<?php

namespace App\Services\Inventory;

use App\Models\InventoryItem;
use App\Models\InventorySyncRun;
use App\Models\Tenant;
use App\Models\User;
use App\Services\BackupScheduling\PolicyTypeResolver;
use App\Services\Graph\GraphClientInterface;
use App\Services\Graph\GraphResponse;
use Carbon\CarbonImmutable;
use Illuminate\Contracts\Cache\Lock;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Log;
use Throwable;

class InventorySyncService
{
    public function __construct(
        private readonly GraphClientInterface $graphClient,
        private readonly PolicyTypeResolver $policyTypeResolver,
        private readonly InventorySelectionHasher $selectionHasher,
        private readonly InventoryMetaSanitizer $metaSanitizer,
        private readonly InventoryConcurrencyLimiter $concurrencyLimiter,
    ) {}

    /**
     * Runs an inventory sync inline (no queue), enforcing locks/concurrency and creating an observable run record.
     *
     * @param  array<string, mixed>  $selectionPayload
     */
    public function syncNow(Tenant $tenant, array $selectionPayload): InventorySyncRun
    {
        $computed = $this->normalizeAndHashSelection($selectionPayload);
        $normalizedSelection = $computed['selection'];
        $selectionHash = $computed['selection_hash'];

        $now = CarbonImmutable::now('UTC');

        $globalSlot = $this->concurrencyLimiter->acquireGlobalSlot();
        if (! $globalSlot instanceof Lock) {
            return $this->createSkippedRun(
                tenant: $tenant,
                selectionHash: $selectionHash,
                selectionPayload: $normalizedSelection,
                now: $now,
                errorCode: 'concurrency_limit_global',
            );
        }

        $tenantSlot = $this->concurrencyLimiter->acquireTenantSlot((int) $tenant->id);
        if (! $tenantSlot instanceof Lock) {
            $globalSlot->release();

            return $this->createSkippedRun(
                tenant: $tenant,
                selectionHash: $selectionHash,
                selectionPayload: $normalizedSelection,
                now: $now,
                errorCode: 'concurrency_limit_tenant',
            );
        }

        $selectionLock = Cache::lock($this->selectionLockKey($tenant, $selectionHash), 900);
        if (! $selectionLock->get()) {
            $tenantSlot->release();
            $globalSlot->release();

            return $this->createSkippedRun(
                tenant: $tenant,
                selectionHash: $selectionHash,
                selectionPayload: $normalizedSelection,
                now: $now,
                errorCode: 'lock_contended',
            );
        }

        $run = InventorySyncRun::query()->create([
            'tenant_id' => $tenant->getKey(),
            'user_id' => null,
            'selection_hash' => $selectionHash,
            'selection_payload' => $normalizedSelection,
            'status' => InventorySyncRun::STATUS_RUNNING,
            'had_errors' => false,
            'error_codes' => [],
            'error_context' => null,
            'started_at' => $now,
            'finished_at' => null,
            'items_observed_count' => 0,
            'items_upserted_count' => 0,
            'errors_count' => 0,
        ]);

        try {
            return $this->executeRun($run, $tenant, $normalizedSelection);
        } finally {
            $selectionLock->release();
            $tenantSlot->release();
            $globalSlot->release();
        }
    }

    /**
     * @return array{policy_types: list<string>, categories: list<string>, include_foundations: bool, include_dependencies: bool}
     */
    public function defaultSelectionPayload(): array
    {
        return [
            'policy_types' => $this->policyTypeResolver->supportedPolicyTypes(),
            'categories' => [],
            'include_foundations' => true,
            'include_dependencies' => true,
        ];
    }

    /**
     * @param  array<string, mixed>  $selectionPayload
     * @return array{selection: array{policy_types: list<string>, categories: list<string>, include_foundations: bool, include_dependencies: bool}, selection_hash: string}
     */
    public function normalizeAndHashSelection(array $selectionPayload): array
    {
        $normalizedSelection = $this->selectionHasher->normalize($selectionPayload);
        $normalizedSelection['policy_types'] = $this->policyTypeResolver->filterRuntime($normalizedSelection['policy_types']);
        $selectionHash = $this->selectionHasher->hash($normalizedSelection);

        return [
            'selection' => $normalizedSelection,
            'selection_hash' => $selectionHash,
        ];
    }

    /**
     * Creates a pending run record attributed to the initiating user so the run remains observable even if queue workers are down.
     *
     * @param  array<string, mixed>  $selectionPayload
     */
    public function createPendingRunForUser(Tenant $tenant, User $user, array $selectionPayload): InventorySyncRun
    {
        $computed = $this->normalizeAndHashSelection($selectionPayload);

        return InventorySyncRun::query()->create([
            'tenant_id' => $tenant->getKey(),
            'user_id' => $user->getKey(),
            'selection_hash' => $computed['selection_hash'],
            'selection_payload' => $computed['selection'],
            'status' => InventorySyncRun::STATUS_PENDING,
            'had_errors' => false,
            'error_codes' => [],
            'error_context' => null,
            'started_at' => null,
            'finished_at' => null,
            'items_observed_count' => 0,
            'items_upserted_count' => 0,
            'errors_count' => 0,
        ]);
    }

