+const no_team = { name: "" };
+
+/* A single player can have multiple connections, (think, multiple
+ * browser windows with a common session cookie). */
+class Player {
+ constructor(id, session_id, name, connection) {
+ this.id = id;
+ this.session_id = session_id;
+ this.name = name;
+ this.connections = [connection];
+ this.team = no_team;
+ this.active = true;
+ }
+
+ add_connection(connection) {
+ /* Don't add a duplicate connection if this player already has it. */
+ for (let c of this.connections) {
+ if (c === connection)
+ return;
+ }
+
+ this.connections.push(connection);
+ }
+
+ /* Returns the number of remaining connections after this one is removed. */
+ remove_connection(connection) {
+ this.connections = this.connections.filter(c => c !== connection);
+ return this.connections.length;
+ }
+
+ /* Send a string to all connections for this player. */
+ send(data) {
+ this.connections.forEach(connection => connection.write(data));
+ }
+
+ info_json() {
+ return JSON.stringify({
+ id: this.id,
+ active: this.active,
+ name: this.name,
+ team: this.team.name,
+ score: this.score
+ });
+ }
+}
+
+/* This replacer function allows for JSON.stringify to give results
+ * for objects of various types that are used in game state.
+ */
+function stringify_replacer(key, value) {
+ if (typeof value === 'object' && value instanceof Set) {
+ return [...value];
+ }
+ return value;
+}
+
/* Base class providing common code for game engine implementations. */
class Game {
- constructor(name) {
- this.name = name;
- this.clients = [];
- this.next_client_id = 1;
+ constructor(id) {
+ this.id = id;
+ this.players = [];
+ this.players_by_session = {};
+ this.active_players = 0;
+ this.next_player_id = 1;
+ this.teams = [];
+ this.state = {
+ team_to_play: no_team
+ };
+ this.first_move = true;
+
+ /* Send a comment to every connected client every 15 seconds. */
+ setInterval(() => {this.broadcast_string(":");}, 15000);
}
- add_client(response) {
- const id = this.next_client_id;
- this.clients.push({id: id,
- response: response});
- this.next_client_id++;
+ /* Suport for game meta-data.
+ *
+ * What we want here is an effectively static field that is
+ * accessible through either the class name (SomeGame.meta) or an
+ * instance (some_game.meta). To pull this off we do keep two copies
+ * of the data. But the game classes can just set SomeGame.meta once
+ * and then reference it either way.
+ */
+ static set meta(data) {
+ /* This allows class access (SomeGame.meta) via the get method below. */
+ this._meta = data;
+
+ /* While this allows access via an instance (some_game.meta). */
+ this.prototype.meta = data;
+ }
+
+ static get meta() {
+ return this._meta;
+ }
+
+ /* Just performs some checks for whether a move is definitely not
+ * legal (such as not the player's turn). A child class is expected
+ * to override this (and call super.add_move early!) to implement
+ * the actual logic for a move. */
+ add_move(player, move) {
+
+ /* The checks here don't apply on the first move. */
+ if (! this.first_move) {
+
+ /* Discard any move asserting to be the first move if it's no
+ * longer the first move. This resolves the race condition if
+ * multiple players attempt to make the first move. */
+ if (move.assert_first_move) {
+ return { legal: false,
+ message: "Your opponent beat you to the first move" };
+ }
- return id;
+ /* Cannot move if you are not on a team. */
+ if (player.team === no_team)
+ {
+ return { legal: false,
+ message: "You must be on a team to take a turn" };
+ }
+
+ /* Cannot move if it's not this player's team's turn. */
+ if (player.team !== this.state.team_to_play)
+ {
+ return { legal: false,
+ message: "It's not your turn to move" };
+ }
+ }
+
+ return { legal: true };
}
- remove_client(id) {
- this.clients = this.clients.filter(client => client.id !== id);
+ /* Assign team only if player is unassigned.
+ * Return true if assignment made, false otherwise. */
+ assign_player_to_team_perhaps(player, team)
+ {
+ if (player.team !== no_team)
+ return false;
+
+ player.team = team;
+ this.broadcast_event("player-update", player.info_json());
+
+ return true;
+ }
+
+ /* This function is called after the child add_move has returned
+ * 'result' so that any generic processing can happen.
+ *
+ * In particular, we assign teams for a two-player game where a
+ * player assumed a team by making the first move. */
+ post_move(player, result)
+ {
+ if (this.first_move && result.legal) {
+ this.first_move = false;
+
+ this.assign_player_to_team_perhaps(player, this.teams[0]);
+
+ /* Yes, start at 1 to skip teams[0] which we just assigned. */
+ for (let i = 1; i < this.teams.length; i++) {
+ const other = this.players.find(p => (p !== player) && (p.team === no_team));
+ if (!other)
+ return;
+ this.assign_player_to_team_perhaps(other, this.teams[i]);
+ }
+ }
}
- /* Send a string to all clients */
+ add_player(session, connection) {
+ let nickname = session.nickname;
+
+ /* First see if we already have a player object for this session. */
+ let existing = this.players_by_session[session.id];
+
+ /* Otherwise, see if we can match an inactive player by name. */
+ if (! existing) {
+ existing = this.players.find(player =>
+ player.name == nickname &&
+ ! player.active);
+ }
+
+ if (existing) {
+ if (! existing.active) {
+ /* If we're re-activating a previously idled player, then we
+ * need to alert everyone that this player is now back.
