worker.js

var fs = require('fs');
var _ = require('lodash');
var express = require('express');
var serveStatic = require('serve-static');
var path = require('path');
var morgan = require('morgan');
var healthChecker = require('sc-framework-health-check');
var StateManager = require('./state-manager').StateManager;
var uuid = require('uuid');
var ChannelGrid = require('./public/channel-grid').ChannelGrid;
var Util = require('./util').Util;
var SAT = require('sat');
var rbush = require('rbush');
var scCodecMinBin = require('sc-codec-min-bin');

var config = require('./config');
var CellController = require('./cell');

var PIXEL_SCALE = config.PIXEL_SCALE;
var TILE_SIZE = config.TILE_SIZE;
var LEVEL_SIZE = config.LEVEL_SIZE;
var BEACH_SIZE = config.BEACH_SIZE;
var WORLD_WIDTH = config.WORLD_WIDTH;
var WORLD_HEIGHT = config.WORLD_HEIGHT;
var WORLD_CELL_WIDTH = config.WORLD_CELL_WIDTH;
var WORLD_CELL_HEIGHT = config.WORLD_CELL_HEIGHT;
var WORLD_COLS = Math.ceil(WORLD_WIDTH / WORLD_CELL_WIDTH);
var WORLD_ROWS = Math.ceil(WORLD_HEIGHT / WORLD_CELL_HEIGHT);
var WORLD_CELLS = WORLD_COLS * WORLD_ROWS;
var WORLD_CELL_OVERLAP_DISTANCE = config.WORLD_CELL_OVERLAP_DISTANCE;
var WORLD_UPDATE_INTERVAL = config.WORLD_UPDATE_INTERVAL;
var WORLD_STALE_TIMEOUT = config.WORLD_STALE_TIMEOUT;
var SPECIAL_UPDATE_INTERVALS = config.SPECIAL_UPDATE_INTERVALS;

var PLAYER_DIAMETER = config.PLAYER_DIAMETER;
var PLAYER_MASS = config.PLAYER_MASS;

var OUTBOUND_STATE_TRANSFORMERS = config.OUTBOUND_STATE_TRANSFORMERS;

var CHANNEL_INBOUND_CELL_PROCESSING = 'internal/cell-processing-inbound';
var CHANNEL_CELL_TRANSITION = 'internal/cell-transition';

var game = {
  stateRefs: {}
};

function getRandomPosition(spriteWidth, spriteHeight) {
  var halfSpriteWidth = spriteWidth / 2;
  var halfSpriteHeight = spriteHeight / 2;
  var widthRandomness = WORLD_WIDTH - spriteWidth;
  var heightRandomness = BEACH_SIZE * 16 * 5 - spriteHeight;
  return {
    x: Math.round(halfSpriteWidth + widthRandomness * Math.random()),
    y: WORLD_HEIGHT - Math.round(halfSpriteHeight + heightRandomness * Math.random())
  };
}

module.exports.run = function (worker) {
  console.log('   >> Worker PID:', process.pid);

  // We use a codec for SC to compress messages between clients and the server
  // to a lightweight binary format to reduce bandwidth consumption.
  // We should probably make our own codec (on top of scCodecMinBin) to compress
  // world-specific entities. For example, instead of emitting the JSON:
  // {id: '...', width: 200, height: 200}
  // We could compress it down to something like: {id: '...', w: 200, h: 200, c: 1000}
  worker.scServer.setCodecEngine(scCodecMinBin);

  var environment = worker.options.environment;
  var serverWorkerId = worker.options.instanceId + ':' + worker.id;

  var app = express();

  var httpServer = worker.httpServer;
  var scServer = worker.scServer;

  if (environment == 'dev') {
    // Log every HTTP request. See https://github.com/expressjs/morgan for other
    // available formats.
    app.use(morgan('dev'));
  }
  app.use(serveStatic(path.resolve(__dirname, 'public')));

  // Add GET /health-check express route
  healthChecker.attach(worker, app);

  httpServer.on('request', app);

  scServer.addMiddleware(scServer.MIDDLEWARE_SUBSCRIBE, function (req, next) {
    if (req.channel.indexOf('internal/') == 0) {
      var err = new Error('Clients are not allowed to subscribe to the ' + req.channel + ' channel.');
      err.name = 'ForbiddenSubscribeError';
      next(err);
    } else {
      next();
    }
  });

  scServer.addMiddleware(scServer.MIDDLEWARE_PUBLISH_IN, function (req, next) {
    // Only allow clients to publish to channels whose names start with 'external/'
    if (req.channel.indexOf('external/') == 0) {
      next();
    } else {
      var err = new Error('Clients are not allowed to publish to the ' + req.channel + ' channel.');
      err.name = 'ForbiddenPublishError';
      next(err);
    }
  });

