/** validate the quantity */
function validateQuantity(iputContainer, lang)
{
	var nb = document.getElementById(iputContainer).value;
	if(nb.length == 0)
	{
		showMessageQuantity(lang);
		return false;
	}
	var value = nb * 1;
	if(isNaN(value))
	{
		showMessageQuantity(lang);
		return false;
	}
	if((value < 0) || (value > 50))
	{
		showMessageQuantity(lang);
		return false;
	}
	return true;
}

/** affiche le message d erreur sur la quantite */
function showMessageQuantity(lang)
{
	if(lang == 'fr')
	{
		alert('Entrez une quantité comprise entre 0 et 50');
	}
	else
	{
		alert('quantity must be between 0 and 50');
	}
}

/** add one element in an input */
function addOne(inputContainer)
{
	if(document.getElementById(inputContainer))
	{
		var nb = document.getElementById(inputContainer).value;
		if(nb.length == 0)
		{
			document.getElementById(inputContainer).value = '1';
			return;
		}
		var value = nb * 1;
		if(isNaN(value))
		{
			document.getElementById(inputContainer).value = '1';
			return;
		}
		if(value < 50)
		{
			document.getElementById(inputContainer).value = (value+1)+'';
		}
	}
}

/** sub one element in an input */
function subOne(inputContainer)
{
	if(document.getElementById(inputContainer))
	{
		var nb = document.getElementById(inputContainer).value;
		if(nb.length == 0)
		{
			document.getElementById(inputContainer).value = '1';
			return;
		}
		var value = nb * 1;
		if(isNaN(value))
		{
			document.getElementById(inputContainer).value = '1';
			return;
		}
		if(value > 1)
		{
			document.getElementById(inputContainer).value = (value-1)+'';
		}
	}
}