package service

import (
	"context"
	"encoding/json"
	"strings"
	"sync/atomic"
	"time"

	"github.com/topfans/backend/pkg/logger"
	pbCastlove "github.com/topfans/backend/pkg/proto/castlove"
	pbCommon "github.com/topfans/backend/pkg/proto/common"
	"github.com/topfans/backend/pkg/models"
	"github.com/topfans/backend/services/assetService/repository"
	"go.uber.org/zap"
	"golang.org/x/sync/singleflight"
)

// CastloveConfigService 铸爱工艺配置 Service 接口
type CastloveConfigService interface {
	// GetConfig 读取全量配置(含 5s 进程内缓存 + singleflight 防击穿)
	// 返回已 sanitize 后的数据
	GetConfig(ctx context.Context) (*pbCastlove.GetCastloveConfigResponse, error)
}

// 缓存 TTL:5 秒(spec §3.4)
// 平衡点:端上体验 vs DB 压力;运营反馈"改完看不到要等 5 秒太久"时可调到 2 秒
const castloveConfigCacheTTL = 5 * time.Second

// castloveConfigService 实现
type castloveConfigService struct {
	repo repository.CastloveConfigRepository

	// 进程内缓存:原子指针,避免锁
	cache atomic.Pointer[castloveConfigCacheEntry]

	// singleflight:多并发同时 miss 时只打一次 DB
	sfGroup singleflight.Group
}

// castloveConfigCacheEntry 缓存条目
type castloveConfigCacheEntry struct {
	data      *pbCastlove.GetCastloveConfigResponse
	expiresAt time.Time
}

// NewCastloveConfigService 创建铸爱工艺配置 Service 实例
func NewCastloveConfigService(repo repository.CastloveConfigRepository) CastloveConfigService {
	return &castloveConfigService{
		repo: repo,
	}
}

// GetConfig 读取全量配置(含 5s 进程内缓存 + singleflight 防击穿)
func (s *castloveConfigService) GetConfig(ctx context.Context) (*pbCastlove.GetCastloveConfigResponse, error) {
	// 1. 命中缓存
	if c := s.cache.Load(); c != nil && time.Now().Before(c.expiresAt) {
		return c.data, nil
	}

	// 2. 缓存未命中或已过期,走 singleflight(多并发只打一次 DB)
	v, err, _ := s.sfGroup.Do("castlove_config", func() (interface{}, error) {
		return s.loadFromDB(ctx)
	})
	if err != nil {
		return nil, err
	}

	resp := v.(*pbCastlove.GetCastloveConfigResponse)

	// 3. 写入缓存(覆盖式)
	s.cache.Store(&castloveConfigCacheEntry{
		data:      resp,
		expiresAt: time.Now().Add(castloveConfigCacheTTL),
	})

	return resp, nil
}

// loadFromDB 从 DB 读取并组装 + sanitize
// (后台直连写库,这里做最低限度的兜底校验,防止脏数据穿透到前端)
func (s *castloveConfigService) loadFromDB(ctx context.Context) (*pbCastlove.GetCastloveConfigResponse, error) {
	categories, err := s.repo.ListActiveCategories()
	if err != nil {
		logger.Logger.Error("castlove_config: list categories failed", zap.Error(err))
		return nil, err
	}

	crafts, err := s.repo.ListActiveCrafts()
	if err != nil {
		logger.Logger.Error("castlove_config: list crafts failed", zap.Error(err))
		return nil, err
	}

	maxUpdatedAt, err := s.repo.MaxUpdatedAt()
	if err != nil {
		// 失败不致命,降级 version = 当前时间
		logger.Logger.Warn("castlove_config: maxUpdatedAt failed, fallback to now", zap.Error(err))
		maxUpdatedAt = time.Now().UnixMilli()
	}

	// 构造 category_id -> []*craft 的 map,方便 O(1) 归类
	craftsByCategory := make(map[int64][]*models.CastloveCraft, len(categories))
	for _, c := range crafts {
		craftsByCategory[c.CategoryID] = append(craftsByCategory[c.CategoryID], c)
	}