  // This allows us to break up our channels into a grid of cells which we can
  // watch and publish to individually.
  // It handles most of the data distribution automatically so that it reaches
  // the intended cells.
  var channelGrid = new ChannelGrid({
    worldWidth: WORLD_WIDTH,
    worldHeight: WORLD_HEIGHT,
    cellOverlapDistance: WORLD_CELL_OVERLAP_DISTANCE,
    rows: WORLD_ROWS,
    cols: WORLD_COLS,
    exchange: scServer.exchange
  });

  var stateManager = new StateManager({
    stateRefs: game.stateRefs,
    channelGrid: channelGrid
  });

  if (WORLD_CELLS % worker.options.workers != 0) {
    var errorMessage = 'The number of cells in your world (determined by WORLD_WIDTH, WORLD_HEIGHT, WORLD_CELL_WIDTH, WORLD_CELL_HEIGHT)' +
      ' should share a common factor with the number of workers or else the workload might get duplicated for some cells.';
    console.error(errorMessage);
  }

  var cellsPerWorker = WORLD_CELLS / worker.options.workers;

  var cellData = {};
  var cellPendingDeletes = {};
  var cellExternalStates = {};

  var util = new Util({
    cellData: cellData
  });

  var cellControllers = {};
  var updateIntervals = {};
  var cellSpecialIntervalTypes = {};

  for (var h = 0; h < cellsPerWorker; h++) {
    var cellIndex = worker.id + h * worker.options.workers;
    cellData[cellIndex] = {};
    cellPendingDeletes[cellIndex] = {};
    cellExternalStates[cellIndex] = {};

    cellControllers[cellIndex] = new CellController({
      cellIndex: cellIndex,
      cellData: cellData[cellIndex],
      cellBounds: channelGrid.getCellBounds(cellIndex),
      worker: worker
    }, util);

    channelGrid.watchCellAtIndex(CHANNEL_INBOUND_CELL_PROCESSING, cellIndex, gridCellDataHandler.bind(null, cellIndex));
    channelGrid.watchCellAtIndex(CHANNEL_CELL_TRANSITION, cellIndex, gridCellTransitionHandler.bind(null, cellIndex));
  }

  function applyOutboundStateTransformer(state) {
    var type = state.type;
    if (OUTBOUND_STATE_TRANSFORMERS[type]) {
      return OUTBOUND_STATE_TRANSFORMERS[type](state);
    }
    return state;
  }

  function setUpdateIntervals(intervalMap) {
    Object.keys(intervalMap).forEach(function (interval) {
      var intervalNumber = parseInt(interval);

      intervalMap[interval].forEach(function (type) {
        cellSpecialIntervalTypes[type] = true;
      });

      updateIntervals[interval] = setInterval(function () {
        var transformedStateList = [];

        Object.keys(cellData).forEach(function (cellIndex) {
          var currentCellData = cellData[cellIndex];

          intervalMap[interval].forEach(function (type) {
            Object.keys(currentCellData[type] || {}).forEach(function (id) {
              transformedStateList.push(
                applyOutboundStateTransformer(currentCellData[type][id])
              );
            });
          });
        });
        // External channel which clients can subscribe to.
        // It will publish to multiple channels based on each state's
        // (x, y) coordinates.
        if (transformedStateList.length) {
          channelGrid.publish('cell-data', transformedStateList);
        }
      }, intervalNumber);
    });
  }

  setUpdateIntervals(SPECIAL_UPDATE_INTERVALS);

  function getSimplifiedState(state) {
    return {
      type: state.type,
      x: Math.round(state.x),
      y: Math.round(state.y)
    };
  }

  function isGroupABetterThanGroupB(groupA, groupB) {
    // If both groups are the same size, the one that has the leader
    // with the lowest alphabetical id wins.
    return groupA.leader.id <= groupB.leader.id;
  }

  /*
    Groups are not passed around between cells/processes. Their purpose is to allow
    states to seamlessly interact with one another across cell boundaries.

