var scale = 40;
var iloscpol = 21;
var snakehtml = document.getElementsByClassName('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 = 200;
var pause = 0;
var length = 0;

function setup(){
   score = 0;
   currscore.innerHTML = 'Current score: </br>' + score;
   speed=200;
   result.classList.toggle('visible');
   playagain.classList.toggle('visible');
   snakejs[0] = 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.update = function(){
      switch(this.dir){
         case 0:
            snakehtml.classList.add('rotate0');
            snakehtml.classList.remove('rotate1');
            snakehtml.classList.remove('rotate3');
            break;
         case 1:
            snakehtml.classList.add('rotate1');
            snakehtml.classList.remove('rotate0');
            snakehtml.classList.remove('rotate2');
            break;
         case 2:
            snakehtml.classList.add('rotate2');
            snakehtml.classList.remove('rotate1');
            snakehtml.classList.remove('rotate3');
            break;
         case 3:
            snakehtml.classList.add('rotate3');
            snakehtml.classList.remove('rotate0');
            snakehtml.classList.remove('rotate2');
            break;
      }
      snakehtml.style.marginTop = (iloscpol-1)*scale - snakejs.y*scale + 'px';
      snakehtml.style.marginLeft = snakejs.x*scale + 'px';
   }
   this.move = function(){
      switch(this.dir){
         case 0:
            if(this.y==iloscpol-1){this.kill();break;}
            snakehtml.classList.add('rotate0');
            snakehtml.classList.remove('rotate1');
            snakehtml.classList.remove('rotate3');
            this.y++;
            break;
         case 1:
            if(this.x==iloscpol-1){this.kill();break;}
            snakehtml.classList.add('rotate1');
            snakehtml.classList.remove('rotate0');
            snakehtml.classList.remove('rotate2');
            this.x++;
            break;
         case 2:
            if(this.y==0){this.kill();break;}
            snakehtml.classList.add('rotate2');
            snakehtml.classList.remove('rotate1');
            snakehtml.classList.remove('rotate3');
            this.y--;
            break;
         case 3:
            if(this.x==0){this.kill();break;}
            snakehtml.classList.add('rotate3');
            snakehtml.classList.remove('rotate0');
            snakehtml.classList.remove('rotate2');
            this.x--;
            break;
      }
      snakehtml.style.marginTop = (iloscpol-1)*scale - snakejs.y*scale + 'px';
      snakehtml.style.marginLeft = snakejs.x*scale + 'px';
   }
   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 = (iloscpol-1)*scale - fruitjs.y*scale + 'px';
   fruithtml.style.marginLeft = fruitjs.x*scale + 'px';
}

function checkfruit(){
   if(snakejs.x==fruitjs.x&&snakejs.y==fruitjs.y){
      switch(snakejs[length-1].dir){
         case 0:
            snakejs[length]= new Snakejs(snakejs[0].x, snakejs[0].y-1);
            break;
         case 1:
            snakejs[length]= new Snakejs(snakejs[0].x-1, snakejs[0].y);
            break;
         case 2:
            snakejs[length]= new Snakejs(snakejs[0].x, snakejs[0].y+1);
            break;
         case 3:
            snakejs[length]= new Snakejs(snakejs[0].x+1, snakejs[0].y);
            break;
      }
      score++;
      currscore.innerHTML = 'Current score: </br>' + score;
      createfruit();
      speed = speed - 6;
      if(speed<90){
         speed=90;
      }
   }
}

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

function pausefunc(){
   //PAUZA XD
}

function continuegame(){
   //WZNOWIENIE XD
   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++;
         if (pause%2==0){
            continuegame();
         }
      } else {
           return 0;
        }
   }

playagain.addEventListener("click", setup);

function run(){
   if(snakejs.alive==false){
      return 0;
   } else if (pause%2==1){
      pausefunc();
      return 0;
   } else {
      for(x=length;x>=0;x--){
         if(x>0){
            snakejs[x].x = snakejs[x-1].x;
            snakejs[x].y = snakejs[x-1].y;
            snakejs[x].dir = snakejs[x-1].dir;
         } else {
            snakejs[0].move();
         }
      }
      checkfruit();
      setTimeout(run, speed);
   }
}


setup();