function isEmpty(inputStr) {

        if (inputStr == "" || inputStr == null) {

                return true
        }
        return false
}

function isNumber(inputStr) {
        for (var i = 0; i < inputStr.length; i++) {
                var oneChar = inputStr.charAt(i)
                if (oneChar < "0" || oneChar > "9") {
                        return false
                }
        }

        return true

}


function inRangeDay(inputStr) {


        num = parseInt(inputStr)
        if (num < 1 || num > 31) {
                return false
        }
        return true
}



function inRangeYear(inputStr) {

        num = parseInt(inputStr)
        if (num < 1900 || num > 3000) {
                return false
        }
        return true
}


function isValidDay(inputStr) {

        if (isEmpty(inputStr)) {
                alert("Въведете ден преди да натиснете Изчисли")
                return false
        } else {

                if (!isNumber(inputStr)) {

                        alert("Денят трябва да бъде само число")
                        return false

                } else {

                        if (!inRangeDay(inputStr)) {
                                alert("Въведете валидна дата")
                                return false
                        }
                }
        }
        return true

}

function isValidYear(inputStr) {
        if (isEmpty(inputStr)) {
                alert("Въведете година преди да натиснете Изчисли")
                return false
        } else {

                if (!isNumber(inputStr)) {
                        alert("Годината трябва да бъде само число")
                        return false
                } else {
                        if (!inRangeYear(inputStr)) {
                                alert("Въведете валидна година")
                                return false
                        }
                }

        }

        return true

}



function makeArray(n) {

        this.length = n

        for (var i=1; i <= n; i++)

                this[i] = null

                return this

}
var maxday = new makeArray(12)

maxday[1] = 31
maxday[2] = 28
maxday[3] = 31
maxday[4] = 30
maxday[5] = 31
maxday[6] = 30
maxday[7] = 31
maxday[8] = 31
maxday[9] = 30
maxday[10] = 31
maxday[11] = 30
maxday[12] = 31

var monthname = new makeArray(12)

monthname[1] = "Януари"
monthname[2] = "Февруари"
monthname[3] = "Март"
monthname[4] = "Aприл"
monthname[5] = "Maй"
monthname[6] = "Юни"
monthname[7] = "Юли"
monthname[8] = "Aвгуст"
monthname[9] = "Септември"
monthname[10] = "Oктомври"
monthname[11] = "Ноември"
monthname[12] = "Декември"



var adddays = new makeArray(7)

adddays[1] = 14
adddays[2] = 35
adddays[3] = 70
adddays[4] = 84
adddays[5] = 161
adddays[6] = 189
adddays[7] = 280
adddays[8] = 235
adddays[9] = 126
adddays[10] = 140
function calcNewDate(month,day,year,adddays) {

        newday = eval(day) + adddays

        newmonth = month + 1

        newyear = eval(year)

        var max



        for (var i = 0; i < 12; i++) {
          if (newmonth == 2 && (newyear % 4) == 0) {
            max = 29
          } else
            max = maxday[newmonth]
          if (newday > max) {

            newday = newday - max
            newmonth = newmonth + 1
            if (newmonth > 12) {
              newyear = newyear + 1
              newmonth = 1
            }
          }
          else
            break
        }
        var datestring =  newday + " " + monthname[newmonth] + "  " + newyear + " г."

        return datestring

}
function calc(form) {

       
		day = document.getElementById('day').selectedIndex + 1;

        year = document.getElementById('year').value;

        monthnum = document.getElementById('month').selectedIndex;

		
		document.getElementById('conception').innerHTML = calcNewDate(monthnum,day,year,adddays[1]);
		document.getElementById('beginrisk').innerHTML = calcNewDate(monthnum,day,year,adddays[2]);
        document.getElementById('endrisk').innerHTML = calcNewDate(monthnum,day,year,adddays[3]);
        document.getElementById('beginorgan').innerHTML = calcNewDate(monthnum,day,year,adddays[2]);
        document.getElementById('endorgan').innerHTML = calcNewDate(monthnum,day,year,adddays[3]);
		document.getElementById('endfirst').innerHTML = calcNewDate(monthnum,day,year,adddays[4]);
		document.getElementById('preemies').innerHTML = calcNewDate(monthnum,day,year,adddays[5])

      	document.getElementById('endsecond').innerHTML = calcNewDate(monthnum,day,year,adddays[6]);
       	document.getElementById('duedate').innerHTML = calcNewDate(monthnum,day,year,adddays[7]); 
		document.getElementById('bolnichen').innerHTML = calcNewDate(monthnum,day,year,adddays[8]);
		document.getElementById('beginmove').innerHTML = calcNewDate(monthnum,day,year,adddays[9]);
       	document.getElementById('endmove').innerHTML = calcNewDate(monthnum,day,year,adddays[10]); 
       
		document.getElementById('calculate').style.display = 'block';
			
            
            /*
            form.endfirst.value = calcNewDate(monthnum,day,year,adddays[4])
            form.preemies.value = calcNewDate(monthnum,day,year,adddays[5])
            form.endsecond.value = calcNewDate(monthnum,day,year,adddays[6])
            form.duedate.value = calcNewDate(monthnum,day,year,adddays[7])
            form.bolnichen.value = calcNewDate(monthnum,day,year,adddays[8])
            form.beginmove.value = calcNewDate(monthnum,day,year,adddays[9])
            form.endmove.value = calcNewDate(monthnum,day,year,adddays[10])
            */
   
}