<?php

namespace App\Services\Chain;

use Illuminate\Http\Client\PendingRequest;
use Illuminate\Support\Facades\Http;
use RuntimeException;

class EthDriver implements ChainDriver
{
    public function chainId(): string
    {
        return 'eth';
    }

    public function deriveAddress(string $mnemonic, int $index = 0): string
    {
        $derived = Bip44::derive($mnemonic, $this->path($index));

        return EthAddress::fromUncompressedPublicKey($derived['public_key_uncompressed']);
    }

    public function sendNative(string $mnemonic, int $index, string $to, string $amount, ?string $from = null): string
    {
        if (! $this->isValidAddress($to)) {
            throw new RuntimeException('Invalid ETH address');
        }

        $derived = Bip44::derive($mnemonic, $this->path($index));
        $from = EthAddress::fromUncompressedPublicKey($derived['public_key_uncompressed']);
        $wei = $this->toWei($amount);

        return $this->sendLegacy($derived['private_key'], $from, $to, $wei, '0x');
    }

    public function sendToken(string $mnemonic, int $index, string $to, string $amount, string $contract): string
    {
        if (! $this->isValidAddress($to) || ! $this->isValidAddress($contract)) {
            throw new RuntimeException('Invalid ETH address');
        }

        $derived = Bip44::derive($mnemonic, $this->path($index));
        $from = EthAddress::fromUncompressedPublicKey($derived['public_key_uncompressed']);
        $units = $this->toTokenUnits($amount, $this->tokenDecimals($contract));
        // transfer(address,uint256) selector = a9059cbb
        $data = '0xa9059cbb'.EthAddress::toWord($to).str_pad(gmp_strval(gmp_init($units, 10), 16), 64, '0', STR_PAD_LEFT);

        return $this->sendLegacy($derived['private_key'], $from, $contract, '0', $data);
    }

    public function isValidAddress(string $address): bool
    {
        return EthAddress::isValid($address);
    }

    public function isActivated(string $address): bool
    {
        if (! $this->isValidAddress($address)) {
            return false;
        }

        try {
            $hex = $this->rpc('eth_getTransactionCount', [EthAddress::normalize($address), 'latest']);
            if (is_string($hex) && bccomp($this->hexToDec($hex), '0', 0) > 0) {
                return true;
            }
        } catch (\Throwable $e) {
            if (ChainHttpTimeout::active()) {
                throw $e;
            }
            // fall through to balances
        }

        try {
            if (bccomp($this->getNativeBalance($address), '0', 18) > 0) {
                return true;
            }
        } catch (\Throwable $e) {
            if (ChainHttpTimeout::active()) {
                throw $e;
            }
            // fall through to token
        }

        $contract = trim((string) config($this->configPrefix().'.usdt_contract', ''));
        if ($contract !== '') {
            try {
                if (bccomp($this->getTokenBalance($address, $contract), '0', 18) > 0) {
                    return true;
                }
            } catch (\Throwable $e) {
                if (ChainHttpTimeout::active()) {
                    throw $e;
                }

                return false;
            }
        }

        return false;
    }

    public function getNativeBalance(string $address): string
    {
        if (! $this->isValidAddress($address)) {
            throw new RuntimeException('Invalid ETH address');
        }

        $hex = $this->rpc('eth_getBalance', [EthAddress::normalize($address), 'latest']);
        if (! is_string($hex)) {
            return '0';
        }

        return $this->fromWei($this->hexToDec($hex));
    }

    public function getTokenBalance(string $address, string $contract): string
    {
        if (! $this->isValidAddress($address) || ! $this->isValidAddress($contract)) {
            throw new RuntimeException('Invalid ETH address');
        }

        // balanceOf(address)
        $data = '0x70a08231'.EthAddress::toWord($address);
        $hex = $this->rpc('eth_call', [[
            'to' => EthAddress::normalize($contract),
            'data' => $data,
        ], 'latest']);
        if (! is_string($hex) || $hex === '' || $hex === '0x') {
            return '0';
        }

        return $this->fromTokenUnits($this->hexToDec($hex), $this->tokenDecimals($contract));
    }

    private function sendLegacy(string $privateKey, string $from, string $to, string $valueWei, string $data): string
    {
        $chainId = (int) config($this->configPrefix().'.chain_id', 1);
        $nonceHex = $this->rpc('eth_getTransactionCount', [EthAddress::normalize($from), 'pending']);
        $gasPriceHex = $this->rpc('eth_gasPrice', []);
        if (! is_string($nonceHex) || ! is_string($gasPriceHex)) {
            throw new RuntimeException('Failed to fetch nonce/gasPrice');
        }

