package lifecycle

import (
	"context"
	"fmt"
	"sync"
	"time"
)

// BaseModule provides a default implementation of the Module interface
type BaseModule struct {
	id           string
	name         string
	version      string
	dependencies []string
	state        ModuleState
	health       ModuleHealth
	metrics      ModuleMetrics
	config       ModuleConfig
}

// NewBaseModule creates a new base module
func NewBaseModule(id, name, version string, dependencies []string) *BaseModule {
	return &BaseModule{
		id:           id,
		name:         name,
		version:      version,
		dependencies: dependencies,
		state:        StateUninitialized,
		health: ModuleHealth{
			Status: HealthUnknown,
		},
		metrics: ModuleMetrics{
			CustomMetrics: make(map[string]interface{}),
		},
	}
}

// Core lifecycle methods

func (bm *BaseModule) Initialize(ctx context.Context, config ModuleConfig) error {
	bm.config = config
	bm.state = StateInitialized
	bm.health.Status = HealthHealthy
	return nil
}

func (bm *BaseModule) Start(ctx context.Context) error {
	if bm.state != StateInitialized && bm.state != StateStopped {
		return fmt.Errorf("invalid state for start: %s", bm.state)
	}

	startTime := time.Now()
	bm.state = StateRunning
	bm.metrics.StartupTime = time.Since(startTime)
	bm.metrics.LastActivity = time.Now()
	bm.health.Status = HealthHealthy
	return nil
}

func (bm *BaseModule) Stop(ctx context.Context) error {
	if bm.state != StateRunning && bm.state != StatePaused {
		return fmt.Errorf("invalid state for stop: %s", bm.state)
	}

	stopTime := time.Now()
	bm.state = StateStopped
	bm.metrics.ShutdownTime = time.Since(stopTime)
	bm.health.Status = HealthUnknown
	return nil
}

func (bm *BaseModule) Pause(ctx context.Context) error {
	if bm.state != StateRunning {
		return fmt.Errorf("invalid state for pause: %s", bm.state)
	}

	bm.state = StatePaused
	return nil
}

func (bm *BaseModule) Resume(ctx context.Context) error {
	if bm.state != StatePaused {
		return fmt.Errorf("invalid state for resume: %s", bm.state)
	}

	bm.state = StateRunning
	bm.metrics.LastActivity = time.Now()
	return nil
}

// Module information

func (bm *BaseModule) GetID() string {
	return bm.id
}

func (bm *BaseModule) GetName() string {
	return bm.name
}

func (bm *BaseModule) GetVersion() string {
	return bm.version
}

func (bm *BaseModule) GetDependencies() []string {
	return bm.dependencies
}

// Health and status

func (bm *BaseModule) GetHealth() ModuleHealth {
	bm.health.LastCheck = time.Now()
	return bm.health
}

func (bm *BaseModule) GetState() ModuleState {
	return bm.state
}

func (bm *BaseModule) GetMetrics() ModuleMetrics {
	return bm.metrics
}

// Protected methods for subclasses

func (bm *BaseModule) SetHealth(status HealthStatus, message string) {
	bm.health.Status = status
	bm.health.Message = message
	bm.health.LastCheck = time.Now()
}

func (bm *BaseModule) SetState(state ModuleState) {
	bm.state = state
}

func (bm *BaseModule) UpdateMetrics(updates map[string]interface{}) {
	for key, value := range updates {
		bm.metrics.CustomMetrics[key] = value
	}
	bm.metrics.LastActivity = time.Now()
}

func (bm *BaseModule) IncrementMetric(name string, value int64) {
	if current, exists := bm.metrics.CustomMetrics[name]; exists {
		if currentVal, ok := current.(int64); ok {
			bm.metrics.CustomMetrics[name] = currentVal + value
		} else {
			bm.metrics.CustomMetrics[name] = value
		}
	} else {
		bm.metrics.CustomMetrics[name] = value
	}
}

