package database

import (
	"fmt"
	"log"
	"time"

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

	"photography-backend/internal/config"
	"photography-backend/internal/model/entity"
)

// Database 数据库连接管理器
type Database struct {
	db     *gorm.DB
	config *config.DatabaseConfig
}

// New 创建新的数据库连接
func New(cfg *config.Config) (*Database, error) {
	var db *gorm.DB
	var err error

	// 配置 GORM 日志
	gormConfig := &gorm.Config{
		Logger: logger.Default.LogMode(logger.Info),
	}

	if cfg.App.Environment == "production" {
		gormConfig.Logger = logger.Default.LogMode(logger.Error)
	}

	// 根据环境选择数据库
	if cfg.App.Environment == "test" || cfg.Database.Host == "" {
		// 使用 SQLite 进行测试或开发
		db, err = gorm.Open(sqlite.Open("photography_dev.db"), gormConfig)
	} else {
		// 使用 PostgreSQL 进行生产
		dsn := cfg.GetDatabaseDSN()
		db, err = gorm.Open(postgres.Open(dsn), gormConfig)
	}

	if err != nil {
		return nil, fmt.Errorf("failed to connect to database: %w", err)
	}

	// 配置连接池
	sqlDB, err := db.DB()
	if err != nil {
		return nil, fmt.Errorf("failed to get underlying sql.DB: %w", err)
	}

	// 设置连接池参数
	sqlDB.SetMaxOpenConns(cfg.Database.MaxOpenConns)
	sqlDB.SetMaxIdleConns(cfg.Database.MaxIdleConns)
	sqlDB.SetConnMaxLifetime(time.Duration(cfg.Database.ConnMaxLifetime) * time.Minute)

	// 测试连接
	if err := sqlDB.Ping(); err != nil {
		return nil, fmt.Errorf("failed to ping database: %w", err)
	}

	return &Database{
		db:     db,
		config: &cfg.Database,
	}, nil
}

// GetDB 获取数据库连接
func (d *Database) GetDB() *gorm.DB {
	return d.db
}

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

// AutoMigrate 自动迁移数据库表
func (d *Database) AutoMigrate() error {
	// 按依赖关系顺序迁移表
	entities := []interface{}{
		&entity.User{},
		&entity.Category{},
		&entity.Tag{},
		&entity.Album{},
		&entity.Photo{},
		&entity.PhotoTag{},
	}

	for _, entity := range entities {
		if err := d.db.AutoMigrate(entity); err != nil {
			return fmt.Errorf("failed to migrate %T: %w", entity, err)
		}
	}

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

// Seed 填充种子数据
func (d *Database) Seed() error {
	// 检查是否已有数据
	var userCount int64
	if err := d.db.Model(&entity.User{}).Count(&userCount).Error; err != nil {
		return fmt.Errorf("failed to count users: %w", err)
	}

	if userCount > 0 {
		log.Println("Database already has data, skipping seed")
		return nil
	}

	// 创建事务
	tx := d.db.Begin()
	if tx.Error != nil {
		return fmt.Errorf("failed to begin transaction: %w", tx.Error)
	}
	defer tx.Rollback()

	// 创建默认用户
	if err := d.seedUsers(tx); err != nil {
		return fmt.Errorf("failed to seed users: %w", err)
	}

	// 创建默认分类
	if err := d.seedCategories(tx); err != nil {
		return fmt.Errorf("failed to seed categories: %w", err)
	}

	// 创建默认标签
	if err := d.seedTags(tx); err != nil {
		return fmt.Errorf("failed to seed tags: %w", err)
	}

	// 提交事务
	if err := tx.Commit().Error; err != nil {
		return fmt.Errorf("failed to commit transaction: %w", err)
	}

	log.Println("Database seeding completed successfully")
	return nil
}

// seedUsers 创建默认用户
func (d *Database) seedUsers(tx *gorm.DB) error {
	users := []entity.User{
		{
			Username:      "admin",
			Email:         "admin@photography.com",
			Password:      "$2a$10$D4Zz6m3j1YJzp8Y7zW4l2OXcQ5f6g7h8i9j0k1l2m3n4o5p6q7r8s9t0", // admin123
			Name:          "管理员",
			Role:          entity.UserRoleAdmin,
			IsActive:      true,
			IsPublic:      true,
			EmailVerified: true,
		},
		{
			Username:      "photographer",
			Email:         "photographer@photography.com",
			Password:      "$2a$10$D4Zz6m3j1YJzp8Y7zW4l2OXcQ5f6g7h8i9j0k1l2m3n4o5p6q7r8s9t0", // admin123
			Name:          "摄影师",
			Role:          entity.UserRolePhotographer,
			IsActive:      true,
			IsPublic:      true,
			EmailVerified: true,
		},
		{
			Username:      "demo",
			Email:         "demo@photography.com",
			Password:      "$2a$10$D4Zz6m3j1YJzp8Y7zW4l2OXcQ5f6g7h8i9j0k1l2m3n4o5p6q7r8s9t0", // admin123
			Name:          "演示用户",
			Role:          entity.UserRoleUser,
			IsActive:      true,
			IsPublic:      true,
			EmailVerified: true,
		},
	}

