Started code review + some fixes (unfinished)

[vchess.git] / server / sockets.js

const url = require('url');

// Node version in Ubuntu 16.04 does not know about URL class
// NOTE: url is already transformed, without ?xxx=yyy... parts
function getJsonFromUrl(url)
{
  const query = url.substr(2); //starts with "/?"
  let result = {};
  query.split("&").forEach((part) => {
    const item = part.split("=");
    result[item[0]] = decodeURIComponent(item[1]);
  });
  return result;
}

// Helper to safe-send some message through a (web-)socket:
function send(socket, message)
{
  if (!!socket && socket.readyState == 1)
    socket.send(JSON.stringify(message));
}

module.exports = function(wss) {
  // Associative array page --> sid --> tmpId --> socket
  // "page" is either "/" for hall or "/game/some_gid" for Game,
  // tmpId is required if a same user (browser) has different tabs
  let clients = {};
  wss.on("connection", (socket, req) => {
    const query = getJsonFromUrl(req.url);
    const sid = query["sid"];
    const tmpId = query["tmpId"];
    const page = query["page"];
    const notifyRoom = (page,code,obj={}) => {
      if (!clients[page])
        return;
      Object.keys(clients[page]).forEach(k => {
        Object.keys(clients[page][k]).forEach(x => {
          if (k == sid && x == tmpId)
            return;
          send(clients[page][k][x], Object.assign({code:code, from:sid}, obj));
        });
      });
    };
    const deleteConnexion = () => {
      if (!clients[page] || !clients[page][sid] || !clients[page][sid][tmpId])
        return; //job already done
      delete clients[page][sid][tmpId];
      if (Object.keys(clients[page][sid]).length == 0)
      {
        delete clients[page][sid];
        if (Object.keys(clients[page]) == 0)
          delete clients[page];
      }
    };
    const doDisconnect = () => {
      deleteConnexion();
      if (!clients[page] || !clients[page][sid])
      {
        // I effectively disconnected from this page:
        notifyRoom(page, "disconnect");
        if (page.indexOf("/game/") >= 0)
          notifyRoom("/", "gdisconnect", {page:page});
      }
    };
    const messageListener = (objtxt) => {
      let obj = JSON.parse(objtxt);
      switch (obj.code)
      {
        // Wait for "connect" message to notify connection to the room,
        // because if game loading is slow the message listener might
        // not be ready too early.
        case "connect":
        {
          notifyRoom(page, "connect");
          if (page.indexOf("/game/") >= 0)
            notifyRoom("/", "gconnect", {page:page});
          break;
        }
        case "disconnect":
          // When page changes:
          doDisconnect();
          break;
        case "killme":
        {
          // Self multi-connect: manual removal + disconnect
          const doKill = (pg) => {
            Object.keys(clients[pg][obj.sid]).forEach(x => {
              send(clients[pg][obj.sid][x], {code: "killed"});
            });
            delete clients[pg][obj.sid];
          };
          const disconnectFromOtherConnexion = (pg,code,o={}) => {
            Object.keys(clients[pg]).forEach(k => {
              if (k != obj.sid)
              {
                Object.keys(clients[pg][k]).forEach(x => {
                  send(clients[pg][k][x], Object.assign({code:code, from:obj.sid}, o));
                });
              }
            });
          };
          Object.keys(clients).forEach(pg => {
            if (!!clients[pg][obj.sid])
            {
              doKill(pg);
              disconnectFromOtherConnexion(pg, "disconnect");
              if (pg.indexOf("/game/") >= 0 && !!clients["/"])
                disconnectFromOtherConnexion("/", "gdisconnect", {page:pg});
            }
          });
          break;
        }
        case "pollclients": //from Hall or Game
        {
          let sockIds = [];
          Object.keys(clients[page]).forEach(k => {
            // Avoid polling myself: no new information to get
            if (k != sid)
              sockIds.push(k);
          });
          send(socket, {code:"pollclients", sockIds:sockIds});
          break;
        }
        case "pollclientsandgamers": //from Hall
        {
          let sockIds = [];
          Object.keys(clients["/"]).forEach(k => {
            // Avoid polling myself: no new information to get
            if (k != sid)
              sockIds.push({sid:k});
          });
          // NOTE: a "gamer" could also just be an observer
          Object.keys(clients).forEach(p => {
            if (p != "/")
            {
              Object.keys(clients[p]).forEach(k => {
                if (k != sid)
                  sockIds.push({sid:k, page:p}); //page needed for gamers
              });
            }
          });
          send(socket, {code:"pollclientsandgamers", sockIds:sockIds});
          break;
        }

        // Asking something: from is fully identified,
        // but the requested resource can be from any tmpId (except current!)
        case "askidentity":
        case "asklastate":
        case "askchallenge":
        case "askgame":
        case "askfullgame":
        {
          const pg = obj.page || page; //required for askidentity and askgame
          const tmpIds = Object.keys(clients[pg][obj.target]);
          if (obj.target == sid) //targetting myself
          {
            const idx_myTmpid = tmpIds.findIndex(x => x == tmpId);
            if (idx_myTmpid >= 0)
              tmpIds.splice(idx_myTmpid, 1);
          }
          const tmpId_idx = Math.floor(Math.random() * tmpIds.length);
          send(clients[pg][obj.target][tmpIds[tmpId_idx]], {code:obj.code, from:[sid,tmpId,page]});
          break;
        }

        // Some Hall events: target all tmpId's (except mine),
        case "refusechallenge":
        case "startgame":
          Object.keys(clients[page][obj.target]).forEach(x => {
            if (obj.target != sid || x != tmpId)
              send(clients[page][obj.target][x], {code:obj.code, data:obj.data});
          });
          break;

        // Notify all room: mostly game events
        case "newchat":
        case "newchallenge":
        case "newgame":
        case "deletechallenge":
        case "newmove":
        case "resign":
        case "abort":
        case "drawoffer":
        case "draw":
          notifyRoom(page, obj.code, {data:obj.data});
          break;

        case "result":
          // Special case: notify all, 'transroom': Game --> Hall
          notifyRoom("/", "result", {gid:obj.gid, score:obj.score});
          break;

        // Passing, relaying something: from isn't needed,
        // but target is fully identified (sid + tmpId)
        case "challenge":
        case "fullgame":
        case "game":
        case "identity":
        case "lastate":
        {
          const pg = obj.target[2] || page; //required for identity and game
          send(clients[pg][obj.target[0]][obj.target[1]], {code:obj.code, data:obj.data});
          break;
        }
      }
    };
    const closeListener = () => {
      // For browser or tab closing (including page reload):
      doDisconnect();
    };
    // Update clients object: add new connexion
    if (!clients[page])
      clients[page] = {[sid]: {[tmpId]: socket}};
    else if (!clients[page][sid])
      clients[page][sid] = {[tmpId]: socket};
    else
      clients[page][sid][tmpId] = socket;
    socket.on("message", messageListener);
    socket.on("close", closeListener);
  });
}