PHP string search algorithm

$INDEX = array('of'=>'long', 'strings that'=>'should', 'be searched for,'=>'transformed to lower case', 'and'=>'without double spaces'); # the values act as slug names e.g. for articles, the keys are the titles
$search = 'search string, transformed to lower case and without double spaces';
$res = array(); # empty array for results

foreach ($INDEX as $key => $val) {
    $searchptr = 0;
    while (TRUE) {
        $str = $key;
        $i = stripos($str, $search[$searchptr]);
        if ($i === FALSE) {
            break 1;
        } else {
            $str = substr($str, $i+1);
            $i = 1; # now used to count matching letters = recognition length threshold (here at 3 chars)
            if ($i === strlen($search)) {
                if (!array_key_exists($val, $res)) { # sorting slugs only, score = relevance of result
                    $res[$val] = 0;
                }
                $res[$val]++;
            }

            $searchptr++;
            while (TRUE) {
                if ($searchptr >= strlen($search)) {
                    break 2;
                } elseif (strlen($str) == 0) {
                    break 1;
                } elseif ($str[0] !== $search[$searchptr]) {
                    /* single mismatch, no score for you! */
                    /* these conditions are 1 char fault tolerant */
                    if ($str[1] === $search[$searchptr]) {
                        # missing char in search
                        $str = substr($str, 1);
                    } elseif ($str[0] === $search[$searchptr+1]) {
                        # missing char in string
                        $searchptr += 2;
                    } elseif ($str[1] === $search[$searchptr+1]) {
                        # char mismatch
                        $str = substr($str, 1);
                        $searchptr += 2;
                    } else {
                        /* none of the next chars match; match has ended */
                        break 1;
                    }
                } else {
                    /* another match! */
                    $str = substr($str, 1);
                    if (++$i > 2 || $i === strlen($search)) {
                        if (!array_key_exists($val, $res)) { # sorting slugs only, score = relevance of result
                            $res[$val] = 0;
                        }
                        $res[$val]++;
                    }
                    $searchptr++;
                }
            }
        }
    }
}