package service

import (
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"time"

	"github.com/freefire/jiang13-bbs/model"
)

// 媒体库（管理后台）：盘点站点内全部图片资源。
// 数据源 = uploads 五个分类目录的磁盘扫描 + attachments 表元数据合并：
//   - 旧站导入图 / 背景图 / 广告素材 / 品牌 Logo 落盘但无附件记录，只有磁盘扫描能覆盖
//   - 附件记录（头像、帖子插图）补充上传者、创建时间等元数据；远程存储对象（/api/media/）仅存在于库中
// 同名（去扩展名）同时存在原图与 WebP 时只展示 WebP，原图 URL 挂在 OriginalURL 供查看。

// 媒体库分类：目录名即分类键，前端 tab 直接使用
var mediaLibraryCategories = []struct {
	Key  string // 分类键（image/avatar/background/ads/brand）
	Dir  string // uploads 下的子目录
	Name string // 展示名
}{
	{"image", "images", "帖子插图"},
	{"avatar", "avatars", "用户头像"},
	{"background", "backgrounds", "站点背景"},
	{"ads", "ads", "广告素材"},
	{"brand", "brand", "品牌资源"},
}

// 衍生分类：不对应 uploads 子目录，按附件 source 归类
const (
	mediaCategoryBook     = "book"
	mediaCategoryBookName = "书籍"
)

// mediaCategoryForAttachment 附件在媒体库中的展示分类：
// 书库封面 / 正文插图（source=library_cover|library_content）统一归“书籍”，
// 其余按 kind 对应磁盘目录分类。
func mediaCategoryForAttachment(kind, source string) (key, name string) {
	if source == model.AttachmentSourceLibraryCover || source == model.AttachmentSourceLibraryContent {
		return mediaCategoryBook, mediaCategoryBookName
	}
	for _, cat := range mediaLibraryCategories {
		if cat.Key == kind {
			return cat.Key, cat.Name
		}
	}
	return kind, kind
}

// MediaLibraryItem 媒体库条目
type MediaLibraryItem struct {
	URL          string     `json:"url"`                    // 展示地址（有 WebP 时为 WebP）
	OriginalURL  string     `json:"original_url,omitempty"` // 同名原图（仅当原图与 WebP 并存）
	Category     string     `json:"category"`               // image/avatar/background/ads/brand
	CategoryName string     `json:"category_name"`
	Name         string     `json:"name"` // 文件名（含扩展名）
	MIME         string     `json:"mime"`
	Size         int64      `json:"size"`
	Width        int        `json:"width"`
	Height       int        `json:"height"`
	Uploader     string     `json:"uploader,omitempty"` // 上传者昵称（取自附件记录，无记录为空）
	UploadedAt   *time.Time `json:"uploaded_at,omitempty"`
	SourceURL    string     `json:"source_url,omitempty"`   // 来源回链（帖子/评论锚点/用户主页）
	SourceLabel  string     `json:"source_label,omitempty"` // 来源描述（如：帖子《…》下的评论）
}

// AdminMediaLibrary 全站图片盘点：磁盘扫描 + 附件元数据合并，按时间倒序。
// 返回条目列表与各分类计数（含全部计数由前端按列表累加）。
func (s *UploadService) AdminMediaLibrary() ([]MediaLibraryItem, map[string]int, error) {
	// 附件元数据索引：URL → 记录（联出上传者昵称）
	type attMeta struct {
		Kind      string
		Source    string
		URL       string
		MIME      string
		Size      int
		Width     int
		Height    int
		Nickname  string
		Username  string
		CreatedAt time.Time
	}
	var rows []attMeta
	if err := s.db.Table("attachments").
		Select("attachments.kind, attachments.source, attachments.url, attachments.mime, attachments.size, attachments.width, attachments.height, attachments.created_at, users.nickname, users.username").
		Joins("LEFT JOIN users ON users.id = attachments.user_id").
		Scan(&rows).Error; err != nil {
		return nil, nil, err
	}
	metaByURL := make(map[string]attMeta, len(rows))
	// 远程存储对象（/api/media/）不在磁盘上，直接作为条目加入
	items := make([]MediaLibraryItem, 0, len(rows))
	for _, r := range rows {
		metaByURL[r.URL] = r // 本地文件在磁盘扫描时按 URL 合并元数据
		if !strings.HasPrefix(r.URL, "/api/media/") {
			continue
		}
		if r.Kind != model.AttachmentKindImage && r.Kind != model.AttachmentKindAvatar {
			continue // 未知 kind 不进媒体库
		}
		uploader := r.Nickname
		if uploader == "" {
			uploader = r.Username
		}
		catKey, catName := mediaCategoryForAttachment(r.Kind, r.Source)
		ca := r.CreatedAt
		items = append(items, MediaLibraryItem{
			URL: r.URL, Category: catKey, CategoryName: catName,
			Name: strings.TrimPrefix(r.URL, "/api/media/"), MIME: r.MIME,
			Size: int64(r.Size), Width: r.Width, Height: r.Height,
			Uploader: uploader, UploadedAt: &ca,
		})
	}

