package services

import (
	"context"
	"fmt"
	"time"

	"go.uber.org/zap"
	"gorm.io/gorm"

	"uzdb/internal/config"
	"uzdb/internal/database"
	"uzdb/internal/models"
	"uzdb/internal/utils"
)

// ConnectionService manages database connections
type ConnectionService struct {
	db            *gorm.DB
	connManager   *database.ConnectionManager
	encryptSvc    *EncryptionService
}

// NewConnectionService creates a new connection service
func NewConnectionService(
	db *gorm.DB,
	connManager *database.ConnectionManager,
	encryptSvc *EncryptionService,
) *ConnectionService {
	return &ConnectionService{
		db:          db,
		connManager: connManager,
		encryptSvc:  encryptSvc,
	}
}

// GetAllConnections returns all user connections
func (s *ConnectionService) GetAllConnections(ctx context.Context) ([]models.UserConnection, error) {
	var connections []models.UserConnection
	
	result := s.db.WithContext(ctx).Find(&connections)
	if result.Error != nil {
		return nil, fmt.Errorf("failed to get connections: %w", result.Error)
	}

	// Mask passwords in response
	for i := range connections {
		connections[i].Password = s.encryptSvc.MaskPasswordForLogging(connections[i].Password)
	}

	config.GetLogger().Debug("retrieved all connections",
		zap.Int("count", len(connections)))

	return connections, nil
}

// GetConnectionByID returns a connection by ID
func (s *ConnectionService) GetConnectionByID(ctx context.Context, id string) (*models.UserConnection, error) {
	var conn models.UserConnection
	
	result := s.db.WithContext(ctx).First(&conn, "id = ?", id)
	if result.Error != nil {
		if result.Error == gorm.ErrRecordNotFound {
			return nil, models.ErrNotFound
		}
		return nil, fmt.Errorf("failed to get connection: %w", result.Error)
	}

	return &conn, nil
}

// CreateConnection creates a new connection
func (s *ConnectionService) CreateConnection(ctx context.Context, req *models.CreateConnectionRequest) (*models.UserConnection, error) {
	// Validate request
	if err := req.Validate(); err != nil {
		return nil, models.ErrValidationFailed
	}

	// Encrypt password
	encryptedPassword := req.Password
	if req.Password != "" {
		var err error
		encryptedPassword, err = s.encryptSvc.EncryptPassword(req.Password)
		if err != nil {
			return nil, fmt.Errorf("failed to encrypt password: %w", err)
		}
	}

	conn := &models.UserConnection{
		ID:        utils.GenerateID(),
		Name:      req.Name,
		Type:      req.Type,
		Host:      req.Host,
		Port:      req.Port,
		Username:  req.Username,
		Password:  encryptedPassword,
		Database:  req.Database,
		SSLMode:   req.SSLMode,
		Timeout:   req.Timeout,
	}

	if conn.Timeout <= 0 {
		conn.Timeout = 30
	}

	result := s.db.WithContext(ctx).Create(conn)
	if result.Error != nil {
		return nil, fmt.Errorf("failed to create connection: %w", result.Error)
	}

	// Mask password in response
	conn.Password = s.encryptSvc.MaskPasswordForLogging(conn.Password)

	config.GetLogger().Info("connection created",
		zap.String("id", conn.ID),
		zap.String("name", conn.Name),
		zap.String("type", string(conn.Type)))

	return conn, nil
}

// UpdateConnection updates an existing connection
func (s *ConnectionService) UpdateConnection(ctx context.Context, id string, req *models.UpdateConnectionRequest) (*models.UserConnection, error) {
	// Get existing connection
	existing, err := s.GetConnectionByID(ctx, id)
	if err != nil {
		return nil, err
	}

	// Update fields
	if req.Name != "" {
		existing.Name = req.Name
	}
	if req.Type != "" {
		existing.Type = req.Type
	}
	if req.Host != "" {
		existing.Host = req.Host
	}
	if req.Port > 0 {
		existing.Port = req.Port
	}
	if req.Username != "" {
		existing.Username = req.Username
	}
	if req.Password != "" {
		// Encrypt new password
		encryptedPassword, err := s.encryptSvc.EncryptPassword(req.Password)
		if err != nil {
			return nil, fmt.Errorf("failed to encrypt password: %w", err)
		}
		existing.Password = encryptedPassword
	}
	if req.Database != "" {
		existing.Database = req.Database
	}
	if req.SSLMode != "" {
		existing.SSLMode = req.SSLMode
	}
	if req.Timeout > 0 {
		existing.Timeout = req.Timeout
	}

	result := s.db.WithContext(ctx).Save(existing)
	if result.Error != nil {
		return nil, fmt.Errorf("failed to update connection: %w", result.Error)
	}

	// Remove cached connection if exists
	if err := s.connManager.RemoveConnection(id); err != nil {
		config.GetLogger().Warn("failed to remove cached connection", zap.Error(err))
	}

	// Mask password in response
	existing.Password = s.encryptSvc.MaskPasswordForLogging(existing.Password)

	config.GetLogger().Info("connection updated",
		zap.String("id", id),
		zap.String("name", existing.Name))

	return existing, nil
}

// DeleteConnection deletes a connection
func (s *ConnectionService) DeleteConnection(ctx context.Context, id string) error {
	// Check if connection exists
	if _, err := s.GetConnectionByID(ctx, id); err != nil {
		return err
	}

	// Remove from connection manager
	if err := s.connManager.RemoveConnection(id); err != nil {
		config.GetLogger().Warn("failed to remove from connection manager", zap.Error(err))
	}

