From 91301197eac5422ebbc1495c9e86777b083f049a Mon Sep 17 00:00:00 2001
From: ganfra <francoisg@matrix.org>
Date: Wed, 13 May 2020 20:04:08 +0200
Subject: [PATCH] Try to communicate with WidgetPostAPI

---
 .idea/codeStyles/Project.xml                  |   3 +
 .../src/main/assets/postMessageAPI.js         |  54 ++++++
 .../matrix/android/api/session/Session.kt     |   4 +-
 .../session/widgets/WidgetPostAPIMediator.kt  |  87 +++++++++
 .../api/session/widgets/WidgetService.kt      |  41 +++++
 .../session/widgets/model/WidgetContent.kt    |  26 ++-
 .../internal/session/DefaultSession.kt        |   5 +-
 .../widgets/DefaultWidgetPostAPIMediator.kt   | 173 ++++++++++++++++++
 .../session/widgets/DefaultWidgetService.kt   |  50 +++++
 ...tFailure.kt => WidgetManagementFailure.kt} |   6 +-
 .../internal/session/widgets/WidgetManager.kt |  18 +-
 .../internal/session/widgets/WidgetModule.kt  |   8 +
 .../widgets/WidgetPostMessageAPIProvider.kt   |  44 +++++
 .../internal/task/CoroutineToCallback.kt      |   6 +-
 14 files changed, 516 insertions(+), 9 deletions(-)
 create mode 100755 matrix-sdk-android/src/main/assets/postMessageAPI.js
 create mode 100644 matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/WidgetPostAPIMediator.kt
 create mode 100644 matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/WidgetService.kt
 create mode 100644 matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/DefaultWidgetPostAPIMediator.kt
 create mode 100644 matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/DefaultWidgetService.kt
 rename matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/{CreateWidgetFailure.kt => WidgetManagementFailure.kt} (80%)
 create mode 100644 matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetPostMessageAPIProvider.kt

diff --git a/.idea/codeStyles/Project.xml b/.idea/codeStyles/Project.xml
index b3719669fd..40ee4ee5cf 100644
--- a/.idea/codeStyles/Project.xml
+++ b/.idea/codeStyles/Project.xml
@@ -1,6 +1,9 @@
 <component name="ProjectCodeStyleConfiguration">
   <code_scheme name="Project" version="173">
     <option name="RIGHT_MARGIN" value="160" />
+    <AndroidXmlCodeStyleSettings>
+      <option name="ARRANGEMENT_SETTINGS_MIGRATED_TO_191" value="true" />
+    </AndroidXmlCodeStyleSettings>
     <JetCodeStyleSettings>
       <option name="PACKAGES_TO_USE_STAR_IMPORTS">
         <value>
diff --git a/matrix-sdk-android/src/main/assets/postMessageAPI.js b/matrix-sdk-android/src/main/assets/postMessageAPI.js
new file mode 100755
index 0000000000..4936a78538
--- /dev/null
+++ b/matrix-sdk-android/src/main/assets/postMessageAPI.js
@@ -0,0 +1,54 @@
+var android_widget_events = {};
+
+var sendObjectMessageToRiotAndroid = function(parameters) {
+    Android.onWidgetEvent(JSON.stringify(parameters));
+};
+
+var onWidgetMessageToRiotAndroid = function(event) {
+    /* Use an internal "_id" field for matching onMessage events and requests
+       _id was originally used by the Modular API. Keep it */
+    if (!event.data._id) {
+        /* The Matrix Widget API v2 spec says:
+           "The requestId field should be unique and included in all requests" */
+        event.data._id = event.data.requestId;
+    }
+    /* Make sure to have one id */
+    if (!event.data._id) {
+        event.data._id = Date.now() + "-" + Math.random().toString(36);
+    }
+
+    console.log("onWidgetMessageToRiotAndroid " + event.data._id);
+
+    if (android_widget_events[event.data._id]) {
+        console.log("onWidgetMessageToRiotAndroid : already managed");
+        return;
+    }
+
+    if (!event.origin) {
+        event.origin = event.originalEvent.origin;
+    }
+
+    android_widget_events[event.data._id] = event;
+
+    console.log("onWidgetMessageToRiotAndroid : manage " + event.data);
+    sendObjectMessageToRiotAndroid({'event.data': event.data});
+};
+
+var sendResponseFromRiotAndroid = function(eventId, res) {
+    var event = android_widget_events[eventId];
+
+    console.log("sendResponseFromRiotAndroid to " + event.data.action + " for "+ eventId + ": " + JSON.stringify(res));
+
+    var data = JSON.parse(JSON.stringify(event.data));
+
+    data.response = res;
+
+    console.log("sendResponseFromRiotAndroid  ---> " + data);
+
+    event.source.postMessage(data, event.origin);
+    android_widget_events[eventId] = true;
+
+    console.log("sendResponseFromRiotAndroid to done");
+};
+
+window.addEventListener('message', onWidgetMessageToRiotAndroid, false);
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/Session.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/Session.kt
index 1afeed922f..3ba275fd5f 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/Session.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/Session.kt
@@ -40,6 +40,7 @@ import im.vector.matrix.android.api.session.signout.SignOutService
 import im.vector.matrix.android.api.session.sync.FilterService
 import im.vector.matrix.android.api.session.sync.SyncState
 import im.vector.matrix.android.api.session.user.UserService
+import im.vector.matrix.android.api.session.widgets.WidgetService
 
