package traefikoidc

import (
	"context"
	"sync"
	"time"

	"github.com/lukaszraczylo/traefikoidc/internal/cache/backends"
	"github.com/lukaszraczylo/traefikoidc/internal/cache/resilience"
)

// UniversalCacheManager manages all cache instances using the universal cache
// It runs a single consolidated cleanup goroutine for all caches, reducing
// goroutine count and CPU overhead compared to per-cache cleanup routines.
type UniversalCacheManager struct {
	sharedBackend            backends.CacheBackend
	ctx                      context.Context
	tokenTypeCache           *UniversalCache
	jwkCache                 *UniversalCache
	sessionCache             *UniversalCache
	introspectionCache       *UniversalCache
	tokenCache               *UniversalCache
	metadataCache            *UniversalCache
	dcrCredentialsCache      *UniversalCache // DCR credentials storage for distributed environments
	sessionInvalidationCache *UniversalCache // Session invalidation cache for backchannel/front-channel logout
	refreshResultCache       *UniversalCache // Short-lived cross-replica refresh-result dedup (paired with RefreshCoordinator)
	logger                   *Logger
	blacklistCache           *UniversalCache
	cancel                   context.CancelFunc
	wg                       sync.WaitGroup
	mu                       sync.RWMutex
	cleanupStarted           bool
}

var (
	universalCacheManager     *UniversalCacheManager
	universalCacheManagerOnce sync.Once
)

// GetUniversalCacheManager returns the singleton universal cache manager
func GetUniversalCacheManager(logger *Logger) *UniversalCacheManager {
	universalCacheManagerOnce.Do(func() {
		if logger == nil {
			logger = GetSingletonNoOpLogger()
		}

		ctx, cancel := context.WithCancel(context.Background())

		universalCacheManager = &UniversalCacheManager{
			logger: logger,
			ctx:    ctx,
			cancel: cancel,
		}

		// Initialize with default in-memory backends
		initializeDefaultCaches(universalCacheManager, logger)

		// Start single consolidated cleanup goroutine for all caches
		// This replaces 7 individual cleanup goroutines with 1
		universalCacheManager.startConsolidatedCleanup()
	})

	return universalCacheManager
}

// GetUniversalCacheManagerWithConfig returns the singleton universal cache manager with Redis configuration
func GetUniversalCacheManagerWithConfig(logger *Logger, redisConfig *RedisConfig) *UniversalCacheManager {
	universalCacheManagerOnce.Do(func() {
		if logger == nil {
			logger = GetSingletonNoOpLogger()
		}

		ctx, cancel := context.WithCancel(context.Background())

		universalCacheManager = &UniversalCacheManager{
			logger: logger,
			ctx:    ctx,
			cancel: cancel,
		}

		if redisConfig != nil && redisConfig.Enabled {
			logger.Infof("Initializing cache manager with Redis backend: %s", redisConfig.Address)
			initializeCachesWithRedis(universalCacheManager, logger, redisConfig)
		} else {
			logger.Info("Initializing cache manager with memory-only backend")
			initializeDefaultCaches(universalCacheManager, logger)
		}

		// Start single consolidated cleanup goroutine for all caches
		// This replaces 7 individual cleanup goroutines with 1
		universalCacheManager.startConsolidatedCleanup()
	})

	return universalCacheManager
}

// initializeDefaultCaches initializes caches with memory-only backends
func initializeDefaultCaches(manager *UniversalCacheManager, logger *Logger) {
	// Initialize token cache - CRITICAL FIX: Reduced from 5000 to 1000
	manager.tokenCache = NewUniversalCache(UniversalCacheConfig{
		Type:            CacheTypeToken,
		MaxSize:         1000,            // CRITICAL FIX: Reduced from 5000 to 1000 items
		MaxMemoryBytes:  5 * 1024 * 1024, // CRITICAL FIX: Added 5MB memory limit
		DefaultTTL:      1 * time.Hour,
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})

	// Initialize blacklist cache
	manager.blacklistCache = NewUniversalCache(UniversalCacheConfig{
		Type:            CacheTypeToken,
		MaxSize:         1000,
		DefaultTTL:      24 * time.Hour,
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})

