calc_grade_term.pl

#!/usr/bin/env perl

use strict;
use warnings;
use DateTime;
use DateTime::Format::MySQL;

my %age_of = (
    0  => '未就学児',
    6  => '小1', 7  => '小2', 8  => '小3', 9  => '小4', 10 => '小5', 11 => '小6',
    12 => '中1', 13 => '中2', 14 => '中3',
    15 => '高1', 16 => '高2', 17 => '高3',
    18 => '大学1', 19 => '大学2', 20 => '大学3', 21 => '大学4',
    22 => '社会人',
);

my $now = DateTime->now;
my $base_date = DateTime::Format::MySQL->parse_datetime(
    sprintf '%04d-04-01 00:00:00', $now->year - ($now->month < 4) * 1
);

my $old_date = $base_date;
my $old_age;
my $old_grade;
for my $age ( sort { $a <=> $b } keys %age_of ) {
    if ( !$old_grade ) {
        $old_grade = $age_of{ $age };
        $old_age = $age;
        next;
    }
    my $end_date = $old_date->ymd;
    $old_date->subtract( years => ( $age - $old_age ) )->add( days => 1 );
    my $start_date = $old_date->ymd;
    print "$start_date -> $end_date($old_grade)\n";
    $old_date->subtract( days => 1 );
    $old_grade = $age_of{ $age };
    $old_age = $age;
}