package sync

import (
	"encoding/json"
	"fmt"
	"log/slog"
	"time"

	"git.mchus.pro/mchus/quoteforge/internal/db"
	"git.mchus.pro/mchus/quoteforge/internal/localdb"
	"git.mchus.pro/mchus/quoteforge/internal/models"
	"git.mchus.pro/mchus/quoteforge/internal/repository"
)

// Service handles synchronization between MariaDB and local SQLite
type Service struct {
	connMgr *db.ConnectionManager
	localDB *localdb.LocalDB
}

// NewService creates a new sync service
func NewService(connMgr *db.ConnectionManager, localDB *localdb.LocalDB) *Service {
	return &Service{
		connMgr: connMgr,
		localDB: localDB,
	}
}

// SyncStatus represents the current sync status
type SyncStatus struct {
	LastSyncAt       *time.Time `json:"last_sync_at"`
	ServerPricelists int        `json:"server_pricelists"`
	LocalPricelists  int        `json:"local_pricelists"`
	NeedsSync        bool       `json:"needs_sync"`
}

// GetStatus returns the current sync status
func (s *Service) GetStatus() (*SyncStatus, error) {
	lastSync := s.localDB.GetLastSyncTime()

	// Count server pricelists (only if already connected, don't reconnect)
	serverCount := 0
	connStatus := s.connMgr.GetStatus()
	if connStatus.IsConnected {
		if mariaDB, err := s.connMgr.GetDB(); err == nil && mariaDB != nil {
			pricelistRepo := repository.NewPricelistRepository(mariaDB)
			activeCount, err := pricelistRepo.CountActive()
			if err == nil {
				serverCount = int(activeCount)
			}
		}
	}

	// Count local pricelists
	localCount := s.localDB.CountLocalPricelists()

	needsSync, _ := s.NeedSync()

	return &SyncStatus{
		LastSyncAt:       lastSync,
		ServerPricelists: serverCount,
		LocalPricelists:  int(localCount),
		NeedsSync:        needsSync,
	}, nil
}

// NeedSync checks if synchronization is needed
// Returns true if there are new pricelists on server or last sync was >1 hour ago
func (s *Service) NeedSync() (bool, error) {
	lastSync := s.localDB.GetLastSyncTime()

	// If never synced, need sync
	if lastSync == nil {
		return true, nil
	}

	// If last sync was more than 1 hour ago, suggest sync
	if time.Since(*lastSync) > time.Hour {
		return true, nil
	}

	// Check if there are new pricelists on server (only if already connected)
	connStatus := s.connMgr.GetStatus()
	if !connStatus.IsConnected {
		// If offline, can't check server, no need to sync
		return false, nil
	}

	mariaDB, err := s.connMgr.GetDB()
	if err != nil {
		// If offline, can't check server, no need to sync
		return false, nil
	}

	pricelistRepo := repository.NewPricelistRepository(mariaDB)
	latestServer, err := pricelistRepo.GetLatestActive()
	if err != nil {
		// If no pricelists on server, no need to sync
		return false, nil
	}

	latestLocal, err := s.localDB.GetLatestLocalPricelist()
	if err != nil {
		// No local pricelists, need to sync
		return true, nil
	}

	// If server has newer pricelist, need sync
	if latestServer.ID != latestLocal.ServerID {
		return true, nil
	}

	return false, nil
}

// SyncPricelists synchronizes all active pricelists from server to local SQLite
func (s *Service) SyncPricelists() (int, error) {
	slog.Info("starting pricelist sync")

	// Get database connection
	mariaDB, err := s.connMgr.GetDB()
	if err != nil {
		return 0, fmt.Errorf("database not available: %w", err)
	}

	// Create repository
	pricelistRepo := repository.NewPricelistRepository(mariaDB)

