package main

import "time"

func wrap (value, around int) (wrapped int) {
	wrapped = value % around
	if wrapped < 0 {
		wrapped += around
	}
	
	return
}

func firstOfMonth (year int, month time.Month) (day time.Time) {
	day = time.Date(year, month, 0, 0, 0, 0, 0, time.Local)
	return
}

func daysInMonth (year int, month time.Month) (days int) {
	switch month {
	case 1:  days = 31
	case 2:
		// betcha didn't know this about leap years
		if year % 4 == 0 && (year % 100 != 0 || year % 400 == 0) {
			days = 29
		} else {
			days = 28
		}
	case 3:  days = 31
	case 4:  days = 30
	case 5:  days = 31
	case 6:  days = 30
	case 7:  days = 31
	case 8:  days = 31
	case 9:  days = 30
	case 10: days = 31
	case 11: days = 30
	case 12: days = 31
	}

	return
}

func canonMonth (when time.Time) (month int) {
	month = int(when.Month() - 1) + when.Year() * 12
	return
}