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)
                }
            }
        }
    }
}