package usecase

import (
	"context"
	"fmt"
	"strings"
	"time"

	app "haixun-backend/internal/library/errors"
	"haixun-backend/internal/library/errors/code"
	libthreads "haixun-backend/internal/library/threadsapi"
	domusecase "haixun-backend/internal/model/threads_account/domain/usecase"
)

func (u *threadsAccountUseCase) ListPostPerformance(
	ctx context.Context,
	tenantID, ownerUID, accountID string,
	limit int,
) (*domusecase.PostPerformanceResult, error) {
	account, err := u.assertOwned(ctx, tenantID, ownerUID, accountID)
	if err != nil {
		return nil, err
	}
	token, err := u.ResolveAccountAPIAccessToken(ctx, tenantID, ownerUID, accountID)
	if err != nil {
		return nil, err
	}
	client := libthreads.NewClient(token)
	if !client.Enabled() {
		return nil, app.For(code.ThreadsAccount).InputMissingRequired("Threads API 未連線")
	}

	if limit <= 0 {
		limit = 15
	}
	if limit > 30 {
		limit = 30
	}

	userID := strings.TrimSpace(account.ThreadsUserID)
	username := strings.TrimSpace(account.Username)
	if profile, perr := libthreads.GetMeProfile(ctx, token); perr == nil && profile != nil {
		if userID == "" {
			userID = profile.ID.String()
		}
		if username == "" {
			username = profile.Username
		}
	}

	result := &domusecase.PostPerformanceResult{
		AccountID:     account.ID,
		Username:      username,
		ThreadsUserID: userID,
		FetchedAt:     time.Now().UnixNano(),
		Capabilities:  postPerformanceCapabilities(),
		AccountInsights: domusecase.AccountInsightsBlock{
			Status:  "skip",
			Message: "缺少 threads_user_id",
		},
		Posts: []domusecase.PostPerformanceItem{},
	}

	if userID != "" {
		result.AccountInsights = fetchAccountInsights(ctx, client, userID)
		posts, err := client.UserThreads(ctx, userID, limit)
		if err != nil {
			return nil, err
		}
		for _, post := range posts {
			item := domusecase.PostPerformanceItem{
				MediaID:    post.ID,
				Text:       post.Text,
				Permalink:  post.Permalink,
				Timestamp:  post.Timestamp,
				LikeCount:  post.LikeCount,
				ReplyCount: post.ReplyCount,
			}
			if stats, serr := client.GetMediaStats(ctx, post.ID); serr == nil && stats != nil {
				item.LikeCount = stats.LikeCount
				item.ReplyCount = stats.ReplyCount
				item.RepostCount = stats.RepostCount
				item.QuoteCount = stats.QuoteCount
				item.Views = stats.Views
				item.Shares = stats.Shares
				item.InsightsStatus = "ok"
			} else {
				item.InsightsStatus = "error"
				if serr != nil {
					item.InsightsMessage = serr.Error()
				} else {
					item.InsightsMessage = "無法讀取貼文洞察"
				}
			}
			result.Posts = append(result.Posts, item)
		}
	}

	return result, nil
}

func postPerformanceCapabilities() []domusecase.PostMetricCapability {
	return []domusecase.PostMetricCapability{
		{
			Scope: "threads_manage_insights", Name: "貼文互動數",
			Metrics:   []string{"likes", "replies", "reposts", "quotes", "views", "shares"},
			Trackable: true, Note: "GET /{media-id}/insights（非 media 物件欄位）",
		},
		{
			Scope: "threads_manage_insights", Name: "貼文洞察",
			Metrics:   []string{"views", "likes", "replies", "reposts", "quotes", "shares"},
			Trackable: true, Note: "GET /{media-id}/insights（lifetime）",
		},
		{
			Scope: "threads_manage_insights", Name: "帳號洞察",
			Metrics:   []string{"views", "likes", "replies", "reposts", "quotes", "followers_count", "clicks"},
			Trackable: true, Note: "GET /{user-id}/threads_insights",
		},
		{
			Scope: "threads_read_replies", Name: "留言內容",
			Metrics:   []string{"reply_list"},
			Trackable: true, Note: "GET /{media-id}/replies（非數字統計）",
		},
		{
			Scope: "threads_keyword_search", Name: "關鍵字搜尋",
			Trackable: false, Note: "搜尋他人貼文，非你的發文成效",
		},
		{
			Scope: "threads_profile_discovery", Name: "帳號查詢",
			Trackable: false, Note: "查他人 profile，非成效統計",
		},
		{
			Scope: "threads_manage_mentions", Name: "提及",
			Trackable: false, Note: "誰 @ 你，非單篇貼文成效",
		},
		{
			Scope: "threads_location_tagging", Name: "地點",
			Trackable: false, Note: "地點標籤搜尋",
		},
		{
			Scope: "threads_content_publish", Name: "發文",
			Trackable: false, Note: "寫入類；發文後用本頁追蹤成效",
		},
		{
			Scope: "threads_delete", Name: "刪文",
			Trackable: false, Note: "寫入類",
		},
		{
			Scope: "threads_manage_replies", Name: "留言管理",
			Trackable: false, Note: "隱藏留言，非統計",
		},
		{
			Scope: "threads_share_to_instagram", Name: "同步 IG",
			Trackable: false, Note: "crosspost 動作",
		},
	}
}

func fetchAccountInsights(ctx context.Context, client *libthreads.Client, userID string) domusecase.AccountInsightsBlock {
	items, err := client.UserInsights(ctx, userID, nil)
	if err != nil {
		msg := err.Error()
		if libthreads.IsPermissionError(err) {
			msg += "（需 threads_manage_insights）"
		}
		return domusecase.AccountInsightsBlock{Status: "error", Message: msg}
	}
	metrics := make([]domusecase.InsightMetricItem, 0, len(items))
	for _, item := range items {
		name := strings.TrimSpace(item.Name)
		if name == "" || len(item.Values) == 0 {
			continue
		}
		metrics = append(metrics, domusecase.InsightMetricItem{Name: name, Value: item.Values[0].Value})
	}
	if len(metrics) == 0 {
		return domusecase.AccountInsightsBlock{Status: "ok", Message: "尚無帳號洞察資料"}
	}
	return domusecase.AccountInsightsBlock{
		Status:  "ok",
		Message: fmt.Sprintf("%d 項指標", len(metrics)),
		Metrics: metrics,
	}
}