fix(share_plus): return correct share result on android (#1301)

packages/share_plus/share_plus/android/src/main/AndroidManifest.xml

@@ -1,6 +1,8 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="dev.fluttercommunity.plus.share">
     <application>
+      <!-- Declares a provider which allows us to store files to share in
+           '.../caches/share_plus' and grant the receiving action access -->
       <provider
         android:name="dev.fluttercommunity.plus.share.ShareFileProvider"
         android:authorities="${applicationId}.flutter.share_provider"
@@ -10,5 +12,12 @@
           android:name="android.support.FILE_PROVIDER_PATHS"
           android:resource="@xml/flutter_share_file_paths"/>
       </provider>
+      <!-- This manifest declared broadcast receiver allows us to use an explicit
+           Intent when creating a PendingItent to be informed of the user's choice -->
+      <receiver android:name=".SharePlusPendingIntent" android:exported="true">
+        <intent-filter>
+          <action android:name="EXTRA_CHOSEN_COMPONENT" />
+        </intent-filter>
+      </receiver>
     </application>
 </manifest>

packages/share_plus/share_plus/android/src/main/kotlin/dev/fluttercommunity/plus/share/Share.kt

@@ -33,7 +33,7 @@ internal class Share(
      */
     private val immutabilityIntentFlags: Int by lazy {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
-            PendingIntent.FLAG_IMMUTABLE
+            PendingIntent.FLAG_MUTABLE
         } else {
             0
         }
@@ -71,7 +71,7 @@ internal class Share(
                 PendingIntent.getBroadcast(
                     context,
                     0,
-                    Intent(ShareSuccessManager.BROADCAST_CHANNEL),
+                    Intent(context, SharePlusPendingIntent::class.java),
                     PendingIntent.FLAG_UPDATE_CURRENT or immutabilityIntentFlags
                 ).intentSender
             )
@@ -129,7 +129,7 @@ internal class Share(
                 PendingIntent.getBroadcast(
                     context,
                     0,
-                    Intent(ShareSuccessManager.BROADCAST_CHANNEL),
+                    Intent(context, SharePlusPendingIntent::class.java),
                     PendingIntent.FLAG_UPDATE_CURRENT or immutabilityIntentFlags
                 ).intentSender
             )

packages/share_plus/share_plus/android/src/main/kotlin/dev/fluttercommunity/plus/share/SharePlusPendingIntent.kt

@@ -0,0 +1,39 @@
+package dev.fluttercommunity.plus.share
+
+import android.content.*
+import android.os.Build
+
+/**
+ * This helper class allows us to use FLAG_MUTABLE on the PendingIntent used in the Share class,
+ * as it allows us to make the underlying Intent explicit, therefore avoiding any risks an implicit
+ * mutable Intent may carry.
+ *
+ * When the PendingIntent is sent, the system will instantiate this class and call `onReceive` on it.
+ */
+internal class SharePlusPendingIntent: BroadcastReceiver() {
+    companion object {
+        /**
+         * Static member to access the result of the system instantiated instance
+         */
+        var result: String = ""
+    }
+
+    /**
+     * Handler called after an action was chosen. Called only on success.
+     */
+    override fun onReceive(context: Context, intent: Intent) {
+        // Extract chosen ComponentName
+        val chosenComponent = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            // Only available from API level 33 onwards
+            intent.getParcelableExtra(Intent.EXTRA_CHOSEN_COMPONENT, ComponentName::class.java)
+        } else {
+            // Deprecated in API level 33
+            intent.getParcelableExtra<ComponentName>(Intent.EXTRA_CHOSEN_COMPONENT)
+        }
+
+        // Unambiguously identify the chosen action
+        if (chosenComponent != null) {
+            result = chosenComponent.flattenToString()
+        }
+    }
+}

packages/share_plus/share_plus/android/src/main/kotlin/dev/fluttercommunity/plus/share/SharePlusPlugin.kt

