package database

import (
	"fmt"
	"log"
	"strings"
	"wx_service/config"

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

var (
	DB            *gorm.DB
	additionalDBs map[string]*gorm.DB
)

func InitDB() error {
	cfg := config.AppConfig.Database

	defaultDB, err := openConnection(cfg.Default)
	if err != nil {
		return fmt.Errorf("连接数据库失败: %v", err)
	}
	DB = defaultDB
	log.Println("默认数据库连接成功")

	if len(cfg.Additional) > 0 {
		additionalDBs = make(map[string]*gorm.DB)
		for name, instanceCfg := range cfg.Additional {
			conn, err := openConnection(instanceCfg)
			if err != nil {
				return fmt.Errorf("连接数据库[%s]失败: %v", name, err)
			}
			additionalDBs[strings.ToLower(name)] = conn
			log.Printf("数据库连接成功: %s\n", name)
		}
	} else {
		additionalDBs = nil
	}
	return nil
}

func openConnection(cfg config.DatabaseInstanceConfig) (*gorm.DB, error) {
	dsn := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?charset=utf8mb4&parseTime=True&loc=Local",
		cfg.User,
		cfg.Password,
		cfg.Host,
		cfg.Port,
		cfg.DBName,
	)

	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
		Logger: logger.Default.LogMode(logger.Info),
	})
	if err != nil {
		return nil, err
	}
	return db, nil
}

func GetAdditionalDB(name string) (*gorm.DB, bool) {
	if name == "" || strings.EqualFold(name, "default") {
		return DB, DB != nil
	}
	if additionalDBs == nil {
		return nil, false
	}
	db, ok := additionalDBs[strings.ToLower(name)]
	return db, ok
}

func AutoMigrate(models ...interface{}) error {
	type tableCommenter interface {
		TableComment() string
	}

	for _, m := range models {
		tx := DB
		comment := ""
		if tc, ok := m.(tableCommenter); ok {
			comment = strings.TrimSpace(tc.TableComment())
			if comment != "" {
				tx = tx.Set("gorm:table_options", fmt.Sprintf("COMMENT='%s'", escapeSQLComment(comment)))
			}
		}

		if err := tx.AutoMigrate(m); err != nil {
			return err
		}

		// 尝试为已存在的表补齐 table comment（即使表已创建，也能更新注释）。
		if comment != "" {
			stmt := &gorm.Statement{DB: DB}
			if err := stmt.Parse(m); err == nil && stmt.Schema != nil && stmt.Schema.Table != "" {
				_ = DB.Exec(fmt.Sprintf("ALTER TABLE `%s` COMMENT = '%s'", stmt.Schema.Table, escapeSQLComment(comment))).Error
			}
		}
	}

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

func escapeSQLComment(s string) string {
	// MySQL: 单引号用两个单引号转义
	return strings.ReplaceAll(s, "'", "''")
}