1 /* A single player can have multiple connections, (think, multiple
2 * browser windows with a common session cookie). */
4 constructor(id, session_id, name, connection) {
6 this.session_id = session_id;
8 this.connections = [connection];
12 add_connection(connection) {
13 /* Don't add a duplicate connection if this player already has it. */
14 for (let c of this.connections) {
19 this.connections.push(connection);
22 /* Returns the number of remaining connections after this one is removed. */
23 remove_connection(connection) {
24 this.connections.filter(c => c !== connection);
25 return this.connections.length;
28 /* Send a string to all connections for this player. */
30 this.connections.forEach(connection => connection.write(data));
34 return JSON.stringify({
42 /* Base class providing common code for game engine implementations. */
47 this.players_by_session = {};
48 this.next_player_id = 1;
53 this.first_move = true;
55 /* Send a comment to every connected client every 15 seconds. */
56 setInterval(() => {this.broadcast_string(":");}, 15000);
59 /* Suport for game meta-data.
61 * What we want here is an effectively static field that is
62 * accessible through either the class name (SomeGame.meta) or an
63 * instance (some_game.meta). To pull this off we do keep two copies
64 * of the data. But the game classes can just set SomeGame.meta once
65 * and then reference it either way.
67 static set meta(data) {
68 /* This allows class access (SomeGame.meta) via the get method below. */
71 /* While this allows access via an instance (some_game.meta). */
72 this.prototype.meta = data;
79 /* Just performs some checks for whether a move is definitely not
80 * legal (such as not the player's turn). A child class is expected
81 * to override this (and call super.add_move early!) to implement
82 * the actual logic for a move. */
83 add_move(player, move) {
85 /* The checks here don't apply on the first move. */
86 if (! this.first_move) {
88 /* Discard any move asserting to be the first move if it's no
89 * longer the first move. This resolves the race condition if
90 * multiple players attempt to make the first move. */
91 if (move.assert_first_move) {
92 return { legal: false,
93 message: "Your opponent beat you to the first move" };
96 /* Cannot move if you are not on a team. */
97 if (player.team === "")
99 return { legal: false,
100 message: "You must be on a team to take a turn" };
103 /* Cannot move if it's not this player's team's turn. */
104 if (player.team !== this.state.team_to_play)
106 return { legal: false,
107 message: "It's not your turn to move" };
111 return { legal: true };
114 /* Assign team only if player is unassigned.
115 * Return true if assignment made, false otherwise. */
116 assign_player_to_team_perhaps(player, team)
118 if (player.team !== "")
122 this.broadcast_event("player-update", player.info_json());
127 /* This function is called after the child add_move has returned
128 * 'result' so that any generic processing can happen.
130 * In particular, we assign teams for a two-player game where a
131 * player assumed a team by making the first move. */
132 post_move(player, result)
134 if (this.first_move && result.legal) {
135 this.first_move = false;
137 this.assign_player_to_team_perhaps(player, this.teams[0]);
139 /* Yes, start at 1 to skip teams[0] which we just assigned. */
140 for (let i = 1; i < this.teams.length; i++) {
141 const other = this.players.find(p => p !== player && p.team === "");
144 this.assign_player_to_team_perhaps(other, this.teams[i]);
149 add_player(session, connection) {
150 /* First see if we already have a player object for this session. */
151 const existing = this.players_by_session[session.id];
153 existing.add_connection(connection);
157 /* No existing player. Add a new one. */
158 const id = this.next_player_id;
159 const player = new Player(id, session.id, session.nickname, connection);
161 /* Broadcast before adding player to list (to avoid announcing the
162 * new player to itself). */
163 const player_data = JSON.stringify({ id: player.id, name: player.name });
164 this.broadcast_event("player-enter", player_data);
166 this.players.push(player);
167 this.players_by_session[session.id] = player;
168 this.next_player_id++;
173 /* Drop a connection object from a player, and if it's the last one,
174 * then drop that player from the game's list of players. */
175 remove_player_connection(player, connection) {
176 const remaining = player.remove_connection(connection);
177 if (remaining === 0) {
178 const player_data = JSON.stringify({ id: player.id });
179 this.players.filter(p => p !== player);
180 delete this.players_by_session[player.session_id];
181 this.broadcast_event("player-exit", player_data);
185 /* Send a string to all players */
186 broadcast_string(str) {
187 this.players.forEach(player => player.send(str + '\n'));
190 /* Send an event to all players.
192 * An event has both a declared type and a separate data block.
193 * It also ends with two newlines (to mark the end of the event).
195 broadcast_event(type, data) {
196 this.broadcast_string(`event: ${type}\ndata: ${data}\n`);
199 handle_events(request, response) {
200 /* These headers will keep the connection open so we can stream events. */
202 "Content-type": "text/event-stream",
203 "Connection": "keep-alive",
204 "Cache-Control": "no-cache"
206 response.writeHead(200, headers);
208 /* Add this new player. */
209 const player = this.add_player(request.session, response);
211 /* And queue up cleanup to be triggered on client close. */
212 request.on('close', () => {
213 this.remove_player_connection(player, response);
216 /* Give the client the game-info event. */
217 const game_info_json = JSON.stringify({
219 url: `${request.protocol}://${request.hostname}/${this.id}`
221 response.write(`event: game-info\ndata: ${game_info_json}\n\n`);
223 /* And the player-info event. */
224 response.write(`event: player-info\ndata: ${player.info_json()}\n\n`);
226 /* Finally, if this game class has a "state" property, stream that
227 * current state to the client. */
229 const state_json = JSON.stringify(this.state);
230 response.write(`event: game-state\ndata: ${state_json}\n\n`);
234 handle_player(request, response) {
235 const player = this.players_by_session[request.session.id];
236 const name = request.body.name;
237 const team = request.body.team;
240 response.sendStatus(404);
244 if (name && (player.name !== name)) {
247 /* In addition to setting the name within this game's player
248 * object, also set the name in the session. */
249 request.session.nickname = name;
250 request.session.save();
255 if (team !== null && (player.team !== team) &&
256 (team === "" || this.teams.includes(team)))
264 this.broadcast_event("player-update", player.info_json());
269 broadcast_move(move) {
270 this.broadcast_event("move", move);
275 module.exports = Game;