From ad6229bc4f3270518adbdc8d4d52c00017bbd5c4 Mon Sep 17 00:00:00 2001
From: Shivek Khurana <khuranashivek@outlook.com>
Date: Wed, 3 Feb 2021 18:41:53 +0530
Subject: [PATCH] Follow short urls to get long url and then use that long url
 with oembed

---
 protocol/urls/urls.go      | 35 +++++++++++++++++++++++++++++++++++
 protocol/urls/urls_test.go | 33 ++++++++++++++++++++++++++++++---
 2 files changed, 65 insertions(+), 3 deletions(-)

diff --git a/protocol/urls/urls.go b/protocol/urls/urls.go
index 979082ad9..172f9565e 100644
--- a/protocol/urls/urls.go
+++ b/protocol/urls/urls.go
@@ -68,6 +68,11 @@ func LinkPreviewWhitelist() []Site {
 			Address:   "tenor.com",
 			ImageSite: true,
 		},
+		Site{
+			Title:     "GIPHY GIFs Short URLS",
+			Address:   "gph.se",
+			ImageSite: true,
+		},
 		Site{
 			Title:     "GIPHY GIFs",
 			Address:   "giphy.com",
@@ -171,6 +176,34 @@ func GetGiphyPreviewData(link string) (previewData LinkPreviewData, err error) {
 	return previewData, nil
 }
 
+// Giphy has a shortener service called gph.se, the oembed service doesn't work with shortened urls,
+// so we need to fetch the long url first
+func GetGiphyLongURL(shortURL string) (longURL string, err error) {
+	res, err := http.Get(shortURL)
+
+	if err != nil {
+		return longURL, fmt.Errorf("can't get bytes from Giphy's short url at %s", shortURL)
+	}
+
+	canonicalURL := res.Request.URL.String()
+	if (canonicalURL == shortURL) {
+		// no redirect, ie. not a valid url
+		return longURL, fmt.Errorf("unable to process Giphy's short url at %s", shortURL)
+	} else {
+		return canonicalURL, err
+	}
+}
+
+func GetGiphyShortURLPreviewData (shortURL string) (data LinkPreviewData, err error) {
+	longURL, err := GetGiphyLongURL(shortURL)
+
+	if err != nil {
+		return data, err
+	} else {
+		return GetGiphyPreviewData(longURL)
+	}
+}
+
 func GetTenorOembed(url string) (data TenorOembedData, err error) {
 	oembedLink := fmt.Sprintf(TenorOembedLink, url)
 
@@ -216,6 +249,8 @@ func GetLinkPreviewData(link string) (previewData LinkPreviewData, err error) {
 		return GetGithubPreviewData(link)
 	case "giphy.com":
 		return GetGiphyPreviewData(link)
+	case "gph.se":
+		return GetGiphyShortURLPreviewData(link)
 	case "tenor.com":
 		return GetTenorPreviewData(link)
 	default:
diff --git a/protocol/urls/urls_test.go b/protocol/urls/urls_test.go
index d9e93a42a..94f1ed653 100644
--- a/protocol/urls/urls_test.go
+++ b/protocol/urls/urls_test.go
@@ -58,16 +58,43 @@ func TestGetGiphyPreviewData(t *testing.T) {
 	require.Error(t, err)
 
 
-	// Other link shapes
-	// shortLink := "https://gph.is/g/aXLyK7P"
 	mediaLink := "https://media.giphy.com/media/lcG3qwtTKSNI2i5vst/giphy.gif"
 
-	// shortLinkData, _ := GetGiphyPreviewData(shortLink)
 	mediaLinkData, _ := GetGiphyPreviewData(mediaLink)
 
 	require.Equal(t, thumbnailUrlWithoutSubdomain(mediaLinkData.ThumbnailURL), thumbnailUrlWithoutSubdomain(previewData.ThumbnailURL))
 }
 
+func TestGetGiphyLongURL(t *testing.T) {
+	shortURL := "https://gph.is/g/aXLyK7P"
+	computedLongURL, _ := GetGiphyLongURL(shortURL)
+	actualLongURL := "https://giphy.com/gifs/FullMag-robot-boston-dynamics-dance-lcG3qwtTKSNI2i5vst"
+
+	require.Equal(t, computedLongURL, actualLongURL)
+
+	_, err := GetGiphyLongURL("http://this-giphy-site-doesn-not-exist.se/bogus-url")
+	require.Error(t, err)
+
+	_, err = GetGiphyLongURL("http://gph.se/bogus-url-but-correct-domain")
+	require.Error(t, err)
+}
+
+
+func TestGetGiphyShortURLPreviewData(t *testing.T) {
+	shortURL := "https://gph.is/g/aXLyK7P"
+	previewData, err := GetGiphyShortURLPreviewData(shortURL)
+
+	bostonDynamicsEthGifData := LinkPreviewData{
+		Site:         "GIPHY",
+		Title:        "Boston Dynamics Yes GIF by FullMag - Find & Share on GIPHY",
+		ThumbnailURL: "https://media1.giphy.com/media/lcG3qwtTKSNI2i5vst/giphy.gif",
+	}
+
+	require.NoError(t, err)
+	require.Equal(t, bostonDynamicsEthGifData.Site, previewData.Site)
+	require.Equal(t, bostonDynamicsEthGifData.Title, previewData.Title)
+}
+
 func TestGetTenorPreviewData(t *testing.T) {
 	validTenorLink := "https://tenor.com/view/robot-dance-do-you-love-me-boston-boston-dynamics-dance-gif-19998728"
 	previewData, err := GetTenorPreviewData(validTenorLink)