Restore opened user query buffers

Closes: https://todo.sr.ht/~emersion/gamja/93

store.js

@@ -35,3 +35,71 @@ export const receipts = {
 		rawReceipts.put(Object.fromEntries(m));
 	},
 };
+
+export class Buffer {
+	raw = new Item("buffers");
+	m = null;
+
+	constructor() {
+		var obj = this.raw.load();
+		this.m = new Map(Object.entries(obj || {}));
+	}
+
+	key(buf) {
+		return JSON.stringify({
+			name: buf.name,
+			server: {
+				url: buf.server.url,
+				nick: buf.server.nick,
+				bouncerNetwork: buf.server.bouncerNetwork,
+			},
+		});
+	}
+
+	save() {
+		if (this.m.size > 0) {
+			this.raw.put(Object.fromEntries(this.m));
+		} else {
+			this.raw.put(null);
+		}
+	}
+
+	put(buf) {
+		this.m.set(this.key(buf), {
+			name: buf.name,
+			server: {
+				url: buf.server.url,
+				nick: buf.server.nick,
+				bouncerNetwork: buf.server.bouncerNetwork,
+			},
+		});
+		this.save();
+	}
+
+	delete(buf) {
+		this.m.delete(this.key(buf));
+		this.save();
+	}
+
+	load(server) {
+		let buffers = [];
+		for (const buf of this.m.values()) {
+			if (buf.server.url !== server.url || buf.server.nick !== server.nick || buf.server.bouncerNetwork !== server.bouncerNetwork) {
+				continue;
+			}
+			buffers.push(buf);
+		}
+		return buffers;
+	}
+
+	clear(server) {
+		if (server) {
+			for (const buf of this.load(server)) {
+				this.m.delete(this.key(buf));
+			}
+		} else {
+			this.m = new Map();
+		}
+		this.save();
+	}
+}