1 files changed, 74 insertions, 1 deletions
diff --git a/ext/bg/js/backend.js b/ext/bg/js/backend.js
index 2fce4be9..ed01c8df 100644
--- a/ext/bg/js/backend.js
+++ b/ext/bg/js/backend.js
@@ -116,8 +116,10 @@ class Backend {
             ['purgeDatabase', {handler: this._onApiPurgeDatabase.bind(this), async: true}],
             ['getMedia', {handler: this._onApiGetMedia.bind(this), async: true}],
             ['log', {handler: this._onApiLog.bind(this), async: false}],
-            ['logIndicatorClear', {handler: this._onApiLogIndicatorClear.bind(this), async: false}]
+            ['logIndicatorClear', {handler: this._onApiLogIndicatorClear.bind(this), async: false}],
+            ['createActionPort', {handler: this._onApiCreateActionPort.bind(this), async: false}]
         ]);
+        this._messageHandlersWithProgress = new Map();
 
         this._commandHandlers = new Map([
             ['search', this._onCommandSearch.bind(this)],
@@ -787,8 +789,79 @@ class Backend {
         this._updateBadge();
     }
 
+    _onApiCreateActionPort(params, sender) {
+        if (!sender || !sender.tab) { throw new Error('Invalid sender'); }
+        const tabId = sender.tab.id;
+        if (typeof tabId !== 'number') { throw new Error('Sender has invalid tab ID'); }
+
+        const frameId = sender.frameId;
+        const id = yomichan.generateId(16);
+        const portName = `action-port-${id}`;
+
+        const port = chrome.tabs.connect(tabId, {name: portName, frameId});
+        try {
+            this._createActionListenerPort(port, sender, this._messageHandlersWithProgress);
+        } catch (e) {
+            port.disconnect();
+            throw e;
+        }
+
+        return portName;
+    }
+
     // Command handlers
 
+    _createActionListenerPort(port, sender, handlers) {
+        let hasStarted = false;
+
+        const onProgress = (data) => {
+            try {
+                if (port === null) { return; }
+                port.postMessage({type: 'progress', data});
+            } catch (e) {
+                // NOP
+            }
+        };
+
+        const onMessage = async ({action, params}) => {
+            if (hasStarted) { return; }
+            hasStarted = true;
+            port.onMessage.removeListener(onMessage);
+
+            try {
+                port.postMessage({type: 'ack'});
+
+                const messageHandler = handlers.get(action);
+                if (typeof messageHandler === 'undefined') {
+                    throw new Error('Invalid action');
+                }
+                const {handler, async} = messageHandler;
+
+                const promiseOrResult = handler(params, sender, onProgress);
+                const result = async ? await promiseOrResult : promiseOrResult;
+                port.postMessage({type: 'complete', data: result});
+            } catch (e) {
+                if (port !== null) {
+                    port.postMessage({type: 'error', data: e});
+                }
+                cleanup();
+            }
+        };
+
+        const cleanup = () => {
+            if (port === null) { return; }
+            if (!hasStarted) {
+                port.onMessage.removeListener(onMessage);
+            }
+            port.onDisconnect.removeListener(cleanup);
+            port = null;
+            handlers = null;
+        };
+
+        port.onMessage.addListener(onMessage);
+        port.onDisconnect.addListener(cleanup);
+    }
+
     _getErrorLevelValue(errorLevel) {
         switch (errorLevel) {
             case 'info': return 0;