package app

import (
	"context"
	"time"

	"go.uber.org/zap"

	"uzdb/internal/config"
	"uzdb/internal/database"
	"uzdb/internal/handler"
	"uzdb/internal/models"
	"uzdb/internal/services"
)

// App is the main application structure for Wails bindings
type App struct {
	ctx             context.Context
	config          *config.Config
	connectionSvc   *services.ConnectionService
	querySvc        *services.QueryService
	httpServer      *handler.HTTPServer
	shutdownFunc    context.CancelFunc
}

// NewApp creates a new App instance
func NewApp() *App {
	return &App{}
}

// Initialize initializes the application with all services
func (a *App) Initialize(
	cfg *config.Config,
	connectionSvc *services.ConnectionService,
	querySvc *services.QueryService,
	httpServer *handler.HTTPServer,
) {
	a.config = cfg
	a.connectionSvc = connectionSvc
	a.querySvc = querySvc
	a.httpServer = httpServer
}

// OnStartup is called when the app starts (public method for Wails)
func (a *App) OnStartup(ctx context.Context) {
	a.ctx = ctx
	
	config.GetLogger().Info("Wails application started")
}

// GetConnections returns all user connections
// Wails binding: frontend can call window.go.app.GetConnections()
func (a *App) GetConnections() []models.UserConnection {
	if a.connectionSvc == nil {
		return []models.UserConnection{}
	}

	connections, err := a.connectionSvc.GetAllConnections(a.ctx)
	if err != nil {
		config.GetLogger().Error("failed to get connections", zap.Error(err))
		return []models.UserConnection{}
	}

	return connections
}

// CreateConnection creates a new database connection
// Returns error message or empty string on success
func (a *App) CreateConnection(conn models.CreateConnectionRequest) string {
	if a.connectionSvc == nil {
		return "Service not initialized"
	}

	_, err := a.connectionSvc.CreateConnection(a.ctx, &conn)
	if err != nil {
		config.GetLogger().Error("failed to create connection", zap.Error(err))
		return err.Error()
	}

	return ""
}

// UpdateConnection updates an existing database connection
// Returns error message or empty string on success
func (a *App) UpdateConnection(conn models.UserConnection) string {
	if a.connectionSvc == nil {
		return "Service not initialized"
	}

	req := &models.UpdateConnectionRequest{
		Name:     conn.Name,
		Type:     conn.Type,
		Host:     conn.Host,
		Port:     conn.Port,
		Username: conn.Username,
		Password: conn.Password,
		Database: conn.Database,
		SSLMode:  conn.SSLMode,
		Timeout:  conn.Timeout,
	}

	_, err := a.connectionSvc.UpdateConnection(a.ctx, conn.ID, req)
	if err != nil {
		config.GetLogger().Error("failed to update connection", zap.Error(err))
		return err.Error()
	}

	return ""
}

// DeleteConnection deletes a database connection
// Returns error message or empty string on success
func (a *App) DeleteConnection(id string) string {
	if a.connectionSvc == nil {
		return "Service not initialized"
	}

	err := a.connectionSvc.DeleteConnection(a.ctx, id)
	if err != nil {
		config.GetLogger().Error("failed to delete connection", zap.Error(err))
		return err.Error()
	}

	return ""
}

// TestConnection tests a database connection
// Returns (success, error_message)
func (a *App) TestConnection(id string) (bool, string) {
	if a.connectionSvc == nil {
		return false, "Service not initialized"
	}

	result, err := a.connectionSvc.TestConnection(a.ctx, id)
	if err != nil {
		config.GetLogger().Error("failed to test connection", zap.Error(err))
		return false, err.Error()
	}

	return result.Success, result.Message
}

// ExecuteQuery executes a SQL query on a connection
// Returns query result or error message
func (a *App) ExecuteQuery(connectionID, sql string) (*models.QueryResult, string) {
	if a.connectionSvc == nil {
		return nil, "Service not initialized"
	}

	result, err := a.connectionSvc.ExecuteQuery(a.ctx, connectionID, sql)
	if err != nil {
		config.GetLogger().Error("failed to execute query",
			zap.String("connection_id", connectionID),
			zap.String("sql", sql),
			zap.Error(err))
		return nil, err.Error()
	}

	return result, ""
}

// GetTables returns all tables for a connection
func (a *App) GetTables(connectionID string) ([]models.Table, string) {
	if a.connectionSvc == nil {
		return []models.Table{}, "Service not initialized"
	}

