package Tracks;

use strict;
use warnings;

use Class::Std;
use Digest::SHA1;
use Audio::FLAC::Header;

use constant SECTOR_OFFSET => 150;

my %tracks_for :ATTR( get => 'tracks' );

sub _get_tracks_from_cdinfo {    
    my $device = shift;
    my @tracks;
    open my $CD_INFO, 'cd-info -q |' or die "Unable to run cd-info: $!";
    while (<$CD_INFO>) {
        next unless /^\s*([0-9]+): \d\d:\d\d:\d\d  (\d{6})/;
        my ($num, $sector) = ($1, $2);
        my $track = {
            number => $num,
            sector => $sector,
        };
        # place leadout track (170) at index 0
        $num != 170 ? $tracks[$num] = $track : $tracks[0] = $track;
    }
    close $CD_INFO;

    return @tracks;
}

sub _get_tracks_from_cdparanoia {
    my $device = shift;
    my @tracks;
    open my $CDP, 'cdparanoia -d ' . $device . ' -Q 2>&1 |' or die "Unable to run cdparanoia: $!";
    while (<$CDP>) {
        if (m{
            ^\s+(\d+)\.               # track number
            \s+(\d+)                  # length
            \s+\[(\d\d:\d\d\.\d\d)\]  # length (MSF)
            \s+(\d+)                  # start
            \s+\[(\d\d:\d\d\.\d\d)\]  # start (MSF)
        }x) {
            my ($track, $length, $length_msf, $start, $start_msf) = ($1, $2, $3, $4, $5);
            $start_msf =~ s/\./:/;
            $tracks[$track] = {
                number => $track,
                sector => $start,
                msf    => $start_msf,
            };
        } elsif (m{TOTAL\s+(\d+)}) {
            my $total = $1;
            my $leadout = $total + $tracks[1]{sector};
            $tracks[0] = {
                number => 170,
                sector => $leadout,
            };        
        }    
    }
    close $CDP;

    return @tracks;
}

sub read_disc {
    my ($self, $device) = @_;
    $tracks_for{ident $self} = [ _get_tracks_from_cdparanoia($device) ];
}

sub get_mbz_discid {
    my ($self) = @_;

    my @tracks = @{ $tracks_for{ident $self} };

    return unless @tracks;

    my $sha1 = Digest::SHA1->new;

    $sha1->add(sprintf('%02X', $tracks[1]{number}));
    $sha1->add(sprintf('%02X', $tracks[-1]{number}));
    for my $i (0 .. 99) {
        my $offset = (defined $tracks[$i]{sector} ? ($tracks[$i]{sector} + SECTOR_OFFSET) : 0);
        $sha1->add(sprintf('%08X', $offset));
    }

    my $digest = $sha1->b64digest;
    $digest =~ tr{+/=}{._-};
    $digest .= '-';  ## why do we need to manually add this?

    return $digest;
}


sub get_cuesheet {
    my ($self) = @_;
    my @tracks = @{ $tracks_for{ident $self} };
    my @cuesheet;
    push @cuesheet, qq{FILE "cdda.wav" WAVE};
    for my $i (1 .. @tracks - 1) {
        my $track = $tracks[$i];
        push @cuesheet, sprintf('  TRACK %02d AUDIO', $i);
        if ($i == 1 && $track->{sector} != 0) {
            push @cuesheet, '    INDEX 00 00:00:00';
        }
        push @cuesheet, '    INDEX 01 ' . $track->{msf};
    }
    return join('', map { "$_\n" } @cuesheet);
}

sub get_cdparanoia_span {
    my ($self) = @_;
    # use a msf start unless track 1 begins at sector
    return $tracks_for{ident $self}[1]{sector} == 0 ? '1-' : '00:00.00-';
}

# module return
1;