From 39aa26713bd1a4f30da65eaeda3c4b1f8b5ac9bf Mon Sep 17 00:00:00 2001
From: Amr Yousef <amr.farid140@gmail.com>
Date: Sat, 6 Mar 2021 13:36:31 +0000
Subject: [PATCH] Fix linking account on Android #43 (#46)

---
 .../FirebaseAuthOAuthPlugin.kt                | 51 ++++++++++++-------
 firebase_auth_oauth/example/lib/main.dart     | 40 ++++++++++++++-
 2 files changed, 73 insertions(+), 18 deletions(-)

diff --git a/firebase_auth_oauth/android/src/main/kotlin/me/amryousef/apple/auth/firebase_auth_oauth/FirebaseAuthOAuthPlugin.kt b/firebase_auth_oauth/android/src/main/kotlin/me/amryousef/apple/auth/firebase_auth_oauth/FirebaseAuthOAuthPlugin.kt
index b33e8ad..271aa47 100644
--- a/firebase_auth_oauth/android/src/main/kotlin/me/amryousef/apple/auth/firebase_auth_oauth/FirebaseAuthOAuthPlugin.kt
+++ b/firebase_auth_oauth/android/src/main/kotlin/me/amryousef/apple/auth/firebase_auth_oauth/FirebaseAuthOAuthPlugin.kt
@@ -84,24 +84,16 @@ class FirebaseAuthOAuthPlugin : FlutterPlugin, ActivityAware, MethodCallHandler
                 FirebaseAuthOAuthPluginError
                     .FirebaseAuthError(error)
                     .toResult(result)
-            } ?: auth.startActivityForSignInWithProvider(it, provider)
-                .addOnSuccessListener { authResult ->
-                    if (call.method == CREATE_USER_METHOD) {
-                        result.success("")
-                        return@addOnSuccessListener
-                    } else if (call.method == LINK_USER_METHOD) {
-                        val user = auth.currentUser
-                        if (user == null) {
-                            FirebaseAuthOAuthPluginError.PluginError(
-                                ""
-                            ).toResult(result)
-                        }
-                        user?.linkWithCredential(authResult.credential!!)
-                    }
+            } ?: run {
+                val task = call.method.toSignInTask(provider, auth, result)
+                task.addOnSuccessListener {
+                    result.success("")
+                    return@addOnSuccessListener
                 }.addOnFailureListener { error ->
-                FirebaseAuthOAuthPluginError
-                    .FirebaseAuthError(error)
-                    .toResult(result)
+                    FirebaseAuthOAuthPluginError
+                        .FirebaseAuthError(error)
+                        .toResult(result)
+                }
             }
         }
     }
@@ -124,4 +116,29 @@ class FirebaseAuthOAuthPlugin : FlutterPlugin, ActivityAware, MethodCallHandler
     override fun onDetachedFromActivityForConfigChanges() {
         activity = null
     }
+
+    private fun String.toSignInTask(
+        provider: OAuthProvider,
+        auth: FirebaseAuth,
+        result: Result
+    ) = activity?.let {
+        when (this) {
+            LINK_USER_METHOD -> {
+                val user = auth.currentUser
+                if (user == null) {
+                    FirebaseAuthOAuthPluginError.PluginError(
+                        ""
+                    ).toResult(result)
+                }
+                user!!.startActivityForLinkWithProvider(it, provider)
+            }
+            CREATE_USER_METHOD -> {
+                auth.startActivityForSignInWithProvider(it, provider)
+            }
+            else -> {
+                FirebaseAuthOAuthPluginError.PluginError("Unknown method called")
+                com.google.android.gms.tasks.Tasks.forCanceled()
+            }
+        }
+    } ?: com.google.android.gms.tasks.Tasks.forCanceled()
 }
diff --git a/firebase_auth_oauth/example/lib/main.dart b/firebase_auth_oauth/example/lib/main.dart
index 32783fc..2dce32d 100644
--- a/firebase_auth_oauth/example/lib/main.dart
+++ b/firebase_auth_oauth/example/lib/main.dart
@@ -28,6 +28,22 @@ class MyApp extends StatelessWidget {
     }
   }
 
+  Future<void> performLink(String provider, List<String> scopes,
+      Map<String, String> parameters) async {
+    try {
+      await FirebaseAuthOAuth()
+          .linkExistingUserWithCredentials(provider, scopes, parameters);
+    } on PlatformException catch (error) {
+      /**
+       * The plugin has the following error codes:
+       * 1. FirebaseAuthError: FirebaseAuth related error
+       * 2. PlatformError: An platform related error
+       * 3. PluginError: An error from this plugin
+       */
+      debugPrint("${error.code}: ${error.message}");
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
@@ -69,13 +85,35 @@ class MyApp extends StatelessWidget {
                         child: Text("Sign in By Github"),
                       )
                     ],
-                    if (snapshot.data != null)
+                    if (snapshot.data != null) ...[
+                      ElevatedButton(
+                        onPressed: () async {
+                          await performLink(
+                              "apple.com", ["email"], {"locale": "en"});
+                        },
+                        child: Text("Link Sign in By Apple"),
+                      ),
+                      ElevatedButton(
+                        onPressed: () async {
+                          await performLink(
+                              "twitter.com", ["email"], {"lang": "en"});
+                        },
+                        child: Text("Link Sign in By Twitter"),
+                      ),
+                      ElevatedButton(
+                        onPressed: () async {
+                          await performLink(
+                              "github.com", ["user:email"], {"lang": "en"});
+                        },
+                        child: Text("Link Sign in By Github"),
+                      ),
                       ElevatedButton(
                         onPressed: () async {
                           await FirebaseAuth.instance.signOut();
                         },
                         child: Text("Logout"),
                       )
+                    ]
                   ],
                 );
               })),