#!/usr/local/bin/perl -w
#Author: Shraddha Kulkarni
use strict;
use File::Copy;

print "Please enter the path of the directory: ";
my $path = <STDIN>;
chomp $path;
print "The pattern/word to be replaced: ";
my $pattern = <STDIN>;
chomp $pattern;
print "New word: ";
my $replacement = <STDIN>;
chomp $replacement;
my @updated_files;
recursive_opendir("$path");
print "\n'find and replace' over.\n\n List of updated files -\n";

foreach(@updated_files){
	print "\t$_\n";
}

#### subroutines of the program follow
sub recursive_opendir{ ## calls itself; a recursive function
opendir (DH, "$_[0]") || die "Can't open directory $_[0]:$!";
my $cur_dir="$_[0]";
my @list = readdir DH;
foreach (@list){
	if(-l "$cur_dir/$_"){
	print "skipping $cur_dir/$_";
	next;
	}
	if(-d "$cur_dir/$_"){
		next if($_ eq "." || $_ eq "..");
		print "\n$_\/ is a directory. Entering $cur_dir/$_\/ now.\n";
		recursive_opendir("$cur_dir/$_");
	}
	
	if (-f "$cur_dir/$_"){
	print $cur_dir."/".$_."\n";
	replace($cur_dir."/".$_);
	}
	else{
		print "some other file type\n";
	}
}
close DH;
}

sub replace{
	my $tmp_file = $_[0].".tmp";
	my $cur_file = $_[0];
	my $replacement_done = "false";
	copy($cur_file,$tmp_file);
	open FWH, ">$tmp_file";
	open FH,"$cur_file";
	 while(<FH>){
	 	if(s#$pattern#$replacement#g && $replacement_done eq "false"){
			$replacement_done = "true";
		}
		print FWH $_;
	 }
	close FH;
	close FWH;
	push (@updated_files, $cur_file) if($replacement_done eq "true");
	move($tmp_file,$cur_file);
}