<?php

/*
 * This file is part of the overtrue/wechat.
 *
 * (c) overtrue <i@overtrue.me>
 *
 * This source file is subject to the MIT license that is bundled
 * with this source code in the file LICENSE.
 */

/**
 * Str.php.
 *
 * @author    overtrue <i@overtrue.me>
 * @copyright 2015 overtrue <i@overtrue.me>
 *
 * @see      https://github.com/overtrue
 * @see      http://overtrue.me
 */

namespace EasyWeChat\Support;

use EasyWeChat\Core\Exceptions\RuntimeException;

class Str
{
    /**
     * The cache of snake-cased words.
     *
     * @var array
     */
    protected static $snakeCache = [];

    /**
     * The cache of camel-cased words.
     *
     * @var array
     */
    protected static $camelCache = [];

    /**
     * The cache of studly-cased words.
     *
     * @var array
     */
    protected static $studlyCache = [];

    /**
     * Convert a value to camel case.
     *
     * @param string $value
     *
     * @return string
     */
    public static function camel($value)
    {
        if (isset(static::$camelCache[$value])) {
            return static::$camelCache[$value];
        }

        return static::$camelCache[$value] = lcfirst(static::studly($value));
    }

    /**
     * Generate a more truly "random" alpha-numeric string.
     *
     * @param int $length
     *
     * @return string
     *
     * @throws \RuntimeException
     */
    public static function random($length = 16)
    {
        $string = '';

        while (($len = strlen($string)) < $length) {
            $size = $length - $len;

            $bytes = static::randomBytes($size);

            $string .= substr(str_replace(['/', '+', '='], '', base64_encode($bytes)), 0, $size);
        }

        return $string;
    }

    /**
     * Generate a more truly "random" bytes.
     *
     * @param int $length
     *
     * @return string
     *
     * @throws RuntimeException
     */
    public static function randomBytes($length = 16)
    {
        if (function_exists('random_bytes')) {
            $bytes = random_bytes($length);
        } elseif (function_exists('openssl_random_pseudo_bytes')) {
            $bytes = openssl_random_pseudo_bytes($length, $strong);
            if (false === $bytes || false === $strong) {
                throw new RuntimeException('Unable to generate random string.');
            }
        } else {
            throw new RuntimeException('OpenSSL extension is required for PHP 5 users.');
        }

        return $bytes;
    }

    /**
     * Generate a "random" alpha-numeric string.
     *
     * Should not be considered sufficient for cryptography, etc.
     *
     * @param int $length
     *
     * @return string
     */
    public static function quickRandom($length = 16)
    {
        $pool = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

        return substr(str_shuffle(str_repeat($pool, $length)), 0, $length);
    }

    /**
     * Convert the given string to upper-case.
     *
     * @param string $value
     *
     * @return string
     */
    public static function upper($value)
    {
        return mb_strtoupper($value);
    }

    /**
     * Convert the given string to title case.
     *
     * @param string $value
     *
     * @return string
     */
    public static function title($value)
    {
        return mb_convert_case($value, MB_CASE_TITLE, 'UTF-8');
    }

    /**
     * Convert a string to snake case.
     *
     * @param string $value
     * @param string $delimiter
     *
     * @return string
     */
    public static function snake($value, $delimiter = '_')
    {
        $key = $value.$delimiter;

        if (isset(static::$snakeCache[$key])) {
            return static::$snakeCache[$key];
        }

        if (!ctype_lower($value)) {
            $value = strtolower(preg_replace('/(.)(?=[A-Z])/', '$1'.$delimiter, $value));
        }

        return static::$snakeCache[$key] = $value;
    }

    /**
     * Convert a value to studly caps case.
     *
     * @param string $value
     *
     * @return string
     */
    public static function studly($value)
    {
        $key = $value;

        if (isset(static::$studlyCache[$key])) {
            return static::$studlyCache[$key];
        }

        $value = ucwords(str_replace(['-', '_'], ' ', $value));

        return static::$studlyCache[$key] = str_replace(' ', '', $value);
    }
}
