class Date;

#my subtype Month of Int where { 1 <= $^a <= 12 };
#my subtype Day of Int where { 1 <= $^a <= 31 };

has Int $.year;
has Int $.month;
has Int $.day; # where {  }; XXX - check that day is valid for month & year

my @MonthLengths =
    ( 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 );

my @LeapYearMonthLengths = @MonthLengths;
@LeapYearMonthLengths[1]++;

my @PreviousMonthDoY =
    ( 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 );

my @PreviousMonthDoLY =
    ( 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335 );

# has DateTime::Locale $.locale


# probably this should be done as "multi submethod BUILD", but that
# makes pugs barf last I checked
multi submethod BUILD () returns Date {
    return $_.today();
}

multi submethod BUILD (Int|Real :$epoch) returns Date {
    $epoch = int $epoch;

    # waiting for localtime in Pugs
    my ( $y, $m, $d ) = (localtime)[5,4,3];
    $y += 1900;
    $m++;

    return $_.SUPER::new( year  => $y,
                          month => $m,
                          day   => $d,
                        );
}

multi submethod BUILD (Str $string) returns Date {
    my $meth;
#    if ( $string ~~ /[today|now] { $meth = 'today }
#                     tomorrow    { $meth = 'tomorrow' }
#                     yesterday   { $meth = 'yesterday' }
#                    / ) {
#        return $_.$meth();
#    }
#    else {
#        # load a heavier weight parser - hand waving ensues
#    }
}

# day as Str where { rx:i/^last$/ }
multi submethod BUILD (Int :$year, Int :$month = 1, Int|Str :$day is copy = 1) returns Date {
    if $day ~~ rx:perl5<i>/^last$/ {
        my @lengths := _is_leap_year($year) ?? @LeapYearMonthLengths !! @MonthLengths;

        $day = @lengths[ $month - 1 ];
    }

    $.year  = $year;
    $.month = $month;
    $.day   = $day;
}

method today () returns Date {
    return $_.new( epoch => time );
}

our &Date::now ::= &Date::today;

method tomorrow () returns Date {
    return $_.new( epoch => time ).add( days => 1 );
}

method yesterday () returns Date {
    return $_.new( epoch => time ).subtract( days => 1 );
}

sub _is_leap_year (Int $year) returns bool {
    if $year % 400 == 0 {
        return bool::true;
    }
    elsif $year % 100 == 0 {
        return bool::false;
    }
    elsif $year % 4 == 0 {
        return bool::true;
    }

    return bool::false;
}

method quarter () returns Int {
    return int( ( 1.0 / 3.1 ) * $.month ) + 1;
}

method day_of_quarter () returns Int {
    my $doy = $_.day_of_year();

    my @doy := _is_leap_year($.year) ?? @PreviousMonthDoLY !! @PreviousMonthDoY;

    return $doy - @doy[ ( 3 * $_.quarter() ) - 3 ];
}

method day_of_year () returns Int {
    my @doy := _is_leap_year($.year) ?? @PreviousMonthDoLY !! @PreviousMonthDoY;

    @doy[$.month - 1] + $.day;
}

method ymd (Str $sep = "-") returns Str {
    return [$.year, $.month, $.day].join($sep);
}

method mdy (Str $sep = "-") returns Str {
    return [$.month, $.day, $.year].join($sep);
}

method dmy (Str $sep = "-") returns Str {
    return [$.day, $.month, $.year].join($sep);
}

=kwid

= NAME

Date - An object representing a single date (without a time)

= SYNOPSIS

  use Date;

  my $date = Date.new( year => 2005, month => 6, day => 29 );
  say $date.year;
  say $date.ymd;

= DESCRIPTION

This class represents a date /without a time/.

Because it is just a date, it does not handle time zones or leap
seconds.

All methods take named parameters unless otherwise specified.

= CONSTRUCTORS

- `new()`

Without any parameters, this returns an object representing the
current /local/ date.

- `new( epoch => Int|Real $epoch)`

Given an epoch time, returns a Date object based on that epoch.

- `new( 'now' | 'today' | 'tomorrow' | 'yesterday' | $date_string )`

Given a string, this module attempts to parse it.  The strings "now",
"today", "tomorrow", and "yesterday" return the appropriate date.

Any other string will be passed to `Date::Something::WaveHands` for
parsing.

- `new( year => $year, month => $month, day => $day )`

Returns a date object for the given values.  The month and day default
to 1 if not given.

The value for day can also be the string "last", in which case the
object returned represents the last day for the specified month.

- `today()`
- `now()`

Synonyms for `Date.new('today')`

- `tomorrow()`

Synonym for `Date.new('tomorrow')`

- `yesterday()`

Synonym for `Date.new('yesterday')`

= OBJECT METHODS

The following methods are available for Date objects:

- `year()`

Returns the year for the object.

- `month()`

Returns the month for the object, from 1 to 12.

- `day()`

Returns the day for the object, from 1 to 31.

- `day_of_year()`

Returns the day of the year, from 1 to 366.

- `quarter()`

Returns the quarter of the year, from 1 to 4.

- `day_of_quarter()`

Returns the day of the quarter, from 1 to 92.

= AUTHOR

Dave Rolsky, <autarch@urth.org>

= COPYRIGHT

Copyright (c) 2005, Dave Rolsky.  All rights reserved.

This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

=cut
