Keep full authentication proedure on the same task stack for better ux on android

Author: Mino5531

flutter_web_auth_2/android/src/main/kotlin/com/linusu/flutter_web_auth_2/AuthenticationManagementActivity.kt

@@ -0,0 +1,85 @@
+package com.linusu.flutter_web_auth_2
+
+import android.app.Activity
+import android.content.Context
+import android.content.Intent
+import android.net.Uri
+import android.os.Bundle
+import androidx.browser.customtabs.CustomTabsIntent
+
+class AuthenticationManagementActivity(
+) : Activity() {
+    companion object {
+        const val KEY_AUTH_STARTED: String = "authStarted"
+        const val KEY_AUTH_URI: String = "authUri"
+        const val KEY_AUTH_OPTION_INTENT_FLAGS: String = "authOptionsIntentFlags"
+        const val KEY_AUTH_OPTION_TARGET_PACKAGE: String = "authOptionsTargetPackage"
+
+        fun createResponseHandlingIntent(context: Context): Intent {
+            val intent = Intent(context, AuthenticationManagementActivity::class.java)
+            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_SINGLE_TOP)
+            return intent
+        }
+    }
+    private var authStarted: Boolean = false
+    private lateinit var authenticationUri: Uri
+    private var intentFlags: Int = 0
+    private var targetPackage: String? = null
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        if (savedInstanceState == null) {
+            extractState(intent.extras)
+        } else {
+            extractState(savedInstanceState)
+        }
+    }
+
+    override fun onResume() {
+        super.onResume()
+
+        if (!authStarted) {
+            val intent = CustomTabsIntent.Builder().build()
+            intent.intent.addFlags(intentFlags)
+
+            if (targetPackage != null) {
+                intent.intent.setPackage(targetPackage)
+            }
+            intent.launchUrl(this, authenticationUri)
+            authStarted = true
+            return
+        }
+        /* If the authentication was already started and we've returned here, the user either
+         * completed or cancelled authentication.
+         * Either way we want to return to our original flutter activity, so just finish here
+         */
+        finish()
+    }
+
+    override fun onNewIntent(intent: Intent?) {
+        super.onNewIntent(intent)
+        setIntent(intent);
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        outState.putBoolean(KEY_AUTH_STARTED, authStarted)
+        outState.putParcelable(KEY_AUTH_URI, authenticationUri)
+        outState.putInt(KEY_AUTH_OPTION_INTENT_FLAGS, intentFlags)
+        outState.putString(
+            KEY_AUTH_OPTION_TARGET_PACKAGE,
+            targetPackage
+        )
+    }
+
+    private fun extractState(state: Bundle?) {
+        if (state == null) {
+            finish()
+            return
+        }
+        authStarted = state.getBoolean(KEY_AUTH_STARTED, false)
+        authenticationUri = state.getParcelable(KEY_AUTH_URI)!!
+        intentFlags = state.getInt(KEY_AUTH_OPTION_INTENT_FLAGS, 0)
+        targetPackage = state.getString(KEY_AUTH_OPTION_TARGET_PACKAGE)
+    }
+}

flutter_web_auth_2/android/src/main/kotlin/com/linusu/flutter_web_auth_2/CallbackActivity.kt

@@ -18,7 +18,8 @@ class CallbackActivity : Activity() {
         if (scheme != null) {
             FlutterWebAuth2Plugin.callbacks.remove(scheme)?.success(url.toString())
         }
-        finishAndRemoveTask()
+        startActivity(AuthenticationManagementActivity.createResponseHandlingIntent(this))
+        finish()
     }
 
 

flutter_web_auth_2/android/src/main/kotlin/com/linusu/flutter_web_auth_2/FlutterWebAuth2Plugin.kt

