<?php

declare(strict_types=1);

namespace App\Controller;

use App\Util\ForumTopics;
use Elastica\Aggregation\Filters as FiltersAgg;
use Elastica\Query;
use Elastica\Query\BoolQuery;
use Elastica\Query\Term;
use Elastica\Query\Terms;
use FOS\ElasticaBundle\Finder\PaginatedFinderInterface;
use Pagerfanta\Pagerfanta;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\DependencyInjection\Attribute\Autowire;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;
use Symfony\Contracts\Cache\CacheInterface;

class ForumController extends AbstractController
{
    #[Route('/forum', name: 'forum')]
    public function index(
        #[Autowire(service: 'fos_elastica.index.articles')] \Elastica\Index $index,
        CacheInterface $cache,
        Request $request
    ): Response {
        // Optional: small cache so we don’t hammer ES on every page view
        //$categoriesWithCounts = $cache->get('forum.index.counts.v2', function (ItemInterface $item) use ($index) {
        //    $item->expiresAfter(30); // 30s is a nice compromise for “live enough”
            $allTags = $this->flattenAllTags(ForumTopics::TOPICS); // ['tag' => true, ...]
            $counts = $this->fetchTagCounts($index, array_keys($allTags)); // ['tag' => count]

        //    return $this->hydrateCategoryCounts(self::TOPICS, $counts);
        //});
        $categoriesWithCounts = $this->hydrateCategoryCounts(ForumTopics::TOPICS, $counts);
        return $this->render('forum/index.html.twig', [
            'topics' => $categoriesWithCounts,
        ]);
    }

    #[Route('/forum/topic/{key}', name: 'forum_topic')]
    public function topic(
        string $key,
        #[Autowire(service: 'fos_elastica.finder.articles')] PaginatedFinderInterface $finder,
        #[Autowire(service: 'fos_elastica.index.articles')] \Elastica\Index $index,
        Request $request
    ): Response {
        // key format: "{category}-{subcategory}"
        $key = strtolower(trim($key));
        [$cat, $sub] = array_pad(explode('-', $key, 2), 2, null);

        if (!$cat || !$sub || !isset(ForumTopics::TOPICS[$cat]['subcategories'][$sub])) {
            throw $this->createNotFoundException('Topic not found');
        }

        $topic = ForumTopics::TOPICS[$cat]['subcategories'][$sub];

        // Count each tag in this subcategory in one shot
        $tags = array_map('strval', $topic['tags']);
        $tagCounts = $this->fetchTagCounts($index, $tags);

        // Fetch articles for the topic
        $bool = new BoolQuery();
        $bool->addFilter(new Terms('topics', $tags));

        $query = new Query($bool);
        $query->setSize(20);
        $query->setSort(['createdAt' => ['order' => 'desc']]);

        /** @var Pagerfanta $pager */
        $pager = $finder->findPaginated($query);
        $pager->setMaxPerPage(20);
        $pager->setCurrentPage(max(1, (int) $request->query->get('page', 1)));
        $articles = iterator_to_array($pager->getCurrentPageResults());

        // (Optional) also show latest threads under this topic scope
        $page    = max(1, (int) $request->query->get('page', 1));
        $perPage = 20;
        $threads = $this->fetchThreads($index, [$tags]); // OR scope: any tag in subcategory
        $threadsPage = array_slice($threads, ($page-1)*$perPage, $perPage);

        return $this->render('forum/topic.html.twig', [
            'categoryKey' => $cat,
            'subcategoryKey' => $sub,
            'topic' => [
                'name' => $topic['name'],
                'tags' => $tags,
            ],
            'tags' => $tagCounts, // ['tag' => count]
            'threads' => $threadsPage,
            'total' => count($threads),
            'page' => $page,
            'perPage' => $perPage,
            'topics' => $this->getHydratedTopics($index),
            'articles' => $articles
        ]);
    }

    #[Route('/forum/tag/{tag}', name: 'forum_tag')]
    public function tag(
        string $tag,
        #[Autowire(service: 'fos_elastica.finder.articles')] PaginatedFinderInterface $finder,
        #[Autowire(service: 'fos_elastica.index.articles')] \Elastica\Index $index,
        Request $request
    ): Response {
        $tag = strtolower(trim($tag));

        $bool = new BoolQuery();
        // Correct Term usage:
        $bool->addFilter(new Term(['topics' => $tag]));

        $query = new Query($bool);
        $query->setSize(20);

        $query->setSort(['createdAt' => ['order' => 'desc']]);