// SimpleEventBus provides a basic implementation of EventBus
type SimpleEventBus struct {
	handlers map[EventType][]EventHandler
	mu       sync.RWMutex
}

func NewSimpleEventBus() *SimpleEventBus {
	return &SimpleEventBus{
		handlers: make(map[EventType][]EventHandler),
	}
}

func (seb *SimpleEventBus) Publish(event ModuleEvent) error {
	seb.mu.RLock()
	defer seb.mu.RUnlock()

	handlers, exists := seb.handlers[event.Type]
	if !exists {
		return nil
	}

	for _, handler := range handlers {
		go func(h EventHandler) {
			if err := h(event); err != nil {
				// Log error but don't fail the publish
			}
		}(handler)
	}

	return nil
}

func (seb *SimpleEventBus) Subscribe(eventType EventType, handler EventHandler) error {
	seb.mu.Lock()
	defer seb.mu.Unlock()

	if _, exists := seb.handlers[eventType]; !exists {
		seb.handlers[eventType] = make([]EventHandler, 0)
	}

	seb.handlers[eventType] = append(seb.handlers[eventType], handler)
	return nil
}

// LifecycleManager coordinates all lifecycle components
type LifecycleManager struct {
	registry        *ModuleRegistry
	healthMonitor   *HealthMonitorImpl
	shutdownManager *ShutdownManager
	container       *Container
	eventBus        *SimpleEventBus
	config          LifecycleConfig
	mu              sync.RWMutex
}

// LifecycleConfig configures the lifecycle manager
type LifecycleConfig struct {
	RegistryConfig            RegistryConfig      `json:"registry_config"`
	HealthMonitorConfig       HealthMonitorConfig `json:"health_monitor_config"`
	ShutdownConfig            ShutdownConfig      `json:"shutdown_config"`
	ContainerConfig           ContainerConfig     `json:"container_config"`
	EnableEventBus            bool                `json:"enable_event_bus"`
	EnableHealthMonitor       bool                `json:"enable_health_monitor"`
	EnableShutdownManager     bool                `json:"enable_shutdown_manager"`
	EnableDependencyInjection bool                `json:"enable_dependency_injection"`
}

// NewLifecycleManager creates a new lifecycle manager
func NewLifecycleManager(config LifecycleConfig) *LifecycleManager {
	lm := &LifecycleManager{
		config: config,
	}

	// Create event bus
	if config.EnableEventBus {
		lm.eventBus = NewSimpleEventBus()
	}

	// Create dependency injection container
	if config.EnableDependencyInjection {
		lm.container = NewContainer(config.ContainerConfig)
	}

	// Create module registry
	lm.registry = NewModuleRegistry(config.RegistryConfig)
	if lm.eventBus != nil {
		lm.registry.SetEventBus(lm.eventBus)
	}

	// Create health monitor
	if config.EnableHealthMonitor {
		lm.healthMonitor = NewHealthMonitor(config.HealthMonitorConfig)
		lm.registry.SetHealthMonitor(lm.healthMonitor)
	}

	// Create shutdown manager
	if config.EnableShutdownManager {
		lm.shutdownManager = NewShutdownManager(lm.registry, config.ShutdownConfig)
	}

	return lm
}

// Initialize initializes the lifecycle manager
func (lm *LifecycleManager) Initialize(ctx context.Context) error {
	lm.mu.Lock()
	defer lm.mu.Unlock()

	// Validate container if enabled
	if lm.container != nil {
		if err := lm.container.Validate(); err != nil {
			return fmt.Errorf("container validation failed: %w", err)
		}
	}

	// Initialize registry
	if err := lm.registry.Initialize(ctx); err != nil {
		return fmt.Errorf("registry initialization failed: %w", err)
	}

	// Start health monitor
	if lm.healthMonitor != nil {
		if err := lm.healthMonitor.Start(); err != nil {
			return fmt.Errorf("health monitor start failed: %w", err)
		}
	}

	// Start shutdown manager
	if lm.shutdownManager != nil {
		if err := lm.shutdownManager.Start(); err != nil {
			return fmt.Errorf("shutdown manager start failed: %w", err)
		}
	}

	return nil
}

// Start starts all modules
func (lm *LifecycleManager) Start(ctx context.Context) error {
	return lm.registry.StartAll(ctx)
}

