116 lines
2.9 KiB
JavaScript
116 lines
2.9 KiB
JavaScript
"use strict";
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/**
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* Client class that implements the InstantChat protocol using WebSockets.
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*
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* Dispatches the following events which can be subscribed/unsubscribed using .on() and .off():
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* - initialized: Connection to server has been established and initialized, ready to send messages.
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* - disconnected: Connection has been closed.
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* - connectionError: Some connection error occurred.
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* - receivedMessage: Chat message has been received. Data: object {from: 'username', text: 'text'}
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*/
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class Client extends EventDispatcher {
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constructor(wsUri) {
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super();
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this.wsUri = wsUri;
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// Create WebSocket and set internal callbacks
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console.log("Initialize Client...")
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this.webSocket = new WebSocket(wsUri);
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this.webSocket.onopen = this._onSocketOpen.bind(this);
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this.webSocket.onclose = this._onSocketClose.bind(this);
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this.webSocket.onerror = this._onSocketError.bind(this);
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this.webSocket.onmessage = this._onSocketMessage.bind(this);
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}
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// Internal WebSocket event handlers
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_onSocketOpen(evt) {
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console.log("Connected to " + this.wsUri);
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this.sendInit();
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}
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_onSocketClose(evt) {
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console.log("Connection closed (code " + evt.code + ").");
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this.dispatch("disconnected");
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}
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_onSocketError(evt) {
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console.error("Connection error: ", evt);
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this.dispatch("connectionError");
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}
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_onSocketMessage(evt) {
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console.log("Received: " + evt.data);
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this._parseMessage(evt.data);
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}
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/**
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* Sends an arbitrary command as JSON.
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*
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* commandObj: The command as an object ('action' specifies type of command).
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*/
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sendCommand(commandObj) {
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const commandJson = JSON.stringify(commandObj);
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console.log("Sending command: " + commandJson);
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this.webSocket.send(commandJson);
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}
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/**
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* Sends the 'init' command which sets up the session. Also sets the chat ID and nickname.
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*/
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sendInit() {
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this.sendCommand({
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action: "init",
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chat_id: "42",
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nickname: "binaryDiv",
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});
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}
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/**
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* Sends the 'message' command which sends a chat message to the chat.
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*
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* msgText: The text of the chat message.
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*/
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sendChatMessage(msgText) {
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this.sendCommand({
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action: "message",
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text: msgText,
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});
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}
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/**
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* Parses an incoming JSON message and dispatches specific events.
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*/
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_parseMessage(msgString) {
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try {
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const msg = JSON.parse(msgString);
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switch (msg.type) {
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// Response to 'init' command (doesn't have much content, I guess)
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case "init":
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console.log("Got init response: ", msg);
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this.dispatch("initialized");
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break;
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// Incoming chat message
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case "message":
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console.log("Received chat message from '" + msg.from + "', text '" + msg.text + "'");
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this.dispatch("receivedMessage", {
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from: msg.from,
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text: msg.text,
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});
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break;
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// TODO Topic change, user join/leave, error, ...
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default:
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console.error("Unknown message type '" + msg.type + "'");
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}
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}
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catch (e) {
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console.error("Error parsing message JSON: " + e.message);
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}
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}
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}
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