Add twitch chat integration

src/main/resources/static/js/broadcast/twitchChat.js

@@ -0,0 +1,121 @@
+const TWITCH_IRC_URL = "wss://irc-ws.chat.twitch.tv:443";
+const ANON_PREFIX = "justinfan";
+const ANON_PASSWORD = "SCHMOOPIIE";
+
+const buildAnonymousNick = () => {
+    const suffix = Math.floor(Math.random() * 100000)
+        .toString()
+        .padStart(5, "0");
+    return `${ANON_PREFIX}${suffix}`;
+};
+
+const parseTags = (rawTags) => {
+    if (!rawTags) {
+        return {};
+    }
+
+    return rawTags.split(";").reduce((acc, entry) => {
+        const [key, value = ""] = entry.split("=");
+        acc[key] = value;
+        return acc;
+    }, {});
+};
+
+const parseIrcMessage = (rawLine) => {
+    let line = rawLine;
+    let tags = {};
+    let prefix = "";
+
+    if (line.startsWith("@")) {
+        const spaceIndex = line.indexOf(" ");
+        tags = parseTags(line.slice(1, spaceIndex));
+        line = line.slice(spaceIndex + 1);
+    }
+
+    if (line.startsWith(":")) {
+        const spaceIndex = line.indexOf(" ");
+        prefix = line.slice(1, spaceIndex);
+        line = line.slice(spaceIndex + 1);
+    }
+
+    const commandEnd = line.indexOf(" ");
+    const command = commandEnd === -1 ? line : line.slice(0, commandEnd);
+    const params = commandEnd === -1 ? "" : line.slice(commandEnd + 1);
+
+    return {
+        command,
+        params,
+        prefix,
+        tags,
+    };
+};
+
+const extractChatMessage = (ircMessage) => {
+    if (ircMessage.command !== "PRIVMSG") {
+        return null;
+    }
+
+    const messageSplit = ircMessage.params.split(" :");
+    const channel = messageSplit[0]?.trim() || "";
+    const message = messageSplit.slice(1).join(" :");
+    const displayName = ircMessage.tags["display-name"] || ircMessage.prefix.split("!")[0];
+
+    return {
+        channel,
+        displayName,
+        message,
+    };
+};
+
+export const connectTwitchChat = (channelName, onMessage = console.log) => {
+    if (!channelName) {
+        console.warn("Twitch chat connection skipped: missing channel name");
+        return () => {};
+    }
+
+    const normalizedChannel = channelName.toLowerCase();
+    const nick = buildAnonymousNick();
+    const socket = new WebSocket(TWITCH_IRC_URL);
+
+    socket.addEventListener("open", () => {
+        socket.send(`PASS ${ANON_PASSWORD}`);
+        socket.send(`NICK ${nick}`);
+        socket.send("CAP REQ :twitch.tv/tags twitch.tv/commands");
+        socket.send(`JOIN #${normalizedChannel}`);
+    });
+
+    socket.addEventListener("message", (event) => {
+        const lines = String(event.data).split("\r\n").filter(Boolean);
+
+        lines.forEach((line) => {
+            if (line.startsWith("PING")) {
+                const payload = line.split(" ")[1] || ":tmi.twitch.tv";
+                socket.send(`PONG ${payload}`);
+                return;
+            }
+
+            const parsed = parseIrcMessage(line);
+            const chatMessage = extractChatMessage(parsed);
+
+            if (chatMessage) {
+                onMessage({
+                    channel: chatMessage.channel,
+                    displayName: chatMessage.displayName,
+                    message: chatMessage.message,
+                });
+            }
+        });
+    });
+
+    socket.addEventListener("close", () => {
+        console.info(`Twitch chat connection closed for #${normalizedChannel}`);
+    });
+
+    socket.addEventListener("error", (event) => {
+        console.error("Twitch chat connection error", event);
+    });
+
+    return () => {
+        socket.close();
+    };
+};