	// Delete from database
	result := s.db.WithContext(ctx).Delete(&models.UserConnection{}, "id = ?", id)
	if result.Error != nil {
		return fmt.Errorf("failed to delete connection: %w", result.Error)
	}

	config.GetLogger().Info("connection deleted", zap.String("id", id))

	return nil
}

// TestConnection tests a database connection
func (s *ConnectionService) TestConnection(ctx context.Context, id string) (*models.ConnectionTestResult, error) {
	// Get connection config
	conn, err := s.GetConnectionByID(ctx, id)
	if err != nil {
		return nil, err
	}

	// Decrypt password
	password, err := s.encryptSvc.DecryptPassword(conn.Password)
	if err != nil {
		return nil, fmt.Errorf("failed to decrypt password: %w", err)
	}

	startTime := time.Now()

	// Create temporary connection
	tempConn, err := s.connManager.GetConnection(conn, password)
	if err != nil {
		return &models.ConnectionTestResult{
			Success:  false,
			Message:  fmt.Sprintf("Connection failed: %v", err),
			Duration: time.Since(startTime).Milliseconds(),
		}, nil
	}

	// Get metadata
	metadata, err := tempConn.GetMetadata()
	if err != nil {
		config.GetLogger().Warn("failed to get metadata", zap.Error(err))
	}

	return &models.ConnectionTestResult{
		Success:  true,
		Message:  "Connection successful",
		Duration: time.Since(startTime).Milliseconds(),
		Metadata: metadata,
	}, nil
}

// ExecuteQuery executes a SQL query on a connection
func (s *ConnectionService) ExecuteQuery(ctx context.Context, connectionID, sql string) (*models.QueryResult, error) {
	// Get connection config
	conn, err := s.GetConnectionByID(ctx, connectionID)
	if err != nil {
		return nil, err
	}

	// Decrypt password
	password, err := s.encryptSvc.DecryptPassword(conn.Password)
	if err != nil {
		return nil, fmt.Errorf("failed to decrypt password: %w", err)
	}

	// Get or create connection
	dbConn, err := s.connManager.GetConnection(conn, password)
	if err != nil {
		return nil, fmt.Errorf("failed to get connection: %w", err)
	}

	// Execute query
	startTime := time.Now()
	
	var result *models.QueryResult
	if utils.IsReadOnlyQuery(sql) {
		result, err = dbConn.ExecuteQuery(sql)
	} else {
		result, err = dbConn.ExecuteStatement(sql)
	}

	duration := time.Since(startTime)

	// Record in history
	history := &models.QueryHistory{
		ConnectionID: connectionID,
		SQL:          utils.TruncateString(sql, 10000),
		Duration:     duration.Milliseconds(),
		Success:      err == nil,
	}
	
	if result != nil {
		history.RowsAffected = result.AffectedRows
	}
	if err != nil {
		history.Error = err.Error()
	}

	s.db.WithContext(ctx).Create(history)

	if err != nil {
		return nil, fmt.Errorf("query execution failed: %w", err)
	}

	return result, nil
}

// GetTables returns all tables for a connection
func (s *ConnectionService) GetTables(ctx context.Context, connectionID string) ([]models.Table, error) {
	// Get connection config
	conn, err := s.GetConnectionByID(ctx, connectionID)
	if err != nil {
		return nil, err
	}

	// Decrypt password
	password, err := s.encryptSvc.DecryptPassword(conn.Password)
	if err != nil {
		return nil, fmt.Errorf("failed to decrypt password: %w", err)
	}

	// Get or create connection
	dbConn, err := s.connManager.GetConnection(conn, password)
	if err != nil {
		return nil, fmt.Errorf("failed to get connection: %w", err)
	}

	return dbConn.GetTables("")
}

// GetTableData returns data from a table
func (s *ConnectionService) GetTableData(
	ctx context.Context,
	connectionID, tableName string,
	limit, offset int,
) (*models.QueryResult, error) {
	// Validate limit
	if limit <= 0 || limit > 1000 {
		limit = 100
	}
	if offset < 0 {
		offset = 0
	}

	// Build query based on connection type
	conn, err := s.GetConnectionByID(ctx, connectionID)
	if err != nil {
		return nil, err
	}

	var query string
	switch conn.Type {
	case models.ConnectionTypeMySQL:
		query = fmt.Sprintf("SELECT * FROM `%s` LIMIT %d OFFSET %d", tableName, limit, offset)
	case models.ConnectionTypePostgreSQL:
		query = fmt.Sprintf(`SELECT * FROM "%s" LIMIT %d OFFSET %d`, tableName, limit, offset)
	case models.ConnectionTypeSQLite:
		query = fmt.Sprintf(`SELECT * FROM "%s" LIMIT %d OFFSET %d`, tableName, limit, offset)
	default:
		return nil, models.ErrValidationFailed
	}

	return s.ExecuteQuery(ctx, connectionID, query)
}

// GetTableStructure returns the structure of a table
func (s *ConnectionService) GetTableStructure(ctx context.Context, connectionID, tableName string) (*models.TableStructure, error) {
	// Get connection config
	conn, err := s.GetConnectionByID(ctx, connectionID)
	if err != nil {
		return nil, err
	}

	// Decrypt password
	password, err := s.encryptSvc.DecryptPassword(conn.Password)
	if err != nil {
		return nil, fmt.Errorf("failed to decrypt password: %w", err)
	}

	// Get or create connection
	dbConn, err := s.connManager.GetConnection(conn, password)
	if err != nil {
		return nil, fmt.Errorf("failed to get connection: %w", err)
	}

	return dbConn.GetTableStructure(tableName)
}