#!/usr/bin/perl

use File::Temp qw(tempfile);

######## STA�E ################################################################

$wersja = "1.8";
@filters = ("$ENV{HOME}/.konwert/filters", "/usr/share/konwert/filters");

######## INICJALIZACJA ########################################################

($ja = $0) =~ s|^.*/(.*?)$|$1|;

######## OPIS U�YCIA ##########################################################

sub uzycie
{
    print { $_[0] ? STDERR : STDOUT } <<EOF;
Usage: $ja FILTER [FILE]... [-o DEST | -O]
This is an interface for conversion between various character encodings.

$ja allows filtering multiple files through multiple filters.
It filters the specified FILEs, or stdin if none are given.

  -o DEST     output goes to this file/directory instead of stdout
  -O          every input file is replaced with its translation
  --help      display this help and exit
  --version   output version information and exit

Simple FILTER is the name of an executable file from one of the
following directories:
  @filters
which itself filters stdin to stdout.

The filtering rule can be more complex:

`$ja FILTER1+FILTER2' means `$ja FILTER1 |$ja FILTER2'.

`$ja FORMAT1-FORMAT2', unless such filter exists, tries to find
a common FORMAT3, such that both filters FORMAT1-FORMAT3 and
FORMAT3-FORMAT1 do exist.

`$ja FILTER/ARG/...' passes arguments to the filter. Arguments can
also be specified here: FORMAT1/ARGS-FORMAT2.

`$ja '(COMMAND ARGS...)'' executes this arbitrary shell command.
EOF
    exit $_[0]
}

######## ANALIZA ARGUMENT�W WYWO�ANIA #########################################

# Nie u�ywam �adnych modu��w getopt itd., bo s� zbyt wolne.

$wy = "-";   # Domy�lnie wynik p�jdzie na stdout
if (@ARGV == 1)
{
    if ($ARGV[0] eq "--help") { uzycie }
    if ($ARGV[0] eq "--version") { print "konwert, version $wersja\n"; exit; }
}
while (@ARGV)
{
    if ($ARGV[0] =~ /^-(.+)$/)   # Jaka� opcja
    {
	shift @ARGV;
	&{${
	{
	    "-" => sub
	    {
		push @we, @ARGV;
		return;
	    },
	    "o" => sub
	    {
		@ARGV or die "$ja: option requires an argument -- $1\n";
		$wy = shift @ARGV;
	    },
	    "O" => sub
	    {
		$wy = "=";
	    }
	}}{$1} or sub { die "$ja: illegal option -- $1\n" } };
    }
    else { push @we, shift @ARGV }
}
@we or uzycie 1;

######## ANALIZA Z�O�ONEGO FILTRU #############################################

sub jest
{
    foreach (@filters)
    {
	if (-x "$_/$_[0]" && !-d _)
	{
	    $_[0] = "$_/$_[0]";
	    return 1;
	}
    }
    0;
}

$filtr = join "|", map
{
    s/^\+//;
    if (/^\(.*\)$/) { $_ }
    else
    {
	my @formaty = split /-/;
	$arg = join "", map { s|^(.*?)(/.*)|$1| and $2 } @formaty;
	$arg =~ s|^/||;
	$arg =~ s|/| |g;
	$_ = join "-", @formaty;
	if (jest $_) { @formaty = $_ }
	else
	{
	    if (@formaty >= 2)
	    {
		my @uni1 = ();
		my @uni2 = ();
		foreach (@filters)
		{
		    opendir DIR, $_ or next;
		    foreach (readdir DIR)
		    {
			/^\Q$formaty[0]\E-(.*)$/ and push @uni1, $1;
			/^(.*)-\Q$formaty[$#formaty]\E$/ and push @uni2, $1;
			    # Nie wiedzie� czemu perl �le rozumie
			    # $formaty[-1] w wyra�eniu regularnym
		    }
		    closedir DIR;
		}
		my $uni = (sort grep { $f = $_; grep { $_ eq $f } @uni2 } @uni1)[0];
		defined $uni or die "$ja: unknown filter -- $formaty[0]-$formaty[-1]\n";
		$formaty[0]  = "$formaty[0]-$uni";
		$formaty[-1] = "$uni-$formaty[-1]";
	    }
	    foreach (@formaty) { jest $_ or die "$ja: unknown filter -- $_\n" }
	}
        $arg =~ s/(?=\W)/\\/g;
	foreach (@formaty) { $_ = "ARG=$arg $_" }
	join "|", @formaty;
    }
} ("+" . shift @we) =~ /\+(?:\(.*?\)|.*?)(?:$|(?=\+))/g;
@we or @we = "-";

######## W�A�CIWA KONWERSJA ###################################################

if ($wy ne "=" && !-d $wy) { open STDOUT, ">$wy" or die "$ja: $wy: $!\n" }
foreach (@we)
{
    open STDIN, "<$_" or die "$ja: $_: $!\n";
    if ($_ ne "-")
    {
	if ($wy eq "=")
	{
	    ($fh, $temp) = tempfile();
	    close $fh;
	    open STDOUT, ">$temp" or die "$ja: $temp: $!\n"
	}
	elsif (-d _)
	{
	    (my $we = $_) =~ s|^.*/||;
	    open STDOUT, ">$wy/$we" or die "$ja: $wy/$we: $!\n"
	}
    }
    system $filtr and die "$ja: error executing filter\n";
    if ($_ ne "-" && $wy eq "=")
    {
	open STDIN, "<$temp" or die "$ja: $temp: $!\n";
	open STDOUT, ">$_" or die "$ja: $_: $!\n";
	unlink $temp;
	print while (<STDIN>);
    }
}

###############################################################################