import static java.time.LocalDateTime.parse
import static java.time.Duration.between

def t1 = '2007-12-03T10:15:30'
def t2 = '2007-12-11T16:01:10'
def t3 = '2007-12-23T11:11:10'


def getDuration = { date1, date2 ->
    def result
    switch(between(parse(date1), parse(date2)).toDays() as Integer) {
        case 8..15:
            result = 'Fortnight'
            break
        case 16..31:
            result = 'Month'
            break
        default:
            result = 'Not matching'
            break
    }
    result
}

println getDuration(t1, t2)
println getDuration(t2, t3)
println getDuration(t1, t3)