 /**
  * This interface defines interactions with a session.
@@ -61,7 +62,8 @@ interface Session :
         HomeServerCapabilitiesService,
         SecureStorageService,
         AccountDataService,
-        AccountService {
+        AccountService,
+        WidgetService {
 
     /**
      * The params associated to the session
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/WidgetPostAPIMediator.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/WidgetPostAPIMediator.kt
new file mode 100644
index 0000000000..34848b7d17
--- /dev/null
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/WidgetPostAPIMediator.kt
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2020 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package im.vector.matrix.android.api.session.widgets
+
+import android.webkit.WebView
+import im.vector.matrix.android.api.util.JsonDict
+
+interface WidgetPostAPIMediator {
+
+    /**
+     * This initialize the mediator and configure the webview.
+     * It will add a JavaScript Interface.
+     * Please call [clear] method when finished to clean the provided webview
+     */
+    fun initialize(webView: WebView, handler: Handler)
+
+    /**
+     * This clear the mediator by removing the JavaScript Interface and cleaning references.
+     */
+    fun clear()
+
+    /**
+     * Inject the necessary javascript into the configured WebView.
+     * Should be called after a web page has been loaded.
+     */
+    fun injectAPI()
+
+    /**
+     * Send a boolean response
+     *
+     * @param response  the response
+     * @param eventData the modular data
+     */
+    fun sendBoolResponse(response: Boolean, eventData: JsonDict)
+
+    /**
+     * Send an integer response
+     *
+     * @param response  the response
+     * @param eventData the modular data
+     */
+    fun sendIntegerResponse(response: Int, eventData: JsonDict)
+
+    /**
+     * Send an object response
+     *
+     * @param response  the response
+     * @param eventData the modular data
+     */
+    fun sendObjectResponse(response: JsonDict?, eventData: JsonDict)
+
+    /**
+     * Send success
+     *
+     * @param eventData the modular data
+     */
+    fun sendSuccess(eventData: JsonDict)
+
+    /**
+     * Send an error
+     *
+     * @param message   the error message
+     * @param eventData the modular data
+     */
+    fun sendError(message: String, eventData: JsonDict)
+
+    interface Handler {
+        /**
+         * Triggered when a widget is posting
+         */
+        fun handleWidgetRequest(data: JsonDict): Boolean
+    }
+}
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/WidgetService.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/WidgetService.kt
new file mode 100644
index 0000000000..3e723d6212
--- /dev/null
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/WidgetService.kt
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2020 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package im.vector.matrix.android.api.session.widgets
+
+import im.vector.matrix.android.api.MatrixCallback
+import im.vector.matrix.android.api.query.QueryStringValue
+import im.vector.matrix.android.api.session.events.model.Content
+import im.vector.matrix.android.api.util.Cancelable
+import im.vector.matrix.android.internal.session.widgets.Widget
+
+interface WidgetService {
+
+    fun getWidgetPostAPIMediator(): WidgetPostAPIMediator
+
+    fun getRoomWidgets(
+            roomId: String,
+            widgetId: QueryStringValue = QueryStringValue.NoCondition,
+            widgetTypes: Set<String>? = null,
+            excludedTypes: Set<String>? = null
+    ): List<Widget>
+
+    fun createRoomWidget(roomId: String, widgetId: String, content: Content, callback: MatrixCallback<Widget>): Cancelable
+
+    fun destroyRoomWidget(roomId: String, widgetId: String, callback: MatrixCallback<Unit>): Cancelable
+
+    fun hasPermissionsToHandleWidgets(roomId: String): Boolean
+}
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/model/WidgetContent.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/model/WidgetContent.kt
index e71b6f61fc..979dc13976 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/model/WidgetContent.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/widgets/model/WidgetContent.kt
@@ -29,4 +29,28 @@ data class WidgetContent(
         @Json(name = "name") val name: String? = null,
         @Json(name = "data") val data: JsonDict = emptyMap(),
         @Json(name = "waitForIframeLoad") val waitForIframeLoad: Boolean = false
-)
+) {
+
+    /**
+     * @return the human name
+     */
+    fun getHumanName(): String {
+        return if (!name.isNullOrBlank()) {
+            "$name widget"
+        } else if (!type.isNullOrBlank()) {
+            when {
+                type.contains("widget") -> {
+                    type
+                }
+                id != null              -> {
+                    "$type $id"
+                }
+                else                    -> {
+                    "$type widget"
+                }
+            }
+        } else {
+            "Widget $id"
+        }
+    }
+}
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/DefaultSession.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/DefaultSession.kt
index 179d905412..aa9df9c496 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/DefaultSession.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/DefaultSession.kt
@@ -44,6 +44,7 @@ import im.vector.matrix.android.api.session.signout.SignOutService
 import im.vector.matrix.android.api.session.sync.FilterService
 import im.vector.matrix.android.api.session.sync.SyncState
 import im.vector.matrix.android.api.session.user.UserService
+import im.vector.matrix.android.api.session.widgets.WidgetService
 import im.vector.matrix.android.internal.auth.SessionParamsStore
 import im.vector.matrix.android.internal.crypto.DefaultCryptoService
 import im.vector.matrix.android.internal.crypto.crosssigning.ShieldTrustUpdater
@@ -88,6 +89,7 @@ internal class DefaultSession @Inject constructor(
         private val fileService: Lazy<FileService>,
         private val secureStorageService: Lazy<SecureStorageService>,
         private val profileService: Lazy<ProfileService>,
+        private val widgetService: Lazy<WidgetService>,
         private val syncThreadProvider: Provider<SyncThread>,
         private val contentUrlResolver: ContentUrlResolver,
         private val syncTokenStore: SyncTokenStore,
@@ -117,7 +119,8 @@ internal class DefaultSession @Inject constructor(
         HomeServerCapabilitiesService by homeServerCapabilitiesService.get(),
         ProfileService by profileService.get(),
         AccountDataService by accountDataService.get(),
-        AccountService by accountService.get() {
+        AccountService by accountService.get(),
+        WidgetService by widgetService.get() {
 