    /**
     * Executes an existing pending run under locks/concurrency, updating that run to running/skipped/terminal.
     */
    /**
     * @param  null|callable(string $policyType, bool $success, ?string $errorCode): void  $onPolicyTypeProcessed
     */
    public function executePendingRun(InventorySyncRun $run, Tenant $tenant, ?callable $onPolicyTypeProcessed = null): InventorySyncRun
    {
        $computed = $this->normalizeAndHashSelection($run->selection_payload ?? []);
        $normalizedSelection = $computed['selection'];
        $selectionHash = $computed['selection_hash'];

        $now = CarbonImmutable::now('UTC');

        $run->update([
            'tenant_id' => $tenant->getKey(),
            'selection_hash' => $selectionHash,
            'selection_payload' => $normalizedSelection,
            'status' => InventorySyncRun::STATUS_RUNNING,
            'had_errors' => false,
            'error_codes' => [],
            'error_context' => null,
            'started_at' => $now,
            'finished_at' => null,
            'items_observed_count' => 0,
            'items_upserted_count' => 0,
            'errors_count' => 0,
        ]);

        $globalSlot = $this->concurrencyLimiter->acquireGlobalSlot();
        if (! $globalSlot instanceof Lock) {
            return $this->markExistingRunSkipped(
                run: $run,
                now: $now,
                errorCode: 'concurrency_limit_global',
            );
        }

        $tenantSlot = $this->concurrencyLimiter->acquireTenantSlot((int) $tenant->id);
        if (! $tenantSlot instanceof Lock) {
            $globalSlot->release();

            return $this->markExistingRunSkipped(
                run: $run,
                now: $now,
                errorCode: 'concurrency_limit_tenant',
            );
        }

        $selectionLock = Cache::lock($this->selectionLockKey($tenant, $selectionHash), 900);
        if (! $selectionLock->get()) {
            $tenantSlot->release();
            $globalSlot->release();

            return $this->markExistingRunSkipped(
                run: $run,
                now: $now,
                errorCode: 'lock_contended',
            );
        }

        try {
            return $this->executeRun($run, $tenant, $normalizedSelection, $onPolicyTypeProcessed);
        } finally {
            $selectionLock->release();
            $tenantSlot->release();
            $globalSlot->release();
        }
    }

    /**
     * @param  array{policy_types: list<string>, categories: list<string>, include_foundations: bool, include_dependencies: bool}  $normalizedSelection
     */
    /**
     * @param  array{policy_types: list<string>, categories: list<string>, include_foundations: bool, include_dependencies: bool}  $normalizedSelection
     * @param  null|callable(string $policyType, bool $success, ?string $errorCode): void  $onPolicyTypeProcessed
     */
    private function executeRun(InventorySyncRun $run, Tenant $tenant, array $normalizedSelection, ?callable $onPolicyTypeProcessed = null): InventorySyncRun
    {
        $observed = 0;
        $upserted = 0;
        $errors = 0;
        $errorCodes = [];
        $hadErrors = false;
        $warnings = [];

        try {
            $typesConfig = $this->supportedTypeConfigByType();

            foreach ($normalizedSelection['policy_types'] as $policyType) {
                $typeConfig = $typesConfig[$policyType] ?? null;

                if (! is_array($typeConfig)) {
                    $hadErrors = true;
                    $errors++;
                    $errorCodes[] = 'unsupported_type';
                    $onPolicyTypeProcessed && $onPolicyTypeProcessed($policyType, false, 'unsupported_type');

                    continue;
                }

                $response = $this->listPoliciesWithRetry($policyType, [
                    'tenant' => $tenant->tenant_id ?? $tenant->external_id,
                    'client_id' => $tenant->app_client_id,
                    'client_secret' => $tenant->app_client_secret,
                    'platform' => $typeConfig['platform'] ?? null,
                    'filter' => $typeConfig['filter'] ?? null,
                ]);

                if ($response->failed()) {
                    $hadErrors = true;
                    $errors++;
                    $errorCode = $this->mapGraphFailureToErrorCode($response);
                    $errorCodes[] = $errorCode;
                    $onPolicyTypeProcessed && $onPolicyTypeProcessed($policyType, false, $errorCode);

                    continue;
                }

                foreach ($response->data as $policyData) {
                    if (! is_array($policyData)) {
                        continue;
                    }

                    if ($this->shouldSkipPolicyForSelectedType($policyType, $policyData)) {
                        continue;
                    }

                    $externalId = $policyData['id'] ?? $policyData['external_id'] ?? null;
                    if (! is_string($externalId) || $externalId === '') {
                        continue;
                    }

                    $observed++;

