extensible mechanism for feed url building

src/main/java/com/commafeed/CommaFeedModule.java

@@ -26,6 +26,9 @@ import com.commafeed.backend.task.OldStatusesCleanupTask;
 import com.commafeed.backend.task.OrphanedContentsCleanupTask;
 import com.commafeed.backend.task.OrphanedFeedsCleanupTask;
 import com.commafeed.backend.task.ScheduledTask;
+import com.commafeed.backend.urlprovider.FeedURLProvider;
+import com.commafeed.backend.urlprovider.InPageReferenceFeedURLProvider;
+import com.commafeed.backend.urlprovider.YoutubeFeedURLProvider;
 import com.google.inject.AbstractModule;
 import com.google.inject.Provides;
 import com.google.inject.multibindings.Multibinder;
@@ -55,6 +58,10 @@ public class CommaFeedModule extends AbstractModule {
 		faviconMultibinder.addBinding().to(FacebookFaviconFetcher.class);
 		faviconMultibinder.addBinding().to(DefaultFaviconFetcher.class);
 
+		Multibinder<FeedURLProvider> urlProviderMultibinder = Multibinder.newSetBinder(binder(), FeedURLProvider.class);
+		urlProviderMultibinder.addBinding().to(InPageReferenceFeedURLProvider.class);
+		urlProviderMultibinder.addBinding().to(YoutubeFeedURLProvider.class);
+
 		Multibinder<ScheduledTask> taskMultibinder = Multibinder.newSetBinder(binder(), ScheduledTask.class);
 		taskMultibinder.addBinding().to(OldStatusesCleanupTask.class);
 		taskMultibinder.addBinding().to(OldEntriesCleanupTask.class);

src/main/java/com/commafeed/backend/feed/FeedFetcher.java

@@ -2,27 +2,24 @@ package com.commafeed.backend.feed;
 
 import java.io.IOException;
 import java.util.Date;
-import java.util.regex.*;
+import java.util.Set;
 
 import javax.inject.Inject;
 import javax.inject.Singleton;
 
-import lombok.RequiredArgsConstructor;
-import lombok.extern.slf4j.Slf4j;
-
 import org.apache.commons.codec.binary.StringUtils;
 import org.apache.commons.codec.digest.DigestUtils;
-import org.apache.http.client.ClientProtocolException;
-import org.jsoup.Jsoup;
-import org.jsoup.nodes.Document;
-import org.jsoup.select.Elements;
 
 import com.commafeed.backend.HttpGetter;
 import com.commafeed.backend.HttpGetter.HttpResult;
 import com.commafeed.backend.HttpGetter.NotModifiedException;
 import com.commafeed.backend.model.Feed;
+import com.commafeed.backend.urlprovider.FeedURLProvider;
 import com.rometools.rome.io.FeedException;
 
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+
 @Slf4j
 @RequiredArgsConstructor(onConstructor = @__({ @Inject }))
 @Singleton
@@ -30,9 +27,10 @@ public class FeedFetcher {
 
 	private final FeedParser parser;
 	private final HttpGetter getter;
+	private final Set<FeedURLProvider> urlProviders;
 
 	public FetchedFeed fetch(String feedUrl, boolean extractFeedUrlFromHtml, String lastModified, String eTag, Date lastPublishedDate,
-			String lastContentHash) throws FeedException, ClientProtocolException, IOException, NotModifiedException {
+			String lastContentHash) throws FeedException, IOException, NotModifiedException {
 		log.debug("Fetching feed {}", feedUrl);
 		FetchedFeed fetchedFeed = null;
 
@@ -45,7 +43,7 @@ public class FeedFetcher {
 			fetchedFeed = parser.parse(result.getUrlAfterRedirect(), content);
 		} catch (FeedException e) {
 			if (extractFeedUrlFromHtml) {
-				String extractedUrl = extractFeedUrl(StringUtils.newStringUtf8(result.getContent()), feedUrl);
+				String extractedUrl = extractFeedUrl(urlProviders, StringUtils.newStringUtf8(result.getContent()), feedUrl);
 				if (org.apache.commons.lang3.StringUtils.isNotBlank(extractedUrl)) {
 					feedUrl = extractedUrl;
 
