<?php

namespace App\Domains\Purchase\Services\Checkout;

use App\Domains\Catalog\Models\Variant;
use App\Domains\Catalog\Services\CatalogInventoryService;
use App\Domains\Purchase\Models\Purchase;
use App\Domains\Purchase\Models\PurchaseItem;
use App\Domains\Purchase\Services\UserPurchaseLimitService;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;
use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;

class EditCheckoutService
{
    public function __construct(
        private readonly CatalogInventoryService $inventory,
        private readonly UserPurchaseLimitService $purchaseLimits,
        private readonly CatalogSelectionResolver $selections,
        private readonly SourceCartService $sourceCart,
        private readonly PurchaseItemSnapshotFactory $snapshots,
        private readonly PurchaseResponseLoader $responses,
    ) {}

    /** @param array<string, string> $customerData */
    public function updateCustomer(Purchase $purchase, array $customerData): Purchase
    {
        return DB::transaction(function () use ($purchase, $customerData): Purchase {
            $purchase = $this->lockPurchase($purchase);
            $this->assertEditable($purchase);

            $purchase->update($customerData);

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

    public function updateItem(
        Purchase $purchase,
        PurchaseItem $purchaseItem,
        ?int $quantity,
        ?int $variantId,
        bool $updateVariant,
    ): Purchase {
        return DB::transaction(function () use (
            $purchase,
            $purchaseItem,
            $quantity,
            $variantId,
            $updateVariant,
        ): Purchase {
            $purchase = $this->lockPurchase($purchase);

            if ($purchase->status !== Purchase::STATUS_CREATED || $this->hasExpired($purchase)) {
                throw ValidationException::withMessages([
                    'purchase' => __('api.purchase.not_editable'),
                ]);
            }

            $purchaseItem = $this->lockPurchaseItem($purchase, $purchaseItem);
            $tenant = $purchase->tenant()->firstOrFail();
            $finalQuantity = $quantity ?? (int) $purchaseItem->cantidad;

            if ($quantity !== null && ! $tenant->cart_editing_policy->allowsQuantityChanges()) {
                throw ValidationException::withMessages([
                    'quantity' => __('api.cart.editing_disabled'),
                ]);
            }

            if ($updateVariant && ! $tenant->cart_editing_policy->allowsVariantChanges()) {
                throw ValidationException::withMessages([
                    'variant_id' => __('api.purchase.variant_change_disabled'),
                ]);
            }

            if ($updateVariant && $variantId !== $purchaseItem->source_variant_id) {
                $this->changeItemVariant(
                    $purchase,
                    $purchaseItem,
                    (int) $variantId,
                    $finalQuantity,
                );
            } else {
                $difference = $finalQuantity - (int) $purchaseItem->cantidad;

                if ($difference !== 0) {
                    $this->adjustReservation($purchase, $purchaseItem, $finalQuantity, $difference);

                    $purchaseItem->update([
                        'cantidad' => $finalQuantity,
                        'total' => (float) $purchaseItem->precio_unitario * $finalQuantity,
                    ]);
                    $this->sourceCart->syncItemQuantity($purchase, $purchaseItem, $finalQuantity);
                }
            }

            $purchase->update([
                'total' => $purchase->calculateCurrentTotalAmount(),
            ]);

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

    private function changeItemVariant(
        Purchase $purchase,
        PurchaseItem $sourceItem,
        int $variantId,
        int $quantity,
    ): void {
        $tenant = $purchase->tenant()->firstOrFail();
        $currentSelection = $this->selections->resolvePurchaseItem($tenant, $sourceItem);
        $targetSelection = $this->selections->resolve(
            $tenant,
            (int) $sourceItem->source_catalog_item_id,
            $variantId,
            'item',
        );

        if (! $targetSelection instanceof Variant) {
            throw ValidationException::withMessages([
                'variant_id' => __('api.cart.variant_required'),
            ]);
        }

        /** @var PurchaseItem|null $targetItem */
        $targetItem = $purchase->items()
            ->where('source_catalog_item_id', $sourceItem->source_catalog_item_id)
            ->where('source_variant_id', $targetSelection->id)
            ->whereKeyNot($sourceItem->getKey())
            ->lockForUpdate()
            ->first();

        if ($targetItem !== null && $targetItem->reservation_status !== PurchaseItem::RESERVATION_ACTIVE) {
            throw ValidationException::withMessages([
                'variant_id' => __('api.purchase.item_not_editable'),
            ]);
        }