    When one state affects another state across cell boundaries (e.g. one player
    pushing another player into a different cell), there is a slight delay for
    the position information to be shared across processes/CPU cores; as a
    result of this, the states may not show up in the exact same position in both cells.
    When two cells report slightly different positions for the same set of
    states, it may cause overlapping and flickering on the front end since the
    front end doesn't know which data to trust.

    A group allows two cells to agree on which cell is responsible for broadcasting the
    position of states that are within the group by considering the group's average position
    instead of looking at the position of member states individually.
  */
  function getStateGroups() {
    var groupMap = {};
    Object.keys(cellData).forEach(function (cellIndex) {
      if (!groupMap[cellIndex]) {
        groupMap[cellIndex] = {};
      }
      var currentCellData = cellData[cellIndex];
      var currentGroupMap = groupMap[cellIndex];
      Object.keys(currentCellData).forEach(function (type) {
        var cellDataStates = currentCellData[type] || {};
        Object.keys(cellDataStates).forEach(function (id) {
          var state = cellDataStates[id];
          if (state.group) {
            var groupSimpleStateMap = {};
            Object.keys(state.group).forEach(function (stateId) {
              groupSimpleStateMap[stateId] = state.group[stateId];
            });

            var groupStateIdList = Object.keys(groupSimpleStateMap).sort();
            var groupId = groupStateIdList.join(',');

            var leaderClone = _.cloneDeep(state);
            leaderClone.x = groupSimpleStateMap[leaderClone.id].x;
            leaderClone.y = groupSimpleStateMap[leaderClone.id].y;

            var group = {
              id: groupId,
              leader: state,
              members: [],
              size: 0,
              x: 0,
              y: 0,
            };
            var expectedMemberCount = groupStateIdList.length;

            for (var i = 0; i < expectedMemberCount; i++) {
              var memberId = groupStateIdList[i];
              var memberSimplifiedState = groupSimpleStateMap[memberId];
              var memberState = currentCellData[memberSimplifiedState.type][memberId];
              if (memberState) {
                var memberStateClone = _.cloneDeep(memberState);
                memberStateClone.x = memberSimplifiedState.x;
                memberStateClone.y = memberSimplifiedState.y;
                group.members.push(memberStateClone);
                group.x += memberStateClone.x;
                group.y += memberStateClone.y;
                group.size++;
              }
            }
            if (group.size) {
              group.x = Math.round(group.x / group.size);
              group.y = Math.round(group.y / group.size);
            }

            var allGroupMembersAreAvailableToThisCell = group.size >= expectedMemberCount;
            var existingGroup = currentGroupMap[groupId];
            if (allGroupMembersAreAvailableToThisCell &&
              (!existingGroup || isGroupABetterThanGroupB(group, existingGroup))) {

              group.tcid = channelGrid.getCellIndex(group);
              currentGroupMap[groupId] = group;
            }
          }
        });
      });
    });
    return groupMap;
  }

  function prepareStatesForProcessing(cellIndex) {
    var currentCellData = cellData[cellIndex];
    var currentCellExternalStates = cellExternalStates[cellIndex];

    Object.keys(currentCellData).forEach(function (type) {
      var cellDataStates = currentCellData[type] || {};
      Object.keys(cellDataStates).forEach(function (id) {
        var state = cellDataStates[id];

        if (state.external) {
          if (!currentCellExternalStates[type]) {
            currentCellExternalStates[type] = {};
          }
          currentCellExternalStates[type][id] = _.cloneDeep(state);
        }
      });
    });
  }

  // We should never modify states which belong to other cells or
  // else it will result in conflicts and lost states. This function
  // restores them to their pre-processed condition.
  function restoreExternalStatesBeforeDispatching(cellIndex) {
    var currentCellData = cellData[cellIndex];
    var currentCellExternalStates = cellExternalStates[cellIndex];

    Object.keys(currentCellExternalStates).forEach(function (type) {
      var externalStatesList = currentCellExternalStates[type];
      Object.keys(externalStatesList).forEach(function (id) {
        currentCellData[type][id] = externalStatesList[id];
        delete externalStatesList[id];
      });
    });
  }

  function prepareGroupStatesBeforeDispatching(cellIndex) {
    var currentCellData = cellData[cellIndex];
    var currentCellExternalStates = cellExternalStates[cellIndex];

