#!/usr/bin/perl
# $Id$
#
# dmakegen - a preprocessor for GNU make to make make directory-aware
#

undef %Generics, $Default;


$err = 0;
$nline = 0;
open(DMAKEROOT, "< Dmakeroot") or die "$0: No Dmakeroot file found\n";
while ( defined($line = <DMAKEROOT>) ) {
    chomp $line;  $nline++;
    while ( $line =~ /\\$/ ) {
	if ( defined($cline = <DMAKEROOT>) ) {
	    chomp $cline;  $nline++;
	    $line = substr($line, 0, length($line)-1) + $cline;
	} else {
	    die "$0: Dmakeroot:$nline: unterminated continuation line\n";
	    $err = 1;
	}
    }

    $line =~ s/\#.*$//;		# Remove comments
    $line =~ s/\s*$//;		# Remove trailing whitespace

    if ( $line eq '' ) {
	# Empty line, do nothing
    } elsif ( $line =~ /^GENERIC:\s*/ ) {
	foreach $generic ( split(/\s+/, $') ) {
	    $Generics{$'} = [];
	}
	push(Generics, split(/\s+/, $'));
    } elsif ( $line =~ /^DEFAULT:\s*/ ) {
	$Default = $';
    } else {
	print "$0: Dmakeroot:$nline: unknown directive\n";
	$err = 1;
    }
}
close(DMAKEROOT);
if ( $err ) {
    exit(1);
}

#
# Recurse through various directories and generate Dmakefragment files
#
@dirlist = ('.');
@dmakefrags = ();

while ( defined($dir = pop(@dirlist)) ) {
    open(DMAKEFILE, "< ${dir}/Dmakefile") or die "$0: ${dir}/Dmakefile not found\n";
    open(DMAKEFRAG, "> ${dir}/Dmakefrag") or die "$0: Cannot create ${dir}/Dmakefrag: $!\n";
    push(@dmakefrags, "${dir}/Dmakefrag");

    $nline = 0;  $err = 0;
    while ( defined($line = <DMAKEFILE>) ) {
	chomp $line;  $nline++;
	while ( $line =~ /\\$/ ) {
	    if ( defined($cline = <DMAKEFILE>) ) {
		chomp $cline;  $nline++;
		$line = substr($line, 0, length($line)-1) + $cline;
	    } else {
		die "$0: ${dir}/Dmakefile:$nline: unterminated continuation line\n";
		$err = 1;
	    }
	}

	### FIX: THIS IS BUGGY - NEED TO HANDLE ESCAPES ###
	$line =~ s/\#.*$//;	# Remove comments
	$line =~ s/\s*$//;	# Remove trailing spaces

	if ( $line eq '' ) {
	    # Do nothing
	} elsif ( $line =~ /^SUBDIRS:\s*/ ) {
	    push(@dirlist, split(/\s+/, $'));
	} elsif ( $line =~ /^\.([^.:]+):\s*(.*)$/ ) {
	    # Rule of the form .c:
	    $suffix = $1;
	    $deps = $2;
	    print DMAKEFRAG "${dir}/%: ${dir}/%.${suffix}";
	    if ( $deps ne '' ) {
		foreach $dep ( split(/\s+/, $deps) ) {
		    print DMAKEFRAG " ${dir}/${dep}";
		}
	    }
	    print "\n";
	} elsif ( $line =~ /^\.([^.:])\.([^.:]+):\s*(.*)$/ ) {
	    # Rule of the form .c.o:
	    $suff1 = $1;
	    $suff2 = $2;
	    $deps = $3;
	    print DMAKEFRAG "${dir}/%.${suff2}: ${dir}/%.${suff1}";
	    if ( $deps ne '' ) {
		foreach $dep ( split(/\s+/, $deps) ) {
		    print DMAKEFRAG " ${dir}/${dep}";
		}
	    }
	    print "\n";
	} elsif ( $line =~ /^(\S|\S.*\S)\s*:\s*(\S|\S.*\S)\s*$/ ) {
	    # Rule of the form foo .. : bar
	    $lhs = $1;
	    $rhs = $2;
	    if ( $lhs ne '' ) {
		foreach $targ ( split(/\s+/, $lhs) ) {
		    if ( defined($Generics{$targ}) ) {
			push(@{$Generics{$targ}}, "${dir}/${targ}");
			print DMAKEFRAG ".PHONY: ${dir}/${targ}\n";
		    }
		    print DMAKEFRAG " ${dir}/${targ}";
		}
	    }
	    print DMAKEFRAG " : ";
	    if ( $rhs ne '' ) {
		foreach $deps ( split(/\s+/, $rhs) ) {
		    print DMAKEFRAG " ${dir}/${deps}";
		}
	    }
	    print "\n";
	} elsif ( $line =~ /^(\s+)(\S.*)$/ ) {
	    print DMAKEFRAG "$1cd \"${dir}\" && $2\n";
	} else {
	    # Handle stuff like local variables here
	}
    }
    close(DMAKEFILE);
    close(DMAKEFRAG);
}

#
# Create the Makefile
#
open(MAKEFILE, "> Makefile") or die "$0: Could not create Makefile\n";

print MAKEFILE ".default: ${Default}\n\n";

print MAKEFILE "Makefile:\n\tdmakegen\n\n";

foreach $gen ( keys(%Generics) ) {
    print MAKEFILE ".PHONY: ${gen}\n";
    print MAKEFILE "${gen}: ";
    foreach $subtarg ( @{$Generics{$gen}} ) {
	print MAKEFILE $subtarg, ' ';
    }
    print MAKEFILE "\n";
}

# Must be done in reverse order (leaf node directories
# before the associated branch node.)
while ( defined($frag = pop(@dmakefrags)) ) {
    print "-include ${frag}\n";
}

close(MAKEFILE);