Facebook oauth login

app/src/main/java/chat/rocket/android/authentication/login/presentation/LoginPresenter.kt

@@ -8,7 +8,6 @@ import chat.rocket.android.infrastructure.LocalRepository
 import chat.rocket.android.server.domain.*
 import chat.rocket.android.server.domain.model.Account
 import chat.rocket.android.server.infraestructure.RocketChatClientFactory
-import chat.rocket.android.server.presentation.CheckServerPresenter
 import chat.rocket.android.util.extensions.*
 import chat.rocket.android.util.retryIO
 import chat.rocket.common.RocketChatAuthException
@@ -31,6 +30,7 @@ private const val SERVICE_NAME_GITHUB = "github"
 private const val SERVICE_NAME_GOOGLE = "google"
 private const val SERVICE_NAME_LINKEDIN = "linkedin"
 private const val SERVICE_NAME_GILAB = "gitlab"
+private const val SERVICE_NAME_FACEBOOK = "facebook"
 
 class LoginPresenter @Inject constructor(
     private val view: LoginView,
@@ -143,9 +143,12 @@ class LoginPresenter @Inject constructor(
                     var totalSocialAccountsEnabled = 0
 
                     if (settings.isFacebookAuthenticationEnabled()) {
-//                        //TODO: Remove until we have this implemented
-//                        view.enableLoginByFacebook()
-//                        totalSocialAccountsEnabled++
+                        val clientId = getOauthClientId(services, SERVICE_NAME_FACEBOOK)
+                        if (clientId != null) {
+                            view.setupFacebookButtonListener(OauthHelper.getFacebookOauthUrl(clientId, currentServer, state), state)
+                            view.enableLoginByFacebook()
+                            totalSocialAccountsEnabled++
+                        }
                     }
                     if (settings.isGithubAuthenticationEnabled()) {
                         val clientId = getOauthClientId(services, SERVICE_NAME_GITHUB)

app/src/main/java/chat/rocket/android/authentication/login/presentation/LoginView.kt

@@ -145,6 +145,14 @@ interface LoginView : LoadingView, MessageView {
      */
     fun setupLinkedinButtonListener(linkedinUrl: String, state: String)
 
+    /**
+     * Setups the Facebook button when tapped.
+     *
+     * @param facebookOauthUrl The Facebook OAuth URL to authenticate with.
+     * @param state A random string generated by the app, which you'll verify later (to protect against forgery attacks).
+     */
+    fun setupFacebookButtonListener(facebookOauthUrl: String, state: String)
+
     /**
      * Shows the "login by Meteor" view if it is enable by the server settings.
      */

app/src/main/java/chat/rocket/android/authentication/login/ui/LoginFragment.kt

@@ -261,6 +261,15 @@ class LoginFragment : Fragment(), LoginView {
         }
     }
 
+    override fun setupFacebookButtonListener(facebookOauthUrl: String, state: String) {
+        ui { activity ->
+            button_facebook.setOnClickListener {
+                startActivityForResult(activity.oauthWebViewIntent(facebookOauthUrl, state), REQUEST_CODE_FOR_OAUTH)
+                activity.overridePendingTransition(R.anim.slide_up, R.anim.hold)
+            }
+        }
+    }
+
     override fun enableLoginByGithub() {
         ui {
             button_github.isClickable = true

app/src/main/java/chat/rocket/android/helper/OauthHelper.kt

@@ -67,4 +67,21 @@ object OauthHelper {
                 "&response_type=code" +
                 "&scope=read_user"
     }
+
+    /**
+     * Returns the Facebook Oauth URL.
+     *
+     * @param clientId The Gitlab client ID.
+     * @param serverUrl The server URL.
+     * @param state An unguessable random string used to protect against forgery attacks.
+     * @return The Facebook Oauth URL.
+     */
+    fun getFacebookOauthUrl(clientId: String, serverUrl: String, state: String): String {
+        return  "https://facebook.com/v2.9/dialog/oauth" +
+                "?client_id=$clientId" +
+                "&redirect_uri=${serverUrl.removeTrailingSlash()}/_oauth/facebook?close" +
+                "&state=$state" +
+                "&response_type=code" +
+                "&scope=email"
+    }
 }
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