<?php

namespace App\Services;

use App\Enums\Invoice\InvoiceStatus;
use App\Enums\Order\OrderStatus;
use App\Enums\TransactionStatus;
use App\Helpers\OrderHelper;
use App\Jobs\Hosting\ProvisionHostingAccountJob;
use App\Jobs\VirtualMachine\Action\VMJobs;
use App\Jobs\VirtualMachine\Create\CreateVirtualMachineJob;
use App\Models\Addon;
use App\Models\Customer;
use App\Models\Invoice;
use App\Models\Log as CustomerActivityLog;
use App\Models\OrderItem;
use App\Models\Service;
use App\Models\ServiceAddon;
use App\Models\Transaction;
use Carbon\Carbon;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Str;

class InvoicePaymentService
{
    /** Trạng thái hoá đơn còn có thể thu tiền. Dùng chung cho cả khách trả lẫn admin xác nhận. */
    public const PAYABLE_STATUSES = [InvoiceStatus::UNPAID->value, InvoiceStatus::OVERDUE->value];

    /**
     * Chặn thu tiền trên hoá đơn đã huỷ/đã hoàn — trước đây chỉ payWithBalance() kiểm tra,
     * markPaidByAdmin() thì không, nên hoá đơn CANCELLED vẫn bật sang PAID và kích hoạt dịch vụ thật.
     */
    public static function assertPayable(Invoice $invoice): void
    {
        if (! in_array((int) $invoice->status, self::PAYABLE_STATUSES, true)) {
            throw new \InvalidArgumentException(sprintf(
                'Hóa đơn #%s đang ở trạng thái "%s", không thể ghi nhận thanh toán.',
                $invoice->invoice_number,
                InvoiceStatus::tryFrom((int) $invoice->status)?->label() ?? 'không xác định',
            ));
        }
    }

    /**
     * @param int|null $amount Số tiền muốn trả lần này. Null = trả hết phần còn thiếu.
     *                         Trả ít hơn thì hoá đơn giữ nguyên UNPAID/OVERDUE, chỉ cộng dồn
     *                         amount_paid — dịch vụ chưa được kích hoạt cho tới khi thu đủ.
     */
    public function payWithBalance(Invoice $invoice, Customer $customer, string $method = 'balance', ?int $amount = null): Invoice
    {
        if ((int) $invoice->customer_id !== (int) $customer->id) {
            throw new \InvalidArgumentException('Hóa đơn không thuộc tài khoản này.');
        }

        // Balance/status are re-checked below under row locks — this is just a fast
        // fail-fast path so we don't open a transaction for an already-paid invoice.
        if ((int) $invoice->status === InvoiceStatus::PAID->value) {
            return $invoice->fresh(['order.orderItems.product', 'services', 'customer']);
        }

        return DB::transaction(function () use ($invoice, $customer, $method, $amount) {
            // Lock both rows so two concurrent payment requests for the same invoice/customer
            // (double-click, retry) cannot both pass the balance check before either commits.
            $invoice = Invoice::where('id', $invoice->id)->lockForUpdate()->firstOrFail();
            $customer = Customer::where('id', $customer->id)->lockForUpdate()->firstOrFail();

            if ((int) $invoice->status === InvoiceStatus::PAID->value) {
                return $invoice->fresh(['order.orderItems.product', 'services', 'customer']);
            }

            self::assertPayable($invoice);

            $outstanding = self::outstanding($invoice);
            $payNow = $amount === null ? $outstanding : min($amount, $outstanding);

            if ($payNow <= 0) {
                throw new \InvalidArgumentException('Số tiền thanh toán phải lớn hơn 0.');
            }

            if ((int) $customer->total < $payNow) {
                throw new \InvalidArgumentException(sprintf(
                    'Số dư không đủ. Hiện có: %s VNĐ, cần: %s VNĐ.',
                    number_format((int) $customer->total),
                    number_format($payNow)
                ));
            }

            $customer->decrement('total', $payNow);

            $paidSoFar = (int) $invoice->amount_paid + $payNow;
            $settled = $paidSoFar >= (int) $invoice->total;

