#!/bin/sh
#! -*-perl-*-

# Rewrite a gnulib.mk, adding prefixes to work with automake's subdir-objects.

# Copyright (C) 2012-2019 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/>.
#
# Written by Jim Meyering

# This is a prologue that allows to run a perl script as an executable
# on systems that are compliant to a POSIX version before POSIX:2017.
# On such systems, the usual invocation of an executable through execlp()
# or execvp() fails with ENOEXEC if it is a script that does not start
# with a #! line.  The script interpreter mentioned in the #! line has
# to be /bin/sh, because on GuixSD systems that is the only program that
# has a fixed file name.  The second line is essential for perl and is
# also useful for editing this file in Emacs.  The next two lines below
# are valid code in both sh and perl.  When executed by sh, they re-execute
# the script through the perl program found in $PATH.  The '-x' option
# is essential as well; without it, perl would re-execute the script
# through /bin/sh.  When executed by  perl, the next two lines are a no-op.
eval 'exec perl -wSx "$0" "$@"'
     if 0;

my $VERSION = '2012-01-21 17:13'; # UTC
# The definition above must lie within the first 8 lines in order
# for the Emacs time-stamp write hook (at end) to update it.
# If you change this file with Emacs, please let the write hook
# do its job.  Otherwise, update this string manually.

use strict;
use IO::File;
use Getopt::Long;
use File::Basename; # for dirname

(my $ME = $0) =~ s|.*/||;

my $prefix;
my $lib_name;

sub usage ($)
{
  my ($exit_code) = @_;
  my $STREAM = ($exit_code == 0 ? *STDOUT : *STDERR);
  if ($exit_code != 0)
    {
      print $STREAM "Try '$ME --help' for more information.\n";
    }
  else
    {
      print $STREAM <<EOF;
Usage: $ME --lib-name=NAME FILE
   or: $ME [--help|--version]
Rewrite a gnulib-tool-generated FILE like lib/gnulib.mk to work with
automake's subdir-objects.

OPTIONS:

This option must be specified:

   --lib-name=NAME    library name, often "lib\$project"

The following are optional:

   --help             display this help and exit
   --version          output version information and exit

EOF
    }
  exit $exit_code;
}

# contents ($FILE_NAME)
# ---------------------
sub contents ($)
{
  my ($file) = @_;
  local $/;                     # Turn on slurp-mode.
  my $f = new IO::File "< $file" or die "$file";
  my $contents = $f->getline or die "$file";
  $f->close;
  return $contents;
}

# prefix_word ($WORD)
# -------------------
# Do not prefix special words such as variable dereferences.  Also,
# "Makefile" is really "Makefile", since precisely there is no
# lib/Makefile.
sub prefix_word ($)
{
  local ($_) = @_;
  $_ = $prefix . $_
    unless (/^-/ || m{^\$\(\w+\)} || $_ eq "Makefile" || $_ eq '\\'
            || $_ eq '@ALLOCA@');
  return $_;
}


# prefix_words ($TEXT)
# --------------------
sub prefix_words ($)
{
  local ($_) = @_;
  s{(\S+)}{prefix_word($1)}gem;
  return $_;
}


# prefix_assignment ($LHS-AND-ASSIGN-OP, $RHS)
# --------------------------------------------
sub prefix_assignment ($$)
{
  my ($lhs_and_assign_op, $rhs) = @_;

  # Some variables are initialized by gnulib.mk, and we don't want
  # that.  Change '=' to '+='.
  if ($lhs_and_assign_op =~ /^(GPERF|V_GPERF.*) =$/)
    {
      # Do not change the RHS, which specifies the GPERF program.
    }
  # Don't change variables such as HAVE_INCLUDE_NEXT.
  elsif ($lhs_and_assign_op =~ /^HAVE_/)
    {
    }
  elsif ($lhs_and_assign_op =~
      /^(SUBDIRS|EXTRA_DIST|BUILT_SOURCES|SUFFIXES|MOSTLYCLEANFILES
         |CLEANFILES|DISTCLEANFILES|MAINTAINERCLEANFILES
         |AM_GNU_GETTEXT)\ =/x)
    {
      $lhs_and_assign_op =~ s/=/+=/;
    }
  # We don't want things such as AM_CPPFLAGS +=
  # -DDEFAULT_TEXT_DOMAIN=\"bison-gnulib\" to apply to the whole
  # Makefile.in: scope it to the library: libbison_a_CPPFLAGS =
  # $(AM_CPPFLAGS) -DDEFAULT_TEXT_DOMAIN=\"bison-gnulib\".
  elsif ($lhs_and_assign_op =~
      /^(AM_CFLAGS|AM_CPPFLAGS)\ \+?=/x)
    {
      $lhs_and_assign_op =~ s/^AM_(\w+)\ \+?=/${lib_name}_a_$1 =/;
      $rhs = " \$(AM_$1)$rhs";
    }
  # We don't want to inherit gnulib's AUTOMAKE_OPTIONS, comment them.
  elsif ($lhs_and_assign_op =~ /^AUTOMAKE_OPTIONS =/)
    {
      $lhs_and_assign_op =~ s/^/# /;
    }
  # Elide any SUFFIXES assignment or concatenation.
  elsif ($lhs_and_assign_op =~ /^SUFFIXES /)
    {
      $lhs_and_assign_op =~ s/^/# /;
    }
  # The words are (probably) paths to files in lib/: prefix them.
  else
    {
      $rhs = prefix_words($rhs)
    }

