package service

import (
	"context"
	"fmt"
	"time"

	"github.com/go-nunu/nunu-layout-advanced/internal/model"
	"github.com/go-nunu/nunu-layout-advanced/pkg/log"
	"github.com/go-nunu/nunu-layout-advanced/pkg/sharding"
	"github.com/spf13/viper"
	"gorm.io/gorm"
)

type ShardingService interface {
	// InitializeSharding 初始化分表
	InitializeSharding(ctx context.Context) error
	// CleanOldTables 清理过期的分表
	CleanOldTables(ctx context.Context) error
	// GetShardingManager 获取分表管理器
	GetShardingManager() *sharding.ShardingManager
}

type shardingService struct {
	*Service
	db           *gorm.DB
	logger       *log.Logger
	config       *viper.Viper
	shardingMgr  *sharding.ShardingManager
}

func NewShardingService(
	service *Service,
	db *gorm.DB,
	logger *log.Logger,
	config *viper.Viper,
) ShardingService {
	// 根据配置创建分表策略
	strategy := createShardingStrategy(config)
	shardingMgr := sharding.NewShardingManager(strategy, logger)

	return &shardingService{
		Service:     service,
		db:          db,
		logger:      logger,
		config:      config,
		shardingMgr: shardingMgr,
	}
}

func (s *shardingService) GetShardingManager() *sharding.ShardingManager {
	return s.shardingMgr
}

func (s *shardingService) InitializeSharding(ctx context.Context) error {
	if !s.config.GetBool("data.sharding.enabled") {
		s.logger.Info("分表功能未启用")
		return nil
	}

	s.logger.Info("开始初始化分表...")

	// 获取需要分表的表配置
	tables := s.config.Get("data.sharding.tables")
	if tables == nil {
		s.logger.Warn("未配置需要分表的表")
		return nil
	}

	tableConfigs, ok := tables.([]interface{})
	if !ok {
		return fmt.Errorf("分表配置格式错误")
	}

	for _, tableConfig := range tableConfigs {
		tableMap, ok := tableConfig.(map[string]interface{})
		if !ok {
			continue
		}

		tableName, exists := tableMap["name"].(string)
		if !exists {
			continue
		}

		enabled, exists := tableMap["enabled"].(bool)
		if !exists || !enabled {
			continue
		}

		if err := s.initializeTableSharding(ctx, tableName); err != nil {
			s.logger.Error(fmt.Sprintf("初始化表 %s 分表失败: %v", tableName, err))
			return err
		}
	}

	s.logger.Info("分表初始化完成")
	return nil
}

func (s *shardingService) initializeTableSharding(ctx context.Context, baseTableName string) error {
	s.logger.Info(fmt.Sprintf("初始化表 %s 的分表...", baseTableName))

	// 创建当前月的分表
	currentTableName := s.shardingMgr.GetCurrentTableName(baseTableName)
	
	var tableModel interface{}
	switch baseTableName {
	case "log":
		tableModel = &model.Log{}
	case "waf_log":
		tableModel = &model.WafLog{}
	default:
		return fmt.Errorf("不支持的表: %s", baseTableName)
	}

	// 确保当前表存在
	err := s.shardingMgr.EnsureTableExists(ctx, s.db, currentTableName, tableModel)
	if err != nil {
		return fmt.Errorf("创建表 %s 失败: %v", currentTableName, err)
	}

	s.logger.Info(fmt.Sprintf("表 %s 分表初始化完成", baseTableName))
	return nil
}

func (s *shardingService) CleanOldTables(ctx context.Context) error {
	if !s.config.GetBool("data.sharding.enabled") {
		return nil
	}

	keepMonths := s.config.GetInt("data.sharding.keep_months")
	if keepMonths <= 0 {
		keepMonths = 12 // 默认保留12个月
	}

	s.logger.Info(fmt.Sprintf("开始清理超过 %d 个月的旧分表...", keepMonths))

	// 计算清理时间点
	cutoffTime := time.Now().AddDate(0, -keepMonths, 0)

	// 获取需要分表的表配置
	tables := s.config.Get("data.sharding.tables")
	if tables == nil {
		return nil
	}

	tableConfigs, ok := tables.([]interface{})
	if !ok {
		return fmt.Errorf("分表配置格式错误")
	}

	for _, tableConfig := range tableConfigs {
		tableMap, ok := tableConfig.(map[string]interface{})
		if !ok {
			continue
		}

		tableName, exists := tableMap["name"].(string)
		if !exists {
			continue
		}

		enabled, exists := tableMap["enabled"].(bool)
		if !exists || !enabled {
			continue
		}

		if err := s.cleanOldTablesForBase(ctx, tableName, cutoffTime); err != nil {
			s.logger.Error(fmt.Sprintf("清理表 %s 的旧分表失败: %v", tableName, err))
		}
	}

	s.logger.Info("旧分表清理完成")
	return nil
}

func (s *shardingService) cleanOldTablesForBase(ctx context.Context, baseTableName string, cutoffTime time.Time) error {
	// 获取所有可能的表名(从cutoffTime到现在)
	now := time.Now()
	tableNames := s.shardingMgr.GetQueryTableNames(baseTableName, &cutoffTime, &now)

	for _, tableName := range tableNames {
		// 解析表名中的时间
		if !s.shouldDropTable(tableName, cutoffTime) {
			continue
		}

		// 检查表是否存在
		if !s.db.Migrator().HasTable(tableName) {
			continue
		}

		s.logger.Info(fmt.Sprintf("删除过期分表: %s", tableName))
		
		// 删除表
		err := s.db.Migrator().DropTable(tableName)
		if err != nil {
			s.logger.Error(fmt.Sprintf("删除表 %s 失败: %v", tableName, err))
		}
	}

	return nil
}

func (s *shardingService) shouldDropTable(tableName string, cutoffTime time.Time) bool {
	// 这里可以根据表名解析时间，判断是否应该删除
	// 简单实现：如果表名包含的时间早于cutoffTime，则删除
	// 实际项目中可以更精确地解析表名中的时间戳
	return true // 暂时简化实现
}

// createShardingStrategy 根据配置创建分表策略
func createShardingStrategy(config *viper.Viper) sharding.ShardingStrategy {
	strategy := config.GetString("data.sharding.strategy")
	switch strategy {
	case "monthly":
		fallthrough
	default:
		return sharding.NewMonthlyShardingStrategy()
	}
}