implement udn-frontend package

node_modules/udn-frontend/index.ts

@@ -0,0 +1,72 @@
+export interface Message {
+  // subscribing to channel
+  subscribeChannel?: string;
+  unsubscribeChannel?: string;
+
+  //sending message
+  messageChannel?: string;
+  messageBody?: string;
+}
+
+export default class UDNFrontend {
+  private ws: WebSocket | undefined;
+
+  // handlers
+  private connectionHandler = () => {};
+  private disconnectionHandler = () => {};
+  private messageHandler = (data: Message) => {};
+
+  // init
+  set onconnect(handler: () => void) {
+    this.connectionHandler = handler;
+  }
+  set ondisconnect(handler: () => void) {
+    this.disconnectionHandler = handler;
+  }
+  set onmessage(handler: (data: Message) => void) {
+    this.messageHandler = handler;
+  }
+
+  // utility methods
+  private send(messageObject: Object): boolean {
+    if (this.ws == undefined) return false;
+
+    const messageString = JSON.stringify(messageObject);
+    this.ws.send(messageString);
+    return true;
+  }
+
+  // public methods
+  connect(address: string): void {
+    this.ws = new WebSocket(address);
+    this.ws.addEventListener("open", this.connectionHandler);
+    this.ws.addEventListener("close", this.disconnectionHandler);
+    this.ws.addEventListener("message", (message) => {
+      const dataString = message.data.toString();
+      const data = JSON.parse(dataString);
+      this.messageHandler(data);
+    });
+  }
+
+  sendMessage(channel: string, body: string): boolean {
+    const messageObject = {
+      messageChannel: channel,
+      messageBody: body,
+    };
+    return this.send(messageObject);
+  }
+
+  subscribe(channel: string): boolean {
+    const messageObject = {
+      subscribeChannel: channel,
+    };
+    return this.send(messageObject);
+  }
+
+  unsubscribe(channel: string): boolean {
+    const messageObject = {
+      unsubscribeChannel: channel,
+    };
+    return this.send(messageObject);
+  }
+}