#!/usr/bin/perl -w
use strict;
use Bio::AlignIO;

my $dir = shift @ARGV || die "need a directory";

my $ext = "\.pep\.aln";
my @aln_array;
opendir(DIR, $dir) || die $!;
for my $file ( readdir(DIR) ) {
 if( $file =~ /$ext$/ ) { 
   my $in = Bio::AlignIO->new(-format => 'fasta',
			      -file   => "$dir/$file");
   if( my $aln = $in->next_aln ) {
      # do something with aln
      push @aln_array, $aln;
   }
 }
}
# print the type of object that I have
# print ref($object), "\n";

my %seqs;
my $i = 0;
for my $aln ( @aln_array ) {
 my $trimmed_aln = $aln->remove_gaps;
 for my $seq ( $trimmed_aln->each_seq ) {
     my $id;
     my $seqid = substr($seq->display_id,0,1);
     if( $seqid eq 'b' ) {
      $id = 'ecoli';
     } elsif( $seqid eq 'y' ) {
      $id = 'yersinia';
     } elsif( $seqid eq 'S' ) {
      $id = 'salmonella';
     } else {
       warning("seqid is $seqid for ",$seq->display_id, "\n");
       $id = 'unknown';
     }
   $seqs{$id} .= $seq->seq;  
 }
}

my $newaln = Bio::SimpleAlign->new;
for my $id ( keys %seqs ) {
  $newaln->add_seq( Bio::LocatableSeq->new(-display_id => $id,
					  -seq         => $seqs{$id}) );
}
my $out = Bio::AlignIO->new(-file => ">concatenated_aln.nex",
			    -format => 'nexus',
			   -show_symbols => 0, # for mrbayes' happiness
			   -show_endblock => 0, # ditto
			  );
$out->write_aln($newaln);