(function (){
    'use strict';

    var nrOfBlocks = 10; 
    var hiddenBlocks = new Array(10);
    var lockedBlocks = new Array(2);
    var lockedCards = new Array(2);
    var temp = document.getElementsByTagName('td');
    var counter= 0;
    
    // Helper functions
    function randomizeBlocks(currPos){
        var randNr = Math.floor((Math.random() * 5) +1);
        
        while(checkForDuplicates(randNr)){
                randNr = Math.floor((Math.random() * 5) +1);
        }
        hiddenBlocks[currPos] = randNr;
    }

    function checkForDuplicates(nr){
        var isDuplicate = false;
        var count = 0;

        for(var i = 0; i < nrOfBlocks; i++){
            if(hiddenBlocks[i] === nr){
                count++;
            }
        }
        if(count === 2){
            isDuplicate = true;
        }
        return isDuplicate;
    }

    function displayHidden(currId){
        var currBlock = document.getElementById(currId);
        currBlock.innerHTML = "";
        currBlock.style.backgroundImage = "url('img/"+hiddenBlocks[currId]+".jpg')";
        currBlock.onclick = function(){ window.alert('You have to choose another card'); };
        counter++;
        console.log('Click: ' + counter);
        checkMatch(currId);
    }
    
    function checkMatch(currId){
        if(counter === 1){
            lockedCards[0] = hiddenBlocks[currId];
            lockedBlocks[0] = currId;
        }
        else if(counter === 2){
            
            lockedCards[1] = hiddenBlocks[currId];
            lockedBlocks[1] = currId;

            if(lockedCards[0] === lockedCards[1]){
                console.log('yeey a match!');    
            }
            else{
                console.log('sorry...no match');
                console.log('flipping back in 3 secs');
                toggleClickable();
                window.setTimeout(function(){
                    for(var i = 0; i < 2; i++){
                        for(var j = 0; j < nrOfBlocks; j++){
                            if(hiddenBlocks[j] === lockedCards[i]){
                                var box = document.getElementById(lockedBlocks[i]);
                                box.style.backgroundImage = 'none';
                                box.innerHTML = '?';
                                box.onclick = function(){
                                        displayHidden(this.id);
                                    };
                            }    
                        }    
                    }
                    toggleClickable();    
                },3000);
            }
            counter = 0;
        }
    }
    function toggleClickable(){
        var box = document.getElementsByTagName('td');
        for(var i = 0; i < nrOfBlocks; i++){
            if(box[i].style.pointerEvents === 'none'){
                box[i].style.pointerEvents = '';
            }
            else{
                box[i].style.pointerEvents = 'none';
            }
        }
    }
    for(var i = 0; i < nrOfBlocks; i++){
        temp[i].setAttribute('id', i);
        temp[i].onclick = function(){
            displayHidden(this.id);
        };
        randomizeBlocks(i);
    }
}());