     override val sharedSecretStorageService: SharedSecretStorageService
         get() = _sharedSecretStorageService.get()
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/DefaultWidgetPostAPIMediator.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/DefaultWidgetPostAPIMediator.kt
new file mode 100644
index 0000000000..d70ccaea90
--- /dev/null
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/DefaultWidgetPostAPIMediator.kt
@@ -0,0 +1,173 @@
+/*
+ * Copyright (c) 2020 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package im.vector.matrix.android.internal.session.widgets
+
+import android.os.Build
+import android.webkit.JavascriptInterface
+import android.webkit.WebView
+import com.squareup.moshi.Moshi
+import im.vector.matrix.android.api.session.widgets.WidgetPostAPIMediator
+import im.vector.matrix.android.api.util.JSON_DICT_PARAMETERIZED_TYPE
+import im.vector.matrix.android.api.util.JsonDict
+import timber.log.Timber
+import java.util.HashMap
+import javax.inject.Inject
+
+internal class DefaultWidgetPostAPIMediator @Inject constructor(moshi: Moshi,
+                                                                private val widgetPostMessageAPIProvider: WidgetPostMessageAPIProvider) : WidgetPostAPIMediator {
+
+    private val adapter = moshi.adapter<JsonDict>(JSON_DICT_PARAMETERIZED_TYPE)
+
+    private var handler: WidgetPostAPIMediator.Handler? = null
+    private var webView: WebView? = null
+
+    override fun initialize(webView: WebView, handler: WidgetPostAPIMediator.Handler) {
+        this.webView = webView
+        this.handler = handler
+        webView.addJavascriptInterface(this, "WidgetPostAPIMediator")
+    }
+
+    override fun clear() {
+        handler = null
+        webView?.removeJavascriptInterface("WidgetPostAPIMediator")
+        webView = null
+    }
+
+    override fun injectAPI() {
+        val js = widgetPostMessageAPIProvider.get()
+        if (null != js) {
+            webView?.loadUrl("javascript:$js")
+        }
+    }
+
+    @JavascriptInterface
+    fun onWidgetEvent(jsonEventData: String) {
+        Timber.d("BRIDGE onWidgetEvent : $jsonEventData")
+        try {
+            val dataAsDict = adapter.fromJson(jsonEventData)
+            @Suppress("UNCHECKED_CAST")
+            val eventData = (dataAsDict?.get("event.data") as? JsonDict) ?: return
+            onWidgetMessage(eventData)
+        } catch (e: Exception) {
+            Timber.e(e, "## onWidgetEvent() failed")
+        }
+    }
+
+    private fun onWidgetMessage(eventData: JsonDict) {
+        try {
+            if (handler?.handleWidgetRequest(eventData) == false) {
+                sendError("", eventData)
+            }
+        } catch (e: Exception) {
+            Timber.e(e, "## onWidgetMessage() : failed")
+            sendError("", eventData)
+        }
+    }
+
+    /*
+   * *********************************************************************************************
+   * Message sending methods
+   * *********************************************************************************************
+   */
+
+    /**
+     * Send a boolean response
+     *
+     * @param response  the response
+     * @param eventData the modular data
+     */
+    override fun sendBoolResponse(response: Boolean, eventData: JsonDict) {
+        val jsString = if (response) "true" else "false"
+        sendResponse(jsString, eventData)
+    }
+
+    /**
+     * Send an integer response
+     *
+     * @param response  the response
+     * @param eventData the modular data
+     */
+    override fun sendIntegerResponse(response: Int, eventData: JsonDict) {
+        sendResponse(response.toString() + "", eventData)
+    }
+
+    /**
+     * Send an object response
+     *
+     * @param response  the response
+     * @param eventData the modular data
+     */
+    override fun sendObjectResponse(response: JsonDict?, eventData: JsonDict) {
+        var jsString: String? = null
+        if (response != null) {
+            try {
+                jsString = "JSON.parse('${adapter.toJson(response)}')"
+            } catch (e: Exception) {
+                Timber.e(e, "## sendObjectResponse() : toJson failed ")
+            }
+        }
+        sendResponse(jsString ?: "null", eventData)
+    }
+
+    /**
+     * Send success