@@ -15,14 +15,12 @@ class SharePlusPlugin : FlutterPlugin, ActivityAware {
     override fun onAttachedToEngine(binding: FlutterPluginBinding) {
         methodChannel = MethodChannel(binding.binaryMessenger, CHANNEL)
         manager = ShareSuccessManager(binding.applicationContext)
-        manager.register()
         share = Share(context = binding.applicationContext, activity = null, manager = manager)
         val handler = MethodCallHandler(share, manager)
         methodChannel.setMethodCallHandler(handler)
     }
 
     override fun onDetachedFromEngine(binding: FlutterPluginBinding) {
-        manager.discard()
         methodChannel.setMethodCallHandler(null)
     }
 

packages/share_plus/share_plus/android/src/main/kotlin/dev/fluttercommunity/plus/share/ShareSuccessManager.kt

@@ -9,31 +9,18 @@ import java.util.concurrent.atomic.AtomicBoolean
  * Handles the callback based status information about a successful or dismissed
  * share. Used to link multiple different callbacks together for easier use.
  */
-internal class ShareSuccessManager(private val context: Context) : BroadcastReceiver(),
-    ActivityResultListener {
+internal class ShareSuccessManager(private val context: Context) : ActivityResultListener {
     private var callback: MethodChannel.Result? = null
     private var isCalledBack: AtomicBoolean = AtomicBoolean(true)
 
-    /**
-     * Register listener. Must be called before any share sheet is opened.
-     */
-    fun register() {
-        context.registerReceiver(this, IntentFilter(BROADCAST_CHANNEL))
-    }
-
-    /**
-     * Deregister listener. Must be called before the base activity is invalidated.
-     */
-    fun discard() {
-        context.unregisterReceiver(this)
-    }
-
     /**
      * Set result callback that will wait for the share-sheet to close and get either
      * the componentname of the chosen option or an empty string on dismissal.
      */
     fun setCallback(callback: MethodChannel.Result): Boolean {
         return if (isCalledBack.compareAndSet(true, false)) {
+            // Prepare all state for new share
+            SharePlusPendingIntent.result = ""
             isCalledBack.set(false)
             this.callback = callback
             true
@@ -51,7 +38,7 @@ internal class ShareSuccessManager(private val context: Context) : BroadcastRece
      * Must be called if `.startActivityForResult` is not available to avoid deadlocking.
      */
     fun unavailable() {
-        returnResult("dev.fluttercommunity.plus/share/unavailable")
+        returnResult(RESULT_UNAVAILABLE)
     }
 
     /**
@@ -70,24 +57,19 @@ internal class ShareSuccessManager(private val context: Context) : BroadcastRece
      */
     override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?): Boolean {
         return if (requestCode == ACTIVITY_CODE) {
-            returnResult("")
+            returnResult(SharePlusPendingIntent.result)
             true
         } else {
             false
         }
     }
 
     /**
-     * Handler called after a sharesheet was closed. Called only on success.
+     * Companion object holds constants used throughout the plugin when attempting to return
+     * the share result.
      */
-    override fun onReceive(context: Context, intent: Intent) {
-        returnResult(
-            intent.getParcelableExtra<ComponentName>(Intent.EXTRA_CHOSEN_COMPONENT).toString()
-        )
-    }
-
     companion object {
-        const val BROADCAST_CHANNEL = "dev.fluttercommunity.plus/share/success"
         const val ACTIVITY_CODE = 17062003
+        const val RESULT_UNAVAILABLE = "dev.fluttercommunity.plus/share/unavailable"
     }
 }

packages/share_plus/share_plus/android/src/main/res/xml/flutter_share_file_paths.xml

@@ -1,4 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<paths>
-    <cache-path name="cache" path="share_plus/" />
+<paths xmlns:android="http://schemas.android.com/apk/res/android">
+  <!-- Used in conjunction with the provider declared in AndroidManifest.xml -->
+  <cache-path name="cache" path="share_plus/" />
 </paths>