	// Get active pricelists from server (up to 100)
	serverPricelists, _, err := pricelistRepo.ListActive(0, 100)
	if err != nil {
		return 0, fmt.Errorf("getting active server pricelists: %w", err)
	}

	synced := 0
	var latestLocalID uint
	var latestServerID uint
	for _, pl := range serverPricelists {
		// Check if pricelist already exists locally
		existing, _ := s.localDB.GetLocalPricelistByServerID(pl.ID)
		if existing != nil {
			// Already synced, track latest by server ID
			if pl.ID > latestServerID {
				latestServerID = pl.ID
				latestLocalID = existing.ID
			}
			continue
		}

		// Create local pricelist
		localPL := &localdb.LocalPricelist{
			ServerID:  pl.ID,
			Version:   pl.Version,
			Name:      pl.Notification, // Using notification as name
			CreatedAt: pl.CreatedAt,
			SyncedAt:  time.Now(),
			IsUsed:    false,
		}

		if err := s.localDB.SaveLocalPricelist(localPL); err != nil {
			slog.Warn("failed to save local pricelist", "version", pl.Version, "error", err)
			continue
		}

		// Sync items for the newly created pricelist
		itemCount, err := s.SyncPricelistItems(localPL.ID)
		if err != nil {
			slog.Warn("failed to sync pricelist items", "version", pl.Version, "error", err)
			// Continue even if items sync fails - we have the pricelist metadata
		} else {
			slog.Debug("synced pricelist with items", "version", pl.Version, "items", itemCount)
		}

		if pl.ID > latestServerID {
			latestServerID = pl.ID
			latestLocalID = localPL.ID
		}
		synced++
	}

	// Update component prices from latest pricelist
	if latestLocalID > 0 {
		updated, err := s.localDB.UpdateComponentPricesFromPricelist(latestLocalID)
		if err != nil {
			slog.Warn("failed to update component prices from pricelist", "error", err)
		} else {
			slog.Info("updated component prices from latest pricelist", "updated", updated)
		}
	}

	// Update last sync time
	s.localDB.SetLastSyncTime(time.Now())

	slog.Info("pricelist sync completed", "synced", synced, "total", len(serverPricelists))
	return synced, nil
}

// SyncPricelistItems synchronizes items for a specific pricelist
func (s *Service) SyncPricelistItems(localPricelistID uint) (int, error) {
	// Get local pricelist
	localPL, err := s.localDB.GetLocalPricelistByID(localPricelistID)
	if err != nil {
		return 0, fmt.Errorf("getting local pricelist: %w", err)
	}

	// Check if items already exist
	existingCount := s.localDB.CountLocalPricelistItems(localPricelistID)
	if existingCount > 0 {
		slog.Debug("pricelist items already synced", "pricelist_id", localPricelistID, "count", existingCount)
		return int(existingCount), nil
	}

	// Get database connection
	mariaDB, err := s.connMgr.GetDB()
	if err != nil {
		return 0, fmt.Errorf("database not available: %w", err)
	}

	// Create repository
	pricelistRepo := repository.NewPricelistRepository(mariaDB)

	// Get items from server
	serverItems, _, err := pricelistRepo.GetItems(localPL.ServerID, 0, 10000, "")
	if err != nil {
		return 0, fmt.Errorf("getting server pricelist items: %w", err)
	}

	// Convert and save locally
	localItems := make([]localdb.LocalPricelistItem, len(serverItems))
	for i, item := range serverItems {
		localItems[i] = localdb.LocalPricelistItem{
			PricelistID: localPricelistID,
			LotName:     item.LotName,
			Price:       item.Price,
		}
	}

	if err := s.localDB.SaveLocalPricelistItems(localItems); err != nil {
		return 0, fmt.Errorf("saving local pricelist items: %w", err)
	}

	slog.Info("synced pricelist items", "pricelist_id", localPricelistID, "items", len(localItems))
	return len(localItems), nil
}

// SyncPricelistItemsByServerID syncs items for a pricelist by its server ID
func (s *Service) SyncPricelistItemsByServerID(serverPricelistID uint) (int, error) {
	localPL, err := s.localDB.GetLocalPricelistByServerID(serverPricelistID)
	if err != nil {
		return 0, fmt.Errorf("local pricelist not found for server ID %d", serverPricelistID)
	}
	return s.SyncPricelistItems(localPL.ID)
}