	tables, err := a.connectionSvc.GetTables(a.ctx, connectionID)
	if err != nil {
		config.GetLogger().Error("failed to get tables",
			zap.String("connection_id", connectionID),
			zap.Error(err))
		return []models.Table{}, err.Error()
	}

	return tables, ""
}

// GetTableData returns data from a table
func (a *App) GetTableData(connectionID, tableName string, limit, offset int) (*models.QueryResult, string) {
	if a.connectionSvc == nil {
		return nil, "Service not initialized"
	}

	result, err := a.connectionSvc.GetTableData(a.ctx, connectionID, tableName, limit, offset)
	if err != nil {
		config.GetLogger().Error("failed to get table data",
			zap.String("connection_id", connectionID),
			zap.String("table", tableName),
			zap.Error(err))
		return nil, err.Error()
	}

	return result, ""
}

// GetTableStructure returns the structure of a table
func (a *App) GetTableStructure(connectionID, tableName string) (*models.TableStructure, string) {
	if a.connectionSvc == nil {
		return nil, "Service not initialized"
	}

	structure, err := a.connectionSvc.GetTableStructure(a.ctx, connectionID, tableName)
	if err != nil {
		config.GetLogger().Error("failed to get table structure",
			zap.String("connection_id", connectionID),
			zap.String("table", tableName),
			zap.Error(err))
		return nil, err.Error()
	}

	return structure, ""
}

// GetQueryHistory returns query history with pagination
func (a *App) GetQueryHistory(connectionID string, page, pageSize int) ([]models.QueryHistory, int64, string) {
	if a.querySvc == nil {
		return []models.QueryHistory{}, 0, "Service not initialized"
	}

	history, total, err := a.querySvc.GetQueryHistory(a.ctx, connectionID, page, pageSize)
	if err != nil {
		config.GetLogger().Error("failed to get query history", zap.Error(err))
		return []models.QueryHistory{}, 0, err.Error()
	}

	return history, total, ""
}

// GetSavedQueries returns all saved queries
func (a *App) GetSavedQueries(connectionID string) ([]models.SavedQuery, string) {
	if a.querySvc == nil {
		return []models.SavedQuery{}, "Service not initialized"
	}

	queries, err := a.querySvc.GetSavedQueries(a.ctx, connectionID)
	if err != nil {
		config.GetLogger().Error("failed to get saved queries", zap.Error(err))
		return []models.SavedQuery{}, err.Error()
	}

	return queries, ""
}

// CreateSavedQuery creates a new saved query
func (a *App) CreateSavedQuery(req models.CreateSavedQueryRequest) (*models.SavedQuery, string) {
	if a.querySvc == nil {
		return nil, "Service not initialized"
	}

	query, err := a.querySvc.CreateSavedQuery(a.ctx, &req)
	if err != nil {
		config.GetLogger().Error("failed to create saved query", zap.Error(err))
		return nil, err.Error()
	}

	return query, ""
}

// UpdateSavedQuery updates a saved query
func (a *App) UpdateSavedQuery(id uint, req models.UpdateSavedQueryRequest) (*models.SavedQuery, string) {
	if a.querySvc == nil {
		return nil, "Service not initialized"
	}

	query, err := a.querySvc.UpdateSavedQuery(a.ctx, id, &req)
	if err != nil {
		config.GetLogger().Error("failed to update saved query", zap.Error(err))
		return nil, err.Error()
	}

	return query, ""
}

// DeleteSavedQuery deletes a saved query
func (a *App) DeleteSavedQuery(id uint) string {
	if a.querySvc == nil {
		return "Service not initialized"
	}

	err := a.querySvc.DeleteSavedQuery(a.ctx, id)
	if err != nil {
		config.GetLogger().Error("failed to delete saved query", zap.Error(err))
		return err.Error()
	}

	return ""
}

// StartHTTPServer starts the HTTP API server in background
func (a *App) StartHTTPServer() string {
	if a.httpServer == nil {
		return "HTTP server not initialized"
	}

	go func() {
		port := a.config.API.Port
		if err := a.httpServer.Start(port); err != nil {
			config.GetLogger().Error("HTTP server error", zap.Error(err))
		}
	}()

	return ""
}

// Shutdown gracefully shuts down the application
func (a *App) Shutdown() {
	config.GetLogger().Info("shutting down application")
	
	if a.shutdownFunc != nil {
		a.shutdownFunc()
	}
	
	if a.httpServer != nil {
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		a.httpServer.Shutdown(ctx)
	}
	
	// Close all database connections
	database.CloseSQLite()
	
	config.Sync()
}