#!perl

use v5.14;

use Encode qw( encode decode );
use MIME::Base64;

binmode STDOUT, ':encoding(UTF-8)';

local $, = "\t";
local $\ = "\n";

@ARGV = <@ARGV>; # Expand wildcards...

LINE:
while (<>) {
    next LINE unless m{
        ^(\S+): # field name
        \s+
        =[?]utf-8[?]B[?]
        ([^?]+) # base64 encoded text
        [?]=
    }ix;

    my ($field_name, $base64_encoded_text) = ($1, $2);

    my $base64_decoded_text = decode_base64($base64_encoded_text);

    my $utf8_decoded_text = decode('UTF-8', $base64_decoded_text);

    next LINE unless $utf8_decoded_text =~ m{
        [^\p{Script=Common}\p{Script=Latin}]
    }x;

    my $damaged_text = $utf8_decoded_text;

    my $repaired_text
        = decode('UTF-8', encode('UCS-2LE', $damaged_text));

    $repaired_text =~ s{\x{00}+$}{};

    print $ARGV, $field_name, $repaired_text, $damaged_text;
}

exit 0;