package handler

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

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"

	"git.sundynix.cn/Blizzard/sundynix-site/server/internal/model"
)

// RSSHandler 输出博客的 RSS 2.0 订阅源。
type RSSHandler struct {
	db      *gorm.DB
	siteURL string
}

func NewRSSHandler(db *gorm.DB) *RSSHandler {
	siteURL := os.Getenv("SUNDYNIX_SITE_URL")
	if siteURL == "" {
		siteURL = "https://sundynix.com"
	}
	return &RSSHandler{db: db, siteURL: siteURL}
}

type rssItem struct {
	Title       string `xml:"title"`
	Link        string `xml:"link"`
	GUID        string `xml:"guid"`
	Description string `xml:"description"`
	Category    string `xml:"category,omitempty"`
	PubDate     string `xml:"pubDate"`
}

type rssFeed struct {
	XMLName xml.Name `xml:"rss"`
	Version string   `xml:"version,attr"`
	Channel struct {
		Title       string    `xml:"title"`
		Link        string    `xml:"link"`
		Description string    `xml:"description"`
		Language    string    `xml:"language"`
		Items       []rssItem `xml:"item"`
	} `xml:"channel"`
}

// Feed GET /rss.xml
func (h *RSSHandler) Feed(c *gin.Context) {
	var posts []model.PostListItem
	err := h.db.Model(&model.Post{}).
		Where("published_at IS NOT NULL").
		Order("published_at DESC").
		Limit(50).
		Find(&posts).Error
	if err != nil {
		c.String(http.StatusInternalServerError, "feed unavailable")
		return
	}

	feed := rssFeed{Version: "2.0"}
	feed.Channel.Title = "sundynix agentix 博客"
	feed.Channel.Link = h.siteURL + "/blog"
	feed.Channel.Description = "事件驱动的 AI Agent 工作台 — 发布日志与工程笔记"
	feed.Channel.Language = "zh-cn"
	for _, p := range posts {
		link := h.siteURL + "/blog/" + p.Slug
		item := rssItem{
			Title:       p.Title,
			Link:        link,
			GUID:        link,
			Description: p.Summary,
			Category:    p.Category,
		}
		if p.PublishedAt != nil {
			item.PubDate = p.PublishedAt.Format(time.RFC1123Z)
		}
		feed.Channel.Items = append(feed.Channel.Items, item)
	}

	c.Header("Content-Type", "application/rss+xml; charset=utf-8")
	c.String(http.StatusOK, xml.Header)
	if out, err := xml.MarshalIndent(feed, "", "  "); err == nil {
		c.Writer.Write(out)
	}
}