@@ -1,5 +1,6 @@
 package com.linusu.flutter_web_auth_2
 
+import android.app.Activity
 import android.content.Context
 import android.content.Intent
 import android.content.pm.PackageManager
@@ -9,16 +10,20 @@ import androidx.browser.customtabs.CustomTabsClient
 import androidx.browser.customtabs.CustomTabsIntent
 
 import io.flutter.embedding.engine.plugins.FlutterPlugin
+import io.flutter.embedding.engine.plugins.activity.ActivityAware
+import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding
 import io.flutter.plugin.common.BinaryMessenger
 import io.flutter.plugin.common.MethodCall
 import io.flutter.plugin.common.MethodChannel
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler
 import io.flutter.plugin.common.MethodChannel.Result
+import java.util.ArrayList
 
 class FlutterWebAuth2Plugin(
     private var context: Context? = null,
-    private var channel: MethodChannel? = null
-) : MethodCallHandler, FlutterPlugin {
+    private var channel: MethodChannel? = null,
+    private var activity: Activity? = null,
+) : MethodCallHandler, FlutterPlugin, ActivityAware {
     companion object {
         val callbacks = mutableMapOf<String, Result>()
     }
@@ -46,17 +51,11 @@ class FlutterWebAuth2Plugin(
                 val options = call.argument<Map<String, Any>>("options")!!
 
                 callbacks[callbackUrlScheme] = resultCallback
-                val intent = CustomTabsIntent.Builder().build()
-                val keepAliveIntent = Intent(context, KeepAliveService::class.java)
-
-                intent.intent.addFlags(options["intentFlags"] as Int)
-                intent.intent.putExtra("android.support.customtabs.extra.KEEP_ALIVE", keepAliveIntent)
-
-                val targetPackage = findTargetBrowserPackageName(options)
-                if (targetPackage != null) {
-                    intent.intent.setPackage(targetPackage)
-                }
-                intent.launchUrl(context!!, url)
+                activity?.startActivity(Intent(activity,AuthenticationManagementActivity::class.java).apply {
+                    putExtra(AuthenticationManagementActivity.KEY_AUTH_URI,url)
+                    putExtra(AuthenticationManagementActivity.KEY_AUTH_OPTION_INTENT_FLAGS, options["intentFlags"] as Int)
+                    putExtra(AuthenticationManagementActivity.KEY_AUTH_OPTION_TARGET_PACKAGE, findTargetBrowserPackageName(options))
+                })
             }
 
             "cleanUpDanglingCalls" -> {
@@ -71,6 +70,22 @@ class FlutterWebAuth2Plugin(
         }
     }
 
+    override fun onAttachedToActivity(binding: ActivityPluginBinding) {
+        activity = binding.activity
+    }
+
+    override fun onDetachedFromActivityForConfigChanges() {
+        onDetachedFromActivity()
+    }
+
+    override fun onReattachedToActivityForConfigChanges(binding: ActivityPluginBinding) {
+        onAttachedToActivity(binding)
+    }
+
+    override fun onDetachedFromActivity() {
+        activity = null
+    }
+
     /**
      * Find Support CustomTabs Browser.
      *
@@ -145,5 +160,4 @@ class FlutterWebAuth2Plugin(
         )
         return value == packageName
     }
-
 }

flutter_web_auth_2/example/android/app/src/main/AndroidManifest.xml

@@ -49,6 +49,8 @@
                 <data android:mimeType="text/plain" />
             </intent-filter>
         </activity>
+        <activity android:name="com.linusu.flutter_web_auth_2.AuthenticationManagementActivity">
+        </activity>
         <!-- Don't delete the meta-data below.
              This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
         <meta-data

flutter_web_auth_2/lib/src/options.dart

@@ -1,12 +1,9 @@
 /// Default intent flags for opening the custom tabs intent on Android.
-/// This is essentially the same as
-/// `FLAG_ACTIVITY_SINGLE_TOP | FLAG_ACTIVITY_NEW_TASK`.
-const defaultIntentFlags = 1 << 29 | 1 << 28;
+const defaultIntentFlags = 0;
 
 /// "Ephemeral" intent flags for opening the custom tabs intent on Android.
 /// This is essentially the same as
-/// `FLAG_ACTIVITY_SINGLE_TOP | FLAG_ACTIVITY_NEW_TASK
-/// | FLAG_ACTIVITY_NO_HISTORY`.
+/// FLAG_ACTIVITY_NO_HISTORY`.
 const ephemeralIntentFlags = defaultIntentFlags | 1 << 30;
 
 /// Default HTML code that generates a nice callback page.