var scale = 40;
var iloscpol = 21;
var snakehtml = document.getElementById('snake');
var snakejs;
var fruithtml = document.getElementById('fruit');
var fruitjs;
var currscore = document.getElementById('currscore');
var playagain = document.getElementById('playagain');
var result = document.getElementById('result');
var pausehtml = document.getElementById('pause');
var r, r2;
var score = 0;
var speed = 300;
var pause = 0;
   pausehtml.classList.toggle('visible');

function setup(){
   score = 0;
   currscore.innerHTML = 'Current score: </br>' + score;
   speed=300;
   result.classList.toggle('visible');
   playagain.classList.toggle('visible');
   snakejs = new Snakejs(Math.floor(iloscpol/2), Math.floor(iloscpol/2))
   createfruit();
   run();
}

function Snakejs(x, y){
   this.x = x;
   this.y = y;
   this.dir = Math.floor(Math.random()*4);
   this.alive = true;
   this.move = function(){
      switch(this.dir){
         case 0:
            if(this.y==0){this.kill();break;}
            this.y--;
            break;
         case 1:
            if(this.x==iloscpol-1){this.kill();break;}
            this.x++;
            break;
         case 2:
            if(this.y==iloscpol-1){this.kill();break;}
            this.y++;
            break;
         case 3:
            if(this.x==0){this.kill();break;}
            this.x--;
            break;
      }
   }
   this.kill = function(){
      this.alive = false;
      aftergame();
   }
   this.turn = function(x){
      if(x==37){
         if(this.dir>0){this.dir--;}
         else {this.dir=3;}
      } else if (x==39){
         if(this.dir<3){this.dir++;}
         else {this.dir=0;}
      }
   }
}

function Fruit(x, y){
   this.x=x;
   this.y=y;
}

function createfruit(){
   r = Math.floor(Math.random()*iloscpol);
   r2 = Math.floor(Math.random()*iloscpol);
   while(r==snake.x&&r2==snake.y||r==snake.x-1&&r2==snake.y-1||r==snake.x+1&&r2==snake.y+1||r==snake.x-1&&r2==snake.y+1||r==snake.x+1&&r2==snake.y-1){
      r = Math.floor(Math.random()*iloscpol);
      r2 = Math.floor(Math.random()*iloscpol);
   }
   fruitjs= new Fruit(r, r2);
   fruithtml.style.marginTop = fruitjs.y*scale + 'px';
   fruithtml.style.marginLeft = fruitjs.x*scale + 'px';
}

function aftergame(){
   result.innerHTML = 'You lost, your score is: </br>' + score;
   result.classList.toggle('visible');
   playagain.classList.toggle('visible');

}

function pausefunc(){
   pausehtml.classList.toggle('visible');
   currscore.classList.toggle('visible');
}
function continuegame(){
   pausehtml.classList.toggle('visible');
   currscore.classList.toggle('visible');
   pause = 0;
   run();
}

window.onkeydown = function(event){
   if (event.keyCode == 37){
      snakejs.turn(37);
   } else if (event.keyCode==39){
      snakejs.turn(39);
   } else if (event.keyCode==32 && snakejs.alive==true){
         pause=pause+1;
         if (pause%2==0){
            continuegame();
         }
      } else if(event.keyCode==32 && snakejs.alive==false){
           return 0;
        }
   }

playagain.addEventListener("click", setup);

function run(){
   if(snakejs.alive==false){
      return 0;
   } else if (pause%2==1){
      pausefunc();
      return 0;
   }else if (pause%2==0){
      snakejs.move();
      snakehtml.style.marginTop = snakejs.y*scale + 'px';
      snakehtml.style.marginLeft = snakejs.x*scale + 'px';
      if(snakejs.x==fruitjs.x&&snakejs.y==fruitjs.y){
         score++;
         currscore.innerHTML = 'Current score: </br>' + score;
         createfruit();
         speed = speed - 25;
         if(speed<100){
            speed=100;
         }
      }
      setTimeout(run, speed);
   }
}


setup();