// defines:
// variable ws (the websocket)
// variable wsReady (boolean)
// variable wsVerbose (boolean)
// wsSend(msg) (send a message when websocket is ready)
// wsOnMessage(function(event) {...}) (react to messages)
// wsOnOpen(function() {}) (react to opening of websocket)
sclass HInitWebSocket {
  S wsVar = "ws"; // TODO: not used everywhere
  S readyMsg = "WebSocket ready!";
  bool handleEvals = true; // automatically handle {"eval":"jsCode();"}
  bool wsVerbose = true; // now defaults to true (it's just so useful)
  bool autoOpen = true; // open websocket immediately - otherwise call ws.open() later
  
  new MapSO params;
  
  // appended to URL it it's not the first connect
  S reconnectParams = "reconnect=1";
  
  *() {}
  *(IWebRequest req) {
    if (req != null && eq(req.get("wsVerbose"), "1"))
      set wsVerbose;
  }
  
  public S headStuff aka get aka toString() {
    ret hreconnectingWebSockets() + hscript(js());
  }
  
  LS dependencies() {
    ret ll(hjssnippet(hreconnectingWebSockets_snippetID(), "data-comment" := "ReconnectingWebSocket"));
  }
  
  S js() {
    ret jsDollarVars([[
      var wsReady = false;
      var wsInitialMsgs = [];
      var wsMsgListeners = [];
      var wsOpenListeners = [];
      var wsWillReconnectListeners = [];
      var wsVerbose = $wsVerbose;
      var wsConnectionCount = 0;
      var wsAugmentURL = function(url) { return url; };
      var wsURL = ((window.location.protocol === "https:") ? "wss://" : "ws://") + window.location.host
        + window.location.pathname + window.location.search;
      if ($params != "")
        wsURL += (wsURL.match(/\?/) ? "&" : "?") + $params;
        
      var $wsVar = new ReconnectingWebSocket(wsURL, null, $options);
      
      $wsVar.onopen = function(event) {
        wsReady = true;
        console.log($readyMsg + " " + ws.url);
        
        if (++wsConnectionCount == 1)
          if ($reconnectParams != "") {
            wsURL += (wsURL.match(/\?/) ? "&" : "?") + $reconnectParams;
            ws.url = wsAugmentURL(wsURL);
          }

        wsOpenListeners.forEach(function(f) { f(); });

        ws.onmessage = function(event) {
          if (wsVerbose) console.log("Got msg: " + event.data.substring(0, 200));
          wsMsgListeners.forEach(function(listener) {
            listener(event);
          });
        };
        
        ws.onclose = function(event) {
          if (wsVerbose) console.log("WebSocket closed");
          wsReady = false;
        };

        wsInitialMsgs.forEach(function(msg) {
          if (wsVerbose) console.log("Sending initial msg: " + msg);
          ws.send(msg);
        });
        wsInitialMsgs = [];
        if (wsVerbose) console.log("Cleared initial msgs");
      };
      
      // send it now if ws is open already or when ws was opened
      function wsSend(msg) {
        if (wsReady) {
          if (wsVerbose) console.log("Sending msg: " + msg);
          ws.send(msg); // TODO: wsReady = false on failed send?
          return;
        } else {
          if (wsVerbose) console.log("Scheduling msg: " + msg);
          wsInitialMsgs.push(msg);
        }
      }
      
      function wsOnOpen(f) {
        wsOpenListeners.push(f);      
      }
      
      function wsOnMessage(f) {
        wsMsgListeners.push(f);      
      }
      
      function wsSetAugmentURL(f) {
        wsAugmentURL = f;
        if (ws) ws.url = wsAugmentURL(wsURL);
      }
      
      ]], wsVar := JS(wsVar), +wsVerbose, +readyMsg,
        params := makePostData(params),
        reconnectParams := unnull(reconnectParams),
        +options())
    + (!handleEvals ? "" : "wsOnMessage(" + js_evalOnWebSocketMessage() + ");\n");
  }
  
  Map options() {
    ret litorderedmap(
      automaticOpen := autoOpen ? null : false
    );
  }
}

Began life as a copy of #1029959