@@ -85,34 +83,13 @@ public class FeedFetcher {
 		return fetchedFeed;
 	}
 
-	private String extractFeedUrl(String html, String baseUri) {
+	private static String extractFeedUrl(Set<FeedURLProvider> urlProviders, String html, String baseUri) {
-		String foundUrl = null;
+		for (FeedURLProvider urlProvider : urlProviders) {
-
+			String url = urlProvider.get(html, baseUri);
-		Document doc = Jsoup.parse(html, baseUri);
+			if (url != null)
-		String root = doc.children().get(0).tagName();
+				return url;
-		if ("html".equals(root)) {
-			Elements atom = doc.select("link[type=application/atom+xml]");
-			Elements rss = doc.select("link[type=application/rss+xml]");
-			if (!atom.isEmpty()) {
-				foundUrl = atom.get(0).attr("abs:href");
-			} else if (!rss.isEmpty()) {
-				foundUrl = rss.get(0).attr("abs:href");
-			} else {
-				foundUrl = extractYoutubeFeedUrl(baseUri);
-			}
-		}
-		return foundUrl;
 		}
 
-	/*
+		return null;
-	* Workaround for Youtube channels:
-	* convert the channel URL to the valid feed URL
-	* https://www.youtube.com/channel/CHANNEL_ID
-	* https://www.youtube.com/feeds/videos.xml?channel_id=CHANNEL_ID
-	*/
-	private String extractYoutubeFeedUrl(String url) {
-		Pattern regexp = Pattern.compile("(.*\\byoutube\\.com)\\/channel\\/([^\\/]+)", Pattern.CASE_INSENSITIVE);
-		Matcher matcher = regexp.matcher(url);
-		return matcher.find() ? matcher.group(1) + "/feeds/videos.xml?channel_id=" + matcher.group(2) : null;
 	}
 }

src/main/java/com/commafeed/backend/urlprovider/FeedURLProvider.java

@@ -0,0 +1,7 @@
+package com.commafeed.backend.urlprovider;
+
+public interface FeedURLProvider {
+
+	String get(String html, String url);
+
+}

src/main/java/com/commafeed/backend/urlprovider/InPageReferenceFeedURLProvider.java

@@ -0,0 +1,28 @@
+package com.commafeed.backend.urlprovider;
+
+import org.jsoup.Jsoup;
+import org.jsoup.nodes.Document;
+import org.jsoup.select.Elements;
+
+public class InPageReferenceFeedURLProvider implements FeedURLProvider {
+
+	@Override
+	public String get(String html, String url) {
+		String foundUrl = null;
+
+		Document doc = Jsoup.parse(html, url);
+		String root = doc.children().get(0).tagName();
+		if ("html".equals(root)) {
+			Elements atom = doc.select("link[type=application/atom+xml]");
+			Elements rss = doc.select("link[type=application/rss+xml]");
+			if (!atom.isEmpty()) {
+				foundUrl = atom.get(0).attr("abs:href");
+			} else if (!rss.isEmpty()) {
+				foundUrl = rss.get(0).attr("abs:href");
+			}
+		}
+
+		return foundUrl;
+	}
+
+}

src/main/java/com/commafeed/backend/urlprovider/YoutubeFeedURLProvider.java

@@ -0,0 +1,22 @@
+package com.commafeed.backend.urlprovider;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Workaround for Youtube channels
+ * 
+ * converts the channel URL https://www.youtube.com/channel/CHANNEL_ID to the valid feed URL
+ * https://www.youtube.com/feeds/videos.xml?channel_id=CHANNEL_ID
+ */
+public class YoutubeFeedURLProvider implements FeedURLProvider {
+
+	private static final Pattern REGEXP = Pattern.compile("(.*\\byoutube\\.com)\\/channel\\/([^\\/]+)", Pattern.CASE_INSENSITIVE);
+
+	@Override
+	public String get(String html, String url) {
+		Matcher matcher = REGEXP.matcher(url);
+		return matcher.find() ? matcher.group(1) + "/feeds/videos.xml?channel_id=" + matcher.group(2) : null;
+	}
+
+}