export class RdfDbChannel {

  // lower level reconnecting websocket -- knows about message types, but not what's inside a patch body

  private ws?: WebSocket = undefined;

  private pinger?: ChannelPinger;

  private connectionId: string = "none"; // server's name for us

  private reconnectTimer?: NodeJS.Timeout = undefined;

  private messagesReceived = 0; // (non-ping messages)

  private messagesSent = 0;

  newConnection: SubEvent<void> = new SubEvent();

  serverMessage: SubEvent<{ evType: string; body: SyncgraphPatchMessage }> = new SubEvent();

  statusDisplay: SubEvent<string> = new SubEvent();

  constructor(public patchSenderUrl: string) {

    this.openConnection();

  }

  sendMessage(body: string): boolean {

    // one try, best effort, true if we think it worked

    if (!this.ws || this.ws.readyState !== this.ws.OPEN) {

      return false;

    }

    log("send patch to server, " + body.length + " bytes");

    this.ws.send(body);

    return true;

  }

  disconnect() {

    // will be followed by an autoconnect

    log("disconnect requested");

    if (this.ws !== undefined) {

      const closeHandler = this.ws.onclose?.bind(this.ws);

      if (!closeHandler) {

        throw new Error();

      }

      closeHandler(new CloseEvent("forced"));

    }

  }

  private openConnection() {

    const wsOrWss = window.location.protocol.replace("http", "ws");

    const fullUrl = wsOrWss + "//" + window.location.host + this.patchSenderUrl;

    if (this.ws !== undefined) {

      this.ws.close();

    }

    this.ws = new WebSocket(fullUrl);

    this.ws.onopen = this.onWsOpen.bind(this, this.ws);

    this.ws.onerror = this.onWsError.bind(this);

import debug from "debug";

import { parseJsonPatch, Patch } from "./patch";

import { RdfDbChannel } from "./RdfDbChannel";

export class RdfDbClient {

  private channel: RdfDbChannel;

  _patchesToSend: Patch[];

  // Send and receive patches from rdfdb. Primarily used in SyncedGraph.

  //

  // What this should do, and does not yet, is keep the graph

  // 'coasting' over a reconnect, applying only the diffs from the old

  // contents to the new ones once they're in. Then, remove all the

  // clearGraph stuff in graph.coffee that doesn't even work right.

  //

  constructor(

    patchSenderUrl: string,

    private clearGraphOnNewConnection: () => void,

    private applyPatch: (p: Patch) => void,

    setStatus: (status: string) => void

  ) {

    this._patchesToSend = [];

    this.channel = new RdfDbChannel(patchSenderUrl);

    this.channel.statusDisplay.subscribe((st: string) => {

      setStatus(st + `; ${this._patchesToSend.length} pending `);

    });

    this.channel.newConnection.subscribe(() => {

      this.clearGraphOnNewConnection();

    });

    this.channel.serverMessage.subscribe((m) => {

      parseJsonPatch(m.body, (p: Patch) => {

        log('patch from server:', p.dump())

        if (p.isEmpty()) {

          return;

        }

        this.applyPatch(p);

      });

    });

  }

  sendPatch(patch: Patch) {

    log("queue patch to server ", patch.summary());

    this._patchesToSend.push(patch);

    this._continueSending();

  }

  disconnect() {

    this.channel.disconnect();

  }

  async _continueSending() {

    // we could call this less often and coalesce patches together to optimize

    while (this._patchesToSend.length) {

      const patch = this._patchesToSend.splice(0, 1)[0];

      const json = await patch.toJsonPatch();

      const ret = this.channel.sendMessage(json);

      if (!ret) {

        setTimeout(this._continueSending.bind(this), 500);

        // this.disconnect()

        return;

      }

    }

  }

}