// Stop stops all modules
func (lm *LifecycleManager) Stop(ctx context.Context) error {
	return lm.registry.StopAll(ctx)
}

// Shutdown gracefully shuts down the entire system
func (lm *LifecycleManager) Shutdown(ctx context.Context) error {
	if lm.shutdownManager != nil {
		return lm.shutdownManager.Shutdown(ctx)
	}
	return lm.registry.Shutdown(ctx)
}

// RegisterModule registers a new module
func (lm *LifecycleManager) RegisterModule(module Module, config ModuleConfig) error {
	return lm.registry.Register(module, config)
}

// GetModule retrieves a module by ID
func (lm *LifecycleManager) GetModule(moduleID string) (Module, error) {
	return lm.registry.Get(moduleID)
}

// GetRegistry returns the module registry
func (lm *LifecycleManager) GetRegistry() *ModuleRegistry {
	lm.mu.RLock()
	defer lm.mu.RUnlock()
	return lm.registry
}

// GetHealthMonitor returns the health monitor
func (lm *LifecycleManager) GetHealthMonitor() *HealthMonitorImpl {
	lm.mu.RLock()
	defer lm.mu.RUnlock()
	return lm.healthMonitor
}

// GetShutdownManager returns the shutdown manager
func (lm *LifecycleManager) GetShutdownManager() *ShutdownManager {
	lm.mu.RLock()
	defer lm.mu.RUnlock()
	return lm.shutdownManager
}

// GetContainer returns the dependency injection container
func (lm *LifecycleManager) GetContainer() *Container {
	lm.mu.RLock()
	defer lm.mu.RUnlock()
	return lm.container
}

// GetEventBus returns the event bus
func (lm *LifecycleManager) GetEventBus() *SimpleEventBus {
	lm.mu.RLock()
	defer lm.mu.RUnlock()
	return lm.eventBus
}

// GetOverallHealth returns the overall system health
func (lm *LifecycleManager) GetOverallHealth() (OverallHealth, error) {
	if lm.healthMonitor == nil {
		return OverallHealth{}, fmt.Errorf("health monitor not enabled")
	}
	return lm.healthMonitor.GetOverallHealth(), nil
}

// CreateDefaultConfig creates a default lifecycle configuration
func CreateDefaultConfig() LifecycleConfig {
	return LifecycleConfig{
		RegistryConfig: RegistryConfig{
			StartTimeout:        30 * time.Second,
			StopTimeout:         15 * time.Second,
			HealthCheckInterval: 30 * time.Second,
			EnableMetrics:       true,
			EnableHealthMonitor: true,
			ParallelStartup:     false,
			ParallelShutdown:    true,
			FailureRecovery:     true,
			AutoRestart:         true,
			MaxRestartAttempts:  3,
		},
		HealthMonitorConfig: HealthMonitorConfig{
			CheckInterval:       30 * time.Second,
			CheckTimeout:        10 * time.Second,
			HistorySize:         100,
			FailureThreshold:    3,
			RecoveryThreshold:   3,
			EnableNotifications: true,
			EnableMetrics:       true,
			EnableTrends:        true,
			ParallelChecks:      true,
			MaxConcurrentChecks: 10,
		},
		ShutdownConfig: ShutdownConfig{
			GracefulTimeout:    30 * time.Second,
			ForceTimeout:       60 * time.Second,
			SignalBufferSize:   10,
			MaxRetries:         3,
			RetryDelay:         time.Second,
			ParallelShutdown:   true,
			SaveState:          true,
			CleanupTempFiles:   true,
			NotifyExternal:     false,
			WaitForConnections: true,
			EnableMetrics:      true,
		},
		ContainerConfig: ContainerConfig{
			EnableReflection:        true,
			EnableCircularDetection: true,
			EnableInterception:      false,
			EnableValidation:        true,
			MaxDepth:                10,
			CacheInstances:          true,
		},
		EnableEventBus:            true,
		EnableHealthMonitor:       true,
		EnableShutdownManager:     true,
		EnableDependencyInjection: true,
	}
}