Find next available date

next-available-date.js

// polyfill
if (!Array.prototype.some) {
  Array.prototype.some = function(fun, thisArg) {
    'use strict';

    if (this == null) {
      throw new TypeError('Array.prototype.some called on null or undefined');
    }

    if (typeof fun !== 'function') {
      throw new TypeError();
    }

    var t = Object(this);
    var len = t.length >>> 0;

    for (var i = 0; i < len; i++) {
      if (i in t && fun.call(thisArg, t[i], i, t)) {
        return true;
      }
    }

    return false;
  };
}

var freeDays = [ // [day, month]
	[30, 4],
	[3, 5],
	[1, 6],
	[21, 6],
	[30, 11],
	[1, 12]
]

function isFreeDay(today) {
	var day = today.getDate()
	var month = today.getMonth() + 1 // getMonth returns current month - 1
	return freeDays.some(function(freeDay) {
		return freeDay[0] == day && freeDay[1] == month
	})
}

function findNextAvailableDate(today) {
	today = today || new Date();
	var dayNumber = today.getDay()
	var hour = today.getHours()

	// no shipment after 15:00
	if (hour > 14) {
		today.setDate(today.getDate() + 1)
		// avoid infinite loop
		today.setHours(1)
		return findNextAvailableDate(today)
	}

	// no shipment during weekend
	if (dayNumber === 0 || dayNumber ===  6) {
		if (dayNumber === 0) { // sunday
			today.setDate(today.getDate() + 1)
		} else { // saturday
			today.setDate(today.getDate() + 1)
		}

		return findNextAvailableDate(today)
	}

	if (isFreeDay(today)) {
		today.setDate(today.getDate() + 1)

		return findNextAvailableDate(today)
	}

	return today
}

var shipmentDate = findNextAvailableDate()
var deliveryDate = new Date(shipmentDate)
deliveryDate.setDate(deliveryDate.getDate() + 1) // 24 hours delivery
deliveryDate = findNextAvailableDate(deliveryDate)