	// 构造响应
	out := &pbCastlove.GetCastloveConfigResponse{
		Base: &pbCommon.BaseResponse{
			Code:      pbCommon.StatusCode_STATUS_OK,
			Message:   "ok",
			Timestamp: time.Now().UnixMilli(),
		},
		Categories: make([]*pbCastlove.CastloveCategoryProto, 0, len(categories)),
		Version:    time.UnixMilli(maxUpdatedAt).UTC().Format(time.RFC3339),
	}

	for _, cat := range categories {
		protoCat := &pbCastlove.CastloveCategoryProto{
			Id:        cat.ID,
			Name:      cat.Name,
			SortOrder: cat.SortOrder,
			Crafts:    make([]*pbCastlove.CastloveCraftProto, 0),
		}
		if cat.TypeKey != nil {
			protoCat.TypeKey = *cat.TypeKey
		}

		// 归类该分类下的卡片
		rawCrafts := craftsByCategory[cat.ID]
		for _, raw := range rawCrafts {
			// sanitize 兜底:返回 nil 表示丢弃
			sanitized := sanitizeCastloveCraft(raw)
			if sanitized == nil {
				continue
			}
			protoCat.Crafts = append(protoCat.Crafts, sanitized)
		}

		out.Categories = append(out.Categories, protoCat)
	}

	return out, nil
}

// sanitizeCastloveCraft 兜底校验
// 返回 nil 表示该卡片应被丢弃(日志 warn,不抛错)
// 规则(spec §3.5):
//   - image_url 必须 http(s) 开头
//   - name 非空
//   - route_path 若非空:必须以 / 开头,且不含 ? / #
//   - route_params 若非空:必须是合法 JSON object
func sanitizeCastloveCraft(c *models.CastloveCraft) *pbCastlove.CastloveCraftProto {
	// 1. image_url 必须 http(s) 开头
	if !strings.HasPrefix(c.ImageURL, "http://") && !strings.HasPrefix(c.ImageURL, "https://") {
		logger.Logger.Warn("castlove_config: drop craft, invalid image_url",
			zap.Int64("craft_id", c.ID),
			zap.String("image_url", c.ImageURL),
		)
		return nil
	}

	// 2. name 非空
	if strings.TrimSpace(c.Name) == "" {
		logger.Logger.Warn("castlove_config: drop craft, empty name",
			zap.Int64("craft_id", c.ID),
		)
		return nil
	}

	// 3. route_path 兜底
	routePath := ""
	if c.RoutePath != nil {
		raw := strings.TrimSpace(*c.RoutePath)
		if raw != "" {
			if !strings.HasPrefix(raw, "/") || strings.ContainsAny(raw, "?#") {
				logger.Logger.Warn("castlove_config: clear route_path (invalid format)",
					zap.Int64("craft_id", c.ID),
					zap.String("route_path", raw),
				)
				// 降级为 NULL/空(行为同"未配置")
				raw = ""
			}
		}
		routePath = raw
	}

	// 4. route_params 兜底:必须是合法 JSON object
	routeParams := ""
	if c.RouteParams != nil {
		raw := strings.TrimSpace(*c.RouteParams)
		if raw != "" {
			var m map[string]json.RawMessage
			if err := json.Unmarshal([]byte(raw), &m); err != nil {
				logger.Logger.Warn("castlove_config: clear route_params (not JSON object)",
					zap.Int64("craft_id", c.ID),
					zap.String("route_params", raw),
					zap.Error(err),
				)
				raw = ""
			}
		}
		routeParams = raw
	}

	return &pbCastlove.CastloveCraftProto{
		Id:          c.ID,
		Name:        c.Name,
		ImageUrl:    c.ImageURL,
		RoutePath:   routePath,
		RouteParams: routeParams,
		SortOrder:   c.SortOrder,
	}
}