<?php

namespace App\Http\Controllers\Checkout;

use App\Http\Controllers\Controller;
use Closure;
use Illuminate\Contracts\Encryption\DecryptException;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Crypt;
use Illuminate\Support\Facades\Storage;
use Illuminate\Support\Facades\Validator;
use Illuminate\Validation\ValidationException;
use Illuminate\View\View;
use Lunar\Exceptions\Carts\CartException;
use Lunar\Models\CartLine;
use Lunar\Models\ProductVariant;
use Modules\Core\Cart\Exceptions\InvalidCouponException;
use Modules\Core\Cart\Services\CartService;

/**
 * Thin storefront cart endpoints for the checkout module. Every action mutates
 * the session cart via boboko-core's CartService and returns the same
 * server-rendered `cart-body` partial — the drawer's Stimulus controller swaps
 * that fragment in place (no JSON, no client-side templating). $cart / $lines
 * for the partial come from the view composer in CheckoutModuleServiceProvider.
 */
class CartController extends Controller
{
    public function __construct(
        private readonly CartService $cart,
    ) {}

    /**
     * CartException here is Lunar's own add_to_cart validation pipeline
     * (CartLineQuantity/CartLineStock) rejecting the line — most commonly
     * "not enough stock at this quantity" for a tracked (purchasable =
     * in_stock) variant. Its own message is an untranslated, hardcoded
     * English string not meant for storefront display, so this returns our
     * own translated one instead rather than passing it through — a
     * storefront.* key rather than checkout.*, since this is a catalog/stock
     * concern the storefront owns, not something specific to the portable
     * checkout module.
     */
    public function add(string $locale, Request $request): View|JsonResponse
    {
        $data = $request->validate([
            'purchasable_id' => ['required', 'integer'],
            'quantity' => ['nullable', 'integer', 'min:1'],
            'custom_fields' => ['nullable', 'array'],
        ]);

        $variant = ProductVariant::findOrFail($data['purchasable_id']);

        try {
            $meta = $this->customFieldsMeta($variant, $data['custom_fields'] ?? []);
        } catch (ValidationException $e) {
            return response()->json(['error' => collect($e->errors())->flatten()->first()], 422);
        }

        try {
            $this->cart->addLine($variant, $data['quantity'] ?? 1, $meta);
        } catch (CartException) {
            return $this->stockError($variant);
        }

        return view('checkout::partials.cart-body');
    }

    /**
     * The shopper's answers to the product's custom fields (boboko-core's
     * Product::$custom_fields — {key, type: text|textarea|file, label,
     * required}), as cart line meta. Lunar copies CartLine.meta onto the
     * OrderLine at order creation, so this is also what the order keeps.
     *
     * Only keys the product actually defines are kept, nested under
     * `custom_fields` — line meta also carries behavior flags (core's
     * `saved_for_later` zeroes the line's price), so shopper input must never
     * be merged into it directly. Label and type are snapshotted alongside
     * each value so the cart/order still reads correctly if the product's
     * fields are edited later.
     *
     * A `file` answer is the opaque reference returned by the host's upload
     * endpoint: an encrypted JSON {disk, path, name, mime}. The module doesn't
     * decide which files are acceptable (that's the host's upload endpoint) —
     * it only checks the reference is genuine and the file still exists.
     *
     * Two adds with identical answers merge into one line (Lunar matches
     * existing lines on meta); different answers stay separate lines.
     */
    private function customFieldsMeta(ProductVariant $variant, array $input): array
    {
        $fields = collect($variant->product?->custom_fields ?? [])->keyBy('key');

        if ($fields->isEmpty()) {
            return [];
        }

        $validated = Validator::make(
            $input,
            $fields->map(fn (array $field) => [
                ($field['required'] ?? false) ? 'required' : 'nullable',
                'string',
                match ($field['type']) {
                    'textarea' => 'max:2000',
                    'file' => function (string $attribute, mixed $value, Closure $fail) {
                        if ($this->decodeUpload($value) === null) {
                            $fail('validation.uploaded')->translate();
                        }
                    },
                    default => 'max:255',
                },
            ])->all(),
            [],
            $fields->map(fn (array $field) => $field['label'])->all(),
        )->validate();

        $answers = $fields
            ->filter(fn (array $field) => filled($validated[$field['key']] ?? null))
            ->map(fn (array $field) => [
                'key' => $field['key'],
                'label' => $field['label'],
                'type' => $field['type'],
                ...($field['type'] === 'file'
                    ? $this->fileAnswer($this->decodeUpload($validated[$field['key']]))
                    : ['value' => $validated[$field['key']]]),
            ])
            ->values()
            ->all();

        return $answers === [] ? [] : ['custom_fields' => $answers];
    }

    /**
     * @return array{disk: string, path: string, name: string, mime: ?string}|null
     */
    private function decodeUpload(string $reference): ?array
    {
        try {
            $upload = json_decode(Crypt::decryptString($reference), true);
        } catch (DecryptException) {
            return null;
        }

        if (! is_array($upload) || ! isset($upload['disk'], $upload['path'], $upload['name'])) {
            return null;
        }

        return Storage::disk($upload['disk'])->exists($upload['path']) ? $upload : null;
    }

    private function fileAnswer(array $upload): array
    {
        return [
            'value' => $upload['name'],
            'disk' => $upload['disk'],
            'path' => $upload['path'],
            'mime' => $upload['mime'] ?? null,
        ];
    }

    public function updateLine(string $locale, Request $request, int $line): View|JsonResponse
    {
        $quantity = (int) $request->validate([
            'quantity' => ['required', 'integer', 'min:0'],
        ])['quantity'];

        try {
            $quantity === 0
                ? $this->cart->removeLine($line)
                : $this->cart->updateLine($line, $quantity);
        } catch (CartException) {
            $variant = CartLine::find($line)?->purchasable;

            return $this->stockError($variant instanceof ProductVariant ? $variant : null);
        }

        return view('checkout::partials.cart-body');
    }

    /**
     * getTotalInventory() is the same number canBeFulfilledAtQuantity()
     * checked against (stock, for a tracked in_stock variant) — telling the
     * shopper how many are actually left beats a generic "not enough stock"
     * they'd otherwise have to guess around by trial and error.
     */
    private function stockError(?ProductVariant $variant): JsonResponse
    {
        $available = $variant?->getTotalInventory() ?? 0;

        return response()->json([
            'error' => trans_choice('storefront.product.add_to_cart_failed', $available, ['count' => $available]),
        ], 422);
    }

    public function remove(string $locale, int $line): View
    {
        $this->cart->removeLine($line);

        return view('checkout::partials.cart-body');
    }

    /**
     * A bad code is a normal, expected outcome here (typo, expired code), not
     * an error state for the request — it re-renders the same cart-body
     * partial with $couponError set, rather than a 4xx/redirect, so the fetch
     * + swap in bbk-cart-controller stays the one code path for every cart
     * mutation.
     */
    public function applyCoupon(string $locale, Request $request): View
    {
        $code = $request->validate([
            'code' => ['required', 'string'],
        ])['code'];

        $couponError = false;

        try {
            $this->cart->applyCoupon($code);
        } catch (InvalidCouponException) {
            $couponError = true;
        }

        return view('checkout::partials.cart-body', ['couponError' => $couponError]);
    }

    public function removeCoupon(string $locale): View
    {
        $this->cart->removeCoupon();

        return view('checkout::partials.cart-body');
    }
}