            $invoice->update([
                'amount_paid' => $paidSoFar,
                'status' => $settled ? InvoiceStatus::PAID->value : $invoice->status,
                'paid_at' => $settled ? now() : null,
                'payment_method' => $method,
            ]);

            $this->recordTransaction(
                $invoice,
                $method,
                'Khách hàng thanh toán hóa đơn #' . $invoice->invoice_number
                    . ($settled ? '' : sprintf(' (một phần: %s/%s VNĐ)', number_format($paidSoFar), number_format((int) $invoice->total))),
                amount: $payNow,
                sequence: $settled && $payNow === (int) $invoice->total ? null : $paidSoFar,
            );

            CustomerActivityLog::create([
                'agent' => 'api',
                'client_ip' => request()?->ip(),
                'customer_id' => $customer->id,
                'description' => sprintf(
                    'Thanh toán hóa đơn #%s. Số tiền: %s VNĐ.%s Số dư còn: %s VNĐ.',
                    $invoice->invoice_number,
                    number_format($payNow),
                    $settled ? '' : sprintf(' Còn thiếu: %s VNĐ.', number_format(self::outstanding($invoice->fresh()))),
                    number_format((int) $customer->fresh()->total)
                ),
            ]);

            if (! $settled) {
                return $invoice->fresh(['order.orderItems.product', 'services', 'customer']);
            }

            if ((int) $invoice->invoice_type === 2) {
                $this->activateRenewal($invoice);
            } elseif ($invoice->order) {
                $this->activateOrder($invoice);
            }

            return $invoice->fresh(['order.orderItems.product', 'services', 'customer']);
        });
    }

    /** Số tiền còn phải thu của một hoá đơn. */
    public static function outstanding(Invoice $invoice): int
    {
        return max(0, (int) $invoice->total - (int) $invoice->amount_paid);
    }

    /**
     * @param int|null $receivedAmount Số tiền admin xác nhận đã thực nhận. Null = thu đủ hoá đơn.
     *                                 Nhập ít hơn thì hoá đơn ghi nhận trả một phần và KHÔNG kích
     *                                 hoạt dịch vụ — tránh việc bấm "Đã thanh toán" khi tiền chưa
     *                                 về đủ mà sổ vẫn ghi đủ như trước.
     */
    public function markPaidByAdmin(
        Invoice $invoice,
        ?int $adminId = null,
        string $method = 'admin',
        ?int $receivedAmount = null,
    ): Invoice {
        if ((int) $invoice->status === InvoiceStatus::PAID->value) {
            return $invoice->fresh(['order.orderItems.product', 'services', 'customer']);
        }

        return DB::transaction(function () use ($invoice, $adminId, $method, $receivedAmount) {
            $invoice = Invoice::where('id', $invoice->id)->lockForUpdate()->firstOrFail();

            if ((int) $invoice->status === InvoiceStatus::PAID->value) {
                return $invoice->fresh(['order.orderItems.product', 'services', 'customer']);
            }

            self::assertPayable($invoice);

            $outstanding = self::outstanding($invoice);
            $received = $receivedAmount === null ? $outstanding : min(max(0, $receivedAmount), $outstanding);

            if ($received <= 0) {
                throw new \InvalidArgumentException('Số tiền thực nhận phải lớn hơn 0.');
            }

            $paidSoFar = (int) $invoice->amount_paid + $received;
            $settled = $paidSoFar >= (int) $invoice->total;

            $invoice->update([
                'amount_paid' => $paidSoFar,
                'status' => $settled ? InvoiceStatus::PAID->value : $invoice->status,
                'paid_at' => $settled ? now() : null,
                'payment_method' => $invoice->payment_method ?: $method,
            ]);

            $this->recordTransaction(
                $invoice,
                $method,
                'Admin xác nhận thanh toán hóa đơn #' . $invoice->invoice_number
                    . ($settled ? '' : sprintf(' (một phần: %s/%s VNĐ)', number_format($paidSoFar), number_format((int) $invoice->total))),
                $adminId,
                amount: $received,
                sequence: $settled && $received === (int) $invoice->total ? null : $paidSoFar,
            );

            if (! $settled) {
                return $invoice->fresh(['order.orderItems.product', 'services', 'customer']);
            }

            if ((int) $invoice->invoice_type === 2) {
                $this->activateRenewal($invoice);
            } elseif ($invoice->order) {
                $this->activateOrder($invoice);
            }

            return $invoice->fresh(['order.orderItems.product', 'services', 'customer']);
        });
    }

