lib/irc: add CapRegistry

lib/irc.js

@@ -794,3 +794,67 @@ export function parseURL(str) {
 
 	return { host, enttype, entity };
 }
+
+export class CapRegistry {
+	available = new Map();
+	enabled = new Set();
+
+	addAvailable(s) {
+		let l = s.split(" ");
+		l.forEach((s) => {
+			let i = s.indexOf("=");
+			let k = s, v = "";
+			if (i >= 0) {
+				k = s.slice(0, i);
+				v = s.slice(i + 1);
+			}
+			this.available.set(k.toLowerCase(), v);
+		});
+	}
+
+	parse(msg) {
+		if (msg.command !== "CAP") {
+			return;
+		}
+
+		let subCmd = msg.params[1];
+		let args = msg.params.slice(2);
+		switch (subCmd) {
+		case "LS":
+			this.addAvailable(args[args.length - 1]);
+			break;
+		case "NEW":
+			this.addAvailable(args[0]);
+			break;
+		case "DEL":
+			args[0].split(" ").forEach((cap) => {
+				cap = cap.toLowerCase();
+				this.available.delete(cap);
+				this.enabled.delete(cap);
+			});
+			break;
+		case "ACK":
+			// TODO: handle `ACK -cap` to
+			args[0].split(" ").forEach((cap) => {
+				cap = cap.toLowerCase();
+				if (cap.startsWith("-")) {
+					this.enabled.delete(cap.slice(1));
+				} else {
+					this.enabled.add(cap);
+				}
+			});
+			break;
+		}
+	}
+
+	requestAvailable(l) {
+		l = l.filter((cap) => {
+			return this.available.has(cap) && !this.enabled.has(cap);
+		});
+
+		if (l.length === 0) {
+			return null;
+		}
+		return { command: "CAP", params: ["REQ", l.join(" ")] };
+	}
+}