// function randn_bm() {
//     var u = 0, v = 0;
//     while(u === 0) u = Math.random(); //Converting [0,1) to (0,1)
//     while(v === 0) v = Math.random();
//     return (Math.sqrt( -2.0 * Math.log( u ) ) * Math.cos( 2.0 * Math.PI * v )); // still multiply with 10%
// }

var spareRandom = null;

function normalRandom()
{
	var val, u, v, s, mul;

	if(spareRandom !== null)
	{
		val = spareRandom;
		spareRandom = null;
	}
	else
	{
		do
		{
			u = Math.random()*2-1;
			v = Math.random()*2-1;

			s = u*u+v*v;
		} while(s === 0 || s >= 1);

		mul = Math.sqrt(-2 * Math.log(s) / s);

		val = u * mul;
		spareRandom = v * mul;
	}

	return val / 14;	// 7 standard deviations on either side
}

function normalRandomInRange(min, max)
{
	var val;
	do
	{
		val = normalRandom();
	} while(val < min || val > max);
	return val;
}

function promiseGenerator({id, timeout}) {
	return new Promise((resolve, reject) => {
  	setTimeout(() => {
      if (jsPsych.data.getURLVariable('debug') === 'true') {
        $('.debug').html(id + ' visible after ' + timeout + 'ms.');
      };
      if (id === '.test') {
          $(id).css({'display': 'block'});
      } else {
        $(id).css({'visibility': 'visible'});
      };
      resolve();
    }, timeout);
    // console.log(id + " at " + timeout);
  })
}

function promiseGenerator_display({id, timeout}) {
	return new Promise((resolve, reject) => {
  	setTimeout(() => {
      if (jsPsych.data.getURLVariable('debug') === 'true') {
        $('.debug').html(id + ' visible after ' + timeout + 'ms.');
      };
      $(id).css({'display': 'block'});
      resolve();
    }, timeout);
    // console.log(id + " at " + timeout);
  })
}

function estBetaParams(mu, sigma) {
    // console.log("b_mu = "+mu+", b_sigma = "+sigma);
    variance = Math.pow(sigma, 2);
    alpha =  ((1 - mu) / variance - 1 / mu) * Math.pow(mu,2);
    beta = alpha * (1 / mu - 1);
    return {
        a: alpha, 
        b: beta
    };
}

function betaRandomInRange(min, max) {
    var betaparams = estBetaParams(0.9, 0.1);
    var random_num = jStat.beta.sample(betaparams.a, betaparams.b);
    // console.log("random_number -> "+random_num);
    var out = min + random_num*(max-min);
    // console.log("out -> "+Math.round(out)+" (min: "+min+", max: "+max+")");
    return Math.round(out);
}