add forms

forms/client/index.js

@@ -0,0 +1,60 @@
+import WebSocket from "ws"
+
+export default class FormsClient {
+    constructor(url = "ws://localhost:4001") {
+        this.url = url
+        this.ws = null
+        this.seq = 0
+        this.handlers = new Map()
+    }
+
+    connect() {
+        this.ws = new WebSocket(this.url)
+
+        this.ws.on("message", msg => this._onMessage(msg))
+        this.ws.on("open", () => console.log("[forms] connected"))
+        this.ws.on("close", () => console.log("[forms] disconnected"))
+    }
+
+    append(form, data) {
+        this.ws.send(JSON.stringify({
+            op: "append",
+            form,
+            data
+        }))
+    }
+
+    watch(form, handler) {
+        if (!this.handlers.has(form)) {
+            this.handlers.set(form, new Set())
+        }
+
+        this.handlers.get(form).add(handler)
+
+        this.ws.send(JSON.stringify({
+            op: "replay",
+            form,
+            fromSeq: this.seq
+        }))
+    }
+
+    _onMessage(raw) {
+        const msg = JSON.parse(raw.toString())
+
+        if (msg.type === "hello") {
+            this.seq = msg.seq
+            return
+        }
+
+        if (msg.type === "form:update") {
+            this.seq = msg.seq
+
+            const set = this.handlers.get(msg.form)
+            if (set) {
+                for (const fn of set) {
+                    fn(msg.data, msg)
+                }
+            }
+        }
+    }
+}