    Object.keys(currentCellData).forEach(function (type) {
      var cellDataStates = currentCellData[type] || {};
      Object.keys(cellDataStates).forEach(function (id) {
        var state = cellDataStates[id];
        if (state.pendingGroup) {
          var serializedMemberList = {};
          Object.keys(state.pendingGroup).forEach(function (memberId) {
            var memberState = state.pendingGroup[memberId];
            serializedMemberList[memberId] = getSimplifiedState(memberState);
          });
          state.group = serializedMemberList;
          delete state.pendingGroup;
        } else if (state.group) {
          delete state.group;
        }
      });
    });
  }

  // Remove decorator functions which were added to the states temporarily
  // for use within the cell controller.
  function cleanupStatesBeforeDispatching(cellIndex) {
    var currentCellData = cellData[cellIndex];

    Object.keys(currentCellData).forEach(function (type) {
      var cellDataStates = currentCellData[type] || {};
      Object.keys(cellDataStates).forEach(function (id) {
        var state = cellDataStates[id];

        if (state.op) {
          delete state.op;
        }
      });
    });
  }

  // Main world update loop.
  setInterval(function () {
    var cellIndexList = Object.keys(cellData);
    var transformedStateList = [];

    cellIndexList.forEach(function (cellIndex) {
      cellIndex = Number(cellIndex);
      prepareStatesForProcessing(cellIndex);
      cellControllers[cellIndex].run(cellData[cellIndex]);
      prepareGroupStatesBeforeDispatching(cellIndex);
      cleanupStatesBeforeDispatching(cellIndex);
      restoreExternalStatesBeforeDispatching(cellIndex);
      dispatchProcessedData(cellIndex);
    });

    var groupMap = getStateGroups();

    cellIndexList.forEach(function (cellIndex) {
      cellIndex = Number(cellIndex);
      var currentCellData = cellData[cellIndex];
      Object.keys(currentCellData).forEach(function (type) {
        if (!cellSpecialIntervalTypes[type]) {
          var cellDataStates = currentCellData[type] || {};
          Object.keys(cellDataStates).forEach(function (id) {
            var state = cellDataStates[id];
            if (!state.group && !state.external &&
              (!cellPendingDeletes[cellIndex][type] || !cellPendingDeletes[cellIndex][type][id])) {

              transformedStateList.push(
                applyOutboundStateTransformer(state)
              );
            }
          });
        }
      });
    });

    // Deletions are processed as part of WORLD_UPDATE_INTERVAL even if
    // that type has its own special interval.
    Object.keys(cellPendingDeletes).forEach(function (cellIndex) {
      cellIndex = Number(cellIndex);
      var currentCellDeletes = cellPendingDeletes[cellIndex];
      Object.keys(currentCellDeletes).forEach(function (type) {
        var cellDeleteStates = currentCellDeletes[type] || {};
        Object.keys(cellDeleteStates).forEach(function (id) {
          // These states should already have a delete property which
          // can be used on the client-side to delete items from the view.
          transformedStateList.push(
            applyOutboundStateTransformer(cellDeleteStates[id])
          );
          delete cellDeleteStates[id];
        });
      });
    });

    Object.keys(groupMap).forEach(function (cellIndex) {
      cellIndex = Number(cellIndex);
      var currentGroupMap = groupMap[cellIndex];
      Object.keys(currentGroupMap).forEach(function (groupId) {
        var group = currentGroupMap[groupId];
        var memberList = group.members;
        if (group.tcid == cellIndex) {
          memberList.forEach(function (member) {
            transformedStateList.push(
              applyOutboundStateTransformer(member)
            );
          });
        }
      });
    });

    // External channel which clients can subscribe to.
    // It will publish to multiple channels based on each state's
    // (x, y) coordinates.
    if (transformedStateList.length) {
      channelGrid.publish('cell-data', transformedStateList);
    }

  }, WORLD_UPDATE_INTERVAL);

  function forEachStateInDataTree(dataTree, callback) {
    var typeList = Object.keys(dataTree);

    typeList.forEach(function (type) {
      var stateList = dataTree[type];
      var ids = Object.keys(stateList);

      ids.forEach(function (id) {
        callback(stateList[id]);
      });
    });
  }

  function updateStateExternalTag(state, cellIndex) {
    if (state.ccid != cellIndex || state.tcid != cellIndex) {
      state.external = true;
    } else {
      delete state.external;
    }
  }

