#!/usr/bin/perl -w

# Copyright © 2002 by Julian Fong <http://www.levork.org/>.  All rights reserved.
#
# Permission to use, copy, modify, distribute, and sell this software
# and its documentation for any purpose is hereby granted without fee,
# provided that the above copyright notice appear in all copies and
# that both that copyright notice and this permission notice appear in
# supporting documentation.  No representations are made about the
# suitability of this software for any purpose.  It is provided "as
# is" without express or implied warranty.
#
# gsr: Global Search & Replace - it does just that on a list of files. Takes:
#   -F: to completely ignore any magic in the patterns
#   -i: case insensitivity in search pattern
#   -v: verbose mode

use strict;
use Getopt::Std;

my (
    $search,
    $replace,
    %options,
    $sopt,
    $filename,
    $matched,
    $scanned
   );

getopts('ivF', \%options);

unless (@ARGV > 2) {
    die "Usage: gsr [-ivF] search_pattern replace_pattern [files]\n"
}

$search = shift(@ARGV);
$replace = shift(@ARGV);

$sopt = "go";
if ($options{'i'}) {
    $sopt .= 'i';
}
foreach $filename (@ARGV) {
    $scanned = "";
    $matched = 0;
    open (IFILE, "$filename") || die ("Can't open file: $!\n");

    # Scan for matching text, preserving the file in $scanned
    # in the meantime.
    while (<IFILE>) {
	if ($options{'F'}) {
	    last if ($matched = eval "m'$search'$sopt");
	} else {
	    last if ($matched = eval "m/$search/$sopt");
	}
	$scanned .= $_;
    }

    if ($matched) {
	if ($options{'v'}) {
	    print "Match: $filename\n";
	}
	rename($filename, "$filename~");
	unlink($filename);
	open (OFILE, ">$filename") || die ("Can't open file: $!\n");

	# Print already scanned text
	print OFILE $scanned;

	# Do first replacement
	if ($options{'F'}) {
	    eval "s'$search'$replace'$sopt; print OFILE";
	} else {
	    eval "s/$search/$replace/$sopt; print OFILE"
	}

	# Scan and print remaining replacements
	while (<IFILE>) {
	    if ($options{'F'}) {
		eval "s'$search'$replace'$sopt; print OFILE";
	    } else {
		eval "s/$search/$replace/$sopt; print OFILE"
	    }
	}
	close OFILE;
    } elsif ($options{'v'}) {
	print "No match: $filename\n";
    }

    close IFILE;
}