package service

import (
	"context"
	"encoding/json"
	"fmt"
	"time"

	"github.com/redis/go-redis/v9"
	"go.uber.org/zap"
	"google.golang.org/grpc/codes"

	appErrors "github.com/topfans/backend/pkg/errors"
	"github.com/topfans/backend/pkg/logger"
	"github.com/topfans/backend/pkg/models"
	pb "github.com/topfans/backend/pkg/proto/asset"
	pbCommon "github.com/topfans/backend/pkg/proto/common"
	"github.com/topfans/backend/services/assetService/model"
	"github.com/topfans/backend/services/assetService/repository"
	"github.com/topfans/backend/services/assetService/util/qrcode"
)

// validSystemTypes spec § 3 枚举表
var validSystemTypes = map[string]struct{}{
	"android":     {},
	"ios":         {},
	"h5":          {},
	"mp-weixin":   {},
	"mp-alipay":   {},
	"mp-baidu":    {},
	"mp-toutiao":  {},
	"mp-lark":     {},
	"mp-qq":       {},
	"mp-kuaishou": {},
	"mp-xhs":      {},
	"app-plus":    {},
	"other":       {},
}

// validResults spec § 3.5 结果枚举
var validResults = map[string]struct{}{
	"success":           {},
	"cancel":            {},
	"fail_app_missing":  {},
	"fail_network":      {},
	"fail_canvas":       {},
	"fail_other":        {},
	"fail_permission":   {},
	"fail_already_saved": {},
}

// validShareTargets spec § 3 分享目标枚举
//
// 包含前端"复制链接"专用值 `copy_link`:
//   - GetAssetQrcode: 前端调用方一般不传(QR 接口主要服务图形分享),
//     但保留兼容,允许空字符串或 copy_link 命中校验。
//   - TrackShare: 前端 copyLink() 走 trackShare 埋点时上报 copy_link,
//     这样"复制链接"也能进入分享统计,与图形分享并列归因。
//
// 同步点:与 frontend/utils/constants.js SHARE_TARGETS 保持一致。
var validShareTargets = map[string]struct{}{
	"weixin_friend": {},
	"weixin_moment": {},
	"qq":            {},
	"qq_zone":       {},
	"sinaweibo":     {},
	"save_image":    {},
	"copy_link":     {},
}

const (
	qrcodeCacheTTL = 7 * 24 * time.Hour
	qrcodeCacheKey = "share:qrcode:%d:%d:%s"
)

// QRUploader 上传 PNG 到 OSS/CDN 的接口(便于测试 mock)
//
// 真实实现见 util/ossutil 包。
type QRUploader interface {
	UploadBytes(ctx context.Context, key string, data []byte, contentType string) (string, error)
}

// ShareRepository 分享数据访问抽象(便于测试 mock)
//
// 生产实现 *repository.ShareRepo 满足该接口;测试可注入内存实现。
type ShareRepository interface {
	Create(ctx context.Context, e *model.ShareEvent) (int64, error)
	AssetExists(ctx context.Context, assetID int64) (bool, error)
	UserExists(ctx context.Context, userID int64) (bool, error)
}

// ShareService 分享业务逻辑(spec § 3 + § 3.5)
//
// 负责:
//   - GetAssetQrcode: 生成/缓存 资产分享二维码 PNG,返回 CDN URL
//   - TrackShare:     落库一次分享动作(用于归因/防刷分析)
type ShareService struct {
	repo        ShareRepository
	redis       *redis.Client
	uploader    QRUploader
	landingBase string
}

// NewShareService 创建 ShareService 实例
//
// repo 入参类型保持 *repository.ShareRepo 以兼容调用方;
// 内部以 ShareRepository 接口存储,便于单测注入 mock 实现。
func NewShareService(repo *repository.ShareRepo, redisClient *redis.Client, uploader QRUploader, landingBase string) *ShareService {
	return &ShareService{
		repo:        repo,
		redis:       redisClient,
		uploader:    uploader,
		landingBase: landingBase,
	}
}

