game: Allow either player to play the first move

[lmno-server] / game.js

diff --git a/game.js b/game.js
index 72c3c7f16fd1c8fd0b24b96935ad588228cdfbf0..24e36adbc4106db5df835ddcfcc3ea403f575988 100644 (file)
--- a/game.js
+++ b/game.js
@@ -50,6 +50,7 @@ class Game {
     this.state = {
       team_to_play: ""
     };
+    this.first_move = true;
 
     /* Send a comment to every connected client every 15 seconds. */
     setInterval(() => {this.broadcast_string(":");}, 15000);
@@ -80,23 +81,71 @@ class Game {
    * to override this (and call super.add_move early!) to implement
    * the actual logic for a move. */
   add_move(player, move) {
-    /* Cannot move if you are not on a team. */
-    if (player.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" };
+    /* 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" };
+      }
+
+      /* Cannot move if you are not on a team. */
+      if (player.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 };
   }
 
+  /* Assign team only if player is unassigned.
+   * Return true if assignment made, false otherwise. */
+  assign_player_to_team_perhaps(player, team)
+  {
+    if (player.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 === "");
+        if (!other)
+          return;
+        this.assign_player_to_team_perhaps(other, this.teams[i]);
+      }
+    }
+  }
+
   add_player(session, connection) {
     /* First see if we already have a player object for this session. */
     const existing = this.players_by_session[session.id];