	// Initialize metadata cache with grace periods
	manager.metadataCache = NewUniversalCache(UniversalCacheConfig{
		Type:       CacheTypeMetadata,
		MaxSize:    100,
		DefaultTTL: 1 * time.Hour,
		MetadataConfig: &MetadataCacheConfig{
			GracePeriod:                    5 * time.Minute,
			ExtendedGracePeriod:            15 * time.Minute,
			MaxGracePeriod:                 30 * time.Minute,
			SecurityCriticalMaxGracePeriod: 15 * time.Minute,
			SecurityCriticalFields: []string{
				"jwks_uri",
				"token_endpoint",
				"authorization_endpoint",
				"issuer",
			},
		},
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})

	// Initialize JWK cache
	manager.jwkCache = NewUniversalCache(UniversalCacheConfig{
		Type:            CacheTypeJWK,
		MaxSize:         200,
		DefaultTTL:      1 * time.Hour,
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})

	// Initialize session cache - CRITICAL FIX: Reduced from 10000 to 2000
	manager.sessionCache = NewUniversalCache(UniversalCacheConfig{
		Type:            CacheTypeSession,
		MaxSize:         2000,            // CRITICAL FIX: Reduced from 10000 to 2000 items
		MaxMemoryBytes:  5 * 1024 * 1024, // CRITICAL FIX: Added 5MB memory limit
		DefaultTTL:      30 * time.Minute,
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})

	// Initialize introspection cache for OAuth 2.0 Token Introspection (RFC 7662)
	manager.introspectionCache = NewUniversalCache(UniversalCacheConfig{
		Type:            CacheTypeToken,  // Use token cache type for introspection results
		MaxSize:         1000,            // Cache up to 1000 introspection results
		DefaultTTL:      5 * time.Minute, // Short TTL for security (introspect frequently)
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})

	// Initialize token type cache for performance optimization
	manager.tokenTypeCache = NewUniversalCache(UniversalCacheConfig{
		Type:            CacheTypeToken,  // Use token cache type for token type detection
		MaxSize:         2000,            // Cache up to 2000 token type detections
		DefaultTTL:      5 * time.Minute, // 5 minute TTL for token type detection
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})

	// Initialize session invalidation cache for backchannel/front-channel logout
	// This cache stores invalidated session IDs and subjects to revoke sessions
	manager.sessionInvalidationCache = NewUniversalCache(UniversalCacheConfig{
		Type:            CacheTypeSession,
		MaxSize:         5000,           // Support many concurrent invalidations
		DefaultTTL:      25 * time.Hour, // Slightly longer than session max age (24h)
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})

	// Refresh-result cache: short-lived store keyed by sha256(refreshToken).
	// In Redis-backed mode this gives cross-replica dedup of refresh grants;
	// in memory-only mode it's effectively redundant with RefreshCoordinator
	// but safe and cheap to keep.
	manager.refreshResultCache = NewUniversalCache(UniversalCacheConfig{
		Type:            CacheTypeToken,
		MaxSize:         1000,
		DefaultTTL:      5 * time.Second,
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})
}

// initializeCachesWithRedis initializes caches with Redis/Hybrid backends based on configuration
func initializeCachesWithRedis(manager *UniversalCacheManager, logger *Logger, redisConfig *RedisConfig) {
	// Apply defaults to Redis config
	redisConfig.ApplyDefaults()

	// Create Redis backend
	redisBackendConfig := &backends.Config{
		Type:          backends.BackendTypeRedis,
		RedisAddr:     redisConfig.Address,
		RedisPassword: redisConfig.Password,
		RedisDB:       redisConfig.DB,
		RedisPrefix:   redisConfig.KeyPrefix,
		PoolSize:      redisConfig.PoolSize,
		EnableMetrics: true,
	}

	// Use concrete type to avoid Yaegi reflection issues with interface assignment
	// The concrete type will be automatically converted to interface when needed
	baseBackend, err := backends.NewRedisBackend(redisBackendConfig)
	if err != nil {
		logger.Errorf("Failed to create Redis backend: %v. Falling back to memory-only mode.", err)
		initializeDefaultCaches(manager, logger)
		return
	}

