package podcasts

import "encoding/xml"

// rssFeed is a pragmatic subset of RSS 2.0 (with the de facto iTunes
// podcast extensions most feeds use) — enough to get channel metadata
// and each episode's title, description, publish date, and audio
// enclosure. Real podcast feeds vary a lot in which optional fields they
// include, so every field here is best-effort.
type rssFeed struct {
	Channel rssChannel `xml:"channel"`
}

type rssChannel struct {
	Title       string    `xml:"title"`
	Description string    `xml:"description"`
	Image       rssImage  `xml:"image"`
	Items       []rssItem `xml:"item"`
}

type rssImage struct {
	URL string `xml:"url"`
}

type rssItem struct {
	GUID        rssGUID      `xml:"guid"`
	Title       string       `xml:"title"`
	Description string       `xml:"description"`
	PubDate     string       `xml:"pubDate"`
	Enclosure   rssEnclosure `xml:"enclosure"`
	Duration    string       `xml:"http://www.itunes.com/dtds/podcast-1.0.dtd duration"`
}

type rssGUID struct {
	Value string `xml:",chardata"`
}

type rssEnclosure struct {
	URL string `xml:"url,attr"`
}

func parseRSS(data []byte) (*rssFeed, error) {
	var feed rssFeed
	if err := xml.Unmarshal(data, &feed); err != nil {
		return nil, err
	}
	return &feed, nil
}

// episodeGUID returns the item's GUID if present, falling back to its
// enclosure URL — some minimal feeds omit <guid> entirely.
func (i rssItem) episodeGUID() string {
	if i.GUID.Value != "" {
		return i.GUID.Value
	}
	return i.Enclosure.URL
}