implement Facebook authentication. refactor logic for getting "state" parameter.

app/src/main/java/chat/rocket/android/fragment/oauth/AbstractOAuthFragment.java

@@ -3,6 +3,7 @@ package chat.rocket.android.fragment.oauth;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.text.TextUtils;
+import android.util.Base64;
 import android.webkit.JavascriptInterface;
 import android.webkit.WebView;
 import chat.rocket.android.api.MethodCallHelper;
@@ -11,6 +12,7 @@ import chat.rocket.android.helper.LogcatIfError;
 import chat.rocket.android.model.ServerConfig;
 import chat.rocket.android.model.ddp.MeteorLoginServiceConfiguration;
 import chat.rocket.android.realm_helper.RealmStore;
+import java.nio.charset.Charset;
 import org.json.JSONException;
 import org.json.JSONObject;
 import timber.log.Timber;
@@ -31,6 +33,18 @@ public abstract class AbstractOAuthFragment extends AbstractWebViewFragment {
         && args.containsKey("serverConfigId");
   }
 
+  protected final String getStateString() {
+    try {
+      return Base64.encodeToString(new JSONObject().put("loginStyle", "popup")
+          .put("credentialToken", getOAuthServiceName() + System.currentTimeMillis())
+          .put("isCordova", true)
+          .toString()
+          .getBytes(Charset.forName("UTF-8")), Base64.NO_WRAP);
+    } catch (JSONException exception) {
+      throw new RuntimeException(exception);
+    }
+  }
+
   @Override public void onCreate(@Nullable Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     Bundle args = getArguments();

app/src/main/java/chat/rocket/android/fragment/oauth/FacebookOAuthFragment.java

+package chat.rocket.android.fragment.oauth;
+
+import chat.rocket.android.model.ddp.MeteorLoginServiceConfiguration;
+import okhttp3.HttpUrl;
+
+public class FacebookOAuthFragment extends AbstractOAuthFragment {
+
+  @Override protected String getOAuthServiceName() {
+    return "facebook";
+  }
+
+  @Override protected String generateURL(MeteorLoginServiceConfiguration oauthConfig) {
+    return new HttpUrl.Builder().scheme("https")
+        .host("www.facebook.com")
+        .addPathSegment("v2.2")
+        .addPathSegment("dialog")
+        .addPathSegment("oauth")
+        .addQueryParameter("client_id", oauthConfig.getAppId())
+        .addQueryParameter("redirect_uri", "https://" + hostname + "/_oauth/facebook?close")
+        .addQueryParameter("display", "popup")
+        .addQueryParameter("scope", "email")
+        .addQueryParameter("state", getStateString())
+        .build()
+        .toString();
+  }
+}

app/src/main/java/chat/rocket/android/fragment/oauth/GitHubOAuthFragment.java

 package chat.rocket.android.fragment.oauth;
 
-import android.util.Base64;
 import chat.rocket.android.model.ddp.MeteorLoginServiceConfiguration;
-import java.nio.charset.Charset;
 import okhttp3.HttpUrl;
-import org.json.JSONObject;
-import timber.log.Timber;
 
 public class GitHubOAuthFragment extends AbstractOAuthFragment {
 
@@ -14,27 +10,15 @@ public class GitHubOAuthFragment extends AbstractOAuthFragment {
   }
 
   @Override protected String generateURL(MeteorLoginServiceConfiguration oauthConfig) {
-    final String clientId = oauthConfig.getClientId();
-    try {
-      String state = Base64.encodeToString(new JSONObject().put("loginStyle", "popup")
-          .put("credentialToken", "github" + System.currentTimeMillis())
-          .put("isCordova", true)
-          .toString()
-          .getBytes(Charset.forName("UTF-8")), Base64.NO_WRAP);
-
-      return new HttpUrl.Builder().scheme("https")
-          .host("github.com")
-          .addPathSegment("login")
-          .addPathSegment("oauth")
-          .addPathSegment("authorize")
-          .addQueryParameter("client_id", clientId)
-          .addQueryParameter("scope", "user:email")
-          .addQueryParameter("state", state)
-          .build()
-          .toString();
-    } catch (Exception exception) {
-      Timber.e(exception, "failed to generate GitHub OAUth URL");
-    }
-    return null;
+    return new HttpUrl.Builder().scheme("https")
+        .host("github.com")
+        .addPathSegment("login")
+        .addPathSegment("oauth")
+        .addPathSegment("authorize")
+        .addQueryParameter("client_id", oauthConfig.getClientId())
+        .addQueryParameter("scope", "user:email")
+        .addQueryParameter("state", getStateString())
+        .build()
+        .toString();
   }
 }

app/src/main/java/chat/rocket/android/fragment/oauth/GoogleOAuthFragment.java

 package chat.rocket.android.fragment.oauth;
 