+     *
+     * @param eventData the modular data
+     */
+    override fun sendSuccess(eventData: JsonDict) {
+        val successResponse = mapOf("success" to true)
+        sendObjectResponse(successResponse, eventData)
+    }
+
+    /**
+     * Send an error
+     *
+     * @param message   the error message
+     * @param eventData the modular data
+     */
+    override fun sendError(message: String, eventData: JsonDict) {
+        Timber.e("## sendError() : eventData $eventData failed $message")
+
+        // TODO: JS has an additional optional parameter: nestedError
+        val params = HashMap<String, Map<String, String>>()
+        val subMap = HashMap<String, String>()
+        subMap["message"] = message
+        params["error"] = subMap
+        sendObjectResponse(params, eventData)
+    }
+
+    /**
+     * Send the response to the javascript
+     *
+     * @param jsString  the response data
+     * @param eventData the modular data
+     */
+    private fun sendResponse(jsString: String, eventData: JsonDict) {
+        try {
+            val functionLine = "sendResponseFromRiotAndroid('" + eventData["_id"] + "' , " + jsString + ");"
+            Timber.v("BRIDGE sendResponse: $functionLine")
+            // call the javascript method
+            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
+                webView?.loadUrl("javascript:$functionLine")
+            } else {
+                webView?.evaluateJavascript(functionLine, null)
+            }
+        } catch (e: Exception) {
+            Timber.e(e, "## sendResponse() failed ")
+        }
+    }
+}
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/DefaultWidgetService.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/DefaultWidgetService.kt
new file mode 100644
index 0000000000..3a3a20e226
--- /dev/null
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/DefaultWidgetService.kt
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2020 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package im.vector.matrix.android.internal.session.widgets
+
+import im.vector.matrix.android.api.MatrixCallback
+import im.vector.matrix.android.api.query.QueryStringValue
+import im.vector.matrix.android.api.session.events.model.Content
+import im.vector.matrix.android.api.session.widgets.WidgetPostAPIMediator
+import im.vector.matrix.android.api.session.widgets.WidgetService
+import im.vector.matrix.android.api.util.Cancelable
+import javax.inject.Inject
+import javax.inject.Provider
+
+internal class DefaultWidgetService @Inject constructor(private val widgetManager: WidgetManager,
+                                                        private val widgetPostAPIMediator: Provider<WidgetPostAPIMediator>) : WidgetService {
+
+    override fun getWidgetPostAPIMediator(): WidgetPostAPIMediator {
+        return widgetPostAPIMediator.get()
+    }
+
+    override fun getRoomWidgets(roomId: String, widgetId: QueryStringValue, widgetTypes: Set<String>?, excludedTypes: Set<String>?): List<Widget> {
+        return widgetManager.getRoomWidgets(roomId, widgetId, widgetTypes, excludedTypes)
+    }
+
+    override fun createRoomWidget(roomId: String, widgetId: String, content: Content, callback: MatrixCallback<Widget>): Cancelable {
+        return widgetManager.createWidget(roomId, widgetId, content, callback)
+    }
+
+    override fun destroyRoomWidget(roomId: String, widgetId: String, callback: MatrixCallback<Unit>): Cancelable {
+        return widgetManager.destroyWidget(roomId, widgetId, callback)
+    }
+
+    override fun hasPermissionsToHandleWidgets(roomId: String): Boolean {
+        return widgetManager.hasPermissionsToHandleWidgets(roomId)
+    }
+}
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/CreateWidgetFailure.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetManagementFailure.kt
similarity index 80%
rename from matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/CreateWidgetFailure.kt
rename to matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetManagementFailure.kt
index c37495d546..7c139e8f54 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/CreateWidgetFailure.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetManagementFailure.kt
@@ -18,7 +18,7 @@ package im.vector.matrix.android.internal.session.widgets
 