        $otherItemQuantity = (int) $purchase->items()
            ->where('source_catalog_item_id', $sourceItem->source_catalog_item_id)
            ->whereKeyNot($sourceItem->getKey())
            ->sum('cantidad');
        $this->purchaseLimits->assertCanPurchase(
            $targetSelection->catalogItem,
            (int) $purchase->user_id,
            $otherItemQuantity + $quantity,
            $purchase->getKey(),
            'variant_id',
        );

        try {
            $this->inventory->release($currentSelection, (int) $sourceItem->cantidad);
            $this->inventory->reserve($targetSelection, $quantity);
        } catch (\InvalidArgumentException) {
            throw ValidationException::withMessages([
                'variant_id' => __('api.purchase.insufficient_stock'),
            ]);
        }

        $previousVariantId = $sourceItem->source_variant_id;
        $finalQuantity = $quantity;

        if ($targetItem !== null) {
            $finalQuantity += (int) $targetItem->cantidad;
            $targetItem->update($this->snapshots->fromVariant($targetSelection, $finalQuantity));
            $sourceItem->delete();
        } else {
            $sourceItem->update($this->snapshots->fromVariant($targetSelection, $finalQuantity));
        }

        $this->sourceCart->syncItemSelection(
            $purchase,
            (int) $sourceItem->source_catalog_item_id,
            $previousVariantId,
            $targetSelection->id,
            $finalQuantity,
        );
    }

    public function prepareItemEditing(Purchase $purchase): Purchase
    {
        return DB::transaction(function () use ($purchase): Purchase {
            $purchase = $this->lockPurchase($purchase);
            $this->assertEditable($purchase);

            if (! $purchase->tenant()->firstOrFail()->cart_editing_policy->allowsModification()) {
                throw ValidationException::withMessages([
                    'purchase' => __('api.cart.editing_disabled'),
                ]);
            }

            $purchase->telepagosQr()->delete();
            $purchase->update([
                'status' => Purchase::STATUS_CREATED,
                'payment_method' => null,
                'transfer_payer_dni' => null,
                'expires_at' => now()->addMinutes(
                    max(1, (int) config('purchase.checkout_expiration_minutes', 30)),
                ),
            ]);

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

    private function adjustReservation(
        Purchase $purchase,
        PurchaseItem $purchaseItem,
        int $quantity,
        int $difference,
    ): void {
        $selection = $this->selections->resolvePurchaseItem($purchase->tenant, $purchaseItem);

        try {
            if ($difference > 0) {
                $otherItemQuantity = (int) $purchase->items()
                    ->where('source_catalog_item_id', $purchaseItem->source_catalog_item_id)
                    ->whereKeyNot($purchaseItem->getKey())
                    ->sum('cantidad');
                $catalogItem = $selection instanceof Variant ? $selection->catalogItem : $selection;

                $this->purchaseLimits->assertCanPurchase(
                    $catalogItem,
                    (int) $purchase->user_id,
                    $otherItemQuantity + $quantity,
                    $purchase->getKey(),
                );
                $this->inventory->reserve($selection, $difference);
            } else {
                $this->inventory->release($selection, abs($difference));
            }
        } catch (\InvalidArgumentException) {
            throw ValidationException::withMessages([
                'quantity' => __('api.purchase.insufficient_stock'),
            ]);
        }
    }

    private function lockPurchaseItem(Purchase $purchase, PurchaseItem $item): PurchaseItem
    {
        /** @var PurchaseItem|null $lockedItem */
        $lockedItem = $purchase->items()
            ->whereKey($item->getKey())
            ->lockForUpdate()
            ->first();

        if ($lockedItem === null) {
            throw new NotFoundHttpException('Purchase item not found.');
        }

        if ($lockedItem->reservation_status !== PurchaseItem::RESERVATION_ACTIVE) {
            throw ValidationException::withMessages([
                'item' => __('api.purchase.item_not_editable'),
            ]);
        }

        return $lockedItem;
    }

    private function assertEditable(Purchase $purchase): void
    {
        if (
            ! in_array($purchase->status, [
                Purchase::STATUS_CREATED,
                Purchase::STATUS_PENDING_PAYMENT,
            ], true)
            || $this->hasExpired($purchase)
        ) {
            throw ValidationException::withMessages([
                'purchase' => __('api.purchase.not_editable'),
            ]);
        }
    }

    private function hasExpired(Purchase $purchase): bool
    {
        return $purchase->expires_at !== null && $purchase->expires_at->isPast();
    }

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

    private function loadPurchase(Purchase $purchase): Purchase
    {
        return $this->responses->load($purchase);
    }
}