<?php

namespace Modules\Core\Catalog\Services;

use Illuminate\Contracts\Pagination\LengthAwarePaginator as LengthAwarePaginatorContract;
use Illuminate\Pagination\LengthAwarePaginator;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\App;
use Lunar\Base\AttributeManifest;
use Lunar\FieldTypes\TranslatedText;
use Lunar\Models\Collection as CollectionModel;
use Modules\Core\Catalog\DTOs\CollectionFilters;
use Modules\Core\Catalog\Enums\CollectionSort;
use Modules\Core\Localization\Services\LanguageCache;

/**
 * Category browsing (tree/nav) AND single-collection lookup, all reading directly
 * from the Meilisearch index (Modules\Core\Catalog\Services\CollectionIndexer) — same
 * shape and reasoning as Modules\Core\Catalog\Services\ProductService. Callers get
 * plain arrays of the indexed document, not Eloquent models.
 */
class CollectionService
{
    public function __construct(
        private readonly LanguageCache $languages,
        private readonly AttributeManifest $attributes,
    ) {}

    /**
     * Returns a real LengthAwarePaginator (not Scout's own paginateRaw() result — see
     * ProductService's "Meilisearch driver quirk" note) so a controller/view gets
     * normal pagination behaviour without ever touching the raw Meilisearch response.
     */
    public function list(?CollectionFilters $filters = null, int $perPage = 24, int $page = 1, ?CollectionSort $sort = null): LengthAwarePaginator
    {
        $options = ['filter' => $this->buildFilter($filters)];

        if ($sort !== null) {
            $options['sort'] = [$sort->toMeilisearchSort()];
        }

        $paginator = CollectionModel::search('')
            ->options($options)
            ->paginateRaw(perPage: $perPage, page: $page);

        $data = collect($this->hitsFrom($paginator))
            ->map(fn (array $collection) => $this->withLocalizedFields($collection))
            ->all();

        return new LengthAwarePaginator(
            items: $data,
            total: $paginator->total(),
            perPage: $paginator->perPage(),
            currentPage: $paginator->currentPage(),
            options: ['path' => LengthAwarePaginator::resolveCurrentPath()],
        );
    }

    /**
     * Look up a single collection by its URL slug (any locale). Returns the full
     * indexed collection document, or null if no collection has that slug.
     */
    public function getBySlug(string $slug): ?array
    {
        return $this->findOneWhere('slugs = "'.addcslashes($slug, '"\\').'"');
    }

    /**
     * Look up a single collection by its primary key. Returns the full indexed
     * collection document, or null if no collection has that id.
     */
    public function getById(int $id): ?array
    {
        return $this->findOneWhere("id = \"{$id}\"");
    }

    private function findOneWhere(string $filter): ?array
    {
        $paginator = CollectionModel::search('')
            ->options(['filter' => $filter])
            ->paginateRaw(perPage: 1, page: 1);

        $collection = $this->hitsFrom($paginator)[0] ?? null;

        return $collection !== null ? $this->withLocalizedFields($collection) : null;
    }

    /**
     * Resolves every translated Collection attribute's current-locale value — same
     * logic as ProductService::withLocalizedFields(), see there for the full
     * reasoning (AttributeManifest-driven, store-default-locale fallback, raw
     * per-locale keys stripped after resolving).
     */
    private function withLocalizedFields(array $collection): array
    {
        $locale = App::getLocale();
        $fallbackLocale = $this->languages->defaultLocale();
        $availableLocales = $this->languages->availableLocales();

        foreach ($this->translatedAttributeHandles() as $handle) {
            $collection[$handle] = $collection[$handle.'_'.$locale] ?? $collection[$handle.'_'.$fallbackLocale] ?? null;

            foreach ($availableLocales as $availableLocale) {
                unset($collection[$handle.'_'.$availableLocale]);
            }
        }

        return $collection;
    }

    /**
     * @return array<int, string>
     */
    private function translatedAttributeHandles(): array
    {
        return $this->attributes->getSearchableAttributes((new CollectionModel)->getMorphClass())
            ->filter(fn ($attribute) => $attribute->type === TranslatedText::class)
            ->pluck('handle')
            ->all();
    }

    /**
     * For the Meilisearch driver, Scout's paginateRaw() puts the whole raw response
     * in items(), not a plain list of hits — see ProductService's identical note.
     */
    private function hitsFrom(LengthAwarePaginatorContract $paginator): array
    {
        $rawResponse = $paginator->items();

        return collect($rawResponse['hits'] ?? [])->values()->all();
    }

    private function buildFilter(?CollectionFilters $filters): ?string
    {
        if ($filters === null) {
            return null;
        }

        $clauses = Collection::make([
            $filters->parentId !== null ? "parent_id = \"{$filters->parentId}\""
                : ($filters->rootOnly ? 'parent_id IS NULL' : null),
            $filters->groupId !== null ? "collection_group_id = \"{$filters->groupId}\"" : null,
        ])->filter();

        return $clauses->isEmpty() ? null : $clauses->join(' AND ');
    }
}