Creating the API for a tic-tac-toe game with AI

game-actions.js

// actions/game.js

// A collection of tasks and helper methods to create a simpel tic-tac-toe game
// - single player 
// - simple AI
// - each connection can only have one active game at a time

exports.gameCreate = {
  name: "gameCreate",
  description: "I create a new game for this connection",
  inputs: {
    required: [],
    optional: [],
  },
  outputExample: {},
  version: 1.0,
  run: function(api, connection, next){
    var game = new api.game.gamePrototype();
    api.game.saveGame(connection, game, function(error){
      connection.error = error;
      next(connection, true);
    });
  }
};

exports.gameView = {
  name: "gameView",
  description: "I view the game board",
  inputs: {
    required: [],
    optional: [],
  },
  outputExample: {},
  version: 1.0,
  run: function(api, connection, next){
    api.game.loadGame(connection, function(error, game){
      connection.error = error;
      connection.response.game = game;
      next(connection, true);
    });
  }
};

exports.gameMove = {
  name: "gameMove",
  description: "a move by a human player of tic-tac-toe",
  inputs: {
    required: ['x', 'y'],
    optional: [],
  },
  outputExample: {},
  version: 1.0,
  run: function(api, connection, next){
    var x = parseInt(connection.params.x);
    var y = parseInt(connection.params.y);
    api.game.loadGame(connection, function(error, game){
      if(error != null){
        connection.error = error;
        next(connection, true);
      }else if(game.state != "playing"){
        connection.error = "this game is over";
        next(connection, true);
      }else if(game.board[y][x] != null){
        connection.error = "you can only draw a new shape on a blank tile";
        next(connection, true);
      }else{
        game.board[y][x] = game.playerMarker;
        game.state = api.game.determineGameState(game);
        api.game.aiTurn(game);
        game.state = api.game.determineGameState(game);
        game.turn++;
        api.game.saveGame(connection, game, function(){
          connection.response.game = game;
          next(connection, true);
        });
      }
    });
  }
};

game-initializers.js

// initializers/game.js

exports.game = function(api, next){

  api.game = {
    gamePrototype: function(data){
      if(data == null){
        this.board = [
          [null, null, null],
          [null, null, null],
          [null, null, null],
        ];
        this.turn = 0;
        this.state = "playing";
        this.playerMarker = "X";
        this.computerMarker = "O";
      }else{
        for(var i in data){
          this[i] = data[i];
        }
      }
    },

    loadGame: function(connection, callback){
      var key = "game_" + connection.id;
      api.cache.load(key, function(error, data){
        callback(error, new api.game.gamePrototype(data));
      });
    },

    saveGame: function(connection, game, callback){
      var key = "game_" + connection.id;
      var data = {
        board: game.board,
        turn: game.turn,
        state: game.state,
        playerMarker: game.playerMarker,
        computerMarker: game.computerMarker,
      }
      api.cache.save(key, data, function(error){
        callback(error);
      });
    },

    determineGameState: function(game){
      // horizontal win
      for(var i in game.board){
        var row = game.board[i]
        if(row[0] != null && row[0] == row[1] && row[0] == row[2]){
          return api.game.determineWinningState(game, row[0]);
        }
      };
      // vertical win
      var i = 0;
      while (i <= 2){
        if(game.board[0][i] != null && game.board[0][i] == game.board[1][i] && game.board[0][i] == game.board[2][i]){
          return api.game.determineWinningState(game, game.board[0][i]);
        }
        i++;
      }
      // diagonal win
      if(
             (game.board[1][1] != null && game.board[0][0] == game.board[1][1] && game.board[0][0] == game.board[2][2]) 
          || (game.board[1][1] != null && game.board[0][2] == game.board[1][1] && game.board[0][2] == game.board[2][0]) 
        ){
        return api.game.determineWinningState(game, game.board[1][1]);
      }
      // tie
      var tied = true;
      game.board.forEach(function(row){
        row.forEach(function(square){
          if(square == null){
            tied = false;
          }
        });
      });
      if(tied == true){
        return "tied";
      }else{
        return "playing"
      }
    },

