function roll(num, sides, exploding, rerolls)
{
	// Holy SHIT this is a mess. What am I DOING.
	var result = {
		"rolled": num + "d" + sides,
		"total": 0,
		"dice": []
	}, u = [];
	for(var i = 0; i < num; i++)
	{
		var r = Math.ceil(Math.random() * sides);
		while(rerolls && (r === 1 || u[r]))
		{
			r = Math.ceil(Math.random() * sides);
		}
		result.total += r;
		u[r] = true;
		if(exploding && r === sides)
		{
			num++;
			result.dice.push(String(r) + "!");
		} else {
			result.dice.push(r);
		}
	}
	return result;
}

function stringify(res)
{
	if(res.total > 0 && res.dice.length > 0)
	{
		return "(" + res.rolled + ": " + res.dice.join(", ") + " = " + res.total + ")";
	} else {
		return "(???)"; // whoops fuck
	}
}
	
function parse(str)
{
	var tokens = str.split(/([\+\-\*\/\^])/gi),
		total = 0,
		result = [],
		modo = null;
	for(var k in tokens)
	{
		var tok = tokens[k];
		if(/^\d*d\d+\!?$/.test(tok))
		{
			// It's a roll
			var d = tok.match(/^(\d*)d(\d+)(\!?)$/);
			if(Number(d[1]) > 0 && Number(d[2]) > 1)
			{
				var r = roll(Number(d[1]), Number(d[2]), d[3] === "!", false),
					s = stringify(r);
				if(typeof(modo) === "function")
				{
					// OPERAAAANDS
					total = modo(total, r.total);
				} else {
					total = r.total;
				}
				result.push(s);
			} else 
			{
				return "Invalid token at index " + k + " (" + tok + ")";
			}
		} else if(/^[\+\-\*\/\^]$/i.test(tok))
		{
			// It's an operand
			modo = operands["+-*/^".indexOf(tok)];
			result.push(tok);
		} else if(/^\d+$/.test(tok))
		{
			// It's a number
			if(typeof(modo) === "function")
			{
				total = modo(total, Number(tok));
			} else {
				total = Number(tok);
			}
			result.push(tok);
		} else {
			return "Invalid token at index " + k + " (" + tok + ")";
		}
	}
	return result.join(" ") + " for a total of " + String(total);
}

var operands = [
	// +-*/^
	function(a, b) { return a+b; },
	function(a, b) { return a-b; },
	function(a, b) { return a*b; },
	function(a, b) { return a/b; },
	function(a, b) { return Math.pow(a, b); }
];

module.exports = parse;