// newShareServiceWithDeps 测试/扩展入口,直接注入 ShareRepository 抽象
func newShareServiceWithDeps(repo ShareRepository, redisClient *redis.Client, uploader QRUploader, landingBase string) *ShareService {
	return &ShareService{
		repo:        repo,
		redis:       redisClient,
		uploader:    uploader,
		landingBase: landingBase,
	}
}

// GetAssetQrcode 生成或获取缓存的二维码 CDN URL(spec § 3)
//
// 流程:
//  1. 校验入参(sharer_user_id / system_type / share_target)
//  2. 校验 asset 存在、user 存在
//  3. 组装落地页 URL(landingBase + asset_id + from=sharer + s=system_type)
//  4. 命中 Redis 缓存直接返回
//  5. 生成 PNG -> 上传 OSS -> 写回 Redis(TTL 7d)
func (s *ShareService) GetAssetQrcode(ctx context.Context, req *pb.GetAssetQrcodeRequest) (*pb.GetAssetQrcodeResponse, error) {
	if req == nil {
		return nil, fmt.Errorf("request is nil")
	}
	if req.SharerUserId == 0 {
		logger.Logger.Warn("GetAssetQrcode missing sharer_user_id",
			zap.Int64("asset_id", req.AssetId),
		)
		return nil, fmt.Errorf("%w: sharer_user_id is required", appErrors.ErrInvalidUserID)
	}
	if req.SystemType == "" {
		return nil, appErrors.ErrInvalidSystemType
	}
	if _, ok := validSystemTypes[req.SystemType]; !ok {
		return nil, fmt.Errorf("%w: unsupported system_type=%q", appErrors.ErrInvalidSystemType, req.SystemType)
	}
	if req.ShareTarget != "" {
		if _, ok := validShareTargets[req.ShareTarget]; !ok {
			return nil, fmt.Errorf("%w: unsupported share_target=%q", appErrors.ErrInvalidShareTarget, req.ShareTarget)
		}
	}
	if req.AssetId <= 0 {
		return nil, fmt.Errorf("%w: invalid asset_id=%d", appErrors.ErrAssetNotFound, req.AssetId)
	}

	exists, err := s.repo.AssetExists(ctx, req.AssetId)
	if err != nil {
		logger.Logger.Error("GetAssetQrcode check asset failed",
			zap.Int64("asset_id", req.AssetId),
			zap.Error(err),
		)
		return nil, fmt.Errorf("check asset: %w", err)
	}
	if !exists {
		return nil, appErrors.ErrAssetNotFound
	}

	userOK, err := s.repo.UserExists(ctx, req.SharerUserId)
	if err != nil {
		logger.Logger.Error("GetAssetQrcode check user failed",
			zap.Int64("sharer_user_id", req.SharerUserId),
			zap.Error(err),
		)
		return nil, fmt.Errorf("check user: %w", err)
	}
	if !userOK {
		return nil, appErrors.ErrUserNotFound
	}

	landingURL := fmt.Sprintf("%s/asset/%d?from=%d&s=%s",
		s.landingBase, req.AssetId, req.SharerUserId, req.SystemType)

	cacheKey := fmt.Sprintf(qrcodeCacheKey, req.AssetId, req.SharerUserId, req.SystemType)
	if s.redis != nil {
		if cached, cerr := s.redis.Get(ctx, cacheKey).Result(); cerr == nil && cached != "" {
			logger.Logger.Debug("GetAssetQrcode cache hit",
				zap.String("cache_key", cacheKey),
				zap.String("qrcode_url", cached),
			)
			return &pb.GetAssetQrcodeResponse{
				Base:      successResp(),
				QrcodeUrl: cached,
				ExpiresAt: time.Now().Add(qrcodeCacheTTL).Unix(),
			}, nil
		}
	}

	pngBytes, err := qrcode.Generate(landingURL, 512)
	if err != nil {
		logger.Logger.Error("GetAssetQrcode generate qrcode failed",
			zap.String("landing_url", landingURL),
			zap.Error(err),
		)
		return nil, fmt.Errorf("generate qrcode: %w", err)
	}

	ossKey := fmt.Sprintf("share/qrcode/%d_%d_%s.png", req.AssetId, req.SharerUserId, req.SystemType)
	cdnURL, err := s.uploader.UploadBytes(ctx, ossKey, pngBytes, "image/png")
	if err != nil {
		logger.Logger.Error("GetAssetQrcode upload qrcode failed",
			zap.String("oss_key", ossKey),
			zap.Error(err),
		)
		return nil, fmt.Errorf("upload qrcode: %w", err)
	}

