<?php
declare(strict_types=1);

namespace App\Modules\Products;

use PDO;
use Throwable;

final class ProductService
{
    public function __construct(
        private readonly PDO $pdo,
        private readonly ProductRepository $products,
        private readonly ProductValidator $validator
    ) {
    }

    /**
     * @param array<string, mixed> $input
     * @param array<string, mixed>|null $actor
     * @return array{ok:bool, errors:array<int, string>, id?:int}
     */
    public function create(array $input, ?array $actor): array
    {
        $errors = $this->validator->validate($input, false);
        if ($errors !== []) {
            return ['ok' => false, 'errors' => $errors];
        }

        $sku = trim((string) ($input['sku'] ?? ''));
        if ($sku !== '' && $this->products->existsSku($sku)) {
            return ['ok' => false, 'errors' => ['Podane SKU produktu jest juz zajete.']];
        }

        $normalized = $this->normalizeForSave($input);
        $updatePayload = $this->toUpdatePayload($normalized['product']);
        $actorId = isset($actor['id']) ? (int) $actor['id'] : null;

        try {
            $this->pdo->beginTransaction();
            $productId = $this->products->create($normalized['product'], $normalized['translation']);
            $this->products->logChange($productId, $actorId, 'product_created', null, $normalized['audit']);
            $this->pdo->commit();

            return ['ok' => true, 'errors' => [], 'id' => $productId];
        } catch (Throwable $exception) {
            if ($this->pdo->inTransaction()) {
                $this->pdo->rollBack();
            }

            return ['ok' => false, 'errors' => ['Nie udalo sie zapisac produktu: ' . $exception->getMessage()]];
        }
    }

    /**
     * @param array<string, mixed> $input
     * @param array<string, mixed>|null $actor
     * @return array{ok:bool, errors:array<int, string>}
     */
    public function update(int $id, array $input, ?array $actor): array
    {
        $existing = $this->products->findById($id, 'pl');
        if ($existing === null) {
            return ['ok' => false, 'errors' => ['Produkt nie istnieje.']];
        }

        $errors = $this->validator->validate($input, true);
        if ($errors !== []) {
            return ['ok' => false, 'errors' => $errors];
        }

        $sku = trim((string) ($input['sku'] ?? ''));
        if ($sku !== '' && $this->products->existsSku($sku, $id)) {
            return ['ok' => false, 'errors' => ['Podane SKU produktu jest juz zajete.']];
        }

        $normalized = $this->normalizeForSave($input);
        $updatePayload = $this->toUpdatePayload($normalized['product']);
        $actorId = isset($actor['id']) ? (int) $actor['id'] : null;

        try {
            $this->pdo->beginTransaction();
            $this->products->update($id, $updatePayload, $normalized['translation']);

            $criticalBefore = $this->extractCriticalFields($existing);
            $criticalAfter = $this->extractCriticalFields($normalized['audit']);
            if ($criticalBefore !== $criticalAfter) {
                $this->products->logChange($id, $actorId, 'product_updated', $criticalBefore, $criticalAfter);
            }

            $this->pdo->commit();
            return ['ok' => true, 'errors' => []];
        } catch (Throwable $exception) {
            if ($this->pdo->inTransaction()) {
                $this->pdo->rollBack();
            }

            return ['ok' => false, 'errors' => ['Nie udalo sie zaktualizowac produktu: ' . $exception->getMessage()]];
        }
    }

    /**
     * @param array<string, mixed>|null $actor
     * @return array{ok:bool, errors:array<int, string>}
     */
    public function delete(int $id, ?array $actor): array
    {
        $existing = $this->products->findById($id, 'pl');
        if ($existing === null) {
            return ['ok' => false, 'errors' => ['Produkt nie istnieje.']];
        }

        $imagePaths = $this->findProductImageStoragePaths($id);

        try {
            $this->pdo->beginTransaction();
            $deleted = $this->products->deleteById($id);
            if (!$deleted) {
                throw new \RuntimeException('Nie udalo sie usunac produktu.');
            }
            $this->pdo->commit();
            $this->deleteProductImageFiles($imagePaths);

            return ['ok' => true, 'errors' => []];
        } catch (Throwable $exception) {
            if ($this->pdo->inTransaction()) {
                $this->pdo->rollBack();
            }

            return ['ok' => false, 'errors' => ['Nie udalo sie usunac produktu: ' . $exception->getMessage()]];
        }
    }

    /**
     * @param array<string, mixed> $input
     * @return array{product:array<string,mixed>, translation:array<string,mixed>, audit:array<string,mixed>}
     */
    private function normalizeForSave(array $input): array
    {
        $vatRaw = trim((string) ($input['vat'] ?? ''));
        $vat = $vatRaw === '' ? null : round((float) $vatRaw, 2);

        $pricePair = $this->resolvePricePair(
            trim((string) ($input['price_brutto'] ?? '')),
            trim((string) ($input['price_netto'] ?? '')),
            $vat,
            (string) ($input['price_input_mode'] ?? 'brutto')
        );

