package DateTime::TimeZone::OlsonDB;

use strict;

use vars qw( %MONTHS %DAYS $PLUS_ONE_DAY_DUR $MINUS_ONE_DAY_DUR );

use Params::Validate qw( validate SCALAR );

sub DEBUG () { 0 }

my $x = 1;
%MONTHS = map { $_ => $x++ }
          qw( Jan Feb Mar Apr May Jun
	      Jul Aug Sep Oct Nov Dec);

$x = 1;
%DAYS = map { $_ => $x++ }
        qw( Mon Tue Wed Thu Fri Sat Sun );

$PLUS_ONE_DAY_DUR =  DateTime::Duration->new( days => 1 );
$MINUS_ONE_DAY_DUR = DateTime::Duration->new( days => -1 );

sub new
{
    my $class = shift;

    return bless { rules => {},
                   zones => {},
                   links => {},
                 }, $class;
}

sub parse_file
{
    my $self = shift;
    my $file = shift;

    open my $fh, "<$file"
        or die "Cannot read $file: $!";

    while (<$fh>)
    {
        chomp;
        $self->_parse_line($_);
    }
}

sub _parse_line
{
    my $self = shift;
    my $line = shift;

    return if $line =~ /^\s+$/;
    return if $line =~ /^#/;

    # remove any comments at the end of the line
    $line =~ s/\s*#.+$//;

    if ( $self->{in_zone} && $line =~ /^\t/ )
    {
        $self->_parse_zone( $line, $self->{in_zone} );
        return;
    }

    foreach ( qw( Rule Zone Link ) )
    {
        if ( substr( $line, 0, 4 ) eq $_ )
        {
            my $m = '_parse_' . lc $_;
            $self->$m($line);
        }
    }
}

sub _parse_rule
{
    my $self = shift;
    my $rule = shift;

    my @items = split /\s+/, $rule, 10;

    shift @items;
    my $name = shift @items;

    my %rule;
    @rule{ qw( from to type in on at save letter ) } = @items;
    delete $rule{letter} if $rule{letter} eq '-';

    # As of the 2003a data, there are no rules with a type set
    delete $rule{type} if $rule{type} eq '-';

    push @{ $self->{rules}{$name} },
        DateTime::TimeZone::OlsonDB::Rule->new( name => $name, %rule );

    undef $self->{in_zone};
}

sub _parse_zone
{
    my $self = shift;