package database

import (
	"fmt"
	"log"
	"os"
	"path/filepath"
	"time"

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

// DB 数据库连接
var DB *gorm.DB

// Init 初始化数据库
func Init(dataDir string) error {
	// 确保数据目录存在
	if err := os.MkdirAll(dataDir, 0755); err != nil {
		return fmt.Errorf("failed to create data directory %s: %w", dataDir, err)
	}

	dbPath := filepath.Join(dataDir, "cluster.db")

	// 检查数据库文件是否存在
	dbExists := false
	if _, err := os.Stat(dbPath); err == nil {
		dbExists = true
		log.Printf("Database file already exists: %s", dbPath)
	} else if !os.IsNotExist(err) {
		return fmt.Errorf("failed to check database file: %w", err)
	} else {
		log.Printf("Creating new database file: %s", dbPath)
	}

	// 配置 GORM logger
	gormLogger := logger.Default
	if os.Getenv("GORM_LOG_LEVEL") == "silent" {
		gormLogger = gormLogger.LogMode(logger.Silent)
	}

	// 打开数据库连接
	var err error
	DB, err = gorm.Open(sqlite.Open(dbPath), &gorm.Config{
		Logger: gormLogger,
	})
	if err != nil {
		return fmt.Errorf("failed to open database: %w", err)
	}

	// 获取底层 sql.DB 以设置连接池
	sqlDB, err := DB.DB()
	if err != nil {
		return fmt.Errorf("failed to get database instance: %w", err)
	}

	// 设置连接池参数
	sqlDB.SetMaxIdleConns(10)
	sqlDB.SetMaxOpenConns(100)
	sqlDB.SetConnMaxLifetime(time.Hour)

	// 启用外键约束
	if err := DB.Exec("PRAGMA foreign_keys = ON").Error; err != nil {
		return fmt.Errorf("failed to enable foreign keys: %w", err)
	}

	// 自动迁移表结构
	if err := autoMigrate(); err != nil {
		return fmt.Errorf("failed to migrate tables: %w", err)
	}

	if !dbExists {
		log.Printf("Database initialized successfully: %s", dbPath)
	} else {
		log.Printf("Database tables verified: %s", dbPath)
	}

	return nil
}

// Close 关闭数据库连接
func Close() error {
	if DB != nil {
		sqlDB, err := DB.DB()
		if err != nil {
			return err
		}
		return sqlDB.Close()
	}
	return nil
}

// autoMigrate 自动迁移表结构
func autoMigrate() error {
	models := []interface{}{
		&Repository{},
		&Manifest{},
		&Blob{},
		&Tag{},
		&BlobUpload{},
		&ManifestBlob{},
	}

	for _, model := range models {
		if err := DB.AutoMigrate(model); err != nil {
			return fmt.Errorf("failed to migrate model %T: %w", model, err)
		}
	}

	log.Printf("Database migration completed successfully")
	return nil
}