pkg/feed.go

package pkg

import (
	"fmt"
	"net/http"

	"go.uber.org/zap"
)

const (
	documentFmt string = `
<opml version="1.1">
    <body>
        <outline text="YouTube Subscriptions" title="YouTube Subscriptions">
%s
        </outline>
    </body>
</opml>
`
	itemFmt string = `
            <outline text="%s" title="%s" type="rss"
                     xmlUrl="https://www.youtube.com/feeds/videos.xml?channel_id=%s"/>
`
)

func ExportHandler(w http.ResponseWriter, r *http.Request) {
	refreshToken := r.URL.Query().Get("refreshToken")
	if refreshToken == "" {
		http.Error(w, "please specify refresh token", http.StatusBadRequest)
		return
	}

	items := readSubsCache(refreshToken)
	if len(items) <= 0 {
		yt, err := ytServiceFromRefreshToken(r.Context(), refreshToken)
		if err != nil {
			http.Error(w, err.Error(), http.StatusUnauthorized)
			return
		}

		var pageToken string
		for {
			logger.Info("making YouTube API request", zap.String("page_token", pageToken))

			resp, err := yt.Subscriptions.
				List("snippet").
				MaxResults(50).
				Order("alphabetical").
				Mine(true).
				PageToken(pageToken).
				Do()
			if err != nil {
				http.Error(w, err.Error(), http.StatusInternalServerError)
				return
			}

			items = append(items, resp.Items...)

			pageToken = resp.NextPageToken
			if resp.NextPageToken == "" {
				break
			}
		}

		logger.Info("received item from API", zap.Int("amount", len(items)))

		storeSubsCache(refreshToken, items)
	}

	var result string
	for _, item := range items {
		if item == nil || item.Snippet == nil || item.Snippet.ResourceId == nil ||
			item.Snippet.ResourceId.ChannelId == "" {
			logger.Warn("skipping item because it does not have all required fields", zap.Any("item", item))
			continue
		}

		result += fmt.Sprintf(itemFmt, item.Snippet.Title, item.Snippet.Title, item.Snippet.ResourceId.ChannelId)
	}

	result = fmt.Sprintf(documentFmt, result)

	w.Header().Set("Content-Type", "application/xml")
	fmt.Fprint(w, result)
}