  // Share states with adjacent cells when those states get near
  // other cells' boundaries and prepare for transition to other cells.
  // This logic is quite complex so be careful when changing any code here.
  function dispatchProcessedData(cellIndex) {
    var now = Date.now();
    var currentCellData = cellData[cellIndex];
    var workerStateRefList = {};
    var statesForNearbyCells = {};

    forEachStateInDataTree(currentCellData, function (state) {
      var id = state.id;
      var swid = state.swid;
      var type = state.type;

      if (!state.external) {
        if (state.version != null) {
          state.version++;
        }
        state.processed = now;
      }

      // The target cell id
      state.tcid = channelGrid.getCellIndex(state);

      // For newly created states (those created from inside the cell).
      if (state.ccid == null) {
        state.ccid = cellIndex;
        state.version = 1;
      }
      updateStateExternalTag(state, cellIndex);

      if (state.ccid == cellIndex) {
        var nearbyCellIndexes = channelGrid.getAllCellIndexes(state);
        nearbyCellIndexes.forEach(function (nearbyCellIndex) {
          if (!statesForNearbyCells[nearbyCellIndex]) {
            statesForNearbyCells[nearbyCellIndex] = [];
          }
          // No need for the cell to send states to itself.
          if (nearbyCellIndex != cellIndex) {
            statesForNearbyCells[nearbyCellIndex].push(state);
          }
        });

        if (state.tcid != cellIndex && swid) {
          if (!workerStateRefList[swid]) {
            workerStateRefList[swid] = [];
          }
          var stateRef = {
            id: state.id,
            swid: state.swid,
            tcid: state.tcid,
            type: state.type
          };

          if (state.delete) {
            stateRef.delete = state.delete;
          }
          workerStateRefList[swid].push(stateRef);
        }
      }

      if (state.delete) {
        if (!cellPendingDeletes[cellIndex][type]) {
          cellPendingDeletes[cellIndex][type] = {};
        }
        cellPendingDeletes[cellIndex][type][id] = state;
        delete currentCellData[type][id];
      }
      if (now - state.processed > WORLD_STALE_TIMEOUT) {
        delete currentCellData[type][id];
      }
    });

    var workerCellTransferIds = Object.keys(workerStateRefList);
    workerCellTransferIds.forEach(function (swid) {
      scServer.exchange.publish('internal/input-cell-transition/' + swid, workerStateRefList[swid]);
    });

    // Pass states off to adjacent cells as they move across grid cells.
    var allNearbyCellIndexes = Object.keys(statesForNearbyCells);
    allNearbyCellIndexes.forEach(function (nearbyCellIndex) {
      channelGrid.publishToCells(CHANNEL_CELL_TRANSITION, statesForNearbyCells[nearbyCellIndex], [nearbyCellIndex]);
    });
  }

  // Receive states which are in other cells and *may* transition to this cell later.
  // We don't manage these states, we just keep a copy so that they are visible
  // inside our cellController (cell.js) - This allows states to interact across
  // cell partitions (which may be hosted on a different process/CPU core).
  function gridCellTransitionHandler(cellIndex, stateList) {
    var currentCellData = cellData[cellIndex];

    stateList.forEach(function (state) {
      var type = state.type;
      var id = state.id;

      if (!currentCellData[type]) {
        currentCellData[type] = {};
      }
      var existingState = currentCellData[type][id];

      if (!existingState || state.version > existingState.version) {
        // Do not overwrite a state which is in the middle of
        // being synchronized with a different cell.
        if (state.tcid == cellIndex) {
          // This is a full transition to our current cell.
          state.ccid = cellIndex;
          currentCellData[type][id] = state;
        } else {
          // This is just external state for us to track but not
          // a complete transition, the state will still be managed by
          // a different cell.
          currentCellData[type][id] = state;
        }
        updateStateExternalTag(state, cellIndex);
      }

      existingState = currentCellData[type][id];
      existingState.processed = Date.now();
    });
  }

