<?php

namespace App\Services;

use App\Models\Product;
use App\Models\ProductSize;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;

class ShopifyService
{
    private string $baseUrl;
    private string $token;

    public function __construct()
    {
        $domain = config('services.shopify.domain');
        $version = config('services.shopify.api_version');
        $this->baseUrl = "https://{$domain}/admin/api/{$version}";
        $this->token   = config('services.shopify.access_token');
    }

    /**
     * Returns all product variants from Shopify.
     * Each entry: ['id', 'sku', 'inventory_quantity', 'product_title']
     */
    public function getAllVariants(): array
    {
        $variants = [];
        $url = "{$this->baseUrl}/products.json?limit=250&fields=id,title,body_html,variants,images";

        while ($url) {
            $response = Http::withHeader('X-Shopify-Access-Token', $this->token)->get($url);

            if ($response->failed()) {
                $status = $response->status();
                $hint   = match (true) {
                    $status === 401 => 'Access Token ungültig oder fehlt',
                    $status === 403 => 'IP-Whitelist: VPS-IP ist in Shopify nicht freigeschalten',
                    $status === 429 => 'Rate Limit überschritten',
                    $status >= 500  => 'Shopify-seitiger Fehler',
                    default         => 'Unbekannter Fehler',
                };
                Log::error("Shopify Sync fehlgeschlagen: {$hint}", [
                    'status' => $status,
                    'url'    => $url,
                    'body'   => $response->body(),
                ]);
                break;
            }

            foreach ($response->json('products', []) as $product) {
                $imageUrls = collect($product['images'] ?? [])->pluck('src')->all();
                foreach ($product['variants'] as $variant) {
                    $variants[] = [
                        'id'                  => (string) $variant['id'],
                        'sku'                 => $variant['sku'] ?? '',
                        'price'               => (float) ($variant['price'] ?? 0),
                        'inventory_quantity'  => (int) ($variant['inventory_quantity'] ?? 0),
                        'product_title'       => $product['title'],
                        'shopify_product_id'  => (string) $product['id'],
                        'product_description' => strip_tags($product['body_html'] ?? ''),
                        'option1'             => $variant['option1'] ?? '',
                        'image_urls'          => $imageUrls,
                    ];
                }
            }

            // Follow Shopify's Link header pagination
            $url = $this->nextPageUrl($response->header('Link'));

            if ($url) {
                usleep(500_000); // 0.5s — stay well within 2 req/s limit
            }
        }

        return $variants;
    }

    public function getProduct(string $shopifyProductId): array
    {
        $response = Http::withHeader('X-Shopify-Access-Token', $this->token)
            ->get("{$this->baseUrl}/products/{$shopifyProductId}.json");

        if ($response->failed()) {
            throw new \RuntimeException(
                'Shopify-Fehler ' . $response->status() . ': ' . $response->body()
            );
        }

        $p = $response->json('product');

        return [
            'description' => strip_tags($p['body_html'] ?? ''),
            'variants'    => collect($p['variants'] ?? [])->map(fn ($v) => [
                'shopify_variant_id' => (string) $v['id'],
                'price'              => (float) ($v['price'] ?? 0),
                'sku'                => $v['sku'] ?? null,
                'gtin'               => $v['barcode'] ?? null,
            ])->all(),
        ];
    }

    public function createProduct(Product $product, \Illuminate\Support\Collection $sizes): array
    {
        $variants = $sizes->map(fn (ProductSize $s) => array_filter([
            'option1' => $s->packing->name . ' ' . $s->packing->size . 'g',
            'price'   => number_format((float) $s->price, 2, '.', ''),
            'sku'     => $s->sku ?: null,
            'barcode' => $s->gtin ?: null,
        ], fn ($v) => $v !== null))->values()->toArray();

        $body = [
            'product' => [
                'title'     => $product->title,
                'body_html' => $product->description
                    ? '<p>' . nl2br(e($product->description)) . '</p>'
                    : '',
                'options'   => [['name' => 'Größe']],
            ],
        ];

        if (! empty($variants)) {
            $body['product']['variants'] = $variants;
        }

        Log::info('Shopify createProduct request', [
            'product_id' => $product->id,
            'sizes'      => $sizes->count(),
            'body'       => $body,
        ]);

        $response = Http::withHeader('X-Shopify-Access-Token', $this->token)
            ->post("{$this->baseUrl}/products.json", $body);

        Log::info('Shopify createProduct response', [
            'status' => $response->status(),
            'body'   => $response->json(),
        ]);

        if ($response->failed()) {
            throw new \RuntimeException(
                'Shopify-Fehler ' . $response->status() . ': ' . $response->body()
            );
        }

        $shopifyProduct  = $response->json('product');
        $shopifyVariants = $shopifyProduct['variants'];

        // Match returned variants back to local sizes by index (same order as sent)
        $variantMap = [];
        foreach ($sizes as $index => $size) {
            if (isset($shopifyVariants[$index])) {
                $variantMap[$size->packing_id] = (string) $shopifyVariants[$index]['id'];
            }
        }

        return [
            'shopify_product_id' => (string) $shopifyProduct['id'],
            'variants'           => $variantMap,
        ];
    }

    public function createVariant(string $shopifyProductId, ProductSize $size): string
    {
        $packing  = $size->packing;
        $option1  = $packing->name . ' ' . $packing->size . 'g';

        $response = Http::withHeader('X-Shopify-Access-Token', $this->token)
            ->post("{$this->baseUrl}/products/{$shopifyProductId}/variants.json", [
                'variant' => array_filter([
                    'option1' => $option1,
                    'price'   => number_format((float) $size->price, 2, '.', ''),
                    'sku'     => $size->sku ?: null,
                    'barcode' => $size->gtin ?: null,
                ]),
            ]);

        if ($response->failed()) {
            throw new \RuntimeException(
                'Shopify-Fehler ' . $response->status() . ': ' . $response->body()
            );
        }

        return (string) $response->json('variant.id');
    }

    public function updateVariant(ProductSize $size): void
    {
        $response = Http::withHeader('X-Shopify-Access-Token', $this->token)
            ->put("{$this->baseUrl}/variants/{$size->shopify_variant_id}.json", [
                'variant' => array_filter([
                    'id'      => $size->shopify_variant_id,
                    'price'   => number_format((float) $size->price, 2, '.', ''),
                    'sku'     => $size->sku ?: null,
                    'barcode' => $size->gtin ?: null,
                ], fn ($v) => $v !== null),
            ]);

        if ($response->failed()) {
            throw new \RuntimeException(
                'Shopify-Fehler ' . $response->status() . ': ' . $response->body()
            );
        }
    }

    private function nextPageUrl(?string $linkHeader): ?string
    {
        if (!$linkHeader) {
            return null;
        }

        // Link: <https://...?page_info=abc>; rel="next"
        if (preg_match('/<([^>]+)>;\s*rel="next"/', $linkHeader, $m)) {
            return $m[1];
        }

        return null;
    }
}