    determineWinningState: function(game, symbol){
      if(symbol == game.playerMarker){
        return "you won"
      }else{
        return "you lost"
      }
    },

    aiTurn: function(game){
      var options = [
        [], [], []
      ];
      var bestMove = [null, null];
      var bestScore = null;
      var y = -1;
      game.board.forEach(function(row){
        y++;
        x = -1;
        row.forEach(function(square){
          x++;
          if(square != null){
            options[y][x] = null
          }else{
            var proposedGameAi = api.utils.objClone(game);
            var proposedGamePlayer = api.utils.objClone(game);
            proposedGameAi.board = JSON.parse(JSON.stringify(game.board));
            proposedGamePlayer.board = JSON.parse(JSON.stringify(game.board));
            proposedGameAi.board[y][x] = game.computerMarker;   
            proposedGamePlayer.board[y][x] = game.playerMarker;

            if(api.game.determineGameState(proposedGameAi) == "you lost"){
              options[y][x] = 1 // I win
              if(1 > bestScore || bestScore == null){ 
                bestScore = 1;
                bestMove = [y,x]
              }
            }else if(api.game.determineGameState(proposedGamePlayer) == "you won"){
              options[y][x] = 0.5 // I blocked a player win
              if(0.5 > bestScore || bestScore == null){ 
                bestScore = 0.5;
                bestMove = [y,x]
              }
            }else{
              options[y][x] = 0
              if(0 > bestScore || bestScore == null){ 
                bestScore = 0;
                bestMove = [y,x]
              }
            }
          }
        }); 
      });
      if(bestScore != null){
        game.board[bestMove[0]][bestMove[1]] = game.computerMarker;
      }
    },

  }
  next();
}

And here is the game played by telnet:

> telnet localhost 5000
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
{"welcome":"Hello! Welcome to the actionHero api","room":"defaultRoom","context":"api"}
gameCreate
{"context":"response","messageCount":1}
gameView
{"game":{"board":[[null,null,null],[null,null,null],[null,null,null]],"turn":0,"state":"playing","playerMarker":"X","computerMarker":"O"},"context":"response","messageCount":2}
setParam y=1
{"error":"Error: setParam is not a known action or that is not a valid apiVersion.","context":"response","messageCount":3}
paramAdd y=1
{"status":"OK","context":"response","data":null,"messageCount":4}
paramAdd x=1
{"status":"OK","context":"response","data":null,"messageCount":5}
gameMove
{"game":{"board":[["O",null,null],[null,"X",null],[null,null,null]],"turn":1,"state":"playing","playerMarker":"X","computerMarker":"O"},"context":"response","messageCount":6}
paramAdd x=0
{"status":"OK","context":"response","data":null,"messageCount":7}
gameMove
{"game":{"board":[["O",null,null],["X","X","O"],[null,null,null]],"turn":2,"state":"playing","playerMarker":"X","computerMarker":"O"},"context":"response","messageCount":8}
paramAdd y=0
{"status":"OK","context":"response","data":null,"messageCount":9}
paramAdd x=1
{"status":"OK","context":"response","data":null,"messageCount":10}
gameMove
{"game":{"board":[["O","X",null],["X","X","O"],[null,"O",null]],"turn":3,"state":"playing","playerMarker":"X","computerMarker":"O"},"context":"response","messageCount":11}
paramAdd x=2
{"status":"OK","context":"response","data":null,"messageCount":12}
gameMove
{"game":{"board":[["O","X","X"],["X","X","O"],["O","O",null]],"turn":4,"state":"playing","playerMarker":"X","computerMarker":"O"},"context":"response","messageCount":13}
paramAdd y=2
{"status":"OK","context":"response","data":null,"messageCount":14}
paramAdd x=2
{"status":"OK","context":"response","data":null,"messageCount":15}
gameMove
{"game":{"board":[["O","X","X"],["X","X","O"],["O","O","X"]],"turn":5,"state":"tied","playerMarker":"X","computerMarker":"O"},"context":"response","messageCount":16}