 import im.vector.matrix.android.api.failure.Failure
 
-sealed class CreateWidgetFailure : Failure.FeatureFailure() {
-    object NotEnoughtPower : CreateWidgetFailure()
-    object CreationFailed : CreateWidgetFailure()
+sealed class WidgetManagementFailure : Failure.FeatureFailure() {
+    object NotEnoughPower : WidgetManagementFailure()
+    object CreationFailed : WidgetManagementFailure()
 }
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetManager.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetManager.kt
index da0d1e3117..9ba6ebbb13 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetManager.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetManager.kt
@@ -101,7 +101,7 @@ internal class WidgetManager @Inject constructor(private val integrationManager:
     fun createWidget(roomId: String, widgetId: String, content: Content, callback: MatrixCallback<Widget>): Cancelable {
         return taskExecutor.executorScope.launchToCallback(callback = callback) {
             if (!hasPermissionsToHandleWidgets(roomId)) {
-                throw CreateWidgetFailure.NotEnoughtPower
+                throw WidgetManagementFailure.NotEnoughPower
             }
             val params = CreateWidgetTask.Params(
                     roomId = roomId,
@@ -112,11 +112,25 @@ internal class WidgetManager @Inject constructor(private val integrationManager:
             try {
                 getRoomWidgets(roomId, widgetId = QueryStringValue.Equals(widgetId, QueryStringValue.Case.INSENSITIVE)).first()
             } catch (failure: Throwable) {
-                throw CreateWidgetFailure.CreationFailed
+                throw WidgetManagementFailure.CreationFailed
             }
         }
     }
 
