<?php

namespace App\Services\Chain;

use FurqanSiddiqui\BIP39\BIP39;
use RuntimeException;

/**
 * Solana address helpers: SLIP-0010 Ed25519 derivation + Base58.
 *
 * Phantom / Solflare path: m/44'/501'/{index}'/0'
 */
final class SolAddress
{
    private const ALPHABET = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';

    /**
     * Derive Solana base58 address from BIP39 mnemonic at account index.
     * Path: m/44'/501'/{index}'/0' (Phantom default).
     */
    public static function fromMnemonic(string $mnemonic, int $index = 0): string
    {
        if ($index < 0) {
            throw new RuntimeException('Invalid derive index');
        }

        $words = preg_split('/\s+/', trim($mnemonic)) ?: [];
        if (count($words) < 12) {
            throw new RuntimeException('Invalid mnemonic');
        }

        $seed = BIP39::Words($words)->generateSeed();
        if (! is_string($seed) || strlen($seed) < 32) {
            throw new RuntimeException('Failed to generate BIP39 seed');
        }

        // SLIP-0010: master from BIP39 seed, then hardened path.
        [$key, $chain] = self::masterFromSeed($seed);
        foreach ([44 | 0x80000000, 501 | 0x80000000, $index | 0x80000000, 0 | 0x80000000] as $child) {
            [$key, $chain] = self::ckdPriv($key, $chain, $child);
        }

        return self::base58Encode(self::publicKeyFromSeed($key));
    }

    public static function isValid(string $address): bool
    {
        $address = trim($address);
        if (! preg_match('/^[1-9A-HJ-NP-Za-km-z]{32,44}$/', $address)) {
            return false;
        }
        $decoded = self::base58Decode($address);

        return $decoded !== null && strlen($decoded) === 32;
    }

    /**
     * @return array{0: string, 1: string} 32-byte key + 32-byte chain code
     */
    private static function masterFromSeed(string $seed): array
    {
        $I = hash_hmac('sha512', $seed, 'ed25519 seed', true);

        return [substr($I, 0, 32), substr($I, 32, 32)];
    }

    /**
     * SLIP-0010 hardened-only child key derivation for Ed25519.
     *
     * @return array{0: string, 1: string}
     */
    private static function ckdPriv(string $kPar, string $cPar, int $index): array
    {
        if (($index & 0x80000000) === 0) {
            throw new RuntimeException('Ed25519 SLIP-0010 only supports hardened derivation');
        }

        $data = "\x00".$kPar.pack('N', $index);
        $I = hash_hmac('sha512', $data, $cPar, true);

        return [substr($I, 0, 32), substr($I, 32, 32)];
    }

    private static function publicKeyFromSeed(string $seed32): string
    {
        if (strlen($seed32) !== 32) {
            throw new RuntimeException('Invalid Ed25519 seed length');
        }
        if (! function_exists('sodium_crypto_sign_seed_keypair')) {
            throw new RuntimeException('ext-sodium is required for Solana address derivation');
        }

        $kp = sodium_crypto_sign_seed_keypair($seed32);

        return sodium_crypto_sign_publickey($kp);
    }

    public static function base58Encode(string $binary): string
    {
        if ($binary === '') {
            return '';
        }

        $leadingZeros = 0;
        $len = strlen($binary);
        for ($i = 0; $i < $len && $binary[$i] === "\x00"; $i++) {
            $leadingZeros++;
        }

        $num = gmp_init(bin2hex($binary), 16);
        $base = gmp_init(58);
        $out = '';
        while (gmp_cmp($num, 0) > 0) {
            [$num, $rem] = [gmp_div_q($num, $base), gmp_intval(gmp_mod($num, $base))];
            $out = self::ALPHABET[$rem].$out;
        }

        return str_repeat('1', $leadingZeros).($out === '' ? '1' : $out);
    }

    public static function base58Decode(string $input): ?string
    {
        $len = strlen($input);
        if ($len === 0) {
            return null;
        }

        $decoded = gmp_init(0);
        $base = gmp_init(58);
        for ($i = 0; $i < $len; $i++) {
            $pos = strpos(self::ALPHABET, $input[$i]);
            if ($pos === false) {
                return null;
            }
            $decoded = gmp_add(gmp_mul($decoded, $base), $pos);
        }

        $hex = gmp_strval($decoded, 16);
        if (strlen($hex) % 2 !== 0) {
            $hex = '0'.$hex;
        }
        $bin = $hex === '0' ? '' : (hex2bin($hex) ?: '');

        $leadingZeros = 0;
        for ($i = 0; $i < $len && $input[$i] === '1'; $i++) {
            $leadingZeros++;
        }

        return str_repeat("\x00", $leadingZeros).$bin;
    }
}