    /**
     * Hoàn tiền hoá đơn đã thu: cộng lại số dư, ghi Transaction âm, chuyển hoá đơn sang REFUNDED.
     * Trước đây chỉ luồng tên miền có hoàn tiền, VPS/hosting phải làm tay và không để lại dấu vết.
     */
    public function refund(Invoice $invoice, ?int $adminId = null, ?int $amount = null, string $reason = ''): Invoice
    {
        if ((int) $invoice->status !== InvoiceStatus::PAID->value) {
            throw new \InvalidArgumentException('Chỉ hoàn tiền được hoá đơn đã thanh toán.');
        }

        return DB::transaction(function () use ($invoice, $adminId, $amount, $reason) {
            $invoice = Invoice::where('id', $invoice->id)->lockForUpdate()->firstOrFail();

            if ((int) $invoice->status !== InvoiceStatus::PAID->value) {
                throw new \InvalidArgumentException('Chỉ hoàn tiền được hoá đơn đã thanh toán.');
            }

            $paid = (int) $invoice->amount_paid ?: (int) $invoice->total;
            $refundAmount = $amount === null ? $paid : min(max(0, $amount), $paid);

            if ($refundAmount <= 0) {
                throw new \InvalidArgumentException('Số tiền hoàn phải lớn hơn 0.');
            }

            $customer = Customer::where('id', $invoice->customer_id)->lockForUpdate()->firstOrFail();
            $customer->increment('total', $refundAmount);

            $invoice->update([
                'status' => InvoiceStatus::REFUNDED->value,
                'amount_paid' => max(0, $paid - $refundAmount),
            ]);

            Transaction::create([
                'uuid' => (string) Str::uuid(),
                'public_code' => 'INV-REF-' . now()->format('Ymd') . '-' . strtoupper(Str::random(6)),
                'trans' => $invoice->invoice_number . '-REFUND',
                'type' => 'refund',
                'amount' => -$refundAmount,
                'received_amount' => -$refundAmount,
                'customer_id' => $customer->id,
                'user_id' => $adminId,
                'status' => TransactionStatus::COMPLETED->value,
                'note' => trim('Hoàn tiền hóa đơn #' . $invoice->invoice_number . ' ' . $reason),
            ]);

            CustomerActivityLog::create([
                'agent' => 'admin',
                'client_ip' => request()?->ip(),
                'customer_id' => $customer->id,
                'description' => sprintf(
                    'Hoàn tiền hóa đơn #%s: %s VNĐ. Số dư mới: %s VNĐ.%s',
                    $invoice->invoice_number,
                    number_format($refundAmount),
                    number_format((int) $customer->fresh()->total),
                    $reason ? ' Lý do: ' . $reason : '',
                ),
            ]);

            return $invoice->fresh(['order.orderItems.product', 'services', 'customer']);
        });
    }

    /**
     * @param int|null $amount   Số thực thu lần này; null = toàn bộ hoá đơn (hành vi cũ).
     * @param int|null $sequence Khoá phụ để mỗi lần trả từng phần là một dòng riêng. Dưới row
     *                           lock, amount_paid sau mỗi lần trả là duy nhất và tăng dần, nên
     *                           vẫn chống được ghi trùng khi job retry.
     */
    public function recordTransaction(
        Invoice $invoice,
        string $method,
        string $note,
        ?int $adminId = null,
        ?int $amount = null,
        ?int $sequence = null,
    ): Transaction {
        $amount = $amount ?? (int) $invoice->total;

        return Transaction::firstOrCreate(
            [
                'customer_id' => $invoice->customer_id,
                'trans' => $invoice->invoice_number . ($sequence === null ? '' : '-P' . $sequence),
                'type' => 'invoice',
            ],
            [
                'uuid' => (string) Str::uuid(),
                'public_code' => 'INV-PAY-' . now()->format('Ymd') . '-' . strtoupper(Str::random(6)),
                'amount' => $amount,
                'received_amount' => $amount,
                'user_id' => $adminId,
                'status' => TransactionStatus::COMPLETED->value,
                'note' => $note . ' (' . $method . ')',
            ]
        );
    }

    private function activateOrder(Invoice $invoice): void
    {
        $order = $invoice->order?->loadMissing(['orderItems.product', 'customer', 'invoice']);
        if (! $order) {
            return;
        }

