#! /usr/bin/perl

use POSIX;
use Fcntl;
use File::Temp;
use Getopt::Long;

if ($0 =~ /autoconf$/) {
    $mode = 'autoconf';
} elsif ($0 =~ /autoheader$/) {
    $mode = 'autoheader';
} elsif ($0 =~ /autoreconf$/) {
    $mode = 'autoreconf';
} else {
    die "autoconf-wrapper: unrecognized mode '$0'\n";
}

OPTION: for ($i = 0; $i <= $#ARGV; $i++) {
    $_ = $arg = $ARGV[$i];

    # --install was added to autoreconf around version 2.50
    if ($mode eq 'autoreconf' && $arg eq '--install') {
	ac250 ();
    }
    # Most options don't tell us anything or need any special handling.
    elsif (/--v.+/ || $arg eq '-V'
	|| $arg eq '--verbose' || $arg eq '-v'
 	|| /^--h.+/ || $arg eq '-h'
	|| $arg eq '--debug' || $arg eq '-d'
	|| /^--output=/ || /^-o.+/
	|| $arg eq '--force' || $arg eq '-f'
	|| $arg eq '--install' || $arg eq '-i'
	|| $arg eq '--symlink' || $arg eq '-s'
	|| /^--m4dir=/ || /^-M.+/
	|| $arg eq '--cygnus'
	|| $arg eq '--foreign'
	|| $arg eq '--gnits'
	|| $arg eq '--gnu'
	|| $arg eq '--include-deps' || $arg eq '-i'
	) {
	# Nothing to do
    }
    # We need to know the macro dir in order to properly search for aclocal.m4.
    # Only a fsckwit would use --macrodir to find aclocal.m4, but I'm trying
    # to be bug-for-bug compatible here.
    elsif ($arg eq '--macrodir' || $arg eq '-m') {
	$macrodir = $ARGV[$i++];
    }
    elsif (/^--macrodir=(.*)$/ || /^-m(.+)$/) {
	$macrodir = $1;
    }

    # Ditto for the local dir.
    elsif ($arg eq '--localdir' || $arg eq '-l') {
	$localdir = $ARGV[$i++];
    }
    elsif (/^--localdir=(.*)$/ || /^-l(.+)$/) {
	$localdir = $1;
    }

    # Some options require that we skip the next argument too.
    elsif ($arg eq '--output' || $arg eq '-o'
	   ) {
	$i++;
    }

    # Some options are new in autoconf 2.50, so we know what version to use.
    elsif (/^--trace/ || /^-t/
	   || /^--autoconf-dir/ || /^-A/
	   || $arg eq '--initialization' || $arg eq '-i'
	   || $arg eq '--m4dir' || $arg eq '-M'
	   || /^--warnings=/ || /^-W.+/ || $arg eq '-W'
	   || /^--include=/ || /^-I.+/ || $arg eq '-I'
	   || /^--prepend-include=/ || /^-B.+/ || $arg eq '-B'
	   ) {
	ac250 ();
    }

    # -- causes us to stop option processing.
    elsif ($arg eq '--') {
	for ($i++; $i <= $#ARGV; $i++) {
	    nonoption_arg ($arg);
	}
	last OPTION;
    }

    # Check for an option we don't understand.
    elsif (/^-.+/) {
	print "autoconf-wrapper: unrecognized option $arg\n";
    }

    # Otherwise, it's a nonoption argument.
    else {
	nonoption_arg ($arg);
    }
}

# If no input file was passed on the command line, 
# find the default.
if (!defined ($infile)) {
    if (-e 'configure.ac') {
	$infile = 'configure.ac';
    } elsif (-e 'configure.in') {
	$infile = 'configure.in';
    } elsif ($mode eq 'autoreconf') {
	# A cop-out, but autoreconf is pretty uncommon in practice.
	ac213 ();
    }
}

if (defined ($infile)) {
    # Assume an input file ending in .ac is 2.50,
    # because that extension was introduced after 2.13.
    if ($infile =~ /\.ac$/) {
	ac250 ();
    }

    # If the input file is stdin, copy it to a temporary file.
    if ($infile eq '-') {
	($fh) = File::Temp::tmpfile ();
	fcntl ($fh, F_SETFD, fcntl ($fh, F_GETFD, 0) & ~FD_CLOEXEC);
	while (<STDIN>) {
	    print $fh $_;
	}
	seek ($fh, SEEK_SET, 0);
    } else {
	$fh = 'INFILE';
	open ($fh, "<$infile") || die "autoconf-wrapper: $infile: $!\n";
    }

    # Read the input file and check for AC_PREREQ calls.
    check_fh ();

    if ($infile ne '-') {
	close ($fh);
    }

    # Check aclocal.m4, too.
    check_file ('aclocal.m4');

    # Check include files, recursively, too.
    while (@included_files) {
	my ($filename) = pop (@included_files);
	check_file ($filename);
    }
}

# Default to 2.13.
ac213 ();

# Check the specified file for AC_PREREQ and include directives.
# Searches the m4 include path to find the file.
sub check_file {
    my ($basename) = @_;
    my ($filename);
    if (-e $basename) {
	$filename = $basename;
    } else {
	foreach $dir ($macrodir, $localdir, split (/:/, $ENV{'M4PATH'})) {
	    my ($try) = "$dir/basename";
	    if (-e $try) {
		$filename = $try;
		last;
	    }
	}
    }

    if (defined ($filename)) {
	$fh = 'INFILE';
	open ($fh, "<$filename") || die ("autoconf-wrapper: $filename: $!\n");
	check_fh ();
	close ($fh);
    }
}

# Checks $fh for a line containing a v2.50+ AC_PREREQ call
# and adds any not-yet-processed included files to @included_files.
sub check_fh {
    while (<$fh>) {
	if (/AC_PREREQ\s*\(\s*\[?\s*2\.(\d+).*\)/) {
	    $prematch = $`;
	    if (!($prematch =~ /(\bdnl\b)|#/)) {
		  if ($1 > 13) {
		      ac250 ();
		  }
	      }
	}
	elsif (/\bs?include\((.*)\)/) {
	    push (@included_files, $1) unless $checked_files{$1};
	    $checked_files{$1} = 1;
	}
    }
}

# Handle nonoption argument. 
sub nonoption_arg {
    my ($arg) = @_;
    die "autoconf-wrapper: invalid number of arguments\n"
	if defined ($infile) || $mode eq 'autoreconf';
    $infile = $arg;
}

sub ac213 {
    run_autoconf ("/scratchbox/tools/bin/${mode}2.13");
}

sub ac250 {
    run_autoconf ("/scratchbox/tools/bin/${mode}2.50");
}

sub run_autoconf {
    my ($binary) = @_;

    # If we read input from stdin, rewind the temporary file
    # and make the temporary stream available as a new stdin.
    if ($infile eq '-') {
	seek ($fh, SEEK_SET, 0);
	dup2 (fileno ($fh), 0);
    }

    #print STDERR "autoconf-wrapper: executing $binary\n";
    exec { $binary } $binary, @ARGV;
    die "couldn't exec $binary: $!";
}