  // Here we handle and prepare data for a single cell within our game grid to be
  // processed by our cell controller.
  function gridCellDataHandler(cellIndex, stateList) {
    var currentCellData = cellData[cellIndex];

    stateList.forEach(function (stateRef) {
      var id = stateRef.id;
      var type = stateRef.type;

      if (!currentCellData[type]) {
        currentCellData[type] = {};
      }

      if (!currentCellData[type][id]) {
        var state;
        if (stateRef.create) {
          // If it is a stateRef, we get the state from the create property.
          state = stateRef.create;
        } else if (stateRef.x != null && stateRef.y != null) {
          // If we have x and y properties, then we know that
          // this is a full state already (probably created directly inside the cell).
          state = stateRef;
        } else {
          throw new Error('Received an invalid state reference');
        }
        state.ccid = cellIndex;
        state.version = 1;
        currentCellData[type][id] = state;
      }
      var cachedState = currentCellData[type][id];
      if (cachedState) {
        if (stateRef.op) {
          cachedState.op = stateRef.op;
        }
        if (stateRef.delete) {
          cachedState.delete = stateRef.delete;
        }
        if (stateRef.data) {
          cachedState.data = stateRef.data;
        }
        cachedState.tcid = channelGrid.getCellIndex(cachedState);
        updateStateExternalTag(cachedState, cellIndex);
        cachedState.processed = Date.now();
      }
    });
  }

  scServer.exchange.subscribe('internal/input-cell-transition/' + serverWorkerId)
  .watch(function (stateList) {
    stateList.forEach(function (state) {
      game.stateRefs[state.id] = state;
    });
  });

  // This is the main input loop which feeds states into various cells
  // based on their (x, y) coordinates.
  function processInputStates() {
    var stateList = [];
    var stateIds = Object.keys(game.stateRefs);

    stateIds.forEach(function (id) {
      var state = game.stateRefs[id];
      // Don't include bots.
      stateList.push(state);
    });

    // Publish to internal channels for processing (e.g. Collision
    // detection and resolution, scoring, etc...)
    // These states will be processed by a cell controllers depending
    // on each state's target cell index (tcid) within the world grid.
    var gridPublishOptions = {
      cellIndexesFactory: function (state) {
        return [state.tcid];
      }
    };
    channelGrid.publish(CHANNEL_INBOUND_CELL_PROCESSING, stateList, gridPublishOptions);

    stateList.forEach(function (state) {
      if (state.op) {
        delete state.op;
      }
      if (state.delete) {
        delete game.stateRefs[state.id];
      }
    });
  }

  setInterval(processInputStates, WORLD_UPDATE_INTERVAL);

  /*
    In here we handle our incoming realtime connections and listen for events.
  */
  scServer.on('connection', function (socket) {

    socket.on('getWorldInfo', function (data, respond) {
      // The first argument to respond can optionally be an Error object.
      respond(null, {
        pixelScale: PIXEL_SCALE,
        tileSize: TILE_SIZE,
        levelSize: LEVEL_SIZE,
        beachSize: BEACH_SIZE,
        width: WORLD_WIDTH,
        height: WORLD_HEIGHT,
        cols: WORLD_COLS,
        rows: WORLD_ROWS,
        cellWidth: WORLD_CELL_WIDTH,
        cellHeight: WORLD_CELL_HEIGHT,
        cellOverlapDistance: WORLD_CELL_OVERLAP_DISTANCE,
        serverWorkerId: serverWorkerId,
        environment: environment
      });
    });

    // socket.on('get-best', function(data, respond) {
    //   var best = [];
    //   if (!cellControllers[0].cellData || !cellControllers[0].cellData.player) {
    //     respond(null, { best: [] });
    //     return;
    //   }
    //   cellControllers[0].cellData.player.forEach((p) => {
    //     best.push({ name: p.name, score: p.boostScore });
    //   });
    //   console.log(best);
    //   respond(null, { best: best });
    // });

    socket.on('join', function (playerOptions, respond) {
      if (socket.player) {
        socket.player.dead = true;
        stateManager.delete(socket.player);
      }

      var startingPos = getRandomPosition(PLAYER_DIAMETER, PLAYER_DIAMETER);
      var player = {
        id: uuid.v4(),
        type: 'player',
        swid: serverWorkerId,
        name: playerOptions.name,
        x: startingPos.x,
        y: startingPos.y,
        diam: PLAYER_DIAMETER,
        mass: PLAYER_MASS,
        score: 0,
        bodyType: Math.floor(Math.random() * 3),
        surfboardType: Math.floor(Math.random() * 5),
      };

      socket.player = stateManager.create(player);

      respond(null, player);
    });

    socket.on('action', function (playerOp) {
      if (socket.player) {
        stateManager.update(socket.player, playerOp);
      }
    });

    socket.on('disconnect', function () {
      if (socket.player) {
        socket.player.dead = true;
        stateManager.delete(socket.player);
      }
    });
  });
};