+    fun destroyWidget(roomId: String, widgetId: String, callback: MatrixCallback<Unit>): Cancelable {
+        return taskExecutor.executorScope.launchToCallback(callback = callback) {
+            if (!hasPermissionsToHandleWidgets(roomId)) {
+                throw WidgetManagementFailure.NotEnoughPower
+            }
+            val params = CreateWidgetTask.Params(
+                    roomId = roomId,
+                    widgetId = widgetId,
+                    content = emptyMap()
+            )
+            createWidgetTask.execute(params)
+        }
+    }
+
     fun hasPermissionsToHandleWidgets(roomId: String): Boolean {
         val powerLevelsEvent = stateEventDataSource.getStateEvent(roomId, EventType.STATE_ROOM_POWER_LEVELS, QueryStringValue.NoCondition)
         val powerLevelsContent = powerLevelsEvent?.content?.toModel<PowerLevelsContent>() ?: return false
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetModule.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetModule.kt
index b3d9ddccfb..f2c9e99439 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetModule.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetModule.kt
@@ -19,6 +19,8 @@ package im.vector.matrix.android.internal.session.widgets
 import dagger.Binds
 import dagger.Module
 import dagger.Provides
+import im.vector.matrix.android.api.session.widgets.WidgetPostAPIMediator
+import im.vector.matrix.android.api.session.widgets.WidgetService
 import im.vector.matrix.android.internal.session.widgets.token.DefaultGetScalarTokenTask
 import im.vector.matrix.android.internal.session.widgets.token.GetScalarTokenTask
 import retrofit2.Retrofit
@@ -35,6 +37,12 @@ internal abstract class WidgetModule {
         }
     }
 
+    @Binds
+    abstract fun bindWidgetService(widgetService: DefaultWidgetService): WidgetService
+
+    @Binds
+    abstract fun bindWidgetPostAPIMediator(widgetPostMessageAPIProvider: DefaultWidgetPostAPIMediator): WidgetPostAPIMediator
+
     @Binds
     abstract fun bindCreateWidgetTask(task: DefaultCreateWidgetTask): CreateWidgetTask
 
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetPostMessageAPIProvider.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetPostMessageAPIProvider.kt
new file mode 100644
index 0000000000..e33b4cdcb8
--- /dev/null
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/widgets/WidgetPostMessageAPIProvider.kt
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2020 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package im.vector.matrix.android.internal.session.widgets
+
+import android.content.Context
+import timber.log.Timber
+import javax.inject.Inject
+
+class WidgetPostMessageAPIProvider @Inject constructor(private val context: Context) {
+
+    private var postMessageAPIString: String? = null
+
+    fun get(): String? {
+        if (postMessageAPIString == null) {
+            postMessageAPIString = readFromAsset(context)
+        }
+        return postMessageAPIString
+    }
+
+    private fun readFromAsset(context: Context): String? {
+        return try {
+            context.assets.open("postMessageAPI.js").bufferedReader().use {
+                it.readText()
+            }
+        } catch (failure: Throwable) {
+            Timber.e(failure, "Reading postMessageAPI.js asset failed")
+            null
+        }
+    }
+}
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/task/CoroutineToCallback.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/task/CoroutineToCallback.kt
index 54c19bd86f..07ab21a743 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/task/CoroutineToCallback.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/task/CoroutineToCallback.kt
@@ -22,7 +22,9 @@ import im.vector.matrix.android.internal.extensions.foldToCallback
 import im.vector.matrix.android.internal.util.toCancelable
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.CoroutineStart
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import kotlin.coroutines.CoroutineContext
 import kotlin.coroutines.EmptyCoroutineContext
 
@@ -34,5 +36,7 @@ internal fun <T> CoroutineScope.launchToCallback(
     val result = runCatching {
         block()
     }
-    result.foldToCallback(callback)
+    withContext(Dispatchers.Main) {
+        result.foldToCallback(callback)
+    }
 }.toCancelable()