package httpapi

import (
	"errors"
	"net/http"
	"strconv"

	"pure-note/internal/store"
)

// handleHealth GET /api/health。
func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
	if err := s.st.DB().Ping(); err != nil {
		writeError(w, http.StatusInternalServerError, "db_unavailable", "数据库不可用")
		return
	}
	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
}

// handleMe GET /api/me：匿名 {authenticated:false}；已认证 {authenticated:true, csrf_token}。
func (s *Server) handleMe(w http.ResponseWriter, r *http.Request) {
	if sess, ok := s.sessionFrom(r); ok {
		s.maybeRotate(w, sess)
		writeJSON(w, http.StatusOK, map[string]any{"authenticated": true, "csrf_token": sess.CSRFToken})
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"authenticated": false})
}

// handleSiteInfo GET /api/site：站点设置白名单视图（标题/副标题/每页条数）。
// 永不包含 admin_password_hash（§9.3）。
func (s *Server) handleSiteInfo(w http.ResponseWriter, r *http.Request) {
	ss, err := s.st.GetSiteSettings()
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	writeJSON(w, http.StatusOK, ss)
}

// publicNoteItem 公开列表项（元信息，不含全文）。
type publicNoteItem struct {
	Slug      string   `json:"slug"`
	Title     string   `json:"title"`
	Summary   string   `json:"summary"`
	Tags      []string `json:"tags"`
	Pinned    bool     `json:"pinned"`
	CreatedAt int64    `json:"created_at"`
	UpdatedAt int64    `json:"updated_at"`
}

// handlePublicNotes GET /api/notes：公开笔记列表（可见性过滤在查询层，§9.1-T10）。
func (s *Server) handlePublicNotes(w http.ResponseWriter, r *http.Request) {
	page, pageSize, ok := s.parsePagination(r)
	if !ok {
		writeError(w, http.StatusBadRequest, "bad_request", "分页参数越界（page ∈ [1,10000]，page_size ∈ [1,100]）")
		return
	}
	tag := r.URL.Query().Get("tag")
	notes, total, err := s.st.ListPublicNotes(page, pageSize, tag)
	if err != nil {
		s.log.Error("查询公开列表失败", "err", err)
		writeError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	items := make([]publicNoteItem, 0, len(notes))
	for _, n := range notes {
		items = append(items, publicNoteItem{
			Slug: n.Slug, Title: n.Title, Summary: n.Summary,
			Tags: n.Tags, Pinned: n.Pinned,
			CreatedAt: n.CreatedAt, UpdatedAt: n.UpdatedAt,
		})
	}
	writeJSON(w, http.StatusOK, map[string]any{
		"items": items, "page": page, "page_size": pageSize, "total": total,
	})
}

// handlePublicNote GET /api/notes/{slug}：public 或管理员会话可读；其余统一 404。
func (s *Server) handlePublicNote(w http.ResponseWriter, r *http.Request) {
	slug := r.PathValue("slug")
	note, err := s.st.GetNoteBySlug(slug)
	if err != nil {
		if errors.Is(err, store.ErrNotFound) {
			writeError(w, http.StatusNotFound, "not_found", "笔记不存在")
			return
		}
		writeError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	if note.DeletedAt != nil {
		// 回收站内容仅经 /api/admin/trash 出口可见（§13）
		writeError(w, http.StatusNotFound, "not_found", "笔记不存在")
		return
	}
	if note.Status != "public" {
		if _, isAdmin := s.sessionFrom(r); !isAdmin {
			// 私有笔记对匿名统一 404（不泄露存在性）；管理员可私有预览
			writeError(w, http.StatusNotFound, "not_found", "笔记不存在")
			return
		}
	}
	prevSlug, prevTitle, _ := s.st.AdjacentPublicNote(note, "prev")
	nextSlug, nextTitle, _ := s.st.AdjacentPublicNote(note, "next")
	writeJSON(w, http.StatusOK, map[string]any{
		"id": note.ID, "slug": note.Slug, "title": note.Title,
		"summary": note.Summary, "content": note.Content,
		"status": note.Status, "tags": note.Tags, "pinned": note.Pinned,
		"created_at": note.CreatedAt, "updated_at": note.UpdatedAt,
		"prev": siblingOrEmpty(prevSlug, prevTitle),
		"next": siblingOrEmpty(nextSlug, nextTitle),
	})
}

func siblingOrEmpty(slug, title string) map[string]any {
	if slug == "" {
		return nil
	}
	return map[string]any{"slug": slug, "title": title}
}

// handleTags GET /api/tags：标签聚合（仅公开且未删除）。
func (s *Server) handleTags(w http.ResponseWriter, r *http.Request) {
	tags, err := s.st.PublicTags()
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	if tags == nil {
		tags = []store.TagCount{}
	}
	writeJSON(w, http.StatusOK, map[string]any{"tags": tags})
}

// handleImage GET /api/images/{id}：并集可见性；未授权与不存在统一 404；
// 缓存头按可见性分流（§7.4）。
func (s *Server) handleImage(w http.ResponseWriter, r *http.Request) {
	idStr := r.PathValue("id")
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil || id <= 0 {
		writeError(w, http.StatusNotFound, "not_found", "图片不存在")
		return
	}
	img, err := s.st.GetImageMeta(id)
	if err != nil {
		writeError(w, http.StatusNotFound, "not_found", "图片不存在")
		return
	}
	public, err := s.st.ImageIsPublic(id)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	if !public {
		if _, isAdmin := s.sessionFrom(r); !isAdmin {
			writeError(w, http.StatusNotFound, "not_found", "图片不存在")
			return
		}
		// 非公开图：每次请求重新判定，禁止缓存
		w.Header().Set("Cache-Control", "private, no-store")
	} else {
		w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
	}
	w.Header().Set("Content-Type", img.MIME)
	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.Header().Set("ETag", `"`+img.SHA256+`"`)
	if r.Header.Get("If-None-Match") == `"`+img.SHA256+`"` {
		w.WriteHeader(http.StatusNotModified)
		return
	}
	data, err := s.st.GetImageData(id)
	if err != nil {
		writeError(w, http.StatusNotFound, "not_found", "图片不存在")
		return
	}
	w.Header().Set("Content-Length", strconv.Itoa(len(data)))
	_, _ = w.Write(data)
}