core ran in a worker thread

src/App/App.js

@@ -5,24 +5,22 @@ const React = require('react');
 const { Router } = require('stremio-router');
 const { Core, Shell, Chromecast, KeyboardShortcuts, ServicesProvider } = require('stremio/services');
 const { NotFound } = require('stremio/routes');
-const { ToastProvider, sanitizeLocationPath, CONSTANTS } = require('stremio/common');
+const { ToastProvider, CONSTANTS } = require('stremio/common');
 const CoreEventsToaster = require('./CoreEventsToaster');
 const ErrorDialog = require('./ErrorDialog');
 const routerViewsConfig = require('./routerViewsConfig');
 const styles = require('./styles');
 
-window.core_imports = {
-    app_version: process.env.VERSION,
-    shell_version: null,
-    sanitize_location_path: sanitizeLocationPath
-};
-
 const App = () => {
     const onPathNotMatch = React.useCallback(() => {
         return NotFound;
     }, []);
     const services = React.useMemo(() => ({
-        core: new Core(),
+        core: new Core({
+            baseURI: document.baseURI,
+            appVersion: process.env.VERSION,
+            shellVersion: null
+        }),
         shell: new Shell(),
         chromecast: new Chromecast(),
         keyboardShortcuts: new KeyboardShortcuts()

src/services/Core/Core.js

@@ -3,7 +3,7 @@
 const EventEmitter = require('eventemitter3');
 const CoreTransport = require('./CoreTransport');
 
-function Core() {
+function Core(args) {
     let active = false;
     let error = null;
     let starting = false;
@@ -66,7 +66,7 @@ function Core() {
         }
 
         starting = true;
-        transport = new CoreTransport();
+        transport = new CoreTransport(args);
         transport.on('init', onTransportInit);
         transport.on('error', onTransportError);
         onStateChanged();

src/services/Core/CoreTransport.js

@@ -1,19 +1,22 @@
 // Copyright (C) 2017-2022 Smart code 203358507
 
 const EventEmitter = require('eventemitter3');
-const { default: initialize_api, initialize_runtime, get_state, get_debug_state, dispatch, analytics, decode_stream } = require('@stremio/stremio-core-web');
+const Bridge = require('./bridge');
 
-function CoreTransport() {
+function CoreTransport(args) {
     const events = new EventEmitter();
+    const worker = new Worker(`${process.env.COMMIT_HASH}/scripts/worker.js`);
+    const bridge = new Bridge(worker, window);
 
-    initialize_api(require('@stremio/stremio-core-web/stremio_core_web_bg.wasm'))
-        .then(() => initialize_runtime(({ name, args }) => {
-            try {
-                events.emit(name, args);
-            } catch (error) {
-                console.error('CoreTransport', error);
-            }
-        }))
+    window.onCoreEvent = ({ name, args }) => {
+        try {
+            events.emit(name, args);
+        } catch (error) {
+            console.error('CoreTransport', error);
+        }
+    };
+
+    bridge.call(['init'], [args])
         .then(() => {
             try {
                 events.emit('init');
@@ -35,27 +38,19 @@ function CoreTransport() {
         events.removeAllListeners();
     };
     this.getState = async function(field) {
-        return Promise.resolve(get_state(field));
+        return bridge.call(['getState'], [field]);
     };
-    this.getDebugState = function() {
-        return get_debug_state();
+    this.getDebugState = async function() {
+        return bridge.call(['getDebugState'], []);
     };
-    this.dispatch = function(action, field) {
-        try {
-            dispatch(action, field);
-        } catch (error) {
-            console.error('CoreTransport', error);
-        }
+    this.dispatch = async function(action, field) {
+        return bridge.call(['dispatch'], [action, field, location.hash]);
     };
-    this.analytics = function(event) {
-        try {
-            analytics(event);
-        } catch (error) {
-            console.error('CoreTransport', error);
-        }
+    this.analytics = async function(event) {
+        return bridge.call(['analytics'], [event, location.hash]);
     };
-    this.decodeStream = function(stream) {
-        return decode_stream(stream);
+    this.decodeStream = async function(stream) {
+        return bridge.call(['decodeStream'], [stream]);
     };
 }
 

src/services/Core/bridge.js

@@ -0,0 +1,45 @@
+function getId() {
+    return Math.random().toString(32).slice(2);
+}
+
+function Bridge(context, scope) {
+    context.addEventListener('message', async ({ data: { request } }) => {
+        if (!request) return;
+
+        const { id, path, args } = request;
+        try {
+            const object = path.reduce((obj, prop) => obj[prop], scope);
+            let data;
+            if (typeof object === 'function') {
+                const thisArg = path.slice(0, path.length - 1).reduce((obj, prop) => obj[prop], scope);
+                data = await object.apply(thisArg, args);
+            } else {
+                data = await object;
+            }
+
+            context.postMessage({ response: { id, result: { data } } });
+        } catch (error) {
+            context.postMessage({ response: { id, result: { error } } });
+        }
+    });
+
+    this.call = async (path, args) => {
+        const id = getId();
+        return new Promise((resolve, reject) => {
+            const onMessage = ({ data: { response } }) => {
+                if (!response || response.id !== id) return;
+
+                context.removeEventListener('message', onMessage);
+                if ('error' in response.result) {
+                    reject(response.result.error);
+                } else {
+                    resolve(response.result.data);
+                }
+            };
+            context.addEventListener('message', onMessage);
+            context.postMessage({ request: { id, path, args } });
+        });
+    };
+}
+
+module.exports = Bridge;

src/services/Core/worker.js

@@ -0,0 +1,23 @@
+const sanitizeLocationPath = require('stremio/common/sanitizeLocationPath');
+const Bridge = require('./bridge');
+
+const bridge = new Bridge(self, self);
+
+self.init = async ({ baseURI, appVersion, shellVersion }) => {
+    self.document = { baseURI };
+    self.app_version = appVersion;
+    self.shell_version = shellVersion;
+    self.sanitize_location_path = sanitizeLocationPath;
+    self.get_location_hash = async () => bridge.call(['location', 'hash'], []);
+    self.local_storage_get_item = async (key) => bridge.call(['localStorage', 'getItem'], [key]);
+    self.local_storage_set_item = async (key, value) => bridge.call(['localStorage', 'setItem'], [key, value]);
+    self.local_storage_remove_item = async (key) => bridge.call(['localStorage', 'removeItem'], [key]);
+    const { default: initialize_api, initialize_runtime, get_state, get_debug_state, dispatch, analytics, decode_stream } = require('@stremio/stremio-core-web');
+    self.getState = get_state;
+    self.getDebugState = get_debug_state;
+    self.dispatch = dispatch;
+    self.analytics = analytics;
+    self.decodeStream = decode_stream;
+    await initialize_api(require('@stremio/stremio-core-web/stremio_core_web_bg.wasm'));
+    await initialize_runtime((event) => bridge.call(['onCoreEvent'], [event]));
+};

webpack.config.js

@@ -15,7 +15,10 @@ const COMMIT_HASH = execSync('git rev-parse HEAD').toString().trim();
 module.exports = (env, argv) => ({
     mode: argv.mode,
     devtool: argv.mode === 'production' ? 'source-map' : 'eval-source-map',
-    entry: './src/index.js',
+    entry: {
+        main: './src/index.js',
+        worker: './src/services/Core/worker.js'
+    },
     output: {
         path: path.join(__dirname, 'build'),
         filename: `${COMMIT_HASH}/scripts/[name].js`