<?php

namespace App\Services\Chain;

use kornrunner\Keccak;
use RuntimeException;

final class TronAddress
{
    public static function fromUncompressedPublicKey(string $publicKeyHex): string
    {
        $hex = strtolower($publicKeyHex);
        if (str_starts_with($hex, '0x')) {
            $hex = substr($hex, 2);
        }
        if (str_starts_with($hex, '04')) {
            $hex = substr($hex, 2);
        }
        if (strlen($hex) !== 128) {
            throw new RuntimeException('Expected uncompressed secp256k1 public key');
        }

        $hash = Keccak::hash(hex2bin($hex), 256);
        $addrHex = '41'.substr($hash, -40);

        return self::hexToBase58Check($addrHex);
    }

    public static function isValid(string $address): bool
    {
        if (! preg_match('/^T[1-9A-HJ-NP-Za-km-z]{33}$/', $address)) {
            return false;
        }

        try {
            $hex = self::base58CheckToHex($address);
        } catch (\Throwable) {
            return false;
        }

        return str_starts_with(strtolower($hex), '41') && strlen($hex) === 42;
    }

    public static function toHex(string $base58): string
    {
        return self::base58CheckToHex($base58);
    }

    public static function hexToBase58Check(string $hex): string
    {
        $alphabet = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';
        $bin = hex2bin($hex);
        if ($bin === false) {
            throw new RuntimeException('Invalid hex');
        }
        $checksum = substr(hash('sha256', hash('sha256', $bin, true), true), 0, 4);
        $bytes = $bin.$checksum;
        $num = gmp_init(bin2hex($bytes), 16);
        $encoded = '';
        while (gmp_cmp($num, 0) > 0) {
            [$num, $rem] = [gmp_div_q($num, 58), gmp_intval(gmp_mod($num, 58))];
            $encoded = $alphabet[$rem].$encoded;
        }
        for ($i = 0, $len = strlen($bytes); $i < $len && $bytes[$i] === "\x00"; $i++) {
            $encoded = '1'.$encoded;
        }

        return $encoded;
    }

    public static function base58CheckToHex(string $address): string
    {
        $alphabet = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';
        $num = gmp_init(0);
        for ($i = 0, $len = strlen($address); $i < $len; $i++) {
            $pos = strpos($alphabet, $address[$i]);
            if ($pos === false) {
                throw new RuntimeException('Invalid base58 character');
            }
            $num = gmp_add(gmp_mul($num, 58), $pos);
        }
        $hex = gmp_strval($num, 16);
        if (strlen($hex) % 2 !== 0) {
            $hex = '0'.$hex;
        }
        // leading ones => leading zero bytes
        for ($i = 0, $len = strlen($address); $i < $len && $address[$i] === '1'; $i++) {
            $hex = '00'.$hex;
        }
        $bin = hex2bin($hex);
        if ($bin === false || strlen($bin) < 5) {
            throw new RuntimeException('Invalid address payload');
        }
        $payload = substr($bin, 0, -4);
        $checksum = substr($bin, -4);
        $expected = substr(hash('sha256', hash('sha256', $payload, true), true), 0, 4);
        if (! hash_equals($expected, $checksum)) {
            throw new RuntimeException('Invalid address checksum');
        }

        return bin2hex($payload);
    }
}