<?php
try {
	if ( $argc != 3 ) {
		throw new Exception('Usage: copy_modlist.php <from modlist.txt> <to modlist.txt>');
	}

	$from_modlist_file = $argv[1];
	$to_modlist_file   = $argv[2];

	if ( is_dir($from_modlist_file) ) {
		$from_modlist_file .= '\modlist.txt';
	}

	if ( is_dir($to_modlist_file) ) {
		$to_modlist_file .= '\modlist.txt';
	}

	if ( !is_readable($from_modlist_file) ) {
		throw new Exception($from_modlist_file . ' is not readable');
	}

	if ( !is_readable($to_modlist_file) ) {
		throw new Exception($to_modlist_file . ' is not readable');
	}

	$from_modlist = get_modlist($from_modlist_file);
	$to_modlist   = get_modlist($to_modlist_file);

	apply_modlist($from_modlist, $to_modlist);
} catch (Exception $e) {
	echo $e->GetMessage() . PHP_EOL;
}

function get_modlist($modlist_file)
{
	$ret = [];

	$fp = fopen($modlist_file, 'r');

	while ( !feof($fp) ) {
		$buf = fgets($fp);
		$buf = trim($buf);

		if ( strlen($buf) == 0 ) {
			continue;
		}

		$ret[] = $buf;
	}

	fclose($fp);

	return $ret;
}

function apply_modlist($from_modlist, $to_modlist)
{
	$fp = fopen('modlist.txt', 'w');

	foreach ($from_modlist as $mod) {
		$flag = substr($mod, 0, 1);

		if ( $flag == '-' || $flag == '+' ) {
			$body = substr($mod, 1);

			if ( in_array('+' . $body, $to_modlist) ) {
				$mod = '+' . $body;
			} else {
				$mod = '-' . $body;
			}
		}

		fputs($fp, $mod . PHP_EOL);
	}

	fclose($fp);
}