ussd/internal/utils/age.go

package utils

import "time"

// CalculateAge calculates the age based on a given birthdate and the current date in the format dd/mm/yy
// It adjusts for cases where the current date is before the birthday in the current year.
func CalculateAge(birthdate, today time.Time) int {
	today = today.In(birthdate.Location())
	ty, tm, td := today.Date()
	today = time.Date(ty, tm, td, 0, 0, 0, 0, time.UTC)
	by, bm, bd := birthdate.Date()
	birthdate = time.Date(by, bm, bd, 0, 0, 0, 0, time.UTC)
	if today.Before(birthdate) {
		return 0
	}
	age := ty - by
	anniversary := birthdate.AddDate(age, 0, 0)
	if anniversary.After(today) {
		age--
	}
	return age
}