        $promoPair = $this->resolvePricePair(
            trim((string) ($input['price_brutto_promo'] ?? '')),
            trim((string) ($input['price_netto_promo'] ?? '')),
            $vat,
            (string) ($input['price_input_mode'] ?? 'brutto'),
            true
        );

        $now = date('Y-m-d H:i:s');

        $product = [
            'uuid' => $this->uuidV4(),
            'type' => (string) ($input['type'] ?? 'simple'),
            'sku' => $this->nullableString($input['sku'] ?? null),
            'ean' => $this->nullableString($input['ean'] ?? null),
            'status' => (int) ($input['status'] ?? 1),
            'promoted' => (int) ($input['promoted'] ?? 0),
            'vat' => $vat,
            'weight' => $this->nullableFloat($input['weight'] ?? null, 3),
            'price_brutto' => $pricePair['brutto'] ?? 0.00,
            'price_brutto_promo' => $promoPair['brutto'],
            'price_netto' => $pricePair['netto'],
            'price_netto_promo' => $promoPair['netto'],
            'quantity' => round((float) ($input['quantity'] ?? 0), 3),
            'producer_id' => $this->nullableInt($input['producer_id'] ?? null),
            'product_unit_id' => $this->nullableInt($input['product_unit_id'] ?? null),
            'created_at' => $now,
            'updated_at' => $now,
        ];

        $translation = [
            'lang' => 'pl',
            'name' => trim((string) ($input['name'] ?? '')),
            'short_description' => $this->nullableString($input['short_description'] ?? null),
            'description' => $this->nullableString($input['description'] ?? null),
            'meta_title' => $this->nullableString($input['meta_title'] ?? null),
            'meta_description' => $this->nullableString($input['meta_description'] ?? null),
            'meta_keywords' => $this->nullableString($input['meta_keywords'] ?? null),
            'seo_link' => $this->nullableString($input['seo_link'] ?? null),
            'created_at' => $now,
            'updated_at' => $now,
        ];

        $audit = [
            'type' => $product['type'],
            'sku' => $product['sku'],
            'ean' => $product['ean'],
            'status' => $product['status'],
            'promoted' => $product['promoted'],
            'vat' => $product['vat'],
            'price_brutto' => $product['price_brutto'],
            'price_netto' => $product['price_netto'],
            'price_brutto_promo' => $product['price_brutto_promo'],
            'price_netto_promo' => $product['price_netto_promo'],
            'quantity' => $product['quantity'],
            'name' => $translation['name'],
        ];

        return [
            'product' => $product,
            'translation' => $translation,
            'audit' => $audit,
        ];
    }

    /**
     * @return array{brutto:float|null, netto:float|null}
     */
    private function resolvePricePair(
        string $bruttoRaw,
        string $nettoRaw,
        ?float $vat,
        string $mode,
        bool $allowEmpty = false
    ): array {
        if ($allowEmpty && $bruttoRaw === '' && $nettoRaw === '') {
            return ['brutto' => null, 'netto' => null];
        }

        $multiplier = 1 + (($vat ?? 0.0) / 100);

        if ($mode === 'netto') {
            if ($nettoRaw === '' && $bruttoRaw !== '') {
                $brutto = round((float) $bruttoRaw, 2);
                $netto = $multiplier > 0 ? round($brutto / $multiplier, 2) : $brutto;
                return ['brutto' => $brutto, 'netto' => $netto];
            }

            $netto = $nettoRaw === '' ? 0.0 : round((float) $nettoRaw, 2);
            $brutto = round($netto * $multiplier, 2);
            return ['brutto' => $brutto, 'netto' => $netto];
        }

        if ($bruttoRaw === '' && $nettoRaw !== '') {
            $netto = round((float) $nettoRaw, 2);
            $brutto = round($netto * $multiplier, 2);
            return ['brutto' => $brutto, 'netto' => $netto];
        }

        $brutto = $bruttoRaw === '' ? 0.0 : round((float) $bruttoRaw, 2);
        $netto = $multiplier > 0 ? round($brutto / $multiplier, 2) : $brutto;

        return ['brutto' => $brutto, 'netto' => $netto];
    }

    /**
     * @param array<string, mixed> $row
     * @return array<string, mixed>
     */
    private function extractCriticalFields(array $row): array
    {
        return [
            'sku' => $row['sku'] ?? null,
            'ean' => $row['ean'] ?? null,
            'status' => $row['status'] ?? null,
            'promoted' => $row['promoted'] ?? null,
            'price_brutto' => $row['price_brutto'] ?? null,
            'price_netto' => $row['price_netto'] ?? null,
            'price_brutto_promo' => $row['price_brutto_promo'] ?? null,
            'price_netto_promo' => $row['price_netto_promo'] ?? null,
            'quantity' => $row['quantity'] ?? null,
            'name' => $row['name'] ?? null,
        ];
    }

