package handler

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

	"podstalk/store"
)

type RSSHandler struct {
	Store     *store.Store
	BaseTitle string
	Link      string
	Author    string
}

func (h *RSSHandler) resolveTitle() string {
	title, err := h.Store.GetSetting("podcast_title")
	if err == nil && title != "" {
		return title
	}
	if h.BaseTitle != "" {
		return h.BaseTitle
	}
	return "Podstalk"
}

func (h *RSSHandler) resolveImage() string {
	img, err := h.Store.GetSetting("podcast_image")
	if err == nil && img != "" {
		return img
	}
	return ""
}

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

type rssChannel struct {
	Title       string    `xml:"title"`
	Link        string    `xml:"link"`
	Description string    `xml:"description"`
	Language    string    `xml:"language"`
	Image       *rssImage `xml:"image,omitempty"`
	ItunesImage *rssItunesImage `xml:"itunes:image,omitempty"`
	Items       []rssItem `xml:"item"`
}

type rssImage struct {
	URL   string `xml:"url"`
	Title string `xml:"title"`
	Link  string `xml:"link"`
}

type rssItunesImage struct {
	Href string `xml:"href,attr"`
}

type rssItem struct {
	Title       string       `xml:"title"`
	Description string       `xml:"description"`
	Enclosure   rssEnclosure `xml:"enclosure"`
	PubDate     string       `xml:"pubDate"`
	GUID        string       `xml:"guid"`
	ItunesImage *rssItunesImage `xml:"itunes:image,omitempty"`
}

type rssEnclosure struct {
	URL    string `xml:"url,attr"`
	Length string `xml:"length,attr,omitempty"`
	Type   string `xml:"type,attr"`
}

func (h *RSSHandler) ServeRSS(w http.ResponseWriter, r *http.Request) {
	episodes, err := h.Store.ListEpisodes()
	if err != nil {
		http.Error(w, "failed to load episodes", http.StatusInternalServerError)
		return
	}

	podcastTitle := h.resolveTitle()
	podcastImage := h.resolveImage()

	items := make([]rssItem, 0, len(episodes))
	for _, ep := range episodes {
		var itemImage *rssItunesImage
		epImage := ep.ImagePath
		if epImage == "" {
			epImage = podcastImage
		}
		if epImage != "" {
			itemImage = &rssItunesImage{Href: h.fullURL(epImage)}
		}

		items = append(items, rssItem{
			Title:       ep.Title,
			Description: ep.Description,
			Enclosure: rssEnclosure{
				URL:  h.fullURL(ep.AudioPath),
				Type: "audio/mpeg",
			},
			PubDate:     ep.PublishedAt.Format(time.RFC1123Z),
			GUID:        h.fullURL(ep.AudioPath),
			ItunesImage: itemImage,
		})
	}

	var chanImage *rssImage
	var chanItunesImage *rssItunesImage
	if podcastImage != "" {
		chanImage = &rssImage{
			URL:   h.fullURL(podcastImage),
			Title: podcastTitle,
			Link:  h.Link,
		}
		chanItunesImage = &rssItunesImage{Href: h.fullURL(podcastImage)}
	}

	feed := rssFeed{
		Version:  "2.0",
		ItunesNS: "http://www.itunes.com/dtds/podcast-1.0.dtd",
		Channel: rssChannel{
			Title:       podcastTitle,
			Link:        h.Link,
			Description: podcastTitle,
			Language:    "en-us",
			Image:       chanImage,
			ItunesImage: chanItunesImage,
			Items:       items,
		},
	}

	w.Header().Set("Content-Type", "application/rss+xml; charset=utf-8")
	w.Write([]byte(xml.Header))
	enc := xml.NewEncoder(w)
	enc.Indent("", "  ")
	enc.Encode(feed)
}

func (h *RSSHandler) fullURL(path string) string {
	if path == "" {
		return ""
	}
	if h.Link == "" {
		return path
	}
	return h.Link + "/uploads/" + path
}