<?php

declare(strict_types=1);

namespace GitContributionGraph\Service\Provider;

use Psr\Log\LoggerInterface;
use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
use Symfony\Contracts\HttpClient\HttpClientInterface;
use Symfony\Contracts\HttpClient\ResponseInterface;

/**
 * Fetches the last 365 days of push/merge events from the GitLab REST API.
 *
 * Required token scopes: read_user, read_api
 * Works with both gitlab.com and self-hosted instances.
 */
final class GitLabProvider implements ProviderInterface
{
    use ProbeTrait;

    private readonly string $baseUrl;

    public function __construct(
        private readonly HttpClientInterface $client,
        private readonly string $username,
        private readonly string $token,
        private readonly LoggerInterface $logger,
        string $baseUrl = '',
    ) {
        $this->baseUrl = rtrim($baseUrl !== '' ? $baseUrl : 'https://gitlab.com', '/');
    }

    public function getName(): string
    {
        return 'gitlab';
    }

    public function isConfigured(): bool
    {
        return $this->username !== '' && $this->token !== '';
    }

    public function ping(): void
    {
       
        $this->client->request('GET', "$this->baseUrl/api/v4/user", [
            'headers' => ['PRIVATE-TOKEN' => $this->token],
        ])->getContent();
    }

    /**
     * Resolves the username to a numeric user ID, then fires the first page of the events request.
     *
     * @return array{baseUrl: string, userId: int, after: string, before: ?string, page: int, response: ResponseInterface}
     *
     * ponytail: the user-id lookup and event pagination stay sequential within
     * this one provider (each page depends on the previous). Parallelism here
     * only spans across providers; revisit only if GitLab pagination itself
     * becomes the bottleneck.
     */
    public function startFetch(?\DateTimeImmutable $since = null, ?\DateTimeImmutable $until = null): array
    {

        $this->logger->debug('GitLabProvider: fetching contributions', ['user' => $this->username, 'url' => $this->baseUrl]);

        $userResponse = $this->client->request('GET', "$this->baseUrl/api/v4/users", [
            'headers' => ['PRIVATE-TOKEN' => $this->token],
            'query'   => ['username' => $this->username],
        ]);

        $users = $userResponse->toArray();
        if (empty($users)) {
            throw new NotFoundHttpException("GitLab: user '{$this->username}' not found on $this->baseUrl");
        }
        $userId = $users[0]['id'];
        $after  = ($since ?? new \DateTimeImmutable('-365 days'))->format('Y-m-d');
        $before = $until?->format('Y-m-d');

        $query = ['after' => $after, 'per_page' => 100, 'page' => 1];
        if ($before !== null) {
            $query['before'] = $before;
        }

        $response = $this->client->request('GET', "$this->baseUrl/api/v4/users/$userId/events", [
            'headers' => ['PRIVATE-TOKEN' => $this->token],
            'query'   => $query,
        ]);

        return ['baseUrl' => $this->baseUrl, 'userId' => $userId, 'after' => $after, 'before' => $before, 'page' => 1, 'response' => $response];
    }

    /**
     * Follows pagination (100 events/page) until a short page is returned, counting events per day.
     *
     * @param  array{baseUrl: string, userId: int, after: string, before: ?string, page: int, response: ResponseInterface} $handle
     * @return array<string, int> date (Y-m-d) => event count
     */
    public function resolveFetch(mixed $handle): array
    {
        ['baseUrl' => $baseUrl, 'userId' => $userId, 'after' => $after, 'before' => $before, 'page' => $page, 'response' => $response] = $handle;

        $result = [];

        do {
            $events = $response->toArray();

            foreach ($events as $event) {
                $date          = substr($event['created_at'], 0, 10);
                $result[$date] = ($result[$date] ?? 0) + 1;
            }

            $page++;

            if (count($events) === 100) {
                $query = ['after' => $after, 'per_page' => 100, 'page' => $page];
                if ($before !== null) {
                    $query['before'] = $before;
                }

                $response = $this->client->request('GET', "$baseUrl/api/v4/users/$userId/events", [
                    'headers' => ['PRIVATE-TOKEN' => $this->token],
                    'query'   => $query,
                ]);
            }
        } while (count($events) === 100);

        $this->logger->info('GitLabProvider: fetched contributions', [
            'user'  => $this->username,
            'pages' => $page - 1,
            'days'  => count($result),
            'total' => array_sum($result),
        ]);

        return $result;
    }
}