package Encode::MIME::Header::ISO_2022_JP;

use strict;
use warnings;

use base qw(Encode::MIME::Header);

$Encode::Encoding{'MIME-Header-ISO_2022_JP'} =
bless { encode => 'B', bpl => 76, Name => 'MIME-Header-ISO_2022_JP' } =>
__PACKAGE__;

use constant HEAD => '=?ISO-2022-JP?B?';
use constant TAIL => '?=';

use Encode::CJKConstants qw(%RE);

our $VERSION = do { my @r = ( q$Revision: 1.3 $ =~ /\d+/g ); sprintf "%d." . "%02d" x $#r, @r };

# I owe the below codes totally to
# Jcode by Dan Kogai & http://www.din.or.jp/~ohzaki/perl.htm#JP_Base64

sub encode {
my $self = shift;
my $str = shift;

utf8::encode($str) if ( Encode::is_utf8($str) );
Encode::from_to( $str, 'utf8', 'euc-jp' );

my ($trailing_crlf) = ( $str =~ /(\n|\r|\x0d\x0a)$/o );

$str = _mime_unstructured_header( $str, $self->{bpl} );

not $trailing_crlf and $str =~ s/(\n|\r|\x0d\x0a)$//o;

return $str;
}

sub _mime_unstructured_header {
my ( $oldheader, $bpl ) = @_;
my $crlf = $oldheader =~ /\n$/;
my ( $header, @words, @wordstmp, $i ) = ('');

$oldheader =~ s/\s+$//;

@wordstmp = split /\s+/, $oldheader;

for ( $i = 0 ; $i < $#wordstmp ; $i++ ) {
if ( $wordstmp[$i] !~ /^[\x21-\x7E]+$/
and $wordstmp[ $i + 1 ] !~ /^[\x21-\x7E]+$/ )
{
$wordstmp[ $i + 1 ] = "$wordstmp[$i] $wordstmp[$i + 1]";
}
else {
push( @words, $wordstmp[$i] );
}
}

push( @words, $wordstmp[-1] );

for my $word (@words) {
if ( $word =~ /^[\x21-\x7E]+$/ ) {
$header =~ /(?:.*\n)*(.*)/;
if ( length($1) + length($word) > $bpl ) {
$header .= "\n $word";
}
else {
$header .= $word;
}
}
else {
$header = _add_encoded_word( $word, $header, $bpl );
}

$header =~ /(?:.*\n)*(.*)/;

if ( length($1) == $bpl ) {
$header .= "\n ";
}
else {
$header .= ' ';
}
}

$header =~ s/\n? $//mg;

$crlf ? "$header\n" : $header;
}

sub _add_encoded_word {
my ( $str, $line, $bpl ) = @_;
my $result = '';

while ( length($str) ) {
my $target = $str;
$str = '';

if (
length($line) + 22 +
( $target =~ /^(?:$RE{EUC_0212}|$RE{EUC_C})/o ) * 8 > $bpl )
{
$line =~ s/[ \t\n\r]*$/\n/;
$result .= $line;
$line = ' ';
}

while (1) {
my $iso_2022_jp = $target;
Encode::from_to( $iso_2022_jp, 'euc-jp', 'iso-2022-jp' );

my $encoded =
HEAD . MIME::Base64::encode_base64( $iso_2022_jp, '' ) . TAIL;

if ( length($encoded) + length($line) > $bpl ) {
$target =~
s/($RE{EUC_0212}|$RE{EUC_KANA}|$RE{EUC_C}|$RE{ASCII})$//o;
$str = $1 . $str;
}
else {
$line .= $encoded;
last;
}
}

}

$result . $line;
}

1;
__END__