	// 磁盘扫描五类目录；同名（去扩展名）成组，WebP 优先展示、原图挂 OriginalURL
	type group struct {
		webp     *MediaLibraryItem
		original *MediaLibraryItem
	}
	for _, cat := range mediaLibraryCategories {
		dir := filepath.Join(s.dir, cat.Dir)
		entries, err := os.ReadDir(dir)
		if err != nil {
			continue // 目录不存在视为空
		}
		groups := map[string]*group{}
		for _, e := range entries {
			if e.IsDir() || strings.HasSuffix(e.Name(), ".partial") {
				continue
			}
			ext := strings.ToLower(filepath.Ext(e.Name()))
			switch ext {
			case ".jpg", ".jpeg", ".png", ".webp", ".gif":
			default:
				continue
			}
			url := "/uploads/" + cat.Dir + "/" + e.Name()
			item := MediaLibraryItem{
				URL: url, Category: cat.Key, CategoryName: cat.Name,
				Name: e.Name(),
				MIME: map[string]string{
					".jpg": "image/jpeg", ".jpeg": "image/jpeg", ".png": "image/png",
					".webp": "image/webp", ".gif": "image/gif",
				}[ext],
			}
			if info, err := e.Info(); err == nil {
				item.Size = info.Size()
				mt := info.ModTime()
				item.UploadedAt = &mt
			}
			if m, ok := metaByURL[url]; ok {
				// 附件记录有上传者与准确创建时间，覆盖磁盘信息
				uploader := m.Nickname
				if uploader == "" {
					uploader = m.Username
				}
				ca := m.CreatedAt
				item.Uploader = uploader
				item.UploadedAt = &ca
				if m.Size > 0 {
					item.Size = int64(m.Size)
				}
				if m.Width > 0 {
					item.Width, item.Height = m.Width, m.Height
				}
				// 书库封面 / 正文插图改归“书籍”分类
				if m.Source == model.AttachmentSourceLibraryCover || m.Source == model.AttachmentSourceLibraryContent {
					item.Category = mediaCategoryBook
					item.CategoryName = mediaCategoryBookName
				}
			}
			// 无尺寸记录时读图片头解析宽高（失败不阻断，保持 0）
			if item.Width == 0 && item.Size > 0 && item.Size <= 20<<20 {
				if f, err := os.Open(filepath.Join(dir, e.Name())); err == nil {
					w, h, derr := decodeImageSizeReader(f, item.MIME)
					_ = f.Close()
					if derr == nil {
						item.Width, item.Height = w, h
					}
				}
			}
			stem := strings.TrimSuffix(e.Name(), filepath.Ext(e.Name()))
			g := groups[stem]
			if g == nil {
				g = &group{}
				groups[stem] = g
			}
			if ext == ".webp" {
				g.webp = &item
			} else if g.original == nil {
				g.original = &item
			}
		}
		for _, g := range groups {
			switch {
			case g.webp != nil && g.original != nil:
				// 原图与 WebP 并存：只展示 WebP，原图作 original_url
				g.webp.OriginalURL = g.original.URL
				if g.webp.Size == 0 {
					g.webp.Size = g.original.Size
				}
				items = append(items, *g.webp)
			case g.webp != nil:
				items = append(items, *g.webp)
			default:
				items = append(items, *g.original)
			}
		}
	}

	sort.Slice(items, func(i, j int) bool {
		ti, tj := items[i].UploadedAt, items[j].UploadedAt
		switch {
		case ti == nil && tj == nil:
			return items[i].URL < items[j].URL
		case ti == nil:
			return false
		case tj == nil:
			return true
		}
		return ti.After(*tj)
	})

	counts := map[string]int{}
	for _, it := range items {
		counts[it.Category]++
	}
	s.attachMediaSources(items)
	return items, counts, nil
}

// attachMediaSources 为条目补来源回链：
//   - 头像：users.avatar 精确匹配 → 用户主页
//   - 其余：分块 LIKE 扫描帖子/评论正文（展示 URL 与同名原图都参与匹配），帖子优先于评论
//
// 内容 LIKE 无索引，纯顺序扫描，但仅管理端低频调用；分块 OR 控制往返次数。
func (s *UploadService) attachMediaSources(items []MediaLibraryItem) {
	urlSet := map[string]bool{}
	for _, it := range items {
		for _, u := range []string{it.URL, it.OriginalURL} {
			if strings.HasPrefix(u, "/uploads/") {
				urlSet[u] = true
			}
		}
	}
	if len(urlSet) == 0 {
		return
	}
	urls := make([]string, 0, len(urlSet))
	for u := range urlSet {
		urls = append(urls, u)
	}

	type postRef struct {
		id    uint
		title string
	}
	postByURL := map[string]postRef{}
	type commentRef struct {
		id, postID uint
		floor      uint
		isRoot     bool
	}
	commentByURL := map[string]commentRef{}

