<?php

namespace App\Domains\Purchase\Services\Checkout;

use App\Domains\Cart\Models\CartItem;
use App\Domains\Catalog\Services\StockReservationService;
use App\Domains\Purchase\Models\Purchase;
use App\Domains\Purchase\Services\PurchaseStateGuard;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;

class CompleteCheckoutService
{
    public function __construct(
        private readonly StockReservationService $reservations,
        private readonly SourceCartService $sourceCart,
        private readonly PurchaseStateGuard $purchaseState,
    ) {}

    public function complete(Purchase $purchase): Purchase
    {
        return DB::transaction(function () use ($purchase): Purchase {
            $purchase = $this->lockPurchase($purchase);
            $this->purchaseState->assertNotExpired($purchase);

            if ($purchase->payment_method === null) {
                throw ValidationException::withMessages([
                    'payment_method' => __('api.purchase.payment_method_required'),
                ]);
            }

            if ($this->isTerminal($purchase)) {
                return $this->loadPurchase($purchase);
            }

            $purchase->update([
                'status' => Purchase::STATUS_PENDING_PAYMENT,
                'total' => $purchase->calculateCurrentTotalAmount(),
            ]);

            return $this->loadPurchase($purchase);
        });
    }

    public function submitForReview(Purchase $purchase): Purchase
    {
        return DB::transaction(function () use ($purchase): Purchase {
            $purchase = $this->lockPurchase($purchase);
            $this->purchaseState->assertNotExpired($purchase);

            if ($purchase->status === Purchase::STATUS_PAID) {
                return $this->loadPurchase($purchase);
            }

            if (
                $purchase->status !== Purchase::STATUS_PENDING_PAYMENT
                || ($purchase->expires_at !== null && $purchase->expires_at->isPast())
            ) {
                throw ValidationException::withMessages([
                    'purchase' => __('api.purchase.not_available_for_review'),
                ]);
            }

            $purchase->update(['expires_at' => null]);
            $this->reservations->syncPurchaseExpiration($purchase);

            return $this->loadPurchase($purchase);
        });
    }

    public function confirm(Purchase $purchase): void
    {
        DB::transaction(function () use ($purchase): void {
            $purchase = $this->lockPurchase($purchase);
            $this->purchaseState->assertNotExpired($purchase);

            if ($purchase->status === Purchase::STATUS_PAID) {
                return;
            }

            if (in_array($purchase->status, [
                Purchase::STATUS_CANCELLED,
                Purchase::STATUS_REJECTED,
                Purchase::STATUS_EXPIRED,
            ], true)) {
                throw ValidationException::withMessages([
                    'purchase' => __('api.purchase.cannot_confirm'),
                ]);
            }

            if (! $purchase->items()->exists()) {
                throw ValidationException::withMessages([
                    'items' => __('api.purchase.inconsistent_reservation'),
                ]);
            }

            $cart = $purchase->cart()->withTrashed()->lockForUpdate()->first();
            if ($cart?->status === 'converted' && $cart->trashed()) {
                return;
            }

            if ($cart === null || $cart->status !== 'checkout') {
                throw ValidationException::withMessages([
                    'items' => __('api.purchase.inconsistent_reservation'),
                ]);
            }

            $cartItems = $cart->items()->orderBy('id')->lockForUpdate()->get();
            if ($cartItems->isEmpty()) {
                throw ValidationException::withMessages([
                    'items' => __('api.purchase.inconsistent_reservation'),
                ]);
            }

            $snapshotQuantities = $purchase->items()
                ->lockForUpdate()
                ->get(['source_catalog_item_id', 'source_variant_id', 'cantidad'])
                ->groupBy(fn ($item): string => $this->itemKey(
                    (int) $item->source_catalog_item_id,
                    $item->source_variant_id === null ? null : (int) $item->source_variant_id,
                ))
                ->map(fn (Collection $items): int => (int) $items->sum('cantidad'))
                ->sortKeys()
                ->all();
            $cartQuantities = $cartItems
                ->groupBy(fn (CartItem $item): string => $this->itemKey(
                    (int) $item->catalog_item_id,
                    $item->variant_id === null ? null : (int) $item->variant_id,
                ))
                ->map(fn (Collection $items): int => (int) $items->sum('cantidad'))
                ->sortKeys()
                ->all();

            if ($snapshotQuantities !== $cartQuantities) {
                throw ValidationException::withMessages([
                    'items' => __('api.purchase.inconsistent_reservation'),
                ]);
            }

            $this->loadCartItems($cartItems);

            foreach ($cartItems as $cartItem) {
                $selection = $cartItem->selectedItem();
                if ($selection === null) {
                    throw ValidationException::withMessages([
                        'items' => __('api.purchase.inconsistent_reservation'),
                    ]);
                }

                try {
                    $this->reservations->commit($cartItem, $selection);
                } catch (\InvalidArgumentException) {
                    throw ValidationException::withMessages([
                        'items' => __('api.purchase.inconsistent_reservation'),
                    ]);
                }
            }

            $this->sourceCart->finalize($purchase);
        });
    }

    private function isTerminal(Purchase $purchase): bool
    {
        return in_array($purchase->status, [
            Purchase::STATUS_PAID,
            Purchase::STATUS_CANCELLED,
            Purchase::STATUS_REJECTED,
            Purchase::STATUS_EXPIRED,
        ], true);
    }

    private function lockPurchase(Purchase $purchase): Purchase
    {
        /** @var Purchase */
        return Purchase::query()->lockForUpdate()->findOrFail($purchase->getKey());
    }

    private function loadPurchase(Purchase $purchase): Purchase
    {
        return $purchase->load(['items.imageAttachment']);
    }

    private function itemKey(int $catalogItemId, ?int $variantId): string
    {
        return $catalogItemId.':'.($variantId ?? 'none');
    }

    /** @param Collection<int, CartItem> $cartItems */
    private function loadCartItems(Collection $cartItems): void
    {
        $cartItems->load([
            'catalogItem.inventory',
            'catalogItem.attachments',
            'variant.inventory',
            'variant.attachments',
            'variant.catalogItem',
            'variant.definitions.itemAttribute.attribute',
            'variant.eventDates',
            'variant.eventDate',
        ]);
    }
}