        $gasLimit = trim((string) config($this->configPrefix().'.gas_limit', ''));
        if ($gasLimit === '' || ! preg_match('/^\d+$/', $gasLimit)) {
            $gasLimit = ($data === '0x' || $data === '') ? '21000' : '100000';
        }
        $tx = [
            'nonce' => $this->hexToDec($nonceHex),
            'gasPrice' => $this->hexToDec($gasPriceHex),
            'gas' => $gasLimit,
            'to' => EthAddress::normalize($to),
            'value' => $valueWei,
            'data' => $data === '' ? '0x' : $data,
        ];

        $raw = EthSigner::signLegacy($privateKey, $tx, $chainId);
        $txid = $this->rpc('eth_sendRawTransaction', [$raw]);
        if (! is_string($txid) || $txid === '') {
            throw new RuntimeException('eth_sendRawTransaction failed');
        }

        return $txid;
    }

    private function path(int $index): string
    {
        return "m/44'/60'/0'/0/{$index}";
    }

    private function toWei(string $amount): string
    {
        if (! preg_match('/^\d+(\.\d{1,18})?$/', $amount)) {
            throw new RuntimeException('Invalid ETH amount');
        }
        [$whole, $frac] = array_pad(explode('.', $amount, 2), 2, '');
        $frac = str_pad(substr($frac, 0, 18), 18, '0', STR_PAD_RIGHT);
        $wei = ltrim($whole.$frac, '0');
        $wei = $wei === '' ? '0' : $wei;
        if (bccomp($wei, '0') <= 0) {
            throw new RuntimeException('Amount must be positive');
        }

        return $wei;
    }

    private function fromWei(string $wei): string
    {
        if (! preg_match('/^\d+$/', $wei)) {
            $wei = '0';
        }
        $human = bcdiv($wei, '1000000000000000000', 18);
        $human = rtrim(rtrim($human, '0'), '.');

        return $human === '' ? '0' : $human;
    }

    protected function configPrefix(): string
    {
        return 'coruna.eth';
    }

    private function tokenDecimals(string $contract): int
    {
        $normalized = EthAddress::normalize($contract);
        $usdt = EthAddress::normalize((string) config($this->configPrefix().'.usdt_contract', ''));
        $decimals = (int) config($this->configPrefix().'.usdt_decimals', 6);
        if ($normalized !== '' && $usdt !== '' && $normalized === $usdt && $decimals > 0) {
            return $decimals;
        }

        return max(1, $decimals > 0 ? $decimals : 6);
    }

    private function toTokenUnits(string $amount, int $decimals): string
    {
        $decimals = max(1, $decimals);
        if (! preg_match('/^\d+(\.\d{1,'.$decimals.'})?$/', $amount)) {
            throw new RuntimeException('Invalid token amount');
        }
        $factor = bcpow('10', (string) $decimals, 0);
        $units = bcmul($amount, $factor, 0);
        if (bccomp($units, '0') <= 0) {
            throw new RuntimeException('Amount must be positive');
        }

        return $units;
    }

    private function fromTokenUnits(string $units, int $decimals): string
    {
        $decimals = max(0, $decimals);
        if (! preg_match('/^\d+$/', $units)) {
            $units = '0';
        }
        $factor = bcpow('10', (string) $decimals, 0);
        $human = bcdiv($units, $factor, $decimals);
        $human = rtrim(rtrim($human, '0'), '.');

        return $human === '' ? '0' : $human;
    }

    private function hexToDec(string $hex): string
    {
        $hex = strtolower($hex);
        if (str_starts_with($hex, '0x')) {
            $hex = substr($hex, 2);
        }
        if ($hex === '' || $hex === '0') {
            return '0';
        }

        return gmp_strval(gmp_init($hex, 16), 10);
    }

    private function rpc(string $method, array $params): mixed
    {
        $url = rtrim((string) config($this->configPrefix().'.rpc_url', 'https://ethereum.publicnode.com'), '/');
        $resp = $this->http()->post($url, [
            'jsonrpc' => '2.0',
            'id' => 1,
            'method' => $method,
            'params' => $params,
        ]);
        if (! $resp->successful()) {
            throw new RuntimeException(strtoupper($this->chainId()).' RPC HTTP '.$resp->status());
        }
        $json = $resp->json();
        if (! is_array($json)) {
            throw new RuntimeException('Invalid '.strtoupper($this->chainId()).' RPC response');
        }
        if (isset($json['error'])) {
            $msg = $json['error']['message'] ?? json_encode($json['error']);
            throw new RuntimeException(strtoupper($this->chainId()).' RPC: '.(is_string($msg) ? $msg : 'error'));
        }

        return $json['result'] ?? null;
    }

    private function http(): PendingRequest
    {
        return ChainHttpTimeout::apply(Http::connectTimeout(20)->timeout(120)->acceptJson()->asJson());
    }
}