package bot

import (
	"TelegramCloud/tgf/config"
	"TelegramCloud/tgf/internal/db"
	"context"
	"fmt"
	"sync"
	"time"

	"github.com/celestix/gotgproto"
	"github.com/celestix/gotgproto/sessionMaker"
	"github.com/glebarez/sqlite"
	"go.uber.org/zap"
)

// BotInstance represents an active bot instance
type BotInstance struct {
	Client    *gotgproto.Client
	UserID    int64
	BotID     int64
	Username  string
	LastUsed  time.Time
	ErrorCount int
}

// InstanceManager manages multiple bot instances
type InstanceManager struct {
	instances    map[int64]*BotInstance // userID -> BotInstance
	mutex        sync.RWMutex
	log          *zap.Logger
	userBotMgr   *db.UserBotManager
	cleanupTicker *time.Ticker
	maxInstances int
	idleTimeout  time.Duration
}

// NewInstanceManager creates a new bot instance manager
func NewInstanceManager(userBotMgr *db.UserBotManager, log *zap.Logger) *InstanceManager {
	im := &InstanceManager{
		instances:    make(map[int64]*BotInstance),
		log:          log.Named("InstanceManager"),
		userBotMgr:   userBotMgr,
		maxInstances: 100, // Maximum concurrent bot instances
		idleTimeout:  30 * time.Minute, // Close idle bots after 30 minutes
	}

	// Start cleanup routine
	im.startCleanupRoutine()
	
	return im
}

// GetBotForUser returns a bot instance for the user (creates if needed)
func (im *InstanceManager) GetBotForUser(ctx context.Context, userID int64) (*gotgproto.Client, error) {
	im.mutex.Lock()
	defer im.mutex.Unlock()

	// Check if we already have an active instance
	if instance, exists := im.instances[userID]; exists {
		instance.LastUsed = time.Now()
		im.log.Debug("Reusing existing bot instance", zap.Int64("userID", userID))
		return instance.Client, nil
	}

	// Check if we're at max capacity
	if len(im.instances) >= im.maxInstances {
		// Remove oldest idle instance
		im.removeOldestInstance()
	}

	// Get user's bot token
	botToken, err := im.userBotMgr.GetDecryptedBotToken(ctx, userID)
	if err != nil {
		return nil, fmt.Errorf("failed to get user bot token: %w", err)
	}

	// Create new bot instance
	instance, err := im.createBotInstance(userID, botToken)
	if err != nil {
		// Record error in database
		im.userBotMgr.RecordBotError(ctx, userID, err.Error())
		return nil, fmt.Errorf("failed to create bot instance: %w", err)
	}

	// Store instance
	im.instances[userID] = instance
	
	// Update usage in database
	im.userBotMgr.UpdateBotUsage(ctx, userID)

	im.log.Info("Created new bot instance", 
		zap.Int64("userID", userID),
		zap.String("botUsername", instance.Username),
		zap.Int("totalInstances", len(im.instances)))

	return instance.Client, nil
}

// createBotInstance creates a new bot client instance
func (im *InstanceManager) createBotInstance(userID int64, botToken string) (*BotInstance, error) {
	// Create unique session path for this user's bot
	sessionPath := fmt.Sprintf("/tmp/userbot_%d.session", userID)
	
	// Create bot client with timeout
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	resultChan := make(chan struct {
		client *gotgproto.Client
		err    error
	})

	go func() {
		client, err := gotgproto.NewClient(
			int(config.ValueOf.ApiID),
			config.ValueOf.ApiHash,
			gotgproto.ClientTypeBot(botToken),
			&gotgproto.ClientOpts{
				Session: sessionMaker.SqlSession(
					sqlite.Open(sessionPath),
				),
				DisableCopyright: true,
			},
		)
		resultChan <- struct {
			client *gotgproto.Client
			err    error
		}{client, err}
	}()

	select {
	case <-ctx.Done():
		return nil, fmt.Errorf("bot creation timeout")
	case result := <-resultChan:
		if result.err != nil {
			return nil, result.err
		}

