package database

import (
	"bytes"
	"fmt"
	"io"
	"log"
	"os"

	"x-ui/config"
	"x-ui/database/model"
	"x-ui/util/crypto"
	"x-ui/xray"

	"gorm.io/driver/mysql"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"
)

var db *gorm.DB

const (
	defaultUsername = "admin"
	defaultPassword = "admin"
)

func initModels() error {
	models := []any{
		&model.User{},
		&model.Inbound{},
		&model.OutboundTraffics{},
		&model.Setting{},
		&model.InboundClientIps{},
		&xray.ClientTraffic{},
		&model.HistoryOfSeeders{},
	}
	for _, model := range models {
		if err := db.AutoMigrate(model); err != nil {
			log.Printf("Error auto migrating model: %v", err)
			return err
		}
	}
	return nil
}

func initUser() error {
	empty, err := isTableEmpty("users")
	if err != nil {
		log.Printf("Error checking if users table is empty: %v", err)
		return err
	}
	if empty {
		hashedPassword, err := crypto.HashPasswordAsBcrypt(defaultPassword)

		if err != nil {
			log.Printf("Error hashing default password: %v", err)
			return err
		}

		user := &model.User{
			Username: defaultUsername,
			Password: hashedPassword,
		}
		return db.Create(user).Error
	}
	return nil
}

func contains(slice []string, item string) bool {
	for _, s := range slice {
		if s == item {
			return s == item
		}
	}
	return false
}

func runSeeders(isUsersEmpty bool) error {
	empty, err := isTableEmpty("history_of_seeders")
	if err != nil {
		log.Printf("Error checking if users table is empty: %v", err)
		return err
	}

	if empty && isUsersEmpty {
		hashSeeder := &model.HistoryOfSeeders{
			SeederName: "UserPasswordHash",
		}
		return db.Create(hashSeeder).Error
	} else {
		var seedersHistory []string
		db.Model(&model.HistoryOfSeeders{}).Pluck("seeder_name", &seedersHistory)

		if !contains(seedersHistory, "UserPasswordHash") && !isUsersEmpty {
			var users []model.User
			db.Find(&users)

			for _, user := range users {
				hashedPassword, err := crypto.HashPasswordAsBcrypt(user.Password)
				if err != nil {
					log.Printf("Error hashing password for user '%s': %v", user.Username, err)
					return err
				}
				db.Model(&user).Update("password", hashedPassword)
			}

			hashSeeder := &model.HistoryOfSeeders{
				SeederName: "UserPasswordHash",
			}
			return db.Create(hashSeeder).Error
		}
	}

	return nil
}

func isTableEmpty(tableName string) (bool, error) {
	var count int64
	err := db.Table(tableName).Count(&count).Error
	return count == 0, err
}

func InitDB(dbPath string) error {
	var gormLogger logger.Interface

	if config.IsDebug() {
		gormLogger = logger.Default
	} else {
		gormLogger = logger.Discard
	}

	dbHost := os.Getenv("DB_HOST")
	dbPort := os.Getenv("DB_PORT")
	dbName := os.Getenv("DB_NAME")
	dbUser := os.Getenv("DB_USER")
	dbPass := os.Getenv("DB_PASSWORD")

	if dbHost == "" || dbPort == "" || dbName == "" || dbUser == "" || dbPass == "" {
		return fmt.Errorf("missing database configuration environment variables")
	}

	dsn := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?charset=utf8mb4&parseTime=True&loc=Local",
		dbUser, dbPass, dbHost, dbPort, dbName)

	var err error
	db, err = gorm.Open(mysql.Open(dsn), &gorm.Config{
		Logger: gormLogger,
	})
	if err != nil {
		return fmt.Errorf("failed to connect to database: %v", err)
	}

	if err := initModels(); err != nil {
		return err
	}

	isUsersEmpty, err := isTableEmpty("users")
	if err != nil {
		return err
	}

	if err := initUser(); err != nil {
		return err
	}
	
	return runSeeders(isUsersEmpty)
}

func CloseDB() error {
	if db != nil {
		sqlDB, err := db.DB()
		if err != nil {
			return err
		}
		return sqlDB.Close()
	}
	return nil
}

func GetDB() *gorm.DB {
	return db
}

func IsNotFound(err error) bool {
	return err == gorm.ErrRecordNotFound
}

func IsSQLiteDB(file io.ReaderAt) (bool, error) {
	signature := []byte("SQLite format 3\x00")
	buf := make([]byte, len(signature))
	_, err := file.ReadAt(buf, 0)
	if err != nil {
		return false, err
	}
	return bytes.Equal(buf, signature), nil
}

func Checkpoint() error {
	// MariaDB doesn't need WAL checkpoint
	return nil
}