #[test]
    fn test_device_discovery() {
        let config = HardwareConfig::default();
        let manager = HardwareManager::new(config);

        let devices = manager.discover_devices().unwrap();
        assert!(!devices.is_empty());
    }

    #[test]
    fn test_resource_allocation() {
        let config = HardwareConfig::default();
        let manager = HardwareManager::new(config);

        let requirements = ResourceRequirements::default();
        let allocation_id = manager.allocate_resources(requirements).unwrap();
        assert!(!allocation_id.is_empty());

        let result = manager.release_resources(&allocation_id);
        assert!(result.is_ok());
    }

    #[test]
    fn test_device_health_check() {
        let config = HardwareConfig::default();
        let manager = HardwareManager::new(config);

        let device_id = "test_device".to_string();
        let health_status = manager.get_device_health(&device_id).unwrap();
        assert_eq!(health_status, HealthStatus::Good);
    }

    #[test]
    fn test_thermal_status() {
        let config = HardwareConfig::default();
        let manager = HardwareManager::new(config);

        let thermal_status = manager.get_thermal_status().unwrap();
        // ThermalStatusReport should have default implementation
    }

    #[test]
    fn test_power_status() {
        let config = HardwareConfig::default();
        let manager = HardwareManager::new(config);

        let power_status = manager.get_power_status().unwrap();
        // PowerStatusReport should have default implementation
    }

    #[test]
    fn test_hardware_command_execution() {
        let config = HardwareConfig::default();
        let manager = HardwareManager::new(config);

        let command = HardwareCommand::default();
        let result = manager.execute_hardware_command(command).unwrap();
        // CommandResult should have default implementation
    }
}
