implement favorited posts list

closes #4

mastodon/src/main/java/org/joinmastodon/android/api/requests/accounts/GetFavourites.java

@@ -0,0 +1,49 @@
+package org.joinmastodon.android.api.requests.accounts;
+
+import com.google.gson.reflect.TypeToken;
+
+import org.joinmastodon.android.api.MastodonAPIRequest;
+import org.joinmastodon.android.model.Status;
+
+import java.io.IOException;
+import java.util.List;
+
+import okhttp3.Response;
+
+public class GetFavourites extends MastodonAPIRequest<List<Status>>{
+    private String maxId;
+
+    public GetFavourites(String maxID, String minID, int limit){
+        super(HttpMethod.GET, "/favourites", new TypeToken<>(){});
+        if(maxID!=null)
+            addQueryParameter("max_id", maxID);
+        if(minID!=null)
+            addQueryParameter("min_id", minID);
+        if(limit>0)
+            addQueryParameter("limit", ""+limit);
+    }
+
+    @Override
+    public void validateAndPostprocessResponse(List<Status> respObj, Response httpResponse) throws IOException {
+        super.validateAndPostprocessResponse(respObj, httpResponse);
+        // <https://mastodon.social/api/v1/bookmarks?max_id=268962>; rel="next",
+        // <https://mastodon.social/api/v1/bookmarks?min_id=268981>; rel="prev"
+        String link=httpResponse.header("link");
+        // parsing link header by hand; using a library would be cleaner
+        // (also, the functionality should be part of the max id logics and implemented in MastodonAPIRequest)
+        if(link==null) return;
+        String maxIdEq="max_id=";
+        for(String s : link.split(",")) {
+            if(s.contains("rel=\"next\"")) {
+                int start=s.indexOf(maxIdEq)+maxIdEq.length();
+                int end=s.indexOf('>');
+                if(start<0 || start>end) return;
+                this.maxId=s.substring(start, end);
+            }
+        }
+    }
+
+    public String getMaxId() {
+        return maxId;
+    }
+}