// GetLocalPriceForLot returns the price for a lot from a local pricelist
func (s *Service) GetLocalPriceForLot(localPricelistID uint, lotName string) (float64, error) {
	return s.localDB.GetLocalPriceForLot(localPricelistID, lotName)
}

// GetPricelistForOffline returns a pricelist suitable for offline use
// If items are not synced, it will sync them first
func (s *Service) GetPricelistForOffline(serverPricelistID uint) (*localdb.LocalPricelist, error) {
	// Ensure pricelist is synced
	localPL, err := s.localDB.GetLocalPricelistByServerID(serverPricelistID)
	if err != nil {
		// Try to sync pricelists first
		if _, err := s.SyncPricelists(); err != nil {
			return nil, fmt.Errorf("syncing pricelists: %w", err)
		}

		// Try again
		localPL, err = s.localDB.GetLocalPricelistByServerID(serverPricelistID)
		if err != nil {
			return nil, fmt.Errorf("pricelist not found on server: %w", err)
		}
	}

	// Ensure items are synced
	if _, err := s.SyncPricelistItems(localPL.ID); err != nil {
		return nil, fmt.Errorf("syncing pricelist items: %w", err)
	}

	return localPL, nil
}

// SyncPricelistsIfNeeded checks for new pricelists and syncs if needed
// This should be called before creating a new configuration when online
func (s *Service) SyncPricelistsIfNeeded() error {
	needSync, err := s.NeedSync()
	if err != nil {
		slog.Warn("failed to check if sync needed", "error", err)
		return nil // Don't fail on check error
	}

	if !needSync {
		slog.Debug("pricelists are up to date, no sync needed")
		return nil
	}

	slog.Info("new pricelists detected, syncing...")
	_, err = s.SyncPricelists()
	if err != nil {
		return fmt.Errorf("syncing pricelists: %w", err)
	}

	return nil
}

// PushPendingChanges pushes all pending changes to the server
func (s *Service) PushPendingChanges() (int, error) {
	changes, err := s.localDB.GetPendingChanges()
	if err != nil {
		return 0, fmt.Errorf("getting pending changes: %w", err)
	}

	if len(changes) == 0 {
		slog.Debug("no pending changes to push")
		return 0, nil
	}

	slog.Info("pushing pending changes", "count", len(changes))
	pushed := 0
	var syncedIDs []int64

	for _, change := range changes {
		err := s.pushSingleChange(&change)
		if err != nil {
			slog.Warn("failed to push change", "id", change.ID, "type", change.EntityType, "operation", change.Operation, "error", err)
			// Increment attempts
			s.localDB.IncrementPendingChangeAttempts(change.ID, err.Error())
			continue
		}

		syncedIDs = append(syncedIDs, change.ID)
		pushed++
	}

	// Mark synced changes as complete by deleting them
	if len(syncedIDs) > 0 {
		if err := s.localDB.MarkChangesSynced(syncedIDs); err != nil {
			slog.Error("failed to mark changes as synced", "error", err)
		}
	}

	slog.Info("pending changes pushed", "pushed", pushed, "failed", len(changes)-pushed)
	return pushed, nil
}

// pushSingleChange pushes a single pending change to the server
func (s *Service) pushSingleChange(change *localdb.PendingChange) error {
	switch change.EntityType {
	case "configuration":
		return s.pushConfigurationChange(change)
	default:
		return fmt.Errorf("unknown entity type: %s", change.EntityType)
	}
}

// pushConfigurationChange pushes a configuration change to the server
func (s *Service) pushConfigurationChange(change *localdb.PendingChange) error {
	switch change.Operation {
	case "create":
		return s.pushConfigurationCreate(change)
	case "update":
		return s.pushConfigurationUpdate(change)
	case "delete":
		return s.pushConfigurationDelete(change)
	default:
		return fmt.Errorf("unknown operation: %s", change.Operation)
	}
}