                    $includeDeps = (bool) ($normalizedSelection['include_dependencies'] ?? true);

                    if ($includeDeps && $this->shouldHydrateAssignments($policyType)) {
                        $existingAssignments = $policyData['assignments'] ?? null;
                        if (! is_array($existingAssignments)) {
                            $hydratedAssignments = $this->fetchAssignmentsForPolicyType($policyType, $tenant, $externalId, $warnings);
                            if (is_array($hydratedAssignments)) {
                                $policyData['assignments'] = $hydratedAssignments;
                            }
                        }
                    }

                    $displayName = $policyData['displayName'] ?? $policyData['name'] ?? null;
                    $displayName = is_string($displayName) ? $displayName : null;

                    $scopeTagIds = $policyData['roleScopeTagIds'] ?? null;
                    $assignmentTargetCount = null;
                    $assignments = $policyData['assignments'] ?? null;
                    if (is_array($assignments)) {
                        $assignmentTargetCount = count($assignments);
                    }

                    $meta = $this->metaSanitizer->sanitize([
                        'odata_type' => $policyData['@odata.type'] ?? $policyData['@OData.Type'] ?? null,
                        'etag' => $policyData['@odata.etag'] ?? null,
                        'scope_tag_ids' => is_array($scopeTagIds) ? $scopeTagIds : null,
                        'assignment_target_count' => $assignmentTargetCount,
                        'warnings' => [],
                    ]);

                    $item = InventoryItem::query()->updateOrCreate(
                        [
                            'tenant_id' => $tenant->getKey(),
                            'policy_type' => $policyType,
                            'external_id' => $externalId,
                        ],
                        [
                            'display_name' => $displayName,
                            'category' => $typeConfig['category'] ?? null,
                            'platform' => $typeConfig['platform'] ?? null,
                            'meta_jsonb' => $meta,
                            'last_seen_at' => now(),
                            'last_seen_run_id' => $run->getKey(),
                        ]
                    );

                    $upserted++;

                    // Extract dependencies if requested in selection
                    if ($includeDeps) {
                        $warnings = array_merge(
                            $warnings,
                            app(\App\Services\Inventory\DependencyExtractionService::class)
                                ->extractForPolicyData($item, $policyData)
                        );
                    }
                }

                $onPolicyTypeProcessed && $onPolicyTypeProcessed($policyType, true, null);
            }

            $status = $hadErrors ? InventorySyncRun::STATUS_PARTIAL : InventorySyncRun::STATUS_SUCCESS;

            $run->update([
                'status' => $status,
                'had_errors' => $hadErrors,
                'error_codes' => array_values(array_unique($errorCodes)),
                'error_context' => [
                    'warnings' => array_values($warnings),
                ],
                'items_observed_count' => $observed,
                'items_upserted_count' => $upserted,
                'errors_count' => $errors,
                'finished_at' => CarbonImmutable::now('UTC'),
            ]);

            return $run->refresh();
        } catch (Throwable $throwable) {
            $errorContext = $this->safeErrorContext($throwable);
            $errorContext['warnings'] = array_values($warnings);

            $run->update([
                'status' => InventorySyncRun::STATUS_FAILED,
                'had_errors' => true,
                'error_codes' => ['unexpected_exception'],
                'error_context' => $errorContext,
                'items_observed_count' => $observed,
                'items_upserted_count' => $upserted,
                'errors_count' => $errors + 1,
                'finished_at' => CarbonImmutable::now('UTC'),
            ]);

            return $run->refresh();
        }
    }

    private function shouldSkipPolicyForSelectedType(string $selectedPolicyType, array $policyData): bool
    {
        $configurationPolicyTypes = ['settingsCatalogPolicy', 'endpointSecurityPolicy', 'securityBaselinePolicy'];

        if (! in_array($selectedPolicyType, $configurationPolicyTypes, true)) {
            return false;
        }

        return $this->resolveConfigurationPolicyType($policyData) !== $selectedPolicyType;
    }

    private function shouldHydrateAssignments(string $policyType): bool
    {
        return in_array($policyType, ['settingsCatalogPolicy', 'endpointSecurityPolicy', 'securityBaselinePolicy'], true);
    }

    /**
     * @param  array<int, array<string, mixed>>  $warnings
     * @return null|array<int, mixed>
     */
    private function fetchAssignmentsForPolicyType(string $policyType, Tenant $tenant, string $externalId, array &$warnings): ?array
    {
        $pathTemplate = config("graph_contracts.types.{$policyType}.assignments_list_path");
        if (! is_string($pathTemplate) || $pathTemplate === '') {
            return null;
        }

        $path = str_replace('{id}', $externalId, $pathTemplate);

        $options = [
            'tenant' => $tenant->tenant_id ?? $tenant->external_id,
            'client_id' => $tenant->app_client_id,
            'client_secret' => $tenant->app_client_secret,
        ];

        $maxAttempts = 3;

        for ($attempt = 1; $attempt <= $maxAttempts; $attempt