	// Build the backend with optional wrappers
	var redisBackend backends.CacheBackend = baseBackend

	// Wrap with circuit breaker if enabled
	if redisConfig.EnableCircuitBreaker {
		cbConfig := resilience.DefaultCircuitBreakerConfig()
		cbConfig.MaxFailures = redisConfig.CircuitBreakerThreshold
		cbConfig.Timeout = time.Duration(redisConfig.CircuitBreakerTimeout) * time.Second
		cbConfig.OnStateChange = func(from, to resilience.State) {
			logger.Infof("Circuit breaker state changed from %s to %s", from, to)
		}

		redisBackend = resilience.NewCircuitBreakerBackend(redisBackend, cbConfig)
		logger.Info("Redis backend wrapped with circuit breaker")
	}

	// Wrap with health checker if enabled
	if redisConfig.EnableHealthCheck {
		hcConfig := &resilience.HealthCheckConfig{
			CheckInterval:      time.Duration(redisConfig.HealthCheckInterval) * time.Second,
			Timeout:            5 * time.Second,
			HealthyThreshold:   2,
			UnhealthyThreshold: 3,
			OnStatusChange: func(from, to resilience.HealthStatus) {
				logger.Infof("Redis backend health status changed from %s to %s", from, to)
			},
		}

		redisBackend = resilience.NewHealthCheckBackend(redisBackend, hcConfig)
		logger.Info("Redis backend wrapped with health checker")
	}

	// Store the fully-wrapped shared backend in the manager so it can be closed properly
	manager.sharedBackend = redisBackend

	// Decide which backend to use based on cache mode
	var createBackend func(cacheType CacheType) backends.CacheBackend

	switch redisConfig.CacheMode {
	case "redis":
		// Redis-only mode
		createBackend = func(cacheType CacheType) backends.CacheBackend {
			return redisBackend
		}
		logger.Info("Using Redis-only cache backend")

	case "hybrid":
		// Hybrid mode is not currently supported due to interface incompatibilities
		// Fall back to Redis-only mode
		logger.Info("Hybrid mode not currently supported, using Redis-only mode")
		createBackend = func(cacheType CacheType) backends.CacheBackend {
			return redisBackend
		}

	default:
		// Memory-only mode (fallback)
		logger.Infof("Invalid cache mode: %s. Using memory-only mode.", redisConfig.CacheMode)
		initializeDefaultCaches(manager, logger)
		return
	}

	// Initialize token cache with backend
	manager.tokenCache = NewUniversalCacheWithBackend(
		UniversalCacheConfig{
			Type:            CacheTypeToken,
			MaxSize:         1000,
			MaxMemoryBytes:  5 * 1024 * 1024,
			DefaultTTL:      1 * time.Hour,
			Logger:          logger,
			SkipAutoCleanup: true, // Managed cleanup
		},
		createBackend(CacheTypeToken),
	)

	// Initialize blacklist cache (CRITICAL - must be consistent across replicas)
	manager.blacklistCache = NewUniversalCacheWithBackend(
		UniversalCacheConfig{
			Type:            CacheTypeToken,
			MaxSize:         1000,
			DefaultTTL:      24 * time.Hour,
			Logger:          logger,
			SkipAutoCleanup: true, // Managed cleanup
		},
		createBackend("blacklist"),
	)

	// Initialize metadata cache
	manager.metadataCache = NewUniversalCacheWithBackend(
		UniversalCacheConfig{
			Type:       CacheTypeMetadata,
			MaxSize:    100,
			DefaultTTL: 1 * time.Hour,
			MetadataConfig: &MetadataCacheConfig{
				GracePeriod:                    5 * time.Minute,
				ExtendedGracePeriod:            15 * time.Minute,
				MaxGracePeriod:                 30 * time.Minute,
				SecurityCriticalMaxGracePeriod: 15 * time.Minute,
				SecurityCriticalFields: []string{
					"jwks_uri",
					"token_endpoint",
					"authorization_endpoint",
					"issuer",
				},
			},
			Logger:          logger,
			SkipAutoCleanup: true, // Managed cleanup
		},
		createBackend(CacheTypeMetadata),
	)