        /** @var Pagerfanta $pager */
        $pager = $finder->findPaginated($query);
        $pager->setMaxPerPage(20);
        $pager->setCurrentPage(max(1, (int) $request->query->get('page', 1)));
        $articles = iterator_to_array($pager->getCurrentPageResults());

        return $this->render('forum/tag.html.twig', [
            'tag' => $tag,
            'articles' => $articles,
            'pager' => $pager, // expose if you want numbered pagination links
            'topics' => $this->getHydratedTopics($index),
        ]);
    }

    // ---------- Helpers ----------

    /**
     * Flatten all tags from the taxonomy into a unique set.
     * @return array<string, true>
     */
    private function flattenAllTags(array $categories): array
    {
        $set = [];
        foreach ($categories as $cat) {
            foreach ($cat['subcategories'] as $sub) {
                foreach ($sub['tags'] as $tag) {
                    $set[strtolower($tag)] = true;
                }
            }
        }
        return $set;
    }

    /**
     * Run one ES query that returns counts for each tag (OR scope per tag).
     * Uses a Filters aggregation keyed by tag to avoid N queries.
     *
     * @param \Elastica\Index $index
     * @param string[] $tags
     * @return array<string,int>
     */
    private function fetchTagCounts(\Elastica\Index $index, array $tags): array
    {
        $tags = array_values(array_unique(array_map('strtolower', array_map('trim', $tags))));
        if (!$tags) return [];

        $q = new Query(new Query\MatchAll());
        $filters = new FiltersAgg('tag_counts');

        foreach ($tags as $tag) {
            $b = new BoolQuery();
            $b->addFilter(new Term(['topics' => $tag])); // topics must be keyword + lowercase normalizer
            $filters->addFilter($b, $tag);
        }

        $q->addAggregation($filters);
        $q->setSize(0);

        $res = $index->search($q);
        $agg = $res->getAggregation('tag_counts')['buckets'] ?? [];

        $out = [];
        foreach ($tags as $tag) {
            $out[$tag] = isset($agg[$tag]['doc_count']) ? (int) $agg[$tag]['doc_count'] : 0;
        }
        return $out;
    }

    /**
     * Rehydrate taxonomy with counts per subcategory (sum of its tags).
     * @param array<string,int> $counts
     */
    private function hydrateCategoryCounts(array $taxonomy, array $counts): array
    {
        $out = [];
        foreach ($taxonomy as $catKey => $cat) {
            $subs = [];
            foreach ($cat['subcategories'] as $subKey => $sub) {
                $sum = 0;
                foreach ($sub['tags'] as $tag) {
                    $sum += $counts[strtolower($tag)] ?? 0;
                }
                $subs[$subKey] = $sub + ['count' => $sum];
            }
            $out[$catKey] = $cat;
            $out[$catKey]['subcategories'] = $subs;
        }
        return $out;
    }

    /**
     * (Optional) Fetch latest threads for a given OR-scope of tag groups.
     * You can replace this with your Finder if you want entity hydration.
     *
     * @param array<int,array<int,string>> $tagGroups  e.g. [ ['bitcoin','lightning'] ]
     * @return array<int,array<string,mixed>>
     */
    private function fetchThreads(\Elastica\Index $index, array $tagGroups, int $size = 200): array
    {
        $bool = new BoolQuery();

        // For a simple OR across tags: use Terms query on 'topics'
        // If you pass multiple groups and want AND across groups, adapt here.
        $flatTags = [];
        foreach ($tagGroups as $g) { foreach ($g as $t) { $flatTags[] = strtolower($t); } }
        $flatTags = array_values(array_unique($flatTags));

        if ($flatTags) {
            $bool->addFilter(new Terms('topics', $flatTags));
        }

        $q = (new Query($bool))
            ->setSize($size)
            ->addSort(['createdAt' => ['order' => 'desc']]);

        $rs = $index->search($q);

        // Map raw sources you need (adjust to your mapping)
        return array_map(static function (\Elastica\Result $hit) {
            $s = $hit->getSource();
            return [
                'id'           => $s['id'] ?? $hit->getId(),
                'title'        => $s['title'] ?? '(untitled)',
                'excerpt'      => $s['excerpt'] ?? null,
                'topics'       => $s['topics'] ?? [],
                'created_at'   => $s['createdAt'] ?? null,
            ];
        }, $rs->getResults());
    }

    private function getHydratedTopics(\Elastica\Index $index): array
    {
        $allTags = $this->flattenAllTags(ForumTopics::TOPICS);
        $counts = $this->fetchTagCounts($index, array_keys($allTags));
        return $this->hydrateCategoryCounts(ForumTopics::TOPICS, $counts);
    }
}