#! /usr/bin/perl
#
# Copyright (C) 2011-2021 Alexis Bienvenüe <paamc@passoire.fr>
#
# This file is part of Auto-Multiple-Choice
#
# Auto-Multiple-Choice is free software: you can redistribute it
# and/or modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation, either version 2 of
# the License, or (at your option) any later version.
#
# Auto-Multiple-Choice is distributed in the hope that it will be
# useful, but WITHOUT ANY WARRANTY; without even the implied warranty
# of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Auto-Multiple-Choice.  If not, see
# <http://www.gnu.org/licenses/>.

######################################################################
#
# auto-multiple-choice latex-link :
#
# Tests if the style file automultiplechoice.sty is accessible for
# LaTeX. If not, tries to make a link from a location inside texmf
# directories to the installed style file, and calls mktexlsr
#
# auto-multiple-choice latex-link remove :
#
# remove the link.
#
######################################################################

use warnings;
use 5.012;

use AMC::Basic;

for my $c (qw/kpsewhich texconfig-sys/) {
    if ( !commande_accessible($c) ) {
        print STDERR
"ERROR: I don't find the command $c. Perhaps LaTeX is not installed?\n";
        exit(1);
    }
}

if ( $> != 0 ) {
    print "WARNING: This command should be called by root!\n";
}

sub get_tex_var {
    my ($k) = @_;
    my $v = '';
    open( SYS, "-|", "texconfig-sys", "conf" )
      or die "Can't exec texconfig-sys: $!";
    for (<SYS>) {
        chomp;
        $v = $1 if (/^$k=(.*)/);
    }
    close(SYS);
    return ($v);
}

my $conf_dir  = "/etc/AMC";
my $link_file = $conf_dir . "/latex-link";
my $link      = '';

if ( -f $link_file ) {
    open( LK, $link_file );
    while (<LK>) {
        chomp;
        $link = $_;
    }
    close(LK);
}

my @styles = get_sty();

sub rehash {
    print "Calling mktexlsr to refresh LaTeX files list...\n";
    open( LSR, "-|", "mktexlsr", "--quiet" );
    while (<LSR>) {
        print $_;
    }
    close(LSR);
    @styles = get_sty();
}

if ( $ARGV[0] =~ /^(remove|rm)$/i ) {
    if ( -l $link ) {
        print "Removing link $link...\n";
        unlink($link);
        if ( -e $link ) {
            die "ERROR: could not remove link $link.\n";
            exit(2);
        } else {
            print("Done.\n");
        }
    } else {
        print "No link to remove.\n";
    }
    exit(0);
}

if ( !@styles ) {
    rehash();
}

if (@styles) {
    print "The style file is already accessible:\n";
    for (@styles) {
        print "$_\n";
    }
    if ( -l $link ) {
        print
          "Use 'auto-multiple-choice latex-link remove' to remove the link\n";
    }
} else {
    my $loc = get_tex_var('TEXMFLOCAL');
    if ( !-d $loc ) {
        print STDERR
          "WARNING: the directory TEXMFLOCAL does not exist ($loc).\n";
        print STDERR "WARNING: trying to create $loc...\n";
        mkdir("$loc");
    }
    my $installed = '/usr/share/texmf/tex/latex/AMC/automultiplechoice.sty';
    if ( !-f $installed ) {
        print STDERR
          "ERROR: I cannot find the installed style file $installed\n";
        exit(2);
    }
    for my $dir (qw:tex tex/latex:) {
        if ( !-d "$loc/$dir" ) {
            print "Creating directory $loc/$dir...\n";
            mkdir("$loc/$dir");
        }
    }
    $link = "$loc/tex/latex/automultiplechoice.sty";
    if ( -l $link ) {
        print
          "WARNING: removing a previously installed non-working symlink...\n";
        unlink($link)
          or die "ERROR: Failed to remove previous symlink $link\n";
    }
    print "Creating link to AMC style file...\n";
    symlink( $installed, $link )
      or die "ERROR: Failed to create symlink $link\n";

    rehash();

    if (@styles) {
        if ( !-d $conf_dir ) {
            mkdir($conf_dir);
        }
        print
          "Saving information about this 'latex-link' run in $link_file...\n";
        open( LF, ">$link_file" )
          or die "Unable to write to $link_file: $!";
        print LF "$link\n";
        close(LF);

        print "Done, 'automultiplechoice.sty' is now reachable from latex.\n";
    } else {
        die
"ERROR: even though the symlink has been properly created, 'automultiplechoice.sty'\n\
         cannot be found using 'kpsewhich -all automultiplechoice.sty'.\n";
    }
}