+ */
+ existing.active = true;
+ this.active_players++;
+ this.broadcast_event("player-enter", existing.info_json());
+ }
+ existing.add_connection(connection);
+ this.players_by_session[session.id] = existing;
+ return existing;
+ }
+
+ /* No existing player. Add a new one. */
+ const id = this.next_player_id;
+ if (nickname === "")
+ nickname = "Guest";
+ const nickname_orig = nickname;
+
+ /* Ensure we don't have a name collision with a previous player. */
+ let unique_suffix = 1;
+ while (this.players.find(player => player.name === nickname))
+ {
+ nickname = `${nickname_orig}${unique_suffix.toString().padStart(2, '0')}`;
+ unique_suffix++;
+ }
+
+ const player = new Player(id, session.id, nickname, connection);
+
+ /* Broadcast before adding player to list (to avoid announcing the
+ * new player to itself). */
+ this.broadcast_event("player-enter", player.info_json());
+
+ this.players.push(player);
+ this.players_by_session[session.id] = player;
+ this.active_players++;
+ this.next_player_id++;
+
+ /* After adding the player to the list, and if we are already past
+ * the first move, assign this player to the first team that
+ * doesn't already have a player assigned (if any). */
+ if (! this.first_move) {
+ const have_players = Array(this.teams.length).fill(false);
+ this.players.forEach(p => {
+ if (p.team.id !== undefined)
+ have_players[p.team.id] = true;
+ });
+ const first_empty = have_players.findIndex(i => i === false);
+ this.assign_player_to_team_perhaps(player, this.teams[first_empty]);
+ }
+
+ return player;
+ }
+
+ /* Drop a connection object from a player, and if it's the last one,
+ * then drop that player from the game's list of players. */
+ remove_player_connection(player, connection) {
+ const remaining = player.remove_connection(connection);
+ if (remaining === 0) {
+ player.active = false;
+ this.active_players--;
+ const player_data = JSON.stringify({ id: player.id });
+ this.broadcast_event("player-exit", player_data);
+ }
+ }
+
+ /* Send a string to all players */
broadcast_string(str) {
- this.clients.forEach(client => client.response.write(str + '\n'));
+ this.players.forEach(player => player.send(str + '\n'));
}
- /* Send an event to all clients.
+ /* Send an event to all players.
*
* An event has both a declared type and a separate data block.
* It also ends with two newlines (to mark the end of the event).
this.broadcast_string(`event: ${type}\ndata: ${data}\n`);
}
+ broadcast_event_object(type, obj) {
+ this.broadcast_event(type, JSON.stringify(obj));
+ }
+
+ game_state_json() {
+ return JSON.stringify(this.state, stringify_replacer);
+ }
+
+ handle_events(request, response) {
+ /* These headers will keep the connection open so we can stream events. */
+ const headers = {
+ "Content-type": "text/event-stream",
+ "Connection": "keep-alive",
+ "Cache-Control": "no-cache"
+ };
+ response.writeHead(200, headers);
+
+ /* Add this new player. */
+ const player = this.add_player(request.session, response);
+
+ /* And queue up cleanup to be triggered on client close. */
+ request.on('close', () => {
+ this.remove_player_connection(player, response);
+ });
+
+ /* Give the client the game-info event. */
+ const game_info_json = JSON.stringify({
+ id: this.id,
+ url: `${request.protocol}://${request.hostname}/${this.id}`
+ });
+ response.write(`event: game-info\ndata: ${game_info_json}\n\n`);
+
+ /* And the player-info event. */
+ response.write(`event: player-info\ndata: ${player.info_json()}\n\n`);
+
+ /* As well as player-enter events for all existing, active players. */
+ this.players.filter(
+ p => (p !== player
+ && (p.active || p.score))).forEach(p => {
+ response.write(`event: player-enter\ndata: ${p.info_json()}\n\n`);
+ });
+
+ /* Finally, if this game class has a "state" property, stream that
+ * current state to the client. */
+ if (this.state) {
+ response.write(`event: game-state\ndata: ${this.game_state_json()}\n\n`);
+ }
+ }
+
+ handle_player(request, response) {
+ const player = this.players_by_session[request.session.id];
+ const name = request.body.name;
+ const team_name = request.body.team;
+ var updated = false;
+ if (! player) {
+ response.sendStatus(404);
+ return;
+ }
+
+ if (name && (player.name !== name)) {
+ player.name = name;
+
+ /* In addition to setting the name within this game's player
+ * object, also set the name in the session. */
+ request.session.nickname = name;
+ request.session.save();
+
+ updated = true;
+ }
+
+ if (team_name !== null && (player.team.name !== team_name))
+ {
+ if (team_name === "") {
+ player.team = no_team;
+ updated = true;
+ } else {
+ const index = this.teams.findIndex(t => t.name === team_name);
+ if (index >= 0) {
+ player.team = this.teams[index];
+ updated = true;
+ }
+ }
+ }
+
+ if (updated)
+ this.broadcast_event("player-update", player.info_json());
+
+ response.send("");
+ }
+
+ broadcast_move(move) {
+ this.broadcast_event("move", JSON.stringify(move));
+ }
+
}
module.exports = Game;
projects / lmno-server / blobdiff