<?php


namespace smpp\helpers;

/**
 * Class capable of encoding GSM 03.38 default alphabet and packing octets into septets as described by GSM 03.38.
 * Based on mapping: http://www.unicode.org/Public/MAPPINGS/ETSI/GSM0338.TXT
 *
 * Copyright (C) 2011 OnlineCity
 * Licensed under the MIT license, which can be read at: http://www.opensource.org/licenses/mit-license.php
 * @author hd@onlinecity.dk
 */
class GsmEncoderHelper
{
    /**
     * Encode an UTF-8 string into GSM 03.38
     * Since UTF-8 is largely ASCII compatible, and GSM 03.38 is somewhat compatible, unnecessary conversions are removed.
     * Specials chars such as € can be encoded by using an escape char \x1B in front of a backwards compatible (similar) char.
     * UTF-8 chars which doesn't have a GSM 03.38 equivalent is replaced with a question mark.
     * UTF-8 continuation bytes (\x08-\xBF) are replaced when encountered in their valid places, but
     * any continuation bytes outside of a valid UTF-8 sequence is not processed.
     *
     * @param string $string
     * @return string
     */
    public static function utf8ToGsm0338(string $string): string
    {
        $dict = [
            '@' => "\x00",
            '£' => "\x01",
            '$' => "\x02",
            '¥' => "\x03",
            'è' => "\x04",
            'é' => "\x05",
            'ù' => "\x06",
            'ì' => "\x07",
            'ò' => "\x08",
            'Ç' => "\x09",
            'Ø' => "\x0B",
            'ø' => "\x0C",
            'Å' => "\x0E",
            'å' => "\x0F",
            'Δ' => "\x10",
            '_' => "\x11",
            'Φ' => "\x12",
            'Γ' => "\x13",
            'Λ' => "\x14",
            'Ω' => "\x15",
            'Π' => "\x16",
            'Ψ' => "\x17",
            'Σ' => "\x18",
            'Θ' => "\x19",
            'Ξ' => "\x1A",
            'Æ' => "\x1C",
            'æ' => "\x1D",
            'ß' => "\x1E",
            'É' => "\x1F",
            'А' => "\x04\x10",
            'Б' => "\x04\x11",
            'В' => "\x04\x12",
            'Г' => "\x04\x13",
            'Д' => "\x04\x14",
            'Е' => "\x04\x15",
            'Ё' => "\x04\x01",
            'Ж' => "\x04\x16",
            'З' => "\x04\x17",
            'И' => "\x04\x18",
            'Й' => "\x04\x19",
            'К' => "\x04\x1A",
            'Л' => "\x04\x1B",
            'М' => "\x04\x1C",
            'Н' => "\x04\x1D",
            'О' => "\x04\x1E",
            'П' => "\x04\x1F",
            'Р' => "\x04\x20",
            'С' => "\x04\x21",
            'Т' => "\x04\x22",
            'У' => "\x04\x23",
            'Ф' => "\x04\x24",
            'Х' => "\x04\x25",
            'Ц' => "\x04\x26",
            'Ч' => "\x04\x27",
            'Ш' => "\x04\x28",
            'Щ' => "\x04\x29",
            'Ь' => "\x04\x2A",
            'Ы' => "\x04\x2B",
            'Ъ' => "\x04\x2C",
            'Э' => "\x04\x2D",
            'Ю' => "\x04\x2E",
            'Я' => "\x04\x2F",
            'а' => "\x04\x30",
            'б' => "\x04\x31",
            'в' => "\x04\x32",
            'г' => "\x04\x33",
            'д' => "\x04\x34",
            'е' => "\x04\x35",
            'ё' => "\x04\x51",
            'ж' => "\x04\x36",
            'з' => "\x04\x37",
            'и' => "\x04\x38",
            'й' => "\x04\x39",
            'к' => "\x04\x3A",
            'л' => "\x04\x3B",
            'м' => "\x04\x3C",
            'н' => "\x04\x3D",
            'о' => "\x04\x3E",
            'п' => "\x04\x3F",
            'р' => "\x04\x40",
            'с' => "\x04\x41",
            'т' => "\x04\x42",
            'у' => "\x04\x43",
            'ф' => "\x04\x44",
            'х' => "\x04\x45",
            'ц' => "\x04\x46",
            'ч' => "\x04\x47",
            'ш' => "\x04\x48",
            'щ' => "\x04\x49",
            'ь' => "\x04\x4A",
            'ы' => "\x04\x4B",
            'ъ' => "\x04\x4C",
            'э' => "\x04\x4D",
            'ю' => "\x04\x4E",
            'я' => "\x04\x4F",
            // all \x2? removed
            // all \x3? removed
            '¡' => "\x40",
            'Ä' => "\x5B",
            'Ö' => "\x5C",
            'Ñ' => "\x5D",
            'Ü' => "\x5E",
            '§' => "\x5F",
            '¿' => "\x60",
            'ä' => "\x7B",
            'ö' => "\x7C",
            'ñ' => "\x7D",
            'ü' => "\x7E",
            'à' => "\x7F",
            '^' => "\x1B\x14",
            '{' => "\x1B\x28",
            '}' => "\x1B\x29",
            '\\' => "\x1B\x2F",
            '[' => "\x1B\x3C",
            '~' => "\x1B\x3D",
            ']' => "\x1B\x3E",
            '|' => "\x1B\x40",
            '€' => "\x1B\x65"
        ];

        // Replace unconverted UTF-8 chars from codepages U+0080-U+07FF, U+0080-U+FFFF and U+010000-U+10FFFF with a single ?
        // return preg_replace('/([\\xC0-\\xDF].)|([\\xE0-\\xEF]..)|([\\xF0-\\xFF]...)/m','?',$converted);
        return strtr($string, $dict);
    }

    /**
     * Count the number of GSM 03.38 chars a conversion would contain.
     * It's about 3 times faster to count than convert and do strlen() if conversion is not required.
     *
     * @param string $utf8String
     *
     * @return integer
     */
    public static function countGsm0338Length(string $utf8String): int
    {
        $len = mb_strlen($utf8String, 'utf-8');
        $len += preg_match_all('/[\\^{}\\\~€|\\[\\]]/mu', $utf8String, $m);
        return $len;
    }

    /**
     * Pack an 8-bit string into 7-bit GSM format
     * Returns the packed string in binary format
     *
     * @param string $data
     *
     * @return string
     */
    public static function pack7bit(string $data): string
    {
        $l = strlen($data);
        $currentByte = 0;
        $offset = 0;
        $packed = '';
        for ($i = 0; $i < $l; $i++) {
            // cap off any excess bytes
            $septet = ord($data[$i]) & 0x7f;
            // append the septet and then cap off excess bytes
            $currentByte |= ($septet << $offset) & 0xff;
            // update offset
            $offset += 7;

            if ($offset > 7) {
                // the current byte is full, add it to the encoded data.
                $packed .= chr($currentByte);
                // shift left and append the left shifted septet to the current byte
                $currentByte = $septet = $septet >> (7 - ($offset - 8));
                // update offset
                // 7 - (7 - ($offset - 8))
                $offset -= 8;
            }
        }
        // append the last byte
        if ($currentByte > 0) {
            $packed .= chr($currentByte);
        }
        return $packed;
    }
}