#!/usr/bin/perl

# Copyright (C) 2007-2022 Ole Tange, http://ole.tange.dk and Free
# Software Foundation, Inc.
#
# This program 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 3 of the License, or
# (at your option) any later version.
#
# This program 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 this program; if not, see <https://www.gnu.org/licenses/>
# or write to the Free Software Foundation, Inc., 51 Franklin St,
# Fifth Floor, Boston, MA 02110-1301 USA
#
# SPDX-FileCopyrightText: 2021-2022 Ole Tange, http://ole.tange.dk and Free Software and Foundation, Inc.
# SPDX-License-Identifier: GPL-3.0-or-later

# This fixes problems in pod2rst conversion

# Conversion errors:

# B<foo `bar` baz>

# Fixed:
# ... B<foo>
# bar

# Fixed:
# =item - - a

# Fixed:
# \\` => \`

# Not fixed (RST does not support Bold-Italic):
# B<cat | xargs -d "\n" -n1 I<command>>

sub pipefunc {
    # Emulate a shell pipe but between Perl functions
    # stdin | func1 | func2 | ... | funcN
    # pipefunc(*func1, *func2, ..., *funcN);
    my $func = pop;

    my $pid = open(my $kid_to_read, "-|");
    defined($pid) || die "can't fork: $!";
    if ($pid) {
	open STDIN, "<&", $kid_to_read or die;
	&$func();
    } else { # child
	close $kid_to_read;
	if($_[1]) {
	    # More than one function remaining: Recurse
	    pipefunc(@_);
	} else {
	    # Only one function remaining: Run it
	    $func = pop;
	    &$func();
	}
	exit 0;
    }
}

sub pre1 {
    while(<STDIN>) {
	# Remove comments
	/^\#/ and next;
	# quote -
	s/^=item -/=item \001/;

	if(/^ /) {
	    # ignore source blocks
	} else {
	    # \\ => \
	    s/\\/\\\\/g;
	}
	print;
    }
}

sub pre2 {
    $/="\n\n";
    while(<STDIN>) {
	# join lines in each paragraph
	s/(\S)\n(\S)/$1 $2/g;
	print;
    }
}

sub pod2rst {
    exec "pod2rst";
}

sub post {
    while(<STDIN>) {
	# =item in =item
	s/- \\[*]/- /;
	# B<*.log>
	s/\\\\[*]/\\*/g;
	# - -
	s/^-(\s+)\001/-$1\\-/g;
	# \\` => \`
	s/\\\\`/\\`/g;
	print;
    }
}

# stdin | pre1() | pre2() | pod2rst() | post()
pipefunc(*pre1,*pre2,*pod2rst,*post);