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     if (this.reveal_index >= this.characters_to_reveal.length) {
  83       clearInterval(this.reveal_interval);
  84       this.broadcast_event("character-reveal", '{"character":""}');
  85       return;
  86     }
  87     const character = this.characters_to_reveal[this.reveal_index];
  88     this.reveal_index++;
  89     const character_data = JSON.stringify({"character":character});
  90     this.broadcast_event("character-reveal", character_data);
  91   }
  92
  93   reveal() {
  94     this.change_state(GameState.REVEAL);
  95
  96     if (this.characters_to_reveal === null) {
  97       this.characters_to_reveal = [];
  98       this.characters_to_reveal = this._players.reduce((characters, player) => {
  99         characters.push(player.character);
 100         return characters;
 101       }, []);
 102       shuffle(this.characters_to_reveal);
 103     }
 104
 105     this.reveal_index = 0;
 106
 107     this.reveal_interval = setInterval(this.reveal_next.bind(this), 3000);
 108   }
 109
 110   start() {
 111     this.change_state(GameState.CAPTURE);
 112   }
 113
 114   capture(captor_id, captee_id) {
 115     /* TODO: Fix to fail on already-captured players (or to move the
 116      * captured player from an old captor to a new—need to clarify in
 117      * the API specification which we want here. */
 118     let captor = this._players.find(player => player.id === captor_id);
 119     captor.captures.push(captee_id);
 120
 121     this.broadcast_event("capture", `{"captor": ${captor_id}, "captee": ${captee_id}}`);
 122   }
 123
 124   liberate(captee_id) {
 125     let captor = this._players.find(player => player.captures.includes(captee_id));
 126     captor.captures.splice(captor.captures.indexOf(captee_id), 1);
 127   }
 128
 129   restart() {
 130     for (const player of this._players) {
 131       player.captures = [];
 132     }
 133   }
 134
 135   get characters() {
 136     return this._players.map(player => player.character);
 137   }
 138
 139   get empires() {
 140     return this._players.map(player => ({id: player.id, captures: player.captures}));
 141   }
 142
 143   get players() {
 144     return this._players.map(player => ({id: player.id, name: player.name }));
 145   }
 146
 147   add_client(response) {
 148     const id = this.next_client_id;
 149     this.clients.push({id: id,
 150                        response: response});
 151     this.next_client_id++;
 152
 153     return id;
 154   }
 155
 156   remove_client(id) {
 157     this.clients = this.clients.filter(client => client.id !== id);
 158   }
 159
 160   /* Send a string to all clients */
 161   broadcast_string(str) {
 162     this.clients.forEach(client => client.response.write(str + '\n'));
 163   }
 164
 165   /* Send an event to all clients.
 166    *
 167    * An event has both a declared type and a separate data block.
 168    * It also ends with two newlines (to mark the end of the event).
 169    */
 170   broadcast_event(type, data) {
 171     this.broadcast_string(`event: ${type}\ndata: ${data}\n`);
 172   }
 173
 174   game_state_event_data(old_state, new_state) {
 175     var old_state_name;
 176     if (old_state)
 177       old_state_name = GameState.properties[old_state].name;
 178     else
 179       old_state_name = "none";
 180     const new_state_name = GameState.properties[new_state].name;
 181
 182     return `{"old_state":"${old_state_name}","new_state":"${new_state_name}"}`;
 183   }
 184
 185   /* Inform clients about a state change. */
 186   broadcast_state_change() {
 187     const event_data = this.game_state_event_data(this.old_state, this.state);
 188     this.broadcast_event("game-state", event_data);
 189   }
 190
 191   /* Change game state and broadcast the change to all clients. */
 192   change_state(state) {
 193     /* Do nothing if there is no actual change happening. */
 194     if (state === this.state)
 195       return;
 196
 197     this.old_state = this.state;
 198     this.state = state;
 199
 200     this.broadcast_state_change();
 201   }
 202 }
 203
 204 const game = new Game();
 205
 206 app.use(body_parser.urlencoded({ extended: false }));
 207 app.use(body_parser.json());
 208
 209 function handle_events(request, response) {
 210   /* These headers will keep the connection open so we can stream events. */
 211   const headers = {
 212     "Content-type": "text/event-stream",
 213     "Connection": "keep-alive",
 214     "Cache-Control": "no-cache"
 215   };
 216   response.writeHead(200, headers);
 217
 218   /* Now that a client has connected, first we need to stream all of
 219    * the existing players (if any). */
 220   if (game._players.length > 0) {
 221     const players_json = JSON.stringify(game.players);
 222     const players_data = `event: players\ndata: ${players_json}\n\n`;
 223     response.write(players_data);
 224   }
 225
 226   /* And we need to inform the client of the current game state.
 227    *
 228    * In fact, we need to cycle through each state transition from the
 229    * beginning so the client can see each.
 230    */
 231   var old_state = null;
 232   for (var state = GameState.JOIN; state <= game.state; state++) {
 233     var event_data = game.game_state_event_data(old_state, state);
 234     response.write("event: game-state\n" + "data: " + event_data + "\n\n");
 235     old_state = state;
 236   }
 237
 238   /* Add this new client to our list of clients. */
 239   const id = game.add_client(response);
 240
 241   /* And queue up cleanup to be triggered on client close. */
 242   request.on('close', () => {
 243     game.remove_client(id);
 244   });
 245 }
 246
 247 app.get('/', (request, response) => {
 248   response.send('Hello World!');
 249 });
 250
 251 app.post('/register', (request, response) => {
 252   game.add_player(request.body.name, request.body.character);
 253   response.send();
 254 });
 255
 256 app.post('/deregister/:id', (request, response) => {
 257   game.remove_player(parseInt(request.params.id));
 258   response.send();
 259 });
 260
 261 app.post('/reveal', (request, response) => {
 262   game.reveal();
 263   response.send();
 264 });
 265
 266 app.post('/start', (request, response) => {
 267   game.start();
 268   response.send();
 269 });
 270
 271 app.post('/reset', (request, response) => {
 272   game.reset();
 273   response.send();
 274 });
 275
 276 app.post('/capture/:captor/:captee', (request, response) => {
 277   game.capture(parseInt(request.params.captor), parseInt(request.params.captee));
 278   response.send();
 279 });
 280
 281 app.post('/liberate/:id', (request, response) => {
 282   game.liberate(parseInt(request.params.id));
 283   response.send();
 284 });
 285
 286 app.post('/restart', (request, response) => {
 287   game.restart(parseInt(request.params.id));
 288     response.send();
 289 });
 290
 291 app.get('/characters', (request, response) => {
 292   response.send(game.characters);
 293 });
 294
 295 app.get('/empires', (request, response) => {
 296   response.send(game.empires);
 297 });
 298
 299 app.get('/players', (request, response) => {
 300   response.send(game.players);
 301 });
 302
 303 app.get('/events', handle_events);
 304
 305 app.listen(3000, function () {
 306   console.log('Empires server listening on localhost:3000');
 307 });