scriptEngine.js

var initScriptEngine = function(){

  //can you take a ladder?
  window.atLadder=false;

  //are you at the canyon?
  window.atCanyon=false;

  //are you at the princess?
  window.atPrincess=false;

  //have you got the ladder?
  window.hasLadder=false;

  //can you cross the canyon (because you put the ladder on it)?
  window.canyonTraversable=false;

  //where the ladder is
  window.ladderLocation=-3;

  //where the canyon is
  window.canyonLocation=11;

  //where the princess is
  window.princessLocation=14;

  //where the hero is
  window.heroLocation=0;

  //the code generated
  var plan='';

  //flag for syntax checking during code generation
  var inCondition=false;
  var justClosedWhile=false;

  //current execution step
  var currentStep=1;

  //list of actions for the B panel
  var planList=new Array();

  //call trace to move the viewPort
  var callTrace= new Array();

  //maximum execution steps allowed to prevent infinite loops
  var maxSteps=100;

  //victory flag, to fix final check
  gameOver=false;

  //container for current instruction
  var scriptedAction=$('<div>');

  //add visible element to script list
  $('#scriptContainer').append(scriptedAction);

  //printable actions map
  var stringActions=new Array();
  stringActions['takeLadder']= 'take the ladder';
  stringActions['dropLadder']= 'drop the ladder';
  stringActions['walkRight']= 'walk right';
  stringActions['walkLeft']= 'walk left';
  stringActions['AtLadder']= 'at the ladder, ';
  stringActions['AtCanyon']= 'at the canyon, ';
  stringActions['AtPrincess']= 'at the princess, ';
  stringActions['HasLadder']= 'have the ladder, ';
  stringActions['while']= 'while ';
  stringActions['if']= 'if ';
  stringActions['not']= 'not ';


  //terminates the game
  function loseGame(){
    message='after some time, the Princess gets tired and goes away: you lost';
    gameLog(message);
    gameOver=true;

    //add to list function calls for the viewport (filter actions that have no graphical relevance)
    callTrace.push('loseGame');
  }

  //checks whether the player won
  function checkGameOutcome(){
    //if you are at the princess, announce victory
    if(AtPrincess()){
      message='you got at the princess: you won';
      gameLog(message);
      gameOver=true;

      //add to list function calls for the viewport (filter actions that have no graphical relevance)
      callTrace.push('winGame');
    }

    //if you reached maximum number of steps, terminate
    if(currentStep >= maxSteps){
      loseGame();
    }
  }

  //increments game step, checks if maximum has been reached and takes action;
  function incrementStepAndCheckExecutionTime(){
    //increment step and check if maximum;
    currentStep+=1;

    //checks victory
    checkGameOutcome();
  }

  //populate the output log
  function gameLog(message){
    //add to list of game events to be sent to B
    planList.push(message);

    //debug in panel A
    console.log(message);
  }

  //check if you have a ladder
  function HasLadder(){
    if(hasLadder) gameLog('you got the ladder');
    else gameLog('you have no ladder');

    return hasLadder;
  }


  //check if you are not at the princess
  function AtPrincess(){
    if(atPrincess) gameLog('you are at the princess');
    else gameLog('you are not yet at the princess');

    return atPrincess;
  }

  //check if you are not at the ladder
  function AtLadder(){
    if(atLadder) gameLog('you are at the ladder');
    else gameLog('you are not yet at the ladder');

    return atLadder;
  }

  //check if you are not at the canyon
  function AtCanyon(){
    if(atCanyon) gameLog('you are at the canyon');
    else gameLog('you are not yet at the canyon');

    return atCanyon;
  }

  //check if the player can reach ladder and canyon
  function updateSurroundingStatus(){
    atCanyon=heroLocation == canyonLocation;
    atLadder=heroLocation == ladderLocation;
    atPrincess=heroLocation == princessLocation;
  }

  //move right
  function walkRight(){
    //count time
    incrementStepAndCheckExecutionTime();

    //check whether you can move past the canyon
    if (atCanyon){
      if(canyonTraversable){
        //move past
        heroLocation+=1;

        //add to list function calls for the viewport
        callTrace.push(arguments.callee.name);

        //update log
        gameLog('you walk over the canyon');

        //winning status, perform check
        checkGameOutcome();
      }else{
        //deny the action
        gameLog('can\'t walk: there is a canyon');
      }
    }else{
      //move right
      heroLocation+=1;

      //add to list function calls for the viewport
      callTrace.push(arguments.callee.name);

      //output log
      gameLog('you walk right');
    }

    //if you have the ladder, the ladder moves with you
    if(hasLadder){
      //update ladder location
      ladderLocation=heroLocation;
    }

