###############################################################################
# Codestriker: Copyright (c) 2001, 2002, 2003 David Sitsky.
# All rights reserved.
# sits@users.sourceforge.net
#
# This program is free software; you can redistribute it and modify it under
# the terms of the GPL.

# Parser object for reading VSS (Visual Source Safe) diffs.

package Codestriker::FileParser::VssDiff;

use strict;
use Codestriker::FileParser::BasicDiffUtils;

# Return the array of filenames, revision number, linenumber, whether its
# binary or not, and the diff text.
# Return () if the file can't be parsed, meaning it is in another format.
sub parse ($$$) {
    my ($type, $fh, $repository) = @_;

    # Array of results found.
    my @result = ();

    my $line = <$fh>;
    while (defined($line)) {
	# Values associated with the diff.
	my $revision;
	my $filename;
	my $repmatch;

	# Skip whitespace.
	while (defined($line) &&
	       ($line =~ /^\s*$/o || $line =~ /^Version not found/o)) {
	    $line = <$fh>;
	}
	return @result unless defined $line;

	# For VSS diffs, the start of the diff block is the "Diffing:" line
	# which contains the filename and version number.  Some diffs may
	# not contain the version number for us.
	if ($line =~ /^Diffing: (.*);(.+)$/o) {
	    $filename = $1;
	    $revision = $2;
	    $repmatch = 1;
	} elsif ($line =~ /^Diffing: (.*)$/o) {
	    $filename = $1;
	    $revision = $Codestriker::PATCH_REVISION;
	    $repmatch = 0;
	} else {
	    # Some other weird format.
	    return ();
	}

	# The next line will be the "Against:" line, followed by a blank line.
	$line = <$fh>;
	return () unless defined $line && $line =~ /^Against:/o;
	$line = <$fh>;
	return () unless defined $line && $line =~ /^\s*$/o;

	# The next part of the diff will be the old style diff format, or
	# possibly "No differences." if there are no differences.
	$line = <$fh>;
	if ($line !~ /^No differences\./o) {
	    my $chunk;
	    do
	    {
		my $leading_context = '';
		my $leading_context_line_count = 0;
		my $trailing_context = '';
		my $trailing_context_line_count = 0;
		if ($line =~ /^\*\*\*\*\*\*\*\*/o ||
		    $line =~ /^ /o) {
		    # Need to record some leading context.
		    $line = <$fh> if $line =~ /^\*\*\*\*\*\*\*\*/o;
		    while ($line =~ /^ (.*)$/o) {
			$leading_context .= "$1\n";
			$leading_context_line_count++;
			$line = <$fh>;
		    }
		}

		$chunk = Codestriker::FileParser::BasicDiffUtils
		    ->read_diff_text($fh, $line, $filename, $revision,
				     $repmatch);
		if (defined $chunk) {
		    # Check for trailing context.
		    $line = <$fh>;
		    while (defined $line && $line =~ /^ (.*)$/o) {
			$trailing_context .= "$1\n";
			$trailing_context_line_count++;
			$line = <$fh>;
		    }

		    # Adjust the chunk accordingly with the leading and
		    # trailing context.
		    if ($leading_context_line_count > 0) {
			$chunk->{old_linenumber} -= $leading_context_line_count;
			$chunk->{new_linenumber} -= $leading_context_line_count;
			$chunk->{text} = $leading_context . $chunk->{text};
		    }
		    if ($trailing_context_line_count > 0) {
			$chunk->{text} .= $trailing_context;
		    }
		    push @result, $chunk;
		}
	    } while (defined $chunk && defined $line);
	}

	# Read the next line.
	$line = <$fh> if defined $line;
    }

    # Return the found diff chunks.
    return @result;
}
	
1;