<?php

declare(strict_types=1);

namespace App;

final class FeedService
{
    /**
     * @param array<int, array<string, mixed>> $feeds
     */
    public function __construct(
        private FeedRepository $repository,
        private FeedFetcher $fetcher,
        private array $feeds,
        private int $ttlSeconds,
        private int $errorRetryTtlSeconds = 300,
        private array $throttledHosts = [],
        private int $throttledHostMax = 1,
    ) {
    }

    /**
     * Refresh every feed whose cached copy is stale. Failures are recorded and
     * skipped so previously cached items remain available.
     *
     * @return array{attempted: int, succeeded: int, failed: int, new_items: int, errors: array<int, string>}
     */
    public function refreshStale(): array
    {
        $this->repository->syncFeeds($this->feeds);

        $report = [
            'attempted' => 0,
            'succeeded' => 0,
            'failed' => 0,
            'new_items' => 0,
            'errors' => [],
        ];

        $hostCounts = [];
        $activeFeeds = $this->repository->enabledFeeds();

        foreach ($this->repository->staleFeeds($activeFeeds, $this->ttlSeconds, $this->errorRetryTtlSeconds) as $feed) {
            $url = (string) $feed['url'];
            $host = (string) parse_url($url, PHP_URL_HOST);

            if (in_array($host, $this->throttledHosts, true)) {
                $seen = $hostCounts[$host] ?? 0;
                if ($seen >= $this->throttledHostMax) {
                    // Leave it stale so a later request picks it up.
                    continue;
                }
                $hostCounts[$host] = $seen + 1;
            }

            $report['attempted']++;

            try {
                $result = $this->fetcher->fetch($feed);
                $report['new_items'] += $this->repository->upsertItems($result['items']);
                $this->repository->recordAttempt($url, true);
                $report['succeeded']++;
            } catch (\Throwable $e) {
                $this->repository->recordAttempt($url, false, $e->getMessage());
                $report['failed']++;
                $report['errors'][] = ($feed['label'] ?? $url) . ': ' . $e->getMessage();
            }
        }

        return $report;
    }

    /**
     * @return array{items: array<int, array<string, mixed>>, page: int, page_size: int, total: int, has_more: bool}
     */
    public function page(?string $source, int $page, int $pageSize, ?string $since = null): array
    {
        $page = max(1, $page);
        $pageSize = max(1, $pageSize);
        $offset = ($page - 1) * $pageSize;

        $items = $this->repository->getItems($pageSize, $offset, $source, $since);
        $total = $this->repository->countItems($source, $since);

        return [
            'items' => $items,
            'page' => $page,
            'page_size' => $pageSize,
            'total' => $total,
            'has_more' => ($offset + count($items)) < $total,
        ];
    }

    /**
     * @return array<int, array<string, mixed>>
     */
    public function feedsStatus(): array
    {
        return $this->repository->feedsStatus();
    }

    /**
     * Sources that currently have at least one enabled feed.
     *
     * @return array<int, string>
     */
    public function sources(): array
    {
        $sources = [];
        foreach ($this->repository->enabledFeeds() as $feed) {
            $sources[(string) $feed['source']] = true;
        }

        return array_keys($sources);
    }
}