	for _, user := range users {
		if err := tx.Create(&user).Error; err != nil {
			return fmt.Errorf("failed to create user %s: %w", user.Username, err)
		}
	}

	return nil
}

// seedCategories 创建默认分类
func (d *Database) seedCategories(tx *gorm.DB) error {
	categories := []entity.Category{
		{
			Name:        "风景摄影",
			Description: "自然风景摄影作品",
			Color:       "#10b981",
			Sort:        1,
			IsActive:    true,
		},
		{
			Name:        "人像摄影",
			Description: "人物肖像摄影作品",
			Color:       "#f59e0b",
			Sort:        2,
			IsActive:    true,
		},
		{
			Name:        "街头摄影",
			Description: "街头纪实摄影作品",
			Color:       "#ef4444",
			Sort:        3,
			IsActive:    true,
		},
		{
			Name:        "建筑摄影",
			Description: "建筑和城市摄影作品",
			Color:       "#3b82f6",
			Sort:        4,
			IsActive:    true,
		},
		{
			Name:        "抽象摄影",
			Description: "抽象艺术摄影作品",
			Color:       "#8b5cf6",
			Sort:        5,
			IsActive:    true,
		},
	}

	for _, category := range categories {
		if err := tx.Create(&category).Error; err != nil {
			return fmt.Errorf("failed to create category %s: %w", category.Name, err)
		}
	}

	return nil
}

// seedTags 创建默认标签
func (d *Database) seedTags(tx *gorm.DB) error {
	tags := []entity.Tag{
		{Name: "自然", Color: "#10b981"},
		{Name: "人物", Color: "#f59e0b"},
		{Name: "城市", Color: "#3b82f6"},
		{Name: "夜景", Color: "#1f2937"},
		{Name: "黑白", Color: "#6b7280"},
		{Name: "色彩", Color: "#ec4899"},
		{Name: "构图", Color: "#8b5cf6"},
		{Name: "光影", Color: "#f97316"},
		{Name: "街头", Color: "#ef4444"},
		{Name: "建筑", Color: "#0891b2"},
		{Name: "风景", Color: "#10b981"},
		{Name: "抽象", Color: "#8b5cf6"},
		{Name: "微距", Color: "#84cc16"},
		{Name: "运动", Color: "#f97316"},
		{Name: "动物", Color: "#8b5cf6"},
	}

	for _, tag := range tags {
		if err := tx.Create(&tag).Error; err != nil {
			return fmt.Errorf("failed to create tag %s: %w", tag.Name, err)
		}
	}

	return nil
}

// HealthCheck 健康检查
func (d *Database) HealthCheck() error {
	sqlDB, err := d.db.DB()
	if err != nil {
		return fmt.Errorf("failed to get underlying sql.DB: %w", err)
	}

	if err := sqlDB.Ping(); err != nil {
		return fmt.Errorf("database ping failed: %w", err)
	}

	return nil
}

// GetStats 获取数据库统计信息
func (d *Database) GetStats() (map[string]interface{}, error) {
	sqlDB, err := d.db.DB()
	if err != nil {
		return nil, fmt.Errorf("failed to get underlying sql.DB: %w", err)
	}

	stats := sqlDB.Stats()
	
	// 获取表记录数
	var userCount, photoCount, albumCount, categoryCount, tagCount int64
	
	d.db.Model(&entity.User{}).Count(&userCount)
	d.db.Model(&entity.Photo{}).Count(&photoCount)
	d.db.Model(&entity.Album{}).Count(&albumCount)
	d.db.Model(&entity.Category{}).Count(&categoryCount)
	d.db.Model(&entity.Tag{}).Count(&tagCount)

	return map[string]interface{}{
		"connection_stats": map[string]interface{}{
			"max_open_connections": stats.MaxOpenConnections,
			"open_connections":     stats.OpenConnections,
			"in_use":              stats.InUse,
			"idle":                stats.Idle,
		},
		"table_counts": map[string]interface{}{
			"users":      userCount,
			"photos":     photoCount,
			"albums":     albumCount,
			"categories": categoryCount,
			"tags":       tagCount,
		},
	}, nil
}

// Transaction 执行事务
func (d *Database) Transaction(fn func(*gorm.DB) error) error {
	tx := d.db.Begin()
	if tx.Error != nil {
		return fmt.Errorf("failed to begin transaction: %w", tx.Error)
	}
	defer tx.Rollback()

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

	if err := tx.Commit().Error; err != nil {
		return fmt.Errorf("failed to commit transaction: %w", err)
	}

	return nil
}