	// Initialize JWK cache
	manager.jwkCache = NewUniversalCacheWithBackend(
		UniversalCacheConfig{
			Type:            CacheTypeJWK,
			MaxSize:         200,
			DefaultTTL:      1 * time.Hour,
			Logger:          logger,
			SkipAutoCleanup: true, // Managed cleanup
		},
		createBackend(CacheTypeJWK),
	)

	// Session cache stays memory-only (high volume, local state)
	manager.sessionCache = NewUniversalCache(UniversalCacheConfig{
		Type:            CacheTypeSession,
		MaxSize:         2000,
		MaxMemoryBytes:  5 * 1024 * 1024,
		DefaultTTL:      30 * time.Minute,
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})

	// Introspection cache uses backend for sharing results
	manager.introspectionCache = NewUniversalCacheWithBackend(
		UniversalCacheConfig{
			Type:            CacheTypeToken,
			MaxSize:         1000,
			DefaultTTL:      5 * time.Minute,
			Logger:          logger,
			SkipAutoCleanup: true, // Managed cleanup
		},
		createBackend(CacheTypeToken),
	)

	// Token type cache stays memory-only (local optimization)
	manager.tokenTypeCache = NewUniversalCache(UniversalCacheConfig{
		Type:            CacheTypeToken,
		MaxSize:         2000,
		DefaultTTL:      5 * time.Minute,
		Logger:          logger,
		SkipAutoCleanup: true, // Managed cleanup
	})

	// DCR credentials cache - CRITICAL for distributed DCR across multiple nodes
	// Uses Redis backend to share client credentials across all Traefik replicas
	manager.dcrCredentialsCache = NewUniversalCacheWithBackend(
		UniversalCacheConfig{
			Type:            CacheTypeGeneral,
			MaxSize:         100,                 // Few providers expected
			DefaultTTL:      30 * 24 * time.Hour, // 30 days default (credentials are long-lived)
			Logger:          logger,
			SkipAutoCleanup: true, // Managed cleanup
		},
		createBackend("dcr"),
	)

	// Session invalidation cache - CRITICAL for distributed backchannel/front-channel logout
	// Uses Redis backend to share session invalidations across all Traefik replicas
	manager.sessionInvalidationCache = NewUniversalCacheWithBackend(
		UniversalCacheConfig{
			Type:            CacheTypeSession,
			MaxSize:         5000,           // Support many concurrent invalidations
			DefaultTTL:      25 * time.Hour, // Slightly longer than session max age (24h)
			Logger:          logger,
			SkipAutoCleanup: true, // Managed cleanup
		},
		createBackend("session_invalidation"),
	)

	// Refresh-result cache - shared via Redis so concurrent refreshes across
	// Traefik replicas can dedup their grants. The 5s TTL is long enough for
	// peers to observe a recent refresh and short enough that a stale entry
	// can't be replayed against a now-rotated refresh token.
	manager.refreshResultCache = NewUniversalCacheWithBackend(
		UniversalCacheConfig{
			Type:            CacheTypeToken,
			MaxSize:         1000,
			DefaultTTL:      5 * time.Second,
			Logger:          logger,
			SkipAutoCleanup: true, // Managed cleanup
		},
		createBackend("refresh_result"),
	)

	logger.Infof("Cache manager initialized with %s backend configuration", redisConfig.CacheMode)
}

// startConsolidatedCleanup starts a single cleanup goroutine for all caches
// This reduces goroutine count from 7 to 1 and consolidates cleanup operations
func (m *UniversalCacheManager) startConsolidatedCleanup() {
	m.mu.Lock()
	if m.cleanupStarted {
		m.mu.Unlock()
		return
	}
	m.cleanupStarted = true
	m.mu.Unlock()

	m.wg.Add(1)
	go func() {
		defer m.wg.Done()

		// Use 5-minute interval for consolidated cleanup
		ticker := time.NewTicker(5 * time.Minute)
		defer ticker.Stop()

		for {
			select {
			case <-m.ctx.Done():
				return
			case <-ticker.C:
				m.performConsolidatedCleanup()
			}
		}
	}()

	m.logger.Info("UniversalCacheManager: Started consolidated cleanup routine for all caches")
}

