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