	for i := 0; i < len(urls); i += 40 {
		end := i + 40
		if end > len(urls) {
			end = len(urls)
		}
		chunk := urls[i:end]
		conds := make([]string, len(chunk))
		args := make([]any, len(chunk))
		for j, u := range chunk {
			conds[j] = "content LIKE ?"
			args[j] = "%" + u + "%"
		}
		where := strings.Join(conds, " OR ")

		var prows []struct {
			ID      uint
			Title   string
			Content string
		}
		if err := s.db.Model(&model.Post{}).Select("id, title, content").
			Where(where, args...).Order("id ASC").Limit(600).Scan(&prows).Error; err != nil {
			return
		}
		for _, p := range prows {
			for _, u := range chunk {
				if strings.Contains(p.Content, u) {
					if _, ok := postByURL[u]; !ok {
						postByURL[u] = postRef{id: p.ID, title: p.Title}
					}
				}
			}
		}

		var crows []struct {
			ID      uint
			PostID  uint
			Content string
		}
		if err := s.db.Model(&model.Comment{}).Select("id, post_id, content").
			Where(where, args...).Order("id ASC").Limit(600).Scan(&crows).Error; err != nil {
			return
		}
		for _, cm := range crows {
			for _, u := range chunk {
				if strings.Contains(cm.Content, u) {
					if _, ok := commentByURL[u]; !ok {
						commentByURL[u] = commentRef{id: cm.ID, postID: cm.PostID}
					}
				}
			}
		}
	}

	// 评论锚点改用所属帖内相对楼层号（#comment-{floor}，楼中楼追加 -r{id}）
	commentIDs := make([]uint, 0, len(commentByURL))
	for _, cm := range commentByURL {
		commentIDs = append(commentIDs, cm.id)
	}
	commentAnchors := CommentAnchors(s.db, commentIDs)
	for u, cm := range commentByURL {
		if a, ok := commentAnchors[cm.id]; ok {
			cm.floor, cm.isRoot = a.Floor, a.IsRoot
			commentByURL[u] = cm
		}
	}

	// 评论来源要带宿主帖子标题，一次性补齐
	postTitle := func(id uint) string {
		var p model.Post
		if err := s.db.Select("id, title").First(&p, id).Error; err != nil {
			return ""
		}
		return p.Title
	}
	commentPostTitle := map[uint]string{}
	for _, cm := range commentByURL {
		if _, ok := commentPostTitle[cm.postID]; !ok {
			commentPostTitle[cm.postID] = postTitle(cm.postID)
		}
	}

	// 头像使用者：users.avatar 精确匹配（同一头像多人使用时取最早的用户）
	userByAvatar := map[string]struct {
		ID                 uint
		Nickname, Username string
	}{}
	var urows []struct {
		ID       uint
		Nickname string
		Username string
		Avatar   string
	}
	if err := s.db.Model(&model.User{}).Select("id, nickname, username, avatar").
		Where("avatar IN ?", urls).Order("id ASC").Find(&urows).Error; err == nil {
		for _, u := range urows {
			if _, ok := userByAvatar[u.Avatar]; !ok {
				userByAvatar[u.Avatar] = struct {
					ID                 uint
					Nickname, Username string
				}{ID: u.ID, Nickname: u.Nickname, Username: u.Username}
			}
		}
	}

	truncate := func(s string, n int) string {
		r := []rune(s)
		if len(r) <= n {
			return s
		}
		return string(r[:n]) + "…"
	}
	postLabel := func(p postRef) string {
		title := p.title
		if title == "" {
			title = fmt.Sprintf("#%d", p.id)
		}
		return "帖子《" + truncate(title, 40) + "》"
	}

	for i := range items {
		it := &items[i]
		// 头像使用者优先（头像正文引用场景极少）
		if u, ok := userByAvatar[it.URL]; ok {
			name := u.Nickname
			if name == "" {
				name = u.Username
			}
			it.SourceURL = fmt.Sprintf("/u/%d", u.ID)
			it.SourceLabel = "@" + name + " 的头像"
			continue
		}
		for _, u := range []string{it.URL, it.OriginalURL} {
			if u == "" || it.SourceURL != "" {
				continue
			}
			if p, ok := postByURL[u]; ok {
				it.SourceURL = fmt.Sprintf("/post/%d", p.id)
				it.SourceLabel = postLabel(p)
				break
			}
			if cm, ok := commentByURL[u]; ok {
				if cm.floor > 0 {
					if cm.isRoot {
						it.SourceURL = fmt.Sprintf("/post/%d#comment-%d", cm.postID, cm.floor)
					} else {
						it.SourceURL = fmt.Sprintf("/post/%d#comment-%d-r%d", cm.postID, cm.floor, cm.id)
					}
				} else {
					it.SourceURL = fmt.Sprintf("/post/%d", cm.postID)
				}
				title := commentPostTitle[cm.postID]
				if title != "" {
					it.SourceLabel = "帖子《" + truncate(title, 40) + "》下的评论"
				} else {
					it.SourceLabel = "帖子评论"
				}
				break
			}
		}
	}
}