#!/usr/bin/perl

use strict;
use Archive::Zip;

my $Usage = "$0 zip_path\n";
die $Usage unless ( @ARGV == 1 and -d $ARGV[0] );

chdir( $ARGV[0] ) or die "chdir $ARGV[0]: $!\n";
my @files = <*.zip>;

for my $zipname ( @files ) {
    # next statement reads the zip file:
    my $newname = rename_contents( $zipname );

    rename( $zipname, $newname );
}

sub rename_contents
{
    my ( $zipname ) = @_;
    my $zip = Archive::Zip->new( $zipname )
        or die "can't read $zipname: $!\n";

    ( my $dataname = $zipname ) =~ s/\.zip$//;
    my $data = $zip->removeMember( $dataname );
    ( my $newdataname = $dataname ) =~ s/^.{4}//;
    $data->fileName( $newdataname );
    $zip->addMember( $data );

    $zip->overwrite();
    return( "$newdataname.zip" );
}