    private function nullableString(mixed $value): ?string
    {
        $text = trim((string) $value);
        return $text === '' ? null : $text;
    }

    private function nullableInt(mixed $value): ?int
    {
        $text = trim((string) $value);
        if ($text === '' || !is_numeric($text)) {
            return null;
        }

        return (int) $text;
    }

    private function nullableFloat(mixed $value, int $precision = 2): ?float
    {
        $text = trim((string) $value);
        if ($text === '' || !is_numeric($text)) {
            return null;
        }

        return round((float) $text, $precision);
    }

    private function uuidV4(): string
    {
        $data = random_bytes(16);
        $data[6] = chr((ord($data[6]) & 0x0f) | 0x40);
        $data[8] = chr((ord($data[8]) & 0x3f) | 0x80);

        return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($data), 4));
    }

    /**
     * @param array<string, mixed> $product
     * @return array<string, mixed>
     */
    private function toUpdatePayload(array $product): array
    {
        return [
            'type' => $product['type'] ?? 'simple',
            'sku' => $product['sku'] ?? null,
            'ean' => $product['ean'] ?? null,
            'status' => $product['status'] ?? 1,
            'promoted' => $product['promoted'] ?? 0,
            'vat' => $product['vat'] ?? null,
            'weight' => $product['weight'] ?? null,
            'price_brutto' => $product['price_brutto'] ?? 0,
            'price_brutto_promo' => $product['price_brutto_promo'] ?? null,
            'price_netto' => $product['price_netto'] ?? null,
            'price_netto_promo' => $product['price_netto_promo'] ?? null,
            'quantity' => $product['quantity'] ?? 0,
            'producer_id' => $product['producer_id'] ?? null,
            'product_unit_id' => $product['product_unit_id'] ?? null,
            'updated_at' => date('Y-m-d H:i:s'),
        ];
    }

    /**
     * @return array<int, string>
     */
    private function findProductImageStoragePaths(int $productId): array
    {
        $stmt = $this->pdo->prepare('SELECT storage_path FROM product_images WHERE product_id = :product_id');
        $stmt->execute(['product_id' => $productId]);
        $rows = $stmt->fetchAll();
        if (!is_array($rows)) {
            return [];
        }

        $paths = [];
        foreach ($rows as $row) {
            if (!is_array($row)) {
                continue;
            }

            $path = trim((string) ($row['storage_path'] ?? ''));
            if ($path !== '') {
                $paths[] = $path;
            }
        }

        return array_values(array_unique($paths));
    }

    /**
     * @param array<int, string> $storagePaths
     */
    private function deleteProductImageFiles(array $storagePaths): void
    {
        foreach ($storagePaths as $storagePath) {
            if ($this->storagePathHasOtherReferences($storagePath)) {
                continue;
            }

            $resolvedFilePath = $this->resolveLocalImageFilePath($storagePath);
            if ($resolvedFilePath === null || !is_file($resolvedFilePath)) {
                continue;
            }

            @unlink($resolvedFilePath);
        }
    }

    private function storagePathHasOtherReferences(string $storagePath): bool
    {
        $stmt = $this->pdo->prepare(
            'SELECT 1 FROM product_images WHERE storage_path = :storage_path LIMIT 1'
        );
        $stmt->execute(['storage_path' => $storagePath]);

        return $stmt->fetchColumn() !== false;
    }

    private function resolveLocalImageFilePath(string $storagePath): ?string
    {
        $path = trim($storagePath);
        if ($path === '') {
            return null;
        }

        if (preg_match('#^https?://#i', $path) === 1 || str_starts_with($path, '//')) {
            return null;
        }

        $projectRoot = dirname(__DIR__, 3);
        $projectRootReal = realpath($projectRoot);
        if ($projectRootReal === false) {
            return null;
        }

        $trimmed = ltrim(str_replace(['\\', '/'], DIRECTORY_SEPARATOR, $path), DIRECTORY_SEPARATOR);
        $candidates = [];

        if ($this->isAbsolutePath($path)) {
            $candidates[] = str_replace(['\\', '/'], DIRECTORY_SEPARATOR, $path);
        }

        $candidates[] = $projectRoot . DIRECTORY_SEPARATOR . 'public' . DIRECTORY_SEPARATOR . $trimmed;
        $candidates[] = $projectRoot . DIRECTORY_SEPARATOR . $trimmed;

        foreach ($candidates as $candidate) {
            $real = realpath($candidate);
            if ($real === false || !is_file($real)) {
                continue;
            }

            if ($real === $projectRootReal || str_starts_with($real, $projectRootReal . DIRECTORY_SEPARATOR)) {
                return $real;
            }
        }

        return null;
    }

    private function isAbsolutePath(string $path): bool
    {
        if ($path === '') {
            return false;
        }

        return preg_match('/^[A-Za-z]:[\\\\\\/]/', $path) === 1 || str_starts_with($path, DIRECTORY_SEPARATOR);
    }
}