var helpers = {
  numbers: {},
  dates: {},
  pdc: {}
}

helpers.numbers.toPercent = function (nbr) {
	return Math.floor(nbr * 100).toString() + '%' || '';
}

helpers.dates.toNumber = function (str, from) {
  return moment(str).diff(from, 'days')
}

helpers.dates.toString = function (nbr, from) {
  return moment(from).add(nbr, 'days').format('YYYY-MM-DD')
}

helpers.pdc.stage = function (claims, from, thru) {

}

helpers.pdc.calc = function (claims, from, thru) {
	_.chain(claims)
		.map(function (item) {
			item._dateOfFill = helpers.dates.toNumber(item.dateOfFill, from);
			item._dateOfFirstDose = helpers.dates.toNumber(item.dateOfFirstDose, from);
			item._dateOfLastDose = helpers.dates.toNumber(item.dateOfLastDose, from);
			item.overlap = item._dateOfFirstDose - item._dateOfFill
			item.calendar = Array(helpers.dates.toNumber(thru, from) + 1).fill(0).fill(1, item._dateOfFirstDose, item._dateOfLastDose + 1)
			return item;
		})
		.sortBy('_dateOfFirstDose')
		.value();

	result = {}
	result.calendar = _.chain(claims)
		.reduce(function (memo, item) {
			for (var i = 0; i <= helpers.dates.toNumber(thru, from); i++) {
				memo[i] = item.calendar[i] | memo[i];
			}
			return memo;
		}, Array(helpers.dates.toNumber(thru, from) + 1).fill(0))
		.value();
	
	result.indexDate = '';
	result.daysInMeasPeriod = 0;
	result.daysCovered = 0;
	for (var i = 0; i <= helpers.dates.toNumber(thru, from); i++) {
		if (result.calendar[i] == 1) {
			if(!result.indexDate) result.indexDate = helpers.dates.toString(i, from)
			result.daysInMeasPeriod += 1;
			result.daysCovered +=1
		} else if (result.daysInMeasPeriod) {
			result.daysInMeasPeriod += 1;
		} else {
			result.calendar[i] = -1;
		}
	}
	
	result.uniqueDatesOfService = _.uniq(claims, false, function (item) { return item.dateOfFill; }).length;
	result.denominator = result.daysInMeasPeriod >= 91 && result.uniqueDatesOfService >= 2;
	result.pdc = helpers.numbers.toPercent(result.daysCovered/result.daysInMeasPeriod);
	result.numerator = result.daysCovered/result.daysInMeasPeriod >= 0.8;
	
	return result;
}