-import android.util.Base64;
 import chat.rocket.android.model.ddp.MeteorLoginServiceConfiguration;
-import java.nio.charset.Charset;
 import okhttp3.HttpUrl;
-import org.json.JSONObject;
-import timber.log.Timber;
 
 public class GoogleOAuthFragment extends AbstractOAuthFragment {
 
@@ -14,29 +10,17 @@ public class GoogleOAuthFragment extends AbstractOAuthFragment {
   }
 
   @Override protected String generateURL(MeteorLoginServiceConfiguration oauthConfig) {
-    final String clientId = oauthConfig.getClientId();
-    try {
-      String state = Base64.encodeToString(new JSONObject().put("loginStyle", "popup")
-          .put("credentialToken", "google" + System.currentTimeMillis())
-          .put("isCordova", true)
-          .toString()
-          .getBytes(Charset.forName("UTF-8")), Base64.NO_WRAP);
-
-      return new HttpUrl.Builder().scheme("https")
-          .host("accounts.google.com")
-          .addPathSegment("o")
-          .addPathSegment("oauth2")
-          .addPathSegment("auth")
-          .addQueryParameter("response_type", "code")
-          .addQueryParameter("client_id", clientId)
-          .addQueryParameter("scope", "profile email")
-          .addQueryParameter("redirect_uri", "https://" + hostname + "/_oauth/google?close")
-          .addQueryParameter("state", state)
-          .build()
-          .toString();
-    } catch (Exception exception) {
-      Timber.e(exception, "failed to generate Google OAUth URL");
-    }
-    return null;
+    return new HttpUrl.Builder().scheme("https")
+        .host("accounts.google.com")
+        .addPathSegment("o")
+        .addPathSegment("oauth2")
+        .addPathSegment("auth")
+        .addQueryParameter("response_type", "code")
+        .addQueryParameter("client_id", oauthConfig.getClientId())
+        .addQueryParameter("scope", "profile email")
+        .addQueryParameter("redirect_uri", "https://" + hostname + "/_oauth/google?close")
+        .addQueryParameter("state", getStateString())
+        .build()
+        .toString();
   }
 }

app/src/main/java/chat/rocket/android/fragment/oauth/TwitterOAuthFragment.java

 package chat.rocket.android.fragment.oauth;
 
-import android.util.Base64;
 import chat.rocket.android.model.ddp.MeteorLoginServiceConfiguration;
-import java.nio.charset.Charset;
-import org.json.JSONObject;
-import timber.log.Timber;
 
 public class TwitterOAuthFragment extends AbstractOAuthFragment {
 
@@ -13,17 +9,7 @@ public class TwitterOAuthFragment extends AbstractOAuthFragment {
   }
 
   @Override protected String generateURL(MeteorLoginServiceConfiguration oauthConfig) {
-    try {
-      String state = Base64.encodeToString(new JSONObject().put("loginStyle", "popup")
-          .put("credentialToken", "twitter" + System.currentTimeMillis())
-          .put("isCordova", true)
-          .toString()
-          .getBytes(Charset.forName("UTF-8")), Base64.NO_WRAP);
-
-      return "https://" + hostname + "/_oauth/twitter/?requestTokenAndRedirect=true&state=" + state;
-    } catch (Exception exception) {
-      Timber.e(exception, "failed to generate Twitter OAUth URL");
-    }
-    return null;
+    return "https://" + hostname + "/_oauth/twitter/"
+        + "?requestTokenAndRedirect=true&state=" + getStateString();
   }
 }

app/src/main/java/chat/rocket/android/layouthelper/oauth/OAuthProviderInfo.java

@@ -2,6 +2,7 @@ package chat.rocket.android.layouthelper.oauth;
 
 import chat.rocket.android.R;
 import chat.rocket.android.fragment.oauth.AbstractOAuthFragment;
+import chat.rocket.android.fragment.oauth.FacebookOAuthFragment;
 import chat.rocket.android.fragment.oauth.GitHubOAuthFragment;
 import chat.rocket.android.fragment.oauth.GoogleOAuthFragment;
 import chat.rocket.android.fragment.oauth.TwitterOAuthFragment;
@@ -27,6 +28,8 @@ public class OAuthProviderInfo {
           "github", R.id.btn_login_with_github, GitHubOAuthFragment.class));
       add(new OAuthProviderInfo(
           "google", R.id.btn_login_with_google, GoogleOAuthFragment.class));
+      add(new OAuthProviderInfo(
+          "facebook", R.id.btn_login_with_facebook, FacebookOAuthFragment.class));
     }
   };
 }

app/src/main/res/layout/fragment_login.xml

@@ -31,7 +31,6 @@
                 android:id="@+id/btn_login_with_facebook"
                 android:layout_width="48dp"
                 android:layout_height="48dp"
-                android:enabled="false"
                 android:layout_marginEnd="@dimen/margin_8"
                 android:text="@string/fa_facebook_official"
                 android:textSize="16dp" />