#!/usr/bin/perl

use strict;
use Getopt::Long;

my $source = "";
my $destination = "";
my $make;
my $help;

my @lines;
my %included;

########################################################################
#
# usage
#

sub usage()
{
    print "Usage: shell_include --source <file> --destination <file> [--make] [--help]\n";
    print "\n";
    print "--make will output makefile dependencies to stdout and exit\n";
    print "--help will output this text and exit\n";
    print "\n";
}
########################################################################
#
# check_options
#

sub check_options()
{
    if ( !GetOptions( 
                     's|source=s' => \$source,
	             'd|destination=s' => \$destination,
                     'm|make' => \$make,
                     'h|help' => \$help ) ) 
    {
        &usage;
        exit 1;
    }

    if ( $help ) {
        &usage;
        exit 0;
    };

    die( "Missing input file - use --source <file>" ) if ( $source eq "" );
    die( "Missing output file - use --destination <file>") if ( $destination eq "" );
}

########################################################################
#
# read_input : Read in the initial input file into @lines
#

sub read_input()
{
    open( SOURCE, $source ) || die ( "Cannot open input file : $source" );
    while ( <SOURCE> ) {
        @lines = ( @lines, $_ );
    };
    close( SOURCE );
}

########################################################################
#
# Process #include directives
#
sub process_includes()
{
    my $changed = 0;
    my @newlines;

    foreach my $line ( @lines ) {

        if ( $line =~ /^(\s*)\#include(\s+)(\S+)/ ) {
            $changed = 1;
            my $filename = $3;
            if ( ! defined $included{ $filename } ) {
                open( INC, $filename ) || die ( "Cannot open include file : $filename" );
                @newlines = ( @newlines, "########################################################################\n" );
                @newlines = ( @newlines, "#\n" );
                @newlines = ( @newlines, "# Included file : $filename\n" );
                @newlines = ( @newlines, "#\n" );
                while( <INC> ) {
                    @newlines = ( @newlines, $_ );
                }
                close( INC );
                @newlines = ( @newlines, "#\n" );
                @newlines = ( @newlines, "# End of included file : $filename\n" );
                @newlines = ( @newlines, "#\n" );
                @newlines = ( @newlines, "########################################################################\n" );
                $included{ $filename } = "";
            }
        } else {
            @newlines = ( @newlines, $line );
        }
    }
    @lines = @newlines;
    return $changed;
}

########################################################################
#
# write_output : write the final set of lines to the output file
#
sub write_output() 
{
    open( DEST, ">$destination" ) || die( "Cannot open output file : $destination" );
    foreach my $line ( @lines ) {
        print DEST $line;
    }
    close( DEST );
}

&check_options;
&read_input;
while ( &process_includes ) { };
if ( $make ) {
    print "$destination: $source ";
    foreach my $inc ( sort( keys( %included ) ) ) {
        print "$inc ";
    };
    print "\n";
} else {
    &write_output;
}