use strict;

use Bio::DB::Sam;
use Data::Dumper;
use MLDBM qw(DB_File Storable);
use Fcntl;

my $foo = $ARGV[0];
chomp $foo;
my $idx;
my $idx2;
if(-e $foo.".lidx") {
    tie %$idx,'MLDBM', $foo.".lidx", O_RDWR, 0666 or die "$! $foo.lidx";
}
else {
    tie %$idx,'MLDBM', $foo.".lidx", O_CREAT|O_RDWR, 0666 or die "$! $foo.lidx";
    my $bam = Bio::DB::Bam->open($foo);

    my $header = $bam->header;
    my $cnt = 0;
    my $pos = $bam->tell;
    while(my $a = $bam->read1()) {
        if( $cnt % 10000 == 0 ) {
            print STDERR "$cnt:". $pos."\n";
            $idx->{$cnt} = $pos;
        }
        $pos = $bam->tell;
        $cnt++;
    }
}

my $bam = Bio::DB::Bam->open($foo);
my $header = $bam->header;
$bam->seek(int($idx->{$ARGV[1]}),0);
print STDERR $bam->tell ." $idx->{$ARGV[1]}\n";
my $aln = $bam->read1();
print $aln->qname."\n";