#!/usr/bin/perl -w
#
# cvsfindchange
#
# 2006-08-15: Written by Steven J. DeRose, sderose@acm.org.

use strict;

my $version = "2010-09-12";

my $csize    = 10;    # how many like to -show around the target
my $max      = 0;     # max num of version to look back
my $pause    = 0;
my $quiet    = 0;
my $showAll  = 0;
my $showDiff = 0;  # display diff to user at end?
my $strict   = 0;
my $verbose  = 0;

# Process arguments
#
while ($ARGV[0]) {
	if (index($ARGV[0],"--")==0) { $ARGV[0] = substr($ARGV[0],1); }
	if ($ARGV[0] eq "-q") {
	   $quiet = 1;
	}
	elsif ($ARGV[0] eq "-show") {
	  	$showDiff = 1;
	}
	elsif ($ARGV[0] eq "-strict") {
	  	$strict = 1;
	}
	elsif ($ARGV[0] eq "-pause") {
	  	$pause = 1;
	}
	elsif ($ARGV[0] eq "-all") {
	  	$showAll = 1;
	}
	elsif ($ARGV[0] eq "-max") {
	    shift;
	  	$max = $ARGV[0] - 0;
	    ($max > 0) || die "-max value '$ARGV[0]' too small.\n";
	}
	elsif ($ARGV[0] eq "-context") {
	    shift;
	  	$csize = int($ARGV[0] - 0);
		$showDiff = 1;
	}
	elsif ($ARGV[0] eq "-version") {
		warn "Version of $version, by Steven J. DeRose.\n";
		exit;
	}
	elsif (substr($ARGV[0],0,1) eq "-") {
	   ($ARGV[0] eq '-h' or $ARGV[0] eq '-help')
	      || print "Unknown option '$ARGV[0]'.\n";
	   showUsage();
	   exit;
	}
    else {
	   last;
    }
    shift;
}

my $tgt = $ARGV[0];
my $file = $ARGV[1];
($file && -e $file) || die "Couldn't find input file.\n";

# Find out how many revisions CVS has for the file
#
my $latest = `cvs status $file | grep 'Repository revision:'`;
$latest =~ s/.*: *//;
$latest =~ s/^[^0-9]*\([0-9][0-9]*\.[0-9][0-9]*\).*$/\1/;
chomp($latest);
my @foo = split(/\./,$latest);
$foo[1] += 0;

($quiet) || print "Latest revision of '$file' is '$foo[0].$foo[1]'.\n";

# Pairwise diff working backward
my $found = 0;
my $lastRev = "$foo[0].$foo[1]";
$lastRev =~ s/^\s*//;

for (my $i=$foo[1]-1; $i>0; $i--) {
    my $thisRev = "$foo[0].$i";
    $thisRev =~ s/^\s*//;
    my $cmd = "cvs diff -r $thisRev -r $lastRev";
    ($quiet) || print "   Trying '$cmd'\n";
    my $lines = `$cmd 2>/dev/null | grep '$tgt'`;
 
    if ($strict) { # Do a tighter test
        my $fromlines = `$cmd 2>/dev/null | grep '^<.*$tgt'`;
        if ($fromlines) { $lines = ""; } # decide it's not really a hit
    }
 
    if ($lines) {
        my $found = 1;
        print "Change found at version $thisRev.\n";
        ($quiet) || system "cvs log -r$thisRev $file";
        if ($showDiff) {
            system "$cmd 2>/dev/null | grep --context $csize $tgt"
				. " | more";
            print "Change found at version $thisRev.\n";
        }
        if (!$showAll) { last; } 
        if ($pause) {
            print "(press Return to continue, or 'q' and Return to quit)...\n";
            my $response = readline;
            chomp($response);
            if ($response eq "q") { exit; }
        }
    }
    $lastRev = $thisRev;
    if ($max != 0) {
       if (--$max <= 0) { last; }
    }
} # for

(!$quiet) && (!$found) && warn "'$tgt' was not found.\n";

exit;


###############################################################################

sub showUsage() {
	warn "

=head1 Usage

findCvsVersionWithChange 'target' file

Searches the CVS history of the file, for which revision(s) had a diff
including 'target'.


=head1 Options

=over


=item * B<-all> Find all versions that added the change, not just the latest

=item * B<-csize n>  Set number of context lines to -show around the target
(default 10 if you just say -show. -csize implies -show)

=item * B<-max n>    Maximum number of versions to go back (default unlimited)

=item * B<-pause>    Pause for user after each diff is found (not working)

=item * B<-q>        Suppress most messages.

=item * B<-show>     Show the actual diff that was found, not just what version.

=item * B<-strict>   Don't accept just any change where line contains target,
but require that target be in one and not the other.

=item * B<-version>  Display version information and exit.

=back


=head1 Ownership

This work by Steven J. DeRose is licensed under a Creative Commons 
Attribution-Share Alike 3.0 Unported License. For further information on
this license, see http://creativecommons.org/licenses/by-sa/3.0/.

The author's present email is sderose at acm.org.

For the most recent version, see http://www.derose.net/steve/utilities/.

=cut
";
}