android: Move sharing logic to MainActivity.

Deletes 'ReceiveSharingActivity' and moves the 'handle receiving
shares from other apps' logic to MainActivity, as this is a better,
simpler logic and we don't have to maintain the dummy component
'SharingRoot' and an extra activity to show that.

Also deletes the now unsued component 'SharingRoot'.

android/app/src/main/AndroidManifest.xml

@@ -45,7 +45,7 @@
 
     <!-- Disabled while the feature is experimental.  See #117 and #4124.
       <activity
-        android:name=".sharing.ReceiveShareActivity"
+        android:name=".MainActivity"
         android:configChanges="keyboard|keyboardHidden|orientation|screenSize"
         android:label="@string/app_name"
         android:launchMode="singleTask"

android/app/src/main/java/com/zulipmobile/MainActivity.kt

@@ -1,8 +1,22 @@
 package com.zulipmobile
 
+import android.content.Context
+import android.content.Intent
+import android.net.Uri
 import android.os.Bundle
+import android.util.Log
 import android.webkit.WebView
+import androidx.annotation.Nullable
 import com.facebook.react.ReactActivity
+import com.facebook.react.ReactApplication
+import com.facebook.react.bridge.Arguments
+import com.facebook.react.bridge.ReactContext
+import com.facebook.react.bridge.WritableMap
+import com.zulipmobile.notifications.*
+import com.zulipmobile.sharing.SharingModule
+
+const val TAG = "MainActivityShare"
+
 
 open class MainActivity : ReactActivity() {
     /**
@@ -13,8 +27,81 @@ open class MainActivity : ReactActivity() {
         return "ZulipMobile"
     }
 
+    private fun sendEvent(reactContext: ReactContext,
+                          eventName: String,
+                          @Nullable params: WritableMap) {
+        Log.d(TAG, "Sending event with shared data")
+        emit(reactContext, eventName, params)
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         WebView.setWebContentsDebuggingEnabled(true)
+
+        if (intent?.action == Intent.ACTION_SEND) {
+            handleSend(intent)
+        }
+        // TODO also handle ACTION_SEND_MULTIPLE?
+        //   See: https://developer.android.com/training/sharing/receive#receiving-data-activity
+    }
+
+    private fun handleSend(intent: Intent) {
+        val params: WritableMap
+        try {
+            params = getParamsFromIntent(intent)
+        } catch (e: ShareParamsParseException) {
+            Log.w(TAG, "Ignoring malformed share Intent: ${e.message}")
+            return
+        }
+
+        // TODO deduplicate this with notifyReact.
+        // Until then, keep in sync when changing.
+        val application = application as ReactApplication
+        val host = application.reactNativeHost
+        val reactContext = host.tryGetReactInstanceManager()?.currentReactContext
+        val appStatus = reactContext?.appStatus
+        Log.d(TAG, "app status is $appStatus")
+        when (appStatus) {
+            null, ReactAppStatus.NOT_RUNNING ->
+                // Either there's no JS environment running, or we haven't yet reached
+                // foreground.  Expect the app to check initialSharedData on launch.
+            {
+                SharingModule.initialSharedData = params
+                Log.d(TAG, "Sharing data as initialSharedData")
+            }
+
+            ReactAppStatus.BACKGROUND, ReactAppStatus.FOREGROUND ->
+                // JS is running and has already reached foreground. It won't check
+                // initialSharedData again, but it will see a shareReceived event.
+                sendEvent(reactContext, "shareReceived", params)
+        }
     }
-}
+
+    private fun getParamsFromIntent(intent: Intent): WritableMap {
+        // For documentation of what fields to expect here, see:
+        //   https://developer.android.com/reference/android/content/Intent#ACTION_SEND
+        val params = Arguments.createMap()
+        when {
+            "text/plain" == intent.type -> {
+                val sharedText = intent.getStringExtra(Intent.EXTRA_TEXT)
+                params.putString("type", "text")
+                params.putString("sharedText", sharedText)
+            }
+            intent.type?.startsWith("image/") == true -> {
+                val url = intent.getParcelableExtra<Uri>(Intent.EXTRA_STREAM)
+                    ?: throw ShareParamsParseException("Could not extract URL from Image Intent")
+                params.putString("type", "image")
+                params.putString("sharedImageUrl", url.toString())
+            }
+            else -> {
+                val url = intent.getParcelableExtra<Uri>(Intent.EXTRA_STREAM)
+                    ?: throw ShareParamsParseException("Could not extract URL from File Intent")
+                params.putString("type", "file")
+                params.putString("sharedFileUrl", url.toString())
+            }
+        }
+        return params
+    }
+}
+
+class ShareParamsParseException(errorMessage: String) : RuntimeException(errorMessage)

index.js

@@ -1,7 +1,5 @@
 /* @flow strict-local */
 import { AppRegistry } from 'react-native';
 import ZulipMobile from './src/ZulipMobile';
-import SharingRoot from './src/sharing/SharingRoot';
 
 AppRegistry.registerComponent('ZulipMobile', () => ZulipMobile);
-AppRegistry.registerComponent('SharingRoot', () => SharingRoot);