<?php

namespace App\Services\Directory;

use App\Models\EntraGroup;
use App\Models\EntraGroupSyncRun;
use App\Models\Tenant;
use App\Models\User;
use App\Services\Graph\GraphClientInterface;
use App\Services\Graph\GraphContractRegistry;
use App\Services\Graph\GraphResponse;
use Carbon\CarbonImmutable;

class EntraGroupSyncService
{
    public function __construct(
        private readonly GraphClientInterface $graph,
        private readonly GraphContractRegistry $contracts,
    ) {}

    public function startManualSync(Tenant $tenant, User $user): EntraGroupSyncRun
    {
        $selectionKey = EntraGroupSelection::allGroupsV1();

        $existing = EntraGroupSyncRun::query()
            ->where('tenant_id', $tenant->getKey())
            ->where('selection_key', $selectionKey)
            ->whereIn('status', [EntraGroupSyncRun::STATUS_PENDING, EntraGroupSyncRun::STATUS_RUNNING])
            ->orderByDesc('id')
            ->first();

        if ($existing instanceof EntraGroupSyncRun) {
            return $existing;
        }

        $run = EntraGroupSyncRun::create([
            'tenant_id' => $tenant->getKey(),
            'selection_key' => $selectionKey,
            'status' => EntraGroupSyncRun::STATUS_PENDING,
            'initiator_user_id' => $user->getKey(),
        ]);

        dispatch(new \App\Jobs\EntraGroupSyncJob(
            tenantId: (int) $tenant->getKey(),
            selectionKey: $selectionKey,
            slotKey: null,
            runId: (int) $run->getKey(),
        ));

        return $run;
    }

    /**
     * @return array{
     *   pages_fetched:int,
     *   items_observed_count:int,
     *   items_upserted_count:int,
     *   error_count:int,
     *   safety_stop_triggered:bool,
     *   safety_stop_reason:?string,
     *   error_code:?string,
     *   error_category:?string,
     *   error_summary:?string
     * }
     */
    public function sync(Tenant $tenant, EntraGroupSyncRun $run): array
    {
        $nowUtc = CarbonImmutable::now('UTC');

        $policyType = $this->contracts->directoryGroupsPolicyType();
        $path = $this->contracts->directoryGroupsListPath();

        $contract = $this->contracts->get($policyType);
        $query = [];

        if (isset($contract['allowed_select']) && is_array($contract['allowed_select']) && $contract['allowed_select'] !== []) {
            $query['$select'] = $contract['allowed_select'];
        }

        $pageSize = (int) config('directory_groups.page_size', 999);
        if ($pageSize > 0) {
            $query['$top'] = $pageSize;
        }

        $sanitized = $this->contracts->sanitizeQuery($policyType, $query);
        $query = $sanitized['query'];

        $maxPages = (int) config('directory_groups.safety_stop.max_pages', 200);
        $maxRuntimeSeconds = (int) config('directory_groups.safety_stop.max_runtime_seconds', 600);
        $deadline = $nowUtc->addSeconds(max(1, $maxRuntimeSeconds));

        $pagesFetched = 0;
        $observed = 0;
        $upserted = 0;

        $safetyStopTriggered = false;
        $safetyStopReason = null;

        $errorCode = null;
        $errorCategory = null;
        $errorSummary = null;
        $errorCount = 0;

        $options = $tenant->graphOptions();
        $useQuery = $query;
        $nextPath = $path;

        while ($nextPath) {
            if (CarbonImmutable::now('UTC')->greaterThan($deadline)) {
                $safetyStopTriggered = true;
                $safetyStopReason = 'runtime_exceeded';

                break;
            }

            if ($pagesFetched >= $maxPages) {
                $safetyStopTriggered = true;
                $safetyStopReason = 'max_pages_exceeded';

                break;
            }

            $response = $this->requestWithRetry('GET', $nextPath, $options + ['query' => $useQuery]);

            if ($response->failed()) {
                [$errorCode, $errorCategory, $errorSummary] = $this->categorizeError($response);
                $errorCount = 1;

                break;
            }

            $pagesFetched++;