		instance := &BotInstance{
			Client:     result.client,
			UserID:     userID,
			BotID:      result.client.Self.ID,
			Username:   result.client.Self.Username,
			LastUsed:   time.Now(),
			ErrorCount: 0,
		}

		return instance, nil
	}
}

// RemoveBotInstance removes a bot instance for a user
func (im *InstanceManager) RemoveBotInstance(userID int64) {
	im.mutex.Lock()
	defer im.mutex.Unlock()

	if instance, exists := im.instances[userID]; exists {
		// Stop the bot client
		instance.Client.Stop()
		delete(im.instances, userID)
		
		im.log.Info("Removed bot instance", 
			zap.Int64("userID", userID),
			zap.String("botUsername", instance.Username))
	}
}

// RecordError records an error for a user's bot instance
func (im *InstanceManager) RecordError(ctx context.Context, userID int64, err error) {
	im.mutex.Lock()
	defer im.mutex.Unlock()

	if instance, exists := im.instances[userID]; exists {
		instance.ErrorCount++
		
		// Remove instance if too many errors
		if instance.ErrorCount >= 3 {
			im.log.Warn("Removing bot instance due to errors", 
				zap.Int64("userID", userID),
				zap.Int("errorCount", instance.ErrorCount),
				zap.Error(err))
			
			instance.Client.Stop()
			delete(im.instances, userID)
		}
	}

	// Record error in database
	im.userBotMgr.RecordBotError(ctx, userID, err.Error())
}

// removeOldestInstance removes the oldest idle instance
func (im *InstanceManager) removeOldestInstance() {
	var oldestUserID int64
	var oldestTime time.Time = time.Now()

	for userID, instance := range im.instances {
		if instance.LastUsed.Before(oldestTime) {
			oldestTime = instance.LastUsed
			oldestUserID = userID
		}
	}

	if oldestUserID != 0 {
		if instance, exists := im.instances[oldestUserID]; exists {
			instance.Client.Stop()
			delete(im.instances, oldestUserID)
			im.log.Info("Removed oldest bot instance to make room", 
				zap.Int64("userID", oldestUserID))
		}
	}
}

// startCleanupRoutine starts the background cleanup routine
func (im *InstanceManager) startCleanupRoutine() {
	im.cleanupTicker = time.NewTicker(10 * time.Minute) // Run every 10 minutes
	
	go func() {
		for range im.cleanupTicker.C {
			im.cleanupIdleInstances()
		}
	}()
}

// cleanupIdleInstances removes idle bot instances
func (im *InstanceManager) cleanupIdleInstances() {
	im.mutex.Lock()
	defer im.mutex.Unlock()

	now := time.Now()
	var toRemove []int64

	for userID, instance := range im.instances {
		if now.Sub(instance.LastUsed) > im.idleTimeout {
			toRemove = append(toRemove, userID)
		}
	}

	for _, userID := range toRemove {
		if instance, exists := im.instances[userID]; exists {
			instance.Client.Stop()
			delete(im.instances, userID)
			im.log.Info("Cleaned up idle bot instance", 
				zap.Int64("userID", userID),
				zap.Duration("idleTime", now.Sub(instance.LastUsed)))
		}
	}

	if len(toRemove) > 0 {
		im.log.Info("Cleanup completed", 
			zap.Int("removedInstances", len(toRemove)),
			zap.Int("activeInstances", len(im.instances)))
	}
}

// GetStats returns statistics about active instances
func (im *InstanceManager) GetStats() map[string]interface{} {
	im.mutex.RLock()
	defer im.mutex.RUnlock()

	return map[string]interface{}{
		"active_instances": len(im.instances),
		"max_instances":    im.maxInstances,
		"idle_timeout":     im.idleTimeout.String(),
	}
}

// Shutdown gracefully shuts down all bot instances
func (im *InstanceManager) Shutdown() {
	im.mutex.Lock()
	defer im.mutex.Unlock()

	if im.cleanupTicker != nil {
		im.cleanupTicker.Stop()
	}

	for userID, instance := range im.instances {
		instance.Client.Stop()
		im.log.Info("Shutdown bot instance", zap.Int64("userID", userID))
	}

	im.instances = make(map[int64]*BotInstance)
	im.log.Info("Instance manager shutdown complete")
}