package model

import (
	"fmt"
	"log"
	"os"
	"strings"
	"sync"
	"time"

	"github.com/QuantumNous/new-api/common"
	"github.com/QuantumNous/new-api/constant"

	"github.com/glebarez/sqlite"
	"gorm.io/driver/mysql"
	"gorm.io/driver/postgres"
	"gorm.io/gorm"
)

var commonGroupCol string
var commonKeyCol string
var commonTrueVal string
var commonFalseVal string

var logKeyCol string
var logGroupCol string

func initCol() {
	// init common column names
	if common.UsingPostgreSQL {
		commonGroupCol = `"group"`
		commonKeyCol = `"key"`
		commonTrueVal = "true"
		commonFalseVal = "false"
	} else {
		commonGroupCol = "`group`"
		commonKeyCol = "`key`"
		commonTrueVal = "1"
		commonFalseVal = "0"
	}
	if os.Getenv("LOG_SQL_DSN") != "" {
		switch common.LogSqlType {
		case common.DatabaseTypePostgreSQL:
			logGroupCol = `"group"`
			logKeyCol = `"key"`
		default:
			logGroupCol = commonGroupCol
			logKeyCol = commonKeyCol
		}
	} else {
		// LOG_SQL_DSN 为空时，日志数据库与主数据库相同
		if common.UsingPostgreSQL {
			logGroupCol = `"group"`
			logKeyCol = `"key"`
		} else {
			logGroupCol = commonGroupCol
			logKeyCol = commonKeyCol
		}
	}
	// log sql type and database type
	//common.SysLog("Using Log SQL Type: " + common.LogSqlType)
}

var DB *gorm.DB

var LOG_DB *gorm.DB

func createRootAccountIfNeed() error {
	var user User
	//if user.Status != common.UserStatusEnabled {
	if err := DB.First(&user).Error; err != nil {
		common.SysLog("no user exists, create a root user for you: username is root, password is 123456")
		hashedPassword, err := common.Password2Hash("123456")
		if err != nil {
			return err
		}
		rootUser := User{
			Username:    "root",
			Password:    hashedPassword,
			Role:        common.RoleRootUser,
			Status:      common.UserStatusEnabled,
			DisplayName: "Root User",
			AccessToken: nil,
			Quota:       100000000,
		}
		DB.Create(&rootUser)
	}
	return nil
}

func CheckSetup() {
	setup := GetSetup()
	if setup == nil {
		// No setup record exists, check if we have a root user
		if RootUserExists() {
			common.SysLog("system is not initialized, but root user exists")
			// Create setup record
			newSetup := Setup{
				Version:       common.Version,
				InitializedAt: time.Now().Unix(),
			}
			err := DB.Create(&newSetup).Error
			if err != nil {
				common.SysLog("failed to create setup record: " + err.Error())
			}
			constant.Setup = true
		} else {
			common.SysLog("system is not initialized and no root user exists")
			constant.Setup = false
		}
	} else {
		// Setup record exists, system is initialized
		common.SysLog("system is already initialized at: " + time.Unix(setup.InitializedAt, 0).String())
		constant.Setup = true
	}
}

func chooseDB(envName string, isLog bool) (*gorm.DB, error) {
	defer func() {
		initCol()
	}()
	dsn := os.Getenv(envName)
	if dsn != "" {
		if strings.HasPrefix(dsn, "postgres://") || strings.HasPrefix(dsn, "postgresql://") {
			// Use PostgreSQL
			common.SysLog("using PostgreSQL as database")
			if !isLog {
				common.UsingPostgreSQL = true
			} else {
				common.LogSqlType = common.DatabaseTypePostgreSQL
			}
			return gorm.Open(postgres.New(postgres.Config{
				DSN:                  dsn,
				PreferSimpleProtocol: true, // disables implicit prepared statement usage
			}), &gorm.Config{
				PrepareStmt: true, // precompile SQL
			})
		}
		if strings.HasPrefix(dsn, "local") {
			common.SysLog("SQL_DSN not set, using SQLite as database")
			if !isLog {
				common.UsingSQLite = true
			} else {
				common.LogSqlType = common.DatabaseTypeSQLite
			}
			return gorm.Open(sqlite.Open(common.SQLitePath), &gorm.Config{
				PrepareStmt: true, // precompile SQL
			})
		}
		// Use MySQL
		common.SysLog("using MySQL as database")
		// check parseTime
		if !strings.Contains(dsn, "parseTime") {
			if strings.Contains(dsn, "?") {
				dsn += "&parseTime=true"
			} else {
				dsn += "?parseTime=true"
			}
		}
		if !isLog {
			common.UsingMySQL = true
		} else {
			common.LogSqlType = common.DatabaseTypeMySQL
		}
		return gorm.Open(mysql.Open(dsn), &gorm.Config{
			PrepareStmt: true, // precompile SQL
		})
	}
	// Use SQLite
	common.SysLog("SQL_DSN not set, using SQLite as database")
	common.UsingSQLite = true
	return gorm.Open(sqlite.Open(common.SQLitePath), &gorm.Config{
		PrepareStmt: true, // precompile SQL
	})
}

