#!/usr/bin/env perl
#
# %CopyrightBegin%
#
# Copyright Ericsson AB 1999-2016. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# %CopyrightEnd%
#
use strict;
use File::Copy;
# This program generates global constants that contains
# config.h, CFLAGS and LDFLAGS

my $file = "";
my %constants = ();
my $prev_file = "";

while (@ARGV) {
    my $d = shift;
    if ( $d =~ /^-o$/ ) {
	$file = shift or die("-o requires argument");
	open FILE, "<$file" or next;
	$prev_file = do { local $/; <FILE> };
	close FILE;
	next;
    }
    if ( $d =~ /^-f/ ) {
	my $var = shift or die("-f requires two argument");
	my $value = shift or die("-f requires two argument");
	open FILE, "<$value";
	$value = do { local $/; <FILE> };
	close FILE;

	$value =~ s/\n/\\n\\\n/g;

	$constants{$var} = $value;
    }
    if ( $d =~ /^-v/ ) {
	my $var = shift or die("-v requires two argument");
	my $value = shift;
	$constants{$var} = $value;
    }
}

foreach(keys %constants) {
    my $value = $constants{$_};
    $value =~ s/"/\\"/g;
    $constants{$_} = $value
}

# Did we want output to a file?
open(my $oldout, ">&STDOUT")     or die "Can't dup STDOUT: $!";
if ( $file ) {
    open STDOUT, ">$file.tmp" or die("can't open $file for writing");
}

my(@prog) = split('/', $0);
my($prog) = $prog[$#prog];
print "/* Warning: Do not edit this file.\n";
print "   Auto-generated by '$prog'.*/\n";

foreach (sort(keys %constants)) {
    print "const char* erts_build_flags_$_ = \"$constants{$_}\";\n"
}

open(STDOUT, ">&", $oldout) or die "Can't dup \$oldout: $!";

open FILE, "<$file.tmp";
my $new_file = do { local $/; <FILE> };
close FILE;

if ($new_file ne $prev_file) {
    move("$file.tmp","$file");
} else {
    unlink("$file.tmp");
}