// pushConfigurationCreate creates a configuration on the server
func (s *Service) pushConfigurationCreate(change *localdb.PendingChange) error {
	var cfg models.Configuration
	if err := json.Unmarshal([]byte(change.Payload), &cfg); err != nil {
		return fmt.Errorf("unmarshaling configuration: %w", err)
	}

	// Get database connection
	mariaDB, err := s.connMgr.GetDB()
	if err != nil {
		return fmt.Errorf("database not available: %w", err)
	}

	// Create repository
	configRepo := repository.NewConfigurationRepository(mariaDB)

	// Create on server
	if err := configRepo.Create(&cfg); err != nil {
		return fmt.Errorf("creating configuration on server: %w", err)
	}

	// Update local configuration with server ID
	localCfg, err := s.localDB.GetConfigurationByUUID(cfg.UUID)
	if err == nil {
		serverID := cfg.ID
		localCfg.ServerID = &serverID
		localCfg.SyncStatus = "synced"
		s.localDB.SaveConfiguration(localCfg)
	}

	slog.Info("configuration created on server", "uuid", cfg.UUID, "server_id", cfg.ID)
	return nil
}

// pushConfigurationUpdate updates a configuration on the server
func (s *Service) pushConfigurationUpdate(change *localdb.PendingChange) error {
	var cfg models.Configuration
	if err := json.Unmarshal([]byte(change.Payload), &cfg); err != nil {
		return fmt.Errorf("unmarshaling configuration: %w", err)
	}

	// Get database connection
	mariaDB, err := s.connMgr.GetDB()
	if err != nil {
		return fmt.Errorf("database not available: %w", err)
	}

	// Create repository
	configRepo := repository.NewConfigurationRepository(mariaDB)

	// Ensure we have a server ID before updating
	// If the payload doesn't have ID, get it from local configuration
	if cfg.ID == 0 {
		localCfg, err := s.localDB.GetConfigurationByUUID(cfg.UUID)
		if err != nil {
			return fmt.Errorf("getting local configuration: %w", err)
		}

		if localCfg.ServerID == nil {
			// Configuration hasn't been synced yet, try to find it on server by UUID
			serverCfg, err := configRepo.GetByUUID(cfg.UUID)
			if err != nil {
				return fmt.Errorf("configuration not yet synced to server: %w", err)
			}
			cfg.ID = serverCfg.ID

			// Update local with server ID
			serverID := serverCfg.ID
			localCfg.ServerID = &serverID
			s.localDB.SaveConfiguration(localCfg)
		} else {
			cfg.ID = *localCfg.ServerID
		}
	}

	// Update on server
	if err := configRepo.Update(&cfg); err != nil {
		return fmt.Errorf("updating configuration on server: %w", err)
	}

	// Update local sync status
	localCfg, err := s.localDB.GetConfigurationByUUID(cfg.UUID)
	if err == nil {
		localCfg.SyncStatus = "synced"
		s.localDB.SaveConfiguration(localCfg)
	}

	slog.Info("configuration updated on server", "uuid", cfg.UUID)
	return nil
}

// pushConfigurationDelete deletes a configuration from the server
func (s *Service) pushConfigurationDelete(change *localdb.PendingChange) error {
	// Get database connection
	mariaDB, err := s.connMgr.GetDB()
	if err != nil {
		return fmt.Errorf("database not available: %w", err)
	}

	// Create repository
	configRepo := repository.NewConfigurationRepository(mariaDB)

	// Get the configuration from server by UUID to get the ID
	cfg, err := configRepo.GetByUUID(change.EntityUUID)
	if err != nil {
		// Already deleted or not found, consider it successful
		slog.Warn("configuration not found on server, considering delete successful", "uuid", change.EntityUUID)
		return nil
	}

	// Delete from server
	if err := configRepo.Delete(cfg.ID); err != nil {
		return fmt.Errorf("deleting configuration from server: %w", err)
	}

	slog.Info("configuration deleted from server", "uuid", change.EntityUUID)
	return nil
}