            $data = $response->data;
            $pageItems = $data['value'] ?? (is_array($data) ? $data : []);

            if (is_array($pageItems)) {
                foreach ($pageItems as $item) {
                    if (! is_array($item)) {
                        continue;
                    }

                    $entraId = $item['id'] ?? null;
                    if (! is_string($entraId) || $entraId === '') {
                        continue;
                    }

                    $displayName = $item['displayName'] ?? null;
                    $groupTypes = $item['groupTypes'] ?? null;

                    $values = [
                        'display_name' => is_string($displayName) ? $displayName : $entraId,
                        'group_types' => is_array($groupTypes) ? $groupTypes : [],
                        'security_enabled' => (bool) ($item['securityEnabled'] ?? false),
                        'mail_enabled' => (bool) ($item['mailEnabled'] ?? false),
                        'last_seen_at' => $nowUtc,
                    ];

                    EntraGroup::query()->updateOrCreate([
                        'tenant_id' => $tenant->getKey(),
                        'entra_id' => $entraId,
                    ], $values);

                    $observed++;
                    $upserted++;
                }
            }

            $nextLink = is_array($data) ? ($data['@odata.nextLink'] ?? null) : null;

            if (! is_string($nextLink) || $nextLink === '') {
                break;
            }

            $nextPath = $this->stripGraphBaseUrl($nextLink);
            $useQuery = [];
        }

        $retentionDays = (int) config('directory_groups.retention_days', 90);
        if ($retentionDays > 0) {
            $cutoff = $nowUtc->subDays($retentionDays);

            EntraGroup::query()
                ->where('tenant_id', $tenant->getKey())
                ->whereNotNull('last_seen_at')
                ->where('last_seen_at', '<', $cutoff)
                ->delete();
        }

        return [
            'pages_fetched' => $pagesFetched,
            'items_observed_count' => $observed,
            'items_upserted_count' => $upserted,
            'error_count' => $errorCount,
            'safety_stop_triggered' => $safetyStopTriggered,
            'safety_stop_reason' => $safetyStopReason,
            'error_code' => $errorCode,
            'error_category' => $errorCategory,
            'error_summary' => $errorSummary,
        ];
    }

    private function requestWithRetry(string $method, string $path, array $options): GraphResponse
    {
        $maxRetries = (int) config('directory_groups.safety_stop.max_retries', 8);
        $maxRetries = max(0, $maxRetries);

        for ($attempt = 0; $attempt <= $maxRetries; $attempt++) {
            $response = $this->graph->request($method, $path, $options);

            if ($response->successful()) {
                return $response;
            }

            $status = (int) ($response->status ?? 0);

            if (! in_array($status, [429, 503], true) || $attempt >= $maxRetries) {
                return $response;
            }

            $baseDelaySeconds = min(30, 1 << $attempt);
            $jitterMillis = random_int(0, 250);
            usleep(($baseDelaySeconds * 1000 + $jitterMillis) * 1000);
        }

        return new GraphResponse(success: false, data: [], status: 500, errors: [['message' => 'Retry loop exceeded']]);
    }

    /**
     * @return array{0:string,1:string,2:string}
     */
    private function categorizeError(GraphResponse $response): array
    {
        $status = (int) ($response->status ?? 0);

        if (in_array($status, [401, 403], true)) {
            return ['permission_denied', 'permission', 'Graph permission denied for groups listing.'];
        }

        if ($status === 429) {
            return ['throttled', 'throttling', 'Graph throttled the groups listing request.'];
        }

        if (in_array($status, [500, 502, 503, 504], true)) {
            return ['graph_unavailable', 'transient', 'Graph returned a transient server error.'];
        }

        return ['graph_request_failed', 'unknown', 'Graph request failed.'];
    }

    private function stripGraphBaseUrl(string $nextLink): string
    {
        $base = rtrim((string) config('graph.base_url', 'https://graph.microsoft.com'), '/')
            .'/'.trim((string) config('graph.version', 'v1.0'), '/');

        if (str_starts_with($nextLink, $base)) {
            return ltrim((string) substr($nextLink, strlen($base)), '/');
        }

        return ltrim($nextLink, '/');
    }
}