ElasticSearch escape date math index names in request path

escape_date_math_index.php

<?php

// @see https://www.elastic.co/guide/en/elasticsearch/reference/5.x/date-math-index-names.html
// @TODO <elastic\\{ON\\}-{now/M}>
function escapePathWithDateMath($path)
{
    $symbols = ['<',   '>',   '/',   '{',   '}',   '|',   '+',   ':',   ','];
    $escaped = ['%3C', '%3E', '%2F', '%7B', '%7D', '%7C', '%2B', '%3A', '%2C'];

    // Check if the string is already escaped
    if (strpos(strtoupper($path), '%2F')) {
        return $path;
    }

    // Check if date math if used at all. E.g. /<log-{now/d}>/log/_refresh
    $pos1 = strpos($path, '>');
    if (false === $pos1) {
        return $path;
    }

    // Check if path starts with string and trim it, e.g. /<log-{now/d}>/log/_refresh
    if ($startsWithSlash = '/' === $path[0]) {
        $path = ltrim($path, '/');
        // Adjust positions we calculated previously
        $pos1--;
    }

    // Find the position up to which we should escape. Should be next slash / after > E.g. <log-{now/d}>/log/_refresh
    $pos2 = strrpos($path, '/', $pos1);
    $pos2 = false !== $pos2 ? $pos2 : strlen($path);

    // Cut out the bit we need to escape: <log-{now/d}>
    $segment = substr($path, 0, $pos2 - 1);
    // Escape using character map
    $escapedSegment = str_replace($symbols, $escaped, $segment);

    // Replace part of the string. E.g. /%3Clog-%7Bnow%2Fd%7D%3E/log/_refresh
    $path = substr_replace($path, $escapedSegment, 0, $pos2 - 1);

    // Prefix with / if it was there before
    return ($startsWithSlash ? '/' : '').$path;
}