	if s.redis != nil {
		if setErr := s.redis.Set(ctx, cacheKey, cdnURL, qrcodeCacheTTL).Err(); setErr != nil {
			// 缓存写失败不阻塞主流程,记 warn
			logger.Logger.Warn("GetAssetQrcode cache set failed",
				zap.String("cache_key", cacheKey),
				zap.Error(setErr),
			)
		}
	}

	logger.Logger.Info("GetAssetQrcode successful",
		zap.Int64("asset_id", req.AssetId),
		zap.Int64("sharer_user_id", req.SharerUserId),
		zap.String("system_type", req.SystemType),
		zap.String("qrcode_url", cdnURL),
	)

	return &pb.GetAssetQrcodeResponse{
		Base:      successResp(),
		QrcodeUrl: cdnURL,
		ExpiresAt: time.Now().Add(qrcodeCacheTTL).Unix(),
	}, nil
}

// TrackShare 记录一次分享动作(spec § 3.5)
func (s *ShareService) TrackShare(ctx context.Context, req *pb.TrackShareRequest) (*pb.TrackShareResponse, error) {
	if req == nil {
		return nil, fmt.Errorf("request is nil")
	}
	if req.SharerUserId == 0 {
		return nil, fmt.Errorf("%w: sharer_user_id is required", appErrors.ErrInvalidUserID)
	}
	if _, ok := validSystemTypes[req.SystemType]; !ok {
		return nil, appErrors.ErrInvalidSystemType
	}
	if _, ok := validShareTargets[req.ShareTarget]; !ok {
		return nil, appErrors.ErrInvalidShareTarget
	}
	if _, ok := validResults[req.Result]; !ok {
		return nil, appErrors.ErrInvalidShareResult
	}
	if req.AssetId <= 0 {
		return nil, fmt.Errorf("%w: invalid asset_id=%d", appErrors.ErrAssetNotFound, req.AssetId)
	}

	userOK, err := s.repo.UserExists(ctx, req.SharerUserId)
	if err != nil {
		return nil, fmt.Errorf("check user: %w", err)
	}
	if !userOK {
		return nil, appErrors.ErrUserNotFound
	}

	e := &model.ShareEvent{
		AssetID:      req.AssetId,
		SharerUserID: req.SharerUserId,
		SystemType:   req.SystemType,
		ShareTarget:  req.ShareTarget,
		Result:       req.Result,
		ClientTs:     req.ClientTs,
		ServerTs:     time.Now().UnixMilli(),
	}
	if req.Extra != nil {
		if raw, mErr := json.Marshal(req.Extra.AsMap()); mErr == nil {
			e.Extra = models.JSONB(raw)
		} else {
			logger.Logger.Warn("TrackShare marshal extra failed, store empty",
				zap.Error(mErr),
			)
			e.Extra = models.JSONB("{}")
		}
	}

	id, err := s.repo.Create(ctx, e)
	if err != nil {
		logger.Logger.Error("TrackShare create event failed",
			zap.Int64("asset_id", req.AssetId),
			zap.Int64("sharer_user_id", req.SharerUserId),
			zap.String("result", req.Result),
			zap.Error(err),
		)
		return nil, fmt.Errorf("create share event: %w", err)
	}

	logger.Logger.Info("TrackShare successful",
		zap.Int64("share_event_id", id),
		zap.Int64("asset_id", req.AssetId),
		zap.Int64("sharer_user_id", req.SharerUserId),
		zap.String("system_type", req.SystemType),
		zap.String("share_target", req.ShareTarget),
		zap.String("result", req.Result),
	)

	return &pb.TrackShareResponse{
		Base:         successResp(),
		ShareEventId: id,
	}, nil
}

// successResp 返回成功的 BaseResponse 助手
func successResp() *pbCommon.BaseResponse {
	return &pbCommon.BaseResponse{
		Code:      uint32(codes.OK),
		Message:   "ok",
		Timestamp: time.Now().UnixMilli(),
	}
}