git.cworth.org Git - empires-server/blob - empires.js

   1 const express = require("express");
   2 const cors = require("cors");
   3 const body_parser = require("body-parser");
   4 const path = require("path");
   5
   6 const app = express();
   7 app.use(cors());
   8 app.use(body_parser.urlencoded({ extended: false }));
   9 app.use(body_parser.json());
  10
  11 const GameState = {
  12   JOIN:    1,
  13   REVEAL:  2,
  14   CAPTURE: 3,
  15   properties: {
  16     1: {name: "join"},
  17     2: {name: "reveal"},
  18     3: {name: "capture"}
  19   }
  20 };
  21
  22 /**
  23  * Shuffles array in place.
  24  * @param {Array} a items An array containing the items.
  25  */
  26 function shuffle(a) {
  27   if (a === undefined)
  28     return;
  29
  30   var j, x, i;
  31   for (i = a.length - 1; i > 0; i--) {
  32     j = Math.floor(Math.random() * (i + 1));
  33     x = a[i];
  34     a[i] = a[j];
  35     a[j] = x;
  36   }
  37 }
  38
  39 class Game {
  40   constructor() {
  41     this._players = [];
  42     this.characters_to_reveal = null;
  43     this.next_player_id = 1;
  44     this.clients = [];
  45     this.next_client_id = 1;
  46     this.state = GameState.JOIN;
  47
  48     /* Send a comment to every connected client every 15 seconds. */
  49     setInterval(() => {this.broadcast_string(":");}, 15000);
  50   }
  51
  52   add_player(name, character) {
  53     const new_player = {id: this.next_player_id,
  54                        name: name,
  55                        character: character,
  56                        captures: [],
  57                        };
  58     this._players.push(new_player);
  59     this.next_player_id++;
  60     /* The syntax here is using an anonymous function to create a new
  61       object from new_player with just the subset of fields that we
  62       want. */
  63     const player_data = JSON.stringify((({id, name}) => ({id, name}))(new_player));
  64     this.broadcast_event("player-join", player_data);
  65   }
  66
  67   remove_player(id) {
  68     const index = this._players.findIndex(player => player.id === id);
  69     this._players.splice(index, 1);
  70
  71     this.broadcast_event("player-leave", `{"id": ${id}}`);
  72   }
  73
  74   reset() {
  75     this._players = [];
  76     this.characters_to_reveal = null;
  77     this.next_player_id = 1;
  78
  79     this.change_state(GameState.JOIN);
  80
  81     this.broadcast_event("players", "{}");
  82   }
  83
  84   reveal_next() {
  85     /* Don't try to reveal anything if we aren't in the reveal state. */
  86     if (this.state != GameState.REVEAL) {
  87       clearInterval(this.reveal_interval);
  88       return;
  89     }
  90
  91     if (this.reveal_index >= this.characters_to_reveal.length) {
  92       clearInterval(this.reveal_interval);
  93       this.broadcast_event("character-reveal", '{"character":""}');
  94       return;
  95     }
  96     const character = this.characters_to_reveal[this.reveal_index];
  97     this.reveal_index++;
  98     const character_data = JSON.stringify({"character":character});
  99     this.broadcast_event("character-reveal", character_data);
 100   }
 101
 102   reveal() {
 103     this.change_state(GameState.REVEAL);
 104
 105     if (this.characters_to_reveal === null) {
 106       this.characters_to_reveal = [];
 107       this.characters_to_reveal = this._players.reduce((characters, player) => {
 108         characters.push(player.character);
 109         return characters;
 110       }, []);
 111       shuffle(this.characters_to_reveal);
 112     }
 113
 114     this.reveal_index = 0;
 115
 116     this.reveal_interval = setInterval(this.reveal_next.bind(this), 3000);
 117   }
 118
 119   start() {
 120     this.change_state(GameState.CAPTURE);
 121   }
 122
 123   capture(captor_id, captee_id) {
 124     /* TODO: Fix to fail on already-captured players (or to move the
 125      * captured player from an old captor to a new—need to clarify in
 126      * the API specification which we want here. */
 127     let captor = this._players.find(player => player.id === captor_id);
 128     captor.captures.push(captee_id);
 129
 130     this.broadcast_event("capture", `{"captor": ${captor_id}, "captee": ${captee_id}}`);
 131   }
 132
 133   liberate(captee_id) {
 134     let captor = this._players.find(player => player.captures.includes(captee_id));
 135     captor.captures.splice(captor.captures.indexOf(captee_id), 1);
 136   }
 137
 138   restart() {
 139     for (const player of this._players) {
 140       player.captures = [];
 141     }
 142   }
 143
 144   get characters() {
 145     return this._players.map(player => player.character);
 146   }
 147
 148   get empires() {
 149     return this._players.map(player => ({id: player.id, captures: player.captures}));
 150   }
 151
 152   get players() {
 153     return this._players.map(player => ({id: player.id, name: player.name }));
 154   }
 155
 156   add_client(response) {
 157     const id = this.next_client_id;
 158     this.clients.push({id: id,
 159                        response: response});
 160     this.next_client_id++;
 161
 162     return id;
 163   }
 164
 165   remove_client(id) {
 166     this.clients = this.clients.filter(client => client.id !== id);
 167   }
 168
 169   /* Send a string to all clients */
 170   broadcast_string(str) {
 171     this.clients.forEach(client => client.response.write(str + '\n'));
 172   }
 173
 174   /* Send an event to all clients.
