#!/usr/bin/perl
#
# File: DAMit2
# Author: Colin Mollenhour (mollenho@cs.utk.edu or colin@mollenhour.com)
# http://colin.mollenhour.com
#
# Reads a DAM (Document for API Modification) document and any number of files,
# and makes changes accordingly.
#
# This is version 2, which adds support for regular expressions in the DAM file!
# It also supports VCS style conflict markers with the --conflict option so that
# you can use your favorite merge tool to merge the DAM changes.
#
# The DAM document should be in this format:
#
# #Comments should be preceded by #
# #Blank lines and comments are allowed anywhere.
# #old and new are separated by ==>
# #if a line does not have a replacement, it is ignored
#
# header1\.h  ==> newheader.h
# rotate_object\dd   ==> RotateObject$1D
# new MyClass  ==> MyClass::factory
# (MyClass1|MyClass1)->   ==> MyNamespace::$1->
# foo_\w+_bar   ==> Foo$1Bar

$USAGE =	
"Usage: DAMit2 [--conflict] [--dry-run] dam.txt file [file] ...
  --conflict   write VCS style conflicts markers, must be removed after reviewing
  --dry-run    output the log, but do not apply changes

Examples:
DAM all files in current directory:
   \$ DAMit2 --conflict dam.txt *.*
DAM all .h, .c, and .cpp files in current directory (recursive):
   \$ DAMit2 dam.txt `find -name \\*.cpp` `find -name \\*.\\[hc\\]`
";


# check arguments for options
$TESTING = 0;
$WRITECONFLICTS = 0;
foreach $arg (@ARGV){
	if(    $arg eq "--dry-run"){  $TESTING = 1; }
	elsif( $arg eq "--conflict"){ $WRITECONFLICTS = 1; }
	elsif( $arg =~ /^-/ ){ die("Invlaid argument $arg\n\n$USAGE"); }
	else{ last; }
}
if($TESTING){ shift(@ARGV); }
if($WRITECONFLICTS){ shift(@ARGV); }
die($USAGE) unless @ARGV > 1;


# build the DAM hash
$damfile = shift(@ARGV);
open(DAM, $damfile) || die( "Unable to open $damfile : $!\n" );
%hash = ();	#hash of old and new function names 
while( <DAM> ){
	next if /^#/;	#skip comments
	chop;
	($old, $new) = split /\s+==>\s+/;     # get old and new function names
	$hash{ $old } = $new if $old && $new;	# add old and new to hash 
}
close DAM;


# process each file
foreach $arg (@ARGV){
	open FILE, "+<$arg" or die "Cannot open $arg: $!\n";
	flock FILE, 2;		# lock the file for rw
	@data = <FILE>;		# buffer all the data

	print "For file: $arg\n";
	$total = 0; # track total number of replacements
	$line = 1;  # line number tracker

	# Variables for tracking conflicts
	@changes = (); $conflict = 0;
	@newdata = ();

	# scan each line
	foreach (@data){
		$before = $_;
		$replace = 0;
		while( ($old, $new) = each %hash ){
			eval '$count = ($_ =~ '."s/\\b$old\\b/$new/g)";
			$replace += $count;
		}
		if($WRITECONFLICTS){
			if($replace){                                        # changes made
				push( @newdata, "<<<<<<< mine\n" ) if !$conflict; # start new conflict
				$conflict = 1;
				push( @changes, $_ );                              # store changes for later
			}
			elsif( $conflict ){                                # no change, write and end conflict
				push( @newdata, "=======\n" );
				push( @newdata, @changes );
				push( @newdata, ">>>>>>> $damfile\n" );
				@changes = ();
				$conflict = 0;
			}
			push( @newdata, $before );
		}
		$total += $replace;
		print "$line: -$before$line: +$_" if $replace;
		$line++;
	}

	# print status and write file (if necessary)
	if( $total == 0 ){
		print "No replacements made in $arg\n\n";
	}else{
		if( !$TESTING ){   #overwrite file with new contents
			seek FILE, 0, 0;
			truncate FILE, 0;
			if($WRITECONFLICTS){
				print FILE @newdata;
			}else{
				print FILE @data;
			}
		}
		print "Made $total total replacements in $arg\n\n";
	}
	close FILE;
}

print "DAM'ed ".scalar(@ARGV)." files.\n";