<?php

namespace App\Services;

use App\Enums\PaymentGateway;
use App\Enums\TransactionStatus;
use App\Enums\TransactionType;
use App\Models\CreditSettlement;
use App\Models\CustomerCredit;
use App\Models\User;
use App\Models\WalletTransaction;
use Illuminate\Support\Facades\DB;
use RuntimeException;

/**
 * سرویس اعتبار چندارزی مشتری.
 * کیف پول (IRR) مرجع است. اعتبار = بدهی به ارز خارجی. تسویه = پرداخت ریالی با نرخ روز.
 */
class CustomerCreditService
{
    /**
     * اعطای اعتبار (بدهی) چندارزی. فقط super_admin (Policy).
     */
    public function grantCredit(
        User $customer,
        string $currencyCode,
        float $amount,
        ?string $reason = null,
        ?string $reference = null,
        ?int $shipmentId = null,
        int $grantedBy
    ): CustomerCredit {
        if ($amount <= 0) {
            throw new RuntimeException('مبلغ اعتبار باید مثبت باشد.');
        }

        return DB::transaction(function () use (
            $customer, $currencyCode, $amount, $reason, $reference, $shipmentId, $grantedBy
        ) {
            return CustomerCredit::create([
                'user_id'        => $customer->id,
                'currency_code'  => strtoupper(trim($currencyCode)),
                'amount'         => $amount,
                'settled_amount' => 0,
                'status'         => 'open',
                'reason'         => $reason,
                'reference'      => $reference,
                'shipment_id'    => $shipmentId,
                'granted_by'     => $grantedBy,
                'granted_at'     => now(),
            ]);
        });
    }

    /**
     * ثبت تسویه (پرداخت ریالی) برای بخشی از یک اعتبار.
     *
     * @param bool $fromWallet اگه true، مبلغ ریالی از کیف پول کسر می‌شه.
     */
    public function settle(
        CustomerCredit $credit,
        float $amountForeign,
        float $exchangeRate,
        string $rateDate,
        bool $fromWallet,
        int $settledBy,
        ?string $reason = null,
        ?string $reference = null
    ): CreditSettlement {
        if ($amountForeign <= 0) {
            throw new RuntimeException('مبلغ تسویه باید مثبت باشد.');
        }
        if ($exchangeRate <= 0) {
            throw new RuntimeException('نرخ ارز باید مثبت باشد.');
        }
        if (! $credit->isOpen()) {
            throw new RuntimeException('این اعتبار قابل تسویه نیست (settled یا بسته).');
        }
        if ($amountForeign > $credit->balance + 0.005) {
            throw new RuntimeException('مبلغ تسویه از مانده بدهی بیشتر است. مانده: '
                . number_format($credit->balance, 2) . ' ' . $credit->currency_code);
        }

        return DB::transaction(function () use (
            $credit, $amountForeign, $exchangeRate, $rateDate, $fromWallet, $settledBy, $reason, $reference
        ) {
            $credit = CustomerCredit::lockForUpdate()->findOrFail($credit->id);

            $settlementAmountIrr = round($amountForeign * $exchangeRate, 2);

            $walletTransactionId = null;

            if ($fromWallet) {
                $wallet = $credit->user->wallet;
                if (! $wallet) {
                    throw new RuntimeException('کاربر کیف پول ندارد.');
                }
                if ($wallet->isFrozen()) {
                    throw new RuntimeException('کیف پول کاربر مسدود است.');
                }
                if (! $wallet->hasSufficientBalance($settlementAmountIrr)) {
                    throw new RuntimeException('موجودی کیف پول کافی نیست. نیاز: '
                        . number_format($settlementAmountIrr) . ' ریال');
                }

                $wt = WalletTransaction::create([
                    'wallet_id'             => $wallet->id,
                    'amount'                => -$settlementAmountIrr,
                    'balance_before'        => $wallet->balance,
                    'balance_after'         => $wallet->balance - $settlementAmountIrr,
                    'type'                  => TransactionType::CREDIT_SETTLEMENT,
                    'status'                => TransactionStatus::COMPLETED,
                    'gateway'               => PaymentGateway::WALLET,
                    'description'           => "تسویه اعتبار {$credit->currency_code} {$amountForeign} (credit #{$credit->id})",
                    'transactionable_type'  => CustomerCredit::class,
                    'transactionable_id'    => $credit->id,
                    'created_by'            => $settledBy,
                ]);

                $wallet->update([
                    'balance'         => $wallet->balance - $settlementAmountIrr,
                    'total_withdrawn' => $wallet->total_withdrawn + $settlementAmountIrr,
                ]);

                $walletTransactionId = $wt->id;
            }

            $settlement = CreditSettlement::create([
                'customer_credit_id'     => $credit->id,
                'settled_amount_foreign' => $amountForeign,
                'currency_code'          => $credit->currency_code,
                'settlement_currency'    => 'IRR',
                'exchange_rate'          => $exchangeRate,
                'rate_date'              => $rateDate,
                'settlement_amount_irr'  => $settlementAmountIrr,
                'wallet_transaction_id'  => $walletTransactionId,
                'reason'                 => $reason,
                'reference'              => $reference,
                'settled_by'             => $settledBy,
                'settled_at'             => now(),
            ]);

            $credit->settled_amount = (float) $credit->settled_amount + $amountForeign;
            $credit->recomputeStatus();

            return $settlement;
        });
    }

    /**
     * بدهی‌های باز مشتری به تفکیک ارز.
     *
     * @return array<int, array{currency_code: string, total_amount: float, total_settled: float, balance: float, count: int}>
     */
    public function getCustomerDebtsByCurrency(User $customer): array
    {
        return CustomerCredit::where('user_id', $customer->id)
            ->whereIn('status', ['open', 'partially_settled'])
            ->select('currency_code')
            ->selectRaw('SUM(amount) as total_amount')
            ->selectRaw('SUM(settled_amount) as total_settled')
            ->selectRaw('SUM(amount - settled_amount) as balance')
            ->selectRaw('COUNT(*) as count')
            ->groupBy('currency_code')
            ->get()
            ->map(function ($row) {
                return [
                    'currency_code' => $row->currency_code,
                    'total_amount'  => (float) $row->total_amount,
                    'total_settled' => (float) $row->total_settled,
                    'balance'       => (float) $row->balance,
                    'count'         => (int) $row->count,
                ];
            })
            ->toArray();
    }
}