package parser

import (
	"encoding/xml"
	"fmt"
)

type FeedType string

const (
	Rss  FeedType = "rss"
	Atom FeedType = "atom"
)

type FeedEntry struct {
	Link    string
	Content string
}

func ParseFeed(feedType FeedType, data []byte) ([]FeedEntry, error) {
	switch feedType {
	case Rss:
		return parseRss(data)
	case Atom:
		return parseAtom(data)
	}
	return nil, fmt.Errorf("Unknown feed type: %s", feedType)
}

func parseAtom(data []byte) ([]FeedEntry, error) {
	v := struct {
		Items []struct {
			Link struct {
				Href string `xml:"href,attr"`
			} `xml:"link"`
			Content string `xml:",innerxml"`
		} `xml:"entry"`
	}{}

	err := xml.Unmarshal(data, &v)
	if err != nil {
		return nil, err
	}

	var feedEntries []FeedEntry
	for _, atomEntry := range v.Items {
		feedEntries = append(feedEntries, FeedEntry{
			Link:    atomEntry.Link.Href,
			Content: atomEntry.Content,
		})
	}
	return feedEntries, nil
}
func parseRss(data []byte) ([]FeedEntry, error) {

	v := struct {
		Items []struct {
			Link    string `xml:"link"`
			Content string `xml:",innerxml"`
		} `xml:"channel>item"`
	}{}

	err := xml.Unmarshal(data, &v)
	if err != nil {
		return nil, err
	}

	var feedEntries []FeedEntry
	for _, rssEntry := range v.Items {
		feedEntries = append(feedEntries, FeedEntry{
			Link:    rssEntry.Link,
			Content: rssEntry.Content,
		})
	}

	return feedEntries, nil
}