<?php

declare(strict_types=1);

namespace Modules\Helpdesk\Http\Controllers;

use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use JsonException;
use Modules\Helpdesk\Models\GitRepository;
use Modules\Helpdesk\Services\GitWebhookIngestionService;

final class GitWebhookController
{
    /**
     * Ingest a signed Git provider webhook for a registered Helpdesk repository.
     */
    public function __invoke(Request $request, GitRepository $repository, GitWebhookIngestionService $service): JsonResponse
    {
        $provider = strtolower((string) ($repository->provider ?: 'git'));
        $event = $this->eventName($request, $provider);
        $deliveryId = $this->deliveryId($request, $provider);
        $rawPayload = $request->getContent();

        if (! $repository->is_active) {
            $result = ['status' => 'rejected', 'message' => 'Repository is inactive.', 'commit_count' => 0, 'linked_count' => 0, 'ignored_count' => 1];
            $service->logWebhook($repository, $provider, $deliveryId, $event, $result);

            return response()->json($result, 403);
        }

        if (! $this->hasValidSignature($request, $repository, $provider, $rawPayload)) {
            $result = ['status' => 'rejected', 'message' => 'Git webhook signature or token validation failed.', 'commit_count' => 0, 'linked_count' => 0, 'ignored_count' => 1];
            $service->logWebhook($repository, $provider, $deliveryId, $event, $result);

            return response()->json($result, 403);
        }

        try {
            /** @var array<string, mixed> $payload */
            $payload = json_decode($rawPayload, true, 512, JSON_THROW_ON_ERROR);
        } catch (JsonException) {
            $result = ['status' => 'rejected', 'message' => 'Invalid JSON webhook payload.', 'commit_count' => 0, 'linked_count' => 0, 'ignored_count' => 1];
            $service->logWebhook($repository, $provider, $deliveryId, $event, $result);

            return response()->json($result, 400);
        }

        $result = $service->ingest($repository, $payload, $provider, $deliveryId, $event);

        return response()->json($result, 202);
    }

    /**
     * Validate provider-specific webhook signatures or tokens.
     */
    private function hasValidSignature(Request $request, GitRepository $repository, string $provider, string $rawPayload): bool
    {
        $secret = trim((string) $repository->webhook_secret);

        if ($secret === '') {
            return false;
        }

        return match ($provider) {
            'github' => $this->hasValidGitHubSignature($request, $secret, $rawPayload),
            'gitlab' => hash_equals($secret, (string) $request->header('X-Gitlab-Token', '')),
            'bitbucket' => $this->hasValidBitbucketSignature($request, $secret, $rawPayload),
            default => $this->hasValidGenericSignature($request, $secret, $rawPayload),
        };
    }

    /**
     * Validate GitHub's current SHA-256 signature and legacy SHA-1 signature.
     */
    private function hasValidGitHubSignature(Request $request, string $secret, string $rawPayload): bool
    {
        $sha256Signature = (string) $request->header('X-Hub-Signature-256', '');
        $sha1Signature = (string) $request->header('X-Hub-Signature', '');

        return hash_equals('sha256=' . hash_hmac('sha256', $rawPayload, $secret), $sha256Signature)
            || hash_equals('sha1=' . hash_hmac('sha1', $rawPayload, $secret), $sha1Signature);
    }

    /**
     * Validate Bitbucket's webhook HMAC signature.
     */
    private function hasValidBitbucketSignature(Request $request, string $secret, string $rawPayload): bool
    {
        $signature = (string) $request->header('X-Hub-Signature', '');

        return hash_equals('sha256=' . hash_hmac('sha256', $rawPayload, $secret), $signature)
            || hash_equals($secret, (string) $request->header('X-Helpdesk-Token', ''));
    }

    /**
     * Validate a generic Git webhook using either a token header or HMAC signature.
     */
    private function hasValidGenericSignature(Request $request, string $secret, string $rawPayload): bool
    {
        $token = (string) ($request->header('X-Helpdesk-Token') ?: $request->header('X-Gitlab-Token'));
        $signature = (string) ($request->header('X-Hub-Signature-256') ?: $request->header('X-Hub-Signature'));

        return hash_equals($secret, $token)
            || hash_equals('sha256=' . hash_hmac('sha256', $rawPayload, $secret), $signature)
            || hash_equals('sha1=' . hash_hmac('sha1', $rawPayload, $secret), $signature);
    }

    /**
     * Read the event name from provider-specific headers.
     */
    private function eventName(Request $request, string $provider): ?string
    {
        return match ($provider) {
            'github' => $request->header('X-GitHub-Event'),
            'gitlab' => $request->header('X-Gitlab-Event'),
            'bitbucket' => $request->header('X-Event-Key'),
            default => $request->header('X-Helpdesk-Event') ?: $request->header('X-GitHub-Event') ?: $request->header('X-Gitlab-Event') ?: 'push',
        };
    }

    /**
     * Read the provider delivery/request id used for idempotent audit tracing.
     */
    private function deliveryId(Request $request, string $provider): ?string
    {
        return match ($provider) {
            'github' => $request->header('X-GitHub-Delivery'),
            'gitlab' => $request->header('X-Gitlab-Event-UUID') ?: $request->header('X-Request-Id'),
            'bitbucket' => $request->header('X-Request-UUID') ?: $request->header('X-Request-Id'),
            default => $request->header('X-Helpdesk-Delivery') ?: $request->header('X-GitHub-Delivery') ?: $request->header('X-Request-Id'),
        };
    }
}