package httpapi

import (
	"encoding/xml"
	"net/http"
	"time"

	"pure-note/internal/markdown"
)

// ---- RSS 2.0（§7.1：仅公开；服务端 goldmark+bluemonday 渲染）----

type rssFeed struct {
	XMLName xml.Name   `xml:"rss"`
	Version string     `xml:"version,attr"`
	Channel rssChannel `xml:"channel"`
}

type rssChannel struct {
	Title       string    `xml:"title"`
	Link        string    `xml:"link"`
	Description string    `xml:"description"`
	Language    string    `xml:"language,omitempty"`
	LastBuild   string    `xml:"lastBuildDate,omitempty"`
	Items       []rssItem `xml:"item"`
}

type rssItem struct {
	Title       string `xml:"title"`
	Link        string `xml:"link"`
	GUID        string `xml:"guid"`
	PubDate     string `xml:"pubDate"`   // RFC 822（RSS 2.0 规范）
	Description string `xml:"description"` // 已清洗的 HTML（经 encoding/xml 自动转义）
}

// feedItemLimit RSS 条目上限（个人规模足够，避免全量渲染）。
const feedItemLimit = 50

func (s *Server) handleRSS(w http.ResponseWriter, r *http.Request) {
	ss, err := s.st.GetSiteSettings()
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	base := baseURL(r)
	notes, err := s.st.ListPublicNotesFull(feedItemLimit)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	items := make([]rssItem, 0, len(notes))
	var lastBuild time.Time
	for _, n := range notes {
		// 服务端渲染：goldmark（默认转义）→ bluemonday 白名单（§7.5）
		html := markdown.Render(n.Content)
		pub := time.Unix(n.UpdatedAt, 0)
		if pub.After(lastBuild) {
			lastBuild = pub
		}
		items = append(items, rssItem{
			Title:       n.Title,
			Link:        base + "/notes/" + n.Slug,
			GUID:        base + "/notes/" + n.Slug,
			PubDate:     pub.Format(time.RFC1123Z),
			Description: html,
		})
	}
	feed := rssFeed{
		Version: "2.0",
		Channel: rssChannel{
			Title:       ss.SiteTitle,
			Link:        base + "/",
			Description: ss.SiteDesc,
			Language:    "zh-CN",
			LastBuild:   lastBuild.Format(time.RFC1123Z),
			Items:       items,
		},
	}
	w.Header().Set("Content-Type", "application/rss+xml; charset=utf-8")
	w.Header().Set("Cache-Control", "public, max-age=300")
	w.Write([]byte(xml.Header))
	enc := xml.NewEncoder(w)
	enc.Indent("", "  ")
	_ = enc.Encode(feed)
}

// ---- sitemap（仅公开笔记）----

type urlSet struct {
	XMLName xml.Name `xml:"urlset"`
	XMLNS   string   `xml:"xmlns,attr"`
	URLs    []siteURL `xml:"url"`
}

type siteURL struct {
	Loc     string    `xml:"loc"`
	LastMod time.Time `xml:"lastmod,omitempty"`
}

func (s *Server) handleSitemap(w http.ResponseWriter, r *http.Request) {
	base := baseURL(r)
	set := urlSet{XMLNS: "http://www.sitemaps.org/schemas/sitemap/0.9"}
	set.URLs = append(set.URLs, siteURL{Loc: base + "/"})
	notes, _, err := s.st.ListPublicNotes(1, 10000, "")
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	for _, n := range notes {
		set.URLs = append(set.URLs, siteURL{
			Loc:     base + "/notes/" + n.Slug,
			LastMod: time.Unix(n.UpdatedAt, 0),
		})
	}
	w.Header().Set("Content-Type", "application/xml; charset=utf-8")
	w.Header().Set("Cache-Control", "public, max-age=3600")
	w.Write([]byte(xml.Header))
	enc := xml.NewEncoder(w)
	enc.Indent("", "  ")
	_ = enc.Encode(set)
}

// ---- robots.txt ----

func (s *Server) handleRobots(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	w.Header().Set("Cache-Control", "public, max-age=86400")
	w.Write([]byte("User-agent: *\nAllow: /\nDisallow: /admin\n\nSitemap: " + baseURL(r) + "/sitemap.xml\n"))
}