    //check what you have at reach
    updateSurroundingStatus();
  }

  //move left
  function walkLeft(){
    //count time
    incrementStepAndCheckExecutionTime();

    //move left
    heroLocation-=1;

    //add to list function calls for the viewport
    callTrace.push(arguments.callee.name);

    //if you have the ladder, the ladder moves with you
    if(hasLadder){
      //update ladder location
      ladderLocation=heroLocation;
    }

    //output log
    gameLog('you walk left');

    //check what you have at reach
    updateSurroundingStatus();
  }

  //take ladder, if you can
  function takeLadder(){
    //count time
    incrementStepAndCheckExecutionTime();

    //output log
    gameLog('you try to take the ladder');

    //check whether you can take the ladder
    if(atLadder){
      //take it
      hasLadder=true;

      //add to list function calls for the viewport
      callTrace.push(arguments.callee.name);

      //output log
      gameLog('you got the ladder');
    }else{
      //deny the action
      gameLog('there is no ladder to take');
    }
  }

  //drop ladder, if you have it
  function dropLadder(){
    //count time
    incrementStepAndCheckExecutionTime();

    //check if you have it
    if(hasLadder){
      //drop it
      hasLadder=false;

      //add to list function calls for the viewport (filter actions that have no graphical relevance)
      callTrace.push(arguments.callee.name);

      //update ladder location
      ladderLocation=heroLocation;

      //special case: dropping it on the canyon makes it traversable
      if(atCanyon){
        //update world status
        canyonTraversable=true;

        //output special log
        gameLog('you drop the ladder over the canyon');
      }else{
        //output log
        gameLog('you drop the ladder');
      }
    }else{
      //deny action
      gameLog('you didn\' have any ladder to drop');
    }

    //check what you have at reach
    updateSurroundingStatus();
  }

  //execute script
  $('#play').on('click',function(){

    //if the flag is still raised, the player left a while without subject action; stop
    if(justClosedWhile){
      $('#modalErrorNoInstruction').openModal();
      return;
    }

    //execute generated code
    eval(plan);
    console.log(plan);
    checkGameOutcome();

    //if plan was not sufficient to carry out goal, kill the player
    if(!gameOver) loseGame();
    console.log(planList);
    console.log(callTrace);

    viewportFunctions.playAnimation(callTrace);
  });

  //reset game
  $('#reset').on('click',function(){
    location.reload()
  });

  //wheneven the player clicks on an action
  $('#actionsContainer').on('click','.line',function(){
    //get action name
    var instruction=$(this).attr("id");


    //while has a strict syntax; if while is selected
    if(('while'==instruction || 'if'==instruction) && !inCondition){

      //take note and demand a condition afterwards
      inCondition=true;

      //select right behaviour for conditional instructions
      switch(instruction) {
        case 'while':
          //generate code for open while (with infinite loop avoidance condition)
          plan=plan.concat('while(currentStep<'+maxSteps+' && ');

          //generate output in the current container
          scriptedAction.append($('<span>').text(stringActions[instruction]));
          break;
        case 'if':
          //generate code for open if
          plan=plan.concat('if( ');

          //generate output in the current container
          scriptedAction.append($('<span>').text(stringActions[instruction]));
          break;
      }
    }else{
      //if it's another action
      //if in while, demand a condition
      if(inCondition){
        //if not a condition
        if(!$(this).hasClass('condition')){

          //demand it
          $('#modalErrorNoCondition').openModal();

          //and refuse to add the action
          return;
        }else{

          //if it's a negation
          if('not'==instruction){

            //generate code for not
            plan=plan.concat('!');

            //generate output in the current container
            scriptedAction.append($('<span>').text(stringActions[instruction]));

          }else{
            //add the condition with closing while parenthese
            plan=plan.concat(instruction+'()) ');

            //generate output in the current container
            scriptedAction.append($('<span>').text(stringActions[instruction]));

            //close the while after action is added
            inCondition=false;

            //raise flag for syntax check of while termination block
            justClosedWhile=true;
          }
        }
      }else{

        //prevent putting a boolean or negation without being in the need of it
        switch(instruction) {
          case 'not':
          case 'AtCanyon':
          case 'AtLadder':
          case 'HasLadder':
            //demand it
            $('#modalErrorConditionNegation').openModal();

            //and refuse to add the action
            return;
        }
        //add the action
        plan=plan.concat(instruction+'(); ');

        //generate output in the current container
        scriptedAction.append($('<span>').text(stringActions[instruction]));

        //create a new visible element container
        scriptedAction=$('<div>');

        //add visible element to script list
        $('#scriptContainer').append(scriptedAction);

        //switch off the flag so we know the syntax is good
        if(justClosedWhile) justClosedWhile=false;
      }
    }

  });
};

window.initScriptEngine = initScriptEngine