var TOKEN_WHITESPACE = '\\s*';
var TOKEN_SEPARATOR = '[,;\\s]*';
var TOKEN_FLOAT = '(-?\\d+(?:\\.\\d+)?)';
var TOKEN_DEG = TOKEN_FLOAT + TOKEN_WHITESPACE + '[°º:d]?';
var TOKEN_MIN = TOKEN_FLOAT + TOKEN_WHITESPACE + '[\'’‘′:]';
var TOKEN_SEC = TOKEN_FLOAT + TOKEN_WHITESPACE + '(?:"|″|’’|\'\'|”|“)?';
var TOKEN_DMS = TOKEN_DEG + optional(TOKEN_WHITESPACE + TOKEN_MIN) + optional(TOKEN_WHITESPACE + TOKEN_SEC);
var TOKEN_DIR = '([NSEW]?)';

function optional(re) {
	return '(?:' + re + ')?';
}
function inRange(value, a, b) {
	return value >= a && value <= b;
}

function dmsToDec(deg, min, sec) {
	deg = parseFloat(deg);
	min = parseFloat(min) || 0;
	sec = parseFloat(sec) || 0;
	var sign = deg < 0 ? -1 : 1;
	if (!inRange(min, 0, 60)) throw new Error('Minutes out of range');
	if (!inRange(sec, 0, 60)) throw new Error('Seconds out of range');
	return (deg + sign * min / 60 + sign * sec / 3600);
}

function apply(deg, min, sec, cardinality, result) {
	if (typeof deg === 'undefined') return;
	var prop = 'lat', coeff = 1;
	if (cardinality === 'e' || cardinality === 'w') {
		prop = 'lon';
	}

	// 1E -> 1.0, 1W -> -1.0
	// 1N -> 1.0, 1S -> -1.0
	if (cardinality === 's') coeff = -1;
	if (cardinality === 'w') coeff = -1;
	result[prop] = coeff * dmsToDec(deg, min, sec);
}

function normalizeCardinality(a, b) {
	a = (a || '').toLowerCase();
	b = (b || '').toLowerCase();
	// +n, +e
	if (!a && !b) return ['n', 'e'];
	if (a && !b) return [a, a === 'n' || a === 's' ? 'e' : 'n'];
	if (!a && b) return [b === 'n' || b === 's' ? 'e' : 'n', b];
	return [a, b];
}


module.exports = function(input) {
	input = input.trim();

	var regExpA = new RegExp('^' + TOKEN_FLOAT + '$', 'ig');
	var regExpB = new RegExp('^' + TOKEN_FLOAT + TOKEN_SEPARATOR + TOKEN_FLOAT + '$', 'ig');
	var regExpC = new RegExp('^' + TOKEN_DMS + TOKEN_WHITESPACE + TOKEN_DIR + '(?:' + TOKEN_SEPARATOR + TOKEN_DMS + TOKEN_WHITESPACE + TOKEN_DIR + ')?$', 'ig'); // 0°W, O°N
	var regExpD = new RegExp('^' + TOKEN_DIR + TOKEN_WHITESPACE + TOKEN_DMS + '(?:' + TOKEN_SEPARATOR + TOKEN_DIR + TOKEN_WHITESPACE + TOKEN_DMS + ')?$', 'ig'); // N0, WO

	var match, cardinality;
	var result = {};
	if (match = regExpA.exec(input)) {
		return parseFloat(match[1]);
	} else if (match = regExpB.exec(input)) {
		return {
			lat: parseFloat(match[1]),
			lon: parseFloat(match[2])
		};
	} else if (match = regExpC.exec(input)) {
		cardinality = normalizeCardinality(match[4], match[8]);
		if (!match[4] && !match[5]) return dmsToDec(match[1], match[2], match[3]);
		apply(match[1], match[2], match[3], cardinality[0], result);
		apply(match[5], match[6], match[7], cardinality[1], result);
	} else if (match = regExpD.exec(input)) {
		cardinality = normalizeCardinality(match[1], match[5]);
		apply(match[2], match[3], match[4], cardinality[0], result);
		apply(match[6], match[7], match[8], cardinality[1], result);
	} else {
		throw new Error('Could not parse string: ' + input);
	}

	return result;
};