use File::Copy;
use Tie::File;

my($input_file1) = $ARGV[0];
my($input2) = $ARGV[1];
my($output_file) = $ARGV[2];

if ( !defined($input_file1) || !defined($input2) || !defined($output_file) ) {
	print "Error: usage: ./SS7Merge input_file1 input_file2 output_file\n";
}
else {
	# -----Backup the input files in case of error-----
	copy( $input_file1, $input_file1 . ".bak" ) or
		die "Could not backup file 1 $input_file1 to $input_file1.bak: $!\n";
	copy( $input2, $input2 . ".bak" ) or
		die "Could not backup file 2 $input_file2 to $input_file2.bak: $!\n";

	# -----Attempt to open all of the files-----
	open( INFILE1, $input_file1 ) || die( "Could not read input file 1 ($input_file1): $!" );
	open( OUTPUT, "> " . $output_file ) || die( "Could not open output file ($output_file): $!" );

# We are going to read file2 into an array. The file will not be loaded into memory which will improve processing of large files.

tie @input2, 'Tie::File', \*FH, or die "Problem tying file $input2: $!"; 

while (<INFILE1>) {
		my $line = $_;
		chomp($line);

		# -----A line starting with a '2' is a header and is left unchanged
		if ( $line !~ m/^2/ ) {

			foreach $line2 (@input2) {
				$date = substr( $line, 6, 6 );
				$number_dialed = substr( $line, 29, 10 );

				if ( index( $line2, $date ) != -1 and index( $line2, $number_dialed ) != -1 ) {
					$record_type = substr( $line, 5, 2 );

					# -----From File2-----
					$carrier_info = substr( $line2, 44, 5 );
					$destination_number = substr( $line2, 122, 10 );

					$connect_time = substr( $line, 54, 6 );
					$send_to_OCN = substr( $line, 186, 4 );

					$record_type = "25";
					$send_to_OCN = "2604";

					-----Generate the output string-----
					$output_line = substr( $line, 0, 4 ) . $record_type . $date . substr( $line, 12, 17 )
						. $number_dialed . substr( $line, 39, 5 )
						. $carrier_info . substr( $line, 49, 5 )
						. $connect_time . substr( $line, 60, 62 )
						. $destination_number . substr( $line, 132, 54 )
						. $send_to_OCN . substr( $line, 190, 20 ) . "\n";

#					-----Debug code. Add in if you are experiencing problems-----
#					print OUTPUT $output_line;
#					print STDOUT "Output " . ++$outputcount . "\n";

					last;
				}
			}
		}
		else {
			print OUTPUT $line . "\n";
		}
	}
# Untie the array before closing the file use

	untie @input2;

# -----Close all of the files-----
	close( INFILE1 );
	close( OUTPUT );
}