func InitDB() (err error) {
	db, err := chooseDB("SQL_DSN", false)
	if err == nil {
		if common.DebugEnabled {
			db = db.Debug()
		}
		DB = db
		// MySQL charset/collation startup check: ensure Chinese-capable charset
		if common.UsingMySQL {
			if err := checkMySQLChineseSupport(DB); err != nil {
				panic(err)
			}
		}
		sqlDB, err := DB.DB()
		if err != nil {
			return err
		}
		sqlDB.SetMaxIdleConns(common.GetEnvOrDefault("SQL_MAX_IDLE_CONNS", 100))
		sqlDB.SetMaxOpenConns(common.GetEnvOrDefault("SQL_MAX_OPEN_CONNS", 1000))
		sqlDB.SetConnMaxLifetime(time.Second * time.Duration(common.GetEnvOrDefault("SQL_MAX_LIFETIME", 60)))

		if !common.IsMasterNode {
			return nil
		}
		if common.UsingMySQL {
			//_, _ = sqlDB.Exec("ALTER TABLE channels MODIFY model_mapping TEXT;") // TODO: delete this line when most users have upgraded
		}
		common.SysLog("database migration started")
		err = migrateDB()
		return err
	} else {
		common.FatalLog(err)
	}
	return err
}

func InitLogDB() (err error) {
	if os.Getenv("LOG_SQL_DSN") == "" {
		LOG_DB = DB
		return
	}
	db, err := chooseDB("LOG_SQL_DSN", true)
	if err == nil {
		if common.DebugEnabled {
			db = db.Debug()
		}
		LOG_DB = db
		// If log DB is MySQL, also ensure Chinese-capable charset
		if common.LogSqlType == common.DatabaseTypeMySQL {
			if err := checkMySQLChineseSupport(LOG_DB); err != nil {
				panic(err)
			}
		}
		sqlDB, err := LOG_DB.DB()
		if err != nil {
			return err
		}
		sqlDB.SetMaxIdleConns(common.GetEnvOrDefault("SQL_MAX_IDLE_CONNS", 100))
		sqlDB.SetMaxOpenConns(common.GetEnvOrDefault("SQL_MAX_OPEN_CONNS", 1000))
		sqlDB.SetConnMaxLifetime(time.Second * time.Duration(common.GetEnvOrDefault("SQL_MAX_LIFETIME", 60)))

		if !common.IsMasterNode {
			return nil
		}
		common.SysLog("database migration started")
		err = migrateLOGDB()
		return err
	} else {
		common.FatalLog(err)
	}
	return err
}

func migrateDB() error {
    err := DB.AutoMigrate(
        &Channel{},
        &Token{},
        &User{},
        &PasskeyCredential{},
		&Option{},
        &Redemption{},
        &Ability{},
        &Log{},
        &Midjourney{},
        &TopUp{},
        &QuotaData{},
        &Task{},
        &Model{},
        &Vendor{},
        &PrefillGroup{},
        &Setup{},
        &TwoFA{},
        &TwoFABackupCode{},
    )
	if err != nil {
		return err
	}
	return nil
}

func migrateDBFast() error {

	var wg sync.WaitGroup

    migrations := []struct {
        model interface{}
        name  string
    }{
        {&Channel{}, "Channel"},
        {&Token{}, "Token"},
        {&User{}, "User"},
        {&PasskeyCredential{}, "PasskeyCredential"},
		{&Option{}, "Option"},
        {&Redemption{}, "Redemption"},
        {&Ability{}, "Ability"},
        {&Log{}, "Log"},
        {&Midjourney{}, "Midjourney"},
        {&TopUp{}, "TopUp"},
        {&QuotaData{}, "QuotaData"},
        {&Task{}, "Task"},
        {&Model{}, "Model"},
        {&Vendor{}, "Vendor"},
        {&PrefillGroup{}, "PrefillGroup"},
        {&Setup{}, "Setup"},
        {&TwoFA{}, "TwoFA"},
        {&TwoFABackupCode{}, "TwoFABackupCode"},
    }
	// 动态计算migration数量，确保errChan缓冲区足够大
	errChan := make(chan error, len(migrations))

	for _, m := range migrations {
		wg.Add(1)
		go func(model interface{}, name string) {
			defer wg.Done()
			if err := DB.AutoMigrate(model); err != nil {
				errChan <- fmt.Errorf("failed to migrate %s: %v", name, err)
			}
		}(m.model, m.name)
	}

	// Wait for all migrations to complete
	wg.Wait()
	close(errChan)