// performConsolidatedCleanup runs cleanup on all caches in sequence
// This is more efficient than parallel cleanup as it reduces lock contention
func (m *UniversalCacheManager) performConsolidatedCleanup() {
	m.mu.RLock()
	caches := []*UniversalCache{
		m.tokenCache,
		m.blacklistCache,
		m.metadataCache,
		m.jwkCache,
		m.sessionCache,
		m.introspectionCache,
		m.tokenTypeCache,
		m.dcrCredentialsCache,
		m.sessionInvalidationCache,
		m.refreshResultCache,
	}
	m.mu.RUnlock()

	for _, cache := range caches {
		if cache != nil {
			// Each cache.Cleanup() is self-contained and handles its own locking
			cache.Cleanup()
		}
	}

	m.logger.Debugf("UniversalCacheManager: Consolidated cleanup completed for all caches")
}

// GetTokenCache returns the token cache
func (m *UniversalCacheManager) GetTokenCache() *UniversalCache {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.tokenCache
}

// GetBlacklistCache returns the blacklist cache
func (m *UniversalCacheManager) GetBlacklistCache() *UniversalCache {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.blacklistCache
}

// GetMetadataCache returns the metadata cache
func (m *UniversalCacheManager) GetMetadataCache() *UniversalCache {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.metadataCache
}

// GetJWKCache returns the JWK cache
func (m *UniversalCacheManager) GetJWKCache() *UniversalCache {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.jwkCache
}

// GetIntrospectionCache returns the token introspection cache
func (m *UniversalCacheManager) GetIntrospectionCache() *UniversalCache {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.introspectionCache
}

// GetTokenTypeCache returns the token type detection cache
func (m *UniversalCacheManager) GetTokenTypeCache() *UniversalCache {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.tokenTypeCache
}

// GetSessionInvalidationCache returns the session invalidation cache for backchannel/front-channel logout
func (m *UniversalCacheManager) GetSessionInvalidationCache() *UniversalCache {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.sessionInvalidationCache
}

// GetRefreshResultCache returns the short-lived refresh-result cache used to
// coalesce refresh-token grants across Traefik replicas.
func (m *UniversalCacheManager) GetRefreshResultCache() *UniversalCache {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.refreshResultCache
}

// GetDCRCredentialsCache returns the DCR credentials cache for distributed storage
func (m *UniversalCacheManager) GetDCRCredentialsCache() *UniversalCache {
	m.mu.RLock()
	defer m.mu.RUnlock()
	return m.dcrCredentialsCache
}

// Close shuts down all caches and the consolidated cleanup routine
func (m *UniversalCacheManager) Close() error {
	// Stop the consolidated cleanup routine first
	if m.cancel != nil {
		m.cancel()
	}

	// Wait for cleanup routine to finish
	m.wg.Wait()

	m.mu.Lock()
	defer m.mu.Unlock()

	// Close all caches first (they won't close the shared backend)
	for _, cache := range []*UniversalCache{
		m.tokenCache, m.blacklistCache, m.metadataCache, m.jwkCache, m.sessionCache, m.introspectionCache, m.tokenTypeCache, m.dcrCredentialsCache, m.sessionInvalidationCache, m.refreshResultCache,
	} {
		if cache != nil {
			_ = cache.Close() // Safe to ignore: best effort cache cleanup
		}
	}

	// Now close the shared backend if present
	if m.sharedBackend != nil {
		if err := m.sharedBackend.Close(); err != nil {
			m.logger.Infof("Failed to close shared cache backend: %v", err)
		} else {
			m.logger.Info("UniversalCacheManager: Closed shared backend")
		}
	}

	m.cleanupStarted = false
	m.logger.Info("UniversalCacheManager: Closed all caches and cleanup routine")
	return nil
}

// ResetUniversalCacheManagerForTesting resets the singleton for testing purposes only
// This should only be called in test code to ensure proper cleanup between tests
func ResetUniversalCacheManagerForTesting() {
	if universalCacheManager != nil {
		_ = universalCacheManager.Close() // Safe to ignore: test cleanup best effort
	}
	universalCacheManagerOnce = sync.Once{}
	universalCacheManager = nil
}