        // payment_method/paid_at always mirror the invoice that was just paid, even if the
        // order's status doesn't change (e.g. it's already ACTIVE from an earlier payment).
        $order->update([
            'status' => OrderStatus::ACTIVE->value,
            'payment_method' => $invoice->payment_method,
            'paid_at' => $invoice->paid_at,
        ]);

        foreach ($order->orderItems as $item) {
            $isHostingProvision = ! $item->os_id
                && $item->server_name
                && $item->product?->product_type === 'hosting';

            $service = Service::firstOrCreate(
                ['order_item_id' => $item->id],
                [
                    'customer_id' => $order->customer_id,
                    'product_id' => $item->product_id,
                    'invoice_id' => $invoice->id,
                    'server_name' => $item->server_name,
                    'status' => ($item->os_id || $isHostingProvision) ? 'pending' : 'active',
                    'auto_renew' => false,
                    'started_at' => now(),
                    'expires_at' => now()->addMonths($item->months ?: OrderHelper::cycleToMonths($item->billing_cycle)),
                ]
            );

            $this->attachServiceAddons($service, $item);

            if ($service->wasRecentlyCreated && $item->product_id) {
                if ($item->os_id) {
                    dispatch(new CreateVirtualMachineJob($item));
                } elseif ($isHostingProvision) {
                    dispatch(new ProvisionHostingAccountJob($item));
                }
            }
        }
    }

    private function activateRenewal(Invoice $invoice): void
    {
        $service = Service::query()
            ->with(['orderItem.product'])
            ->where('invoice_id', $invoice->id)
            ->first();

        if (! $service) {
            return;
        }

        if ($invoice->order) {
            // Same rule as activateOrder(): payment_method/paid_at always mirror the invoice
            // that was just paid, regardless of whether the order's status actually changes.
            $invoice->order->update([
                'status' => OrderStatus::ACTIVE->value,
                'payment_method' => $invoice->payment_method,
                'paid_at' => $invoice->paid_at,
            ]);
        }

        $months = (int) ($invoice->invoiceItems()->where('type', 'renewal')->value('months') ?: $service->orderItem?->months ?: 1);
        $baseDate = $service->expires_at && $service->expires_at->isFuture()
            ? $service->expires_at
            : now();
        $expiresAt = Carbon::parse($baseDate)->addMonths($months);

        $service->update([
            'status' => 'active',
            'expires_at' => $expiresAt,
            'suspended_at' => null,
        ]);

        if ($service->vm_id) {
            dispatch(new VMJobs((int) $service->vm_id, 'Start', false))->delay(now()->addSeconds(5));
        }
    }

    private function attachServiceAddons(Service $service, OrderItem $item): void
    {
        if ($service->addons()->exists()) {
            return;
        }

        $product = $item->product;
        if ($product) {
            foreach (['cpu' => $product->cpu, 'ram' => $product->ram, 'disk' => $product->disk, 'bandwidth' => $product->bandwidth] as $type => $value) {
                if ($value !== null && $value !== '') {
                    ServiceAddon::create([
                        'service_id' => $service->id,
                        'addon_type' => $type,
                        'addon_value' => (string) $value,
                        'price' => 0,
                    ]);
                }
            }
        }

        $addonsMeta = is_array($item->addons_meta)
            ? $item->addons_meta
            : json_decode($item->addons_meta ?? '[]', true);

        foreach ((array) $addonsMeta as $meta) {
            $addon = Addon::find($meta['addon_id'] ?? null);
            if (!$addon) {
                continue;
            }
            ServiceAddon::create([
                'service_id'  => $service->id,
                'addon_type'  => strtolower((string) $addon->code),
                'addon_value' => (string) ($meta['qty'] ?? 1),
                'price'       => (int) ($meta['price'] ?? $addon->price),
            ]);
        }
    }

}