	// Check for any errors
	for err := range errChan {
		if err != nil {
			return err
		}
	}
	common.SysLog("database migrated")
	return nil
}

func migrateLOGDB() error {
	var err error
	if err = LOG_DB.AutoMigrate(&Log{}); err != nil {
		return err
	}
	return nil
}

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

func CloseDB() error {
	if LOG_DB != DB {
		err := closeDB(LOG_DB)
		if err != nil {
			return err
		}
	}
	return closeDB(DB)
}

// checkMySQLChineseSupport ensures the MySQL connection and current schema
// default charset/collation can store Chinese characters. It allows common
// Chinese-capable charsets (utf8mb4, utf8, gbk, big5, gb18030) and panics otherwise.
func checkMySQLChineseSupport(db *gorm.DB) error {
	// 仅检测：当前库默认字符集/排序规则 + 各表的排序规则（隐含字符集）

	// Read current schema defaults
	var schemaCharset, schemaCollation string
	err := db.Raw("SELECT DEFAULT_CHARACTER_SET_NAME, DEFAULT_COLLATION_NAME FROM information_schema.SCHEMATA WHERE SCHEMA_NAME = DATABASE()").Row().Scan(&schemaCharset, &schemaCollation)
	if err != nil {
		return fmt.Errorf("读取当前库默认字符集/排序规则失败 / Failed to read schema default charset/collation: %v", err)
	}

	toLower := func(s string) string { return strings.ToLower(s) }
	// Allowed charsets that can store Chinese text
	allowedCharsets := map[string]string{
		"utf8mb4": "utf8mb4_",
		"utf8":    "utf8_",
		"gbk":     "gbk_",
		"big5":    "big5_",
		"gb18030": "gb18030_",
	}
	isChineseCapable := func(cs, cl string) bool {
		csLower := toLower(cs)
		clLower := toLower(cl)
		if prefix, ok := allowedCharsets[csLower]; ok {
			if clLower == "" {
				return true
			}
			return strings.HasPrefix(clLower, prefix)
		}
		// 如果仅提供了排序规则，尝试按排序规则前缀判断
		for _, prefix := range allowedCharsets {
			if strings.HasPrefix(clLower, prefix) {
				return true
			}
		}
		return false
	}

	// 1) 当前库默认值必须支持中文
	if !isChineseCapable(schemaCharset, schemaCollation) {
		return fmt.Errorf("当前库默认字符集/排序规则不支持中文：schema(%s/%s)。请将库设置为 utf8mb4/utf8/gbk/big5/gb18030 / Schema default charset/collation is not Chinese-capable: schema(%s/%s). Please set to utf8mb4/utf8/gbk/big5/gb18030",
			schemaCharset, schemaCollation, schemaCharset, schemaCollation)
	}

	// 2) 所有物理表的排序规则（隐含字符集）必须支持中文
	type tableInfo struct {
		Name      string
		Collation *string
	}
	var tables []tableInfo
	if err := db.Raw("SELECT TABLE_NAME, TABLE_COLLATION FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE() AND TABLE_TYPE = 'BASE TABLE'").Scan(&tables).Error; err != nil {
		return fmt.Errorf("读取表排序规则失败 / Failed to read table collations: %v", err)
	}

	var badTables []string
	for _, t := range tables {
		// NULL 或空表示继承库默认设置，已在上面校验库默认，视为通过
		if t.Collation == nil || *t.Collation == "" {
			continue
		}
		cl := *t.Collation
		// 仅凭排序规则判断是否中文可用
		ok := false
		lower := strings.ToLower(cl)
		for _, prefix := range allowedCharsets {
			if strings.HasPrefix(lower, prefix) {
				ok = true
				break
			}
		}
		if !ok {
			badTables = append(badTables, fmt.Sprintf("%s(%s)", t.Name, cl))
		}
	}

	if len(badTables) > 0 {
		// 限制输出数量以避免日志过长
		maxShow := 20
		shown := badTables
		if len(shown) > maxShow {
			shown = shown[:maxShow]
		}
		return fmt.Errorf(
			"存在不支持中文的表，请修复其排序规则/字符集。示例（最多展示 %d 项）：%v / Found tables not Chinese-capable. Please fix their collation/charset. Examples (showing up to %d): %v",
			maxShow, shown, maxShow, shown,
		)
	}
	return nil
}

var (
	lastPingTime time.Time
	pingMutex    sync.Mutex
)

func PingDB() error {
	pingMutex.Lock()
	defer pingMutex.Unlock()

	if time.Since(lastPingTime) < time.Second*10 {
		return nil
	}

	sqlDB, err := DB.DB()
	if err != nil {
		log.Printf("Error getting sql.DB from GORM: %v", err)
		return err
	}

	err = sqlDB.Ping()
	if err != nil {
		log.Printf("Error pinging DB: %v", err)
		return err
	}

	lastPingTime = time.Now()
	common.SysLog("Database pinged successfully")
	return nil
}