  # Variables whose name depend on the location: libbison_a_SOURCES =>
  # lib_libbison_a_SOURCES.
  $lhs_and_assign_op =~ s/($lib_name)/lib_$1/g;

  $lhs_and_assign_op . $rhs;
}

# prefix $CONTENTS
# ----------------
# $CONTENTS is a Makefile content.  Post-process it so that each file-name
# is prefixed with $prefix (e.g., "lib/").
#
# Relies heavily on the regularity of the file generated by gnulib-tool.
sub prefix ($)
{
  # Work on $_.
  local ($_) = @_;

  # Prefix all the occurrence of files in rules.  If there is nothing
  # after in the :, it's probably a phony target, or a suffix rule.
  # Don't touch it.
  s{^([-\w+/]+\.[-\w.]+ *: *\S.*)$}
   {prefix_words($1)}gem;

  # Prefix files in variables.
  s{^([\w.]+\s*\+?=)(.*)$}
   {prefix_assignment($1, $2)}gem;

  # $(srcdir)/ is actually $(top_srcdir)/$prefix/.
  # The trailing slash is required to avoid matching this rule:
  #   test '$(srcdir)' = . || rm -f $(top_builddir)/GNUmakefile
  s{\$\(srcdir\)/}{\$(top_srcdir)/$prefix}g;

  # Sometimes, t-$@ is used instead of $@-t, which, of course, does
  # not work when we have a $@ with a directory in it.
  s{t-\$\@}{\$\@-t}g;

  # Some AC_SUBST patterns remain and would better be Make macros.
  s{\@(MKDIR_P)\@}{\$($1)}g;

  # Adjust paths in mkdir.
  s{(\$\(MKDIR_P\))\s*(\w+)}{$1 $prefix$2}g;

  return $_;
}

# process ($IN)
# -------------
sub process ($)
{
  my ($file) = @_;
  my ($bak) = "$file.bak";
  rename ($file, $bak) or die "$ME: rename $file $bak failed: $!\n";
  my $contents = contents ($bak);
  $contents = prefix ($contents);
  my $out = new IO::File(">$file")
    or die "$ME: $file: failed to open for writing: $!\n";
  print $out $contents;
}

{
  GetOptions
    (
     'lib-name=s' => \$lib_name,
     help => sub { usage 0 },
     version => sub { print "$ME version $VERSION\n"; exit },
    ) or usage 1;

  my $fail = 0;
  defined $lib_name
    or (warn "$ME: no library name; use --lib-name=NAME\n"), $fail = 1;

  # There must be exactly one argument.
  @ARGV == 0
    and (warn "$ME: missing FILE argument\n"), $fail = 1;
  1 < @ARGV
    and (warn "$ME: too many arguments:\n", join ("\n", @ARGV), "\n"),
      $fail = 1;
  $fail
    and usage 1;

  my $file = $ARGV[0];
  $prefix = (dirname $file) . '/';
  warn "prefix=$prefix\n";

  process $file;
}

### Setup "GNU" style for perl-mode and cperl-mode.
## Local Variables:
## perl-indent-level: 2
## perl-continued-statement-offset: 2
## perl-continued-brace-offset: 0
## perl-brace-offset: 0
## perl-brace-imaginary-offset: 0
## perl-label-offset: -2
## cperl-indent-level: 2
## cperl-brace-offset: 0
## cperl-continued-brace-offset: 0
## cperl-label-offset: -2
## cperl-extra-newline-before-brace: t
## cperl-merge-trailing-else: nil
## cperl-continued-statement-offset: 2
## eval: (add-hook 'before-save-hook 'time-stamp)
## time-stamp-line-limit: 50
## time-stamp-start: "my $VERSION = '"
## time-stamp-format: "%:y-%02m-%02d %02H:%02M"
## time-stamp-time-zone: "UTC0"
## time-stamp-end: "'; # UTC"
## End: