<?php

class Qs_String
{
    public static function decamelize($string)
    {
        return ucfirst(preg_replace('/([a-z])([A-Z])/', '$1 $2', $string));
    }

    public static function camelize($string)
    {
        $string = str_replace(['-', '_'], ' ', $string);
        $string = ucwords($string);
        return str_replace(' ', '', $string);
    }

    public static function dasherize($string)
    {
        return strtolower(preg_replace('/([a-z])([A-Z])/', '$1-$2', $string));
    }

    public static function fill($string, array $placeholders, $delimiters = '%%')
    {
        if (!is_string($delimiters) || strlen($delimiters) != 2) {
            trigger_error('Delimiters argument must be 2 characters string', E_USER_WARNING);
            return false;
        }
        $leftDelimiter = $delimiters[0];
        $rightDelimiter = $delimiters[1];
        $keys = array_map(
            function ($value) use ($leftDelimiter, $rightDelimiter) {
                return "{$leftDelimiter}{$value}{$rightDelimiter}";
            },
            array_keys($placeholders)
        );
        if (false !== strpos($string, '[')) {
            $string = self::clearOptionals($string, $placeholders, $delimiters);
        }
        return str_replace($keys, $placeholders, $string);
    }

    /**
     * Clear placeholders wrapper in "[]" that have empty values
     * @param $format string like '{var1}[ - {var2}] - {var3}'
     * @param array $placeholders
     * @param string $delimiters
     * @return bool|string like like '{var1} - {var}' if var2 is empty
     */
    public static function clearOptionals($format, array $placeholders, $delimiters = '%%')
    {
        if (!is_string($delimiters) || strlen($delimiters) != 2) {
            trigger_error('Delimiters argument must be 2 characters string', E_USER_WARNING);
            return false;
        }
        foreach ($placeholders as $placeholder => $value) {
            if (!empty($value)) {
                continue;
            }
            $placeholder = $delimiters[0] . $placeholder . $delimiters[1];
            $format = preg_replace('/\[[^\[]*' . preg_quote($placeholder) . '[^\]]*\]/', '', $format);
        }
        $chars = str_split($format);
        $length = count($chars);
        for ($i = 0; $i < $length; $i++) {
            if (in_array($chars[$i], ['[', ']']) && ($i == 0 || $chars[$i - 1] != '\\')) {
                unset($chars[$i]);
            }
        }
        return str_replace(['\\[', '\\]'], ['[', ']'], implode($chars));
    }
}