 175    *
 176    * An event has both a declared type and a separate data block.
 177    * It also ends with two newlines (to mark the end of the event).
 178    */
 179   broadcast_event(type, data) {
 180     this.broadcast_string(`event: ${type}\ndata: ${data}\n`);
 181   }
 182
 183   game_state_event_data(old_state, new_state) {
 184     var old_state_name;
 185     if (old_state)
 186       old_state_name = GameState.properties[old_state].name;
 187     else
 188       old_state_name = "none";
 189     const new_state_name = GameState.properties[new_state].name;
 190
 191     return `{"old_state":"${old_state_name}","new_state":"${new_state_name}"}`;
 192   }
 193
 194   /* Inform clients about a state change. */
 195   broadcast_state_change() {
 196     const event_data = this.game_state_event_data(this.old_state, this.state);
 197     this.broadcast_event("game-state", event_data);
 198   }
 199
 200   /* Change game state and broadcast the change to all clients. */
 201   change_state(state) {
 202     /* Do nothing if there is no actual change happening. */
 203     if (state === this.state)
 204       return;
 205
 206     this.old_state = this.state;
 207     this.state = state;
 208
 209     this.broadcast_state_change();
 210   }
 211 }
 212
 213 function handle_events(request, response) {
 214   const game = request.game;
 215   /* These headers will keep the connection open so we can stream events. */
 216   const headers = {
 217     "Content-type": "text/event-stream",
 218     "Connection": "keep-alive",
 219     "Cache-Control": "no-cache"
 220   };
 221   response.writeHead(200, headers);
 222
 223   /* Now that a client has connected, first we need to stream all of
 224    * the existing players (if any). */
 225   if (game._players.length > 0) {
 226     const players_json = JSON.stringify(game.players);
 227     const players_data = `event: players\ndata: ${players_json}\n\n`;
 228     response.write(players_data);
 229   }
 230
 231   /* And we need to inform the client of the current game state.
 232    *
 233    * In fact, we need to cycle through each state transition from the
 234    * beginning so the client can see each.
 235    */
 236   var old_state = null;
 237   for (var state = GameState.JOIN; state <= game.state; state++) {
 238     var event_data = game.game_state_event_data(old_state, state);
 239     response.write("event: game-state\n" + "data: " + event_data + "\n\n");
 240     old_state = state;
 241   }
 242
 243   /* Add this new client to our list of clients. */
 244   const id = game.add_client(response);
 245
 246   /* And queue up cleanup to be triggered on client close. */
 247   request.on('close', () => {
 248     game.remove_client(id);
 249   });
 250 }
 251
 252 app.get('/', (request, response) => {
 253   response.sendFile(path.join(__dirname, './game.html'));
 254 });
 255
 256 app.post('/register', (request, response) => {
 257   const game = request.game;
 258   game.add_player(request.body.name, request.body.character);
 259   response.send();
 260 });
 261
 262 app.post('/deregister/:id', (request, response) => {
 263   const game = request.game;
 264   game.remove_player(parseInt(request.params.id));
 265   response.send();
 266 });
 267
 268 app.post('/reveal', (request, response) => {
 269   const game = request.game;
 270   game.reveal();
 271   response.send();
 272 });
 273
 274 app.post('/start', (request, response) => {
 275   const game = request.game;
 276   game.start();
 277   response.send();
 278 });
 279
 280 app.post('/reset', (request, response) => {
 281   const game = request.game;
 282   game.reset();
 283   response.send();
 284 });
 285
 286 app.post('/capture/:captor/:captee', (request, response) => {
 287   const game = request.game;
 288   game.capture(parseInt(request.params.captor), parseInt(request.params.captee));
 289   response.send();
 290 });
 291
 292 app.post('/liberate/:id', (request, response) => {
 293   const game = request.game;
 294   game.liberate(parseInt(request.params.id));
 295   response.send();
 296 });
 297
 298 app.post('/restart', (request, response) => {
 299   const game = request.game;
 300   game.restart(parseInt(request.params.id));
 301     response.send();
 302 });
 303
 304 app.get('/characters', (request, response) => {
 305   const game = request.game;
 306   response.send(game.characters);
 307 });
 308
 309 app.get('/empires', (request, response) => {
 310   const game = request.game;
 311   response.send(game.empires);
 312 });
 313
 314 app.get('/players', (request, response) => {
 315   const game = request.game;
 316   response.send(game.players);
 317 });
 318
 319 app.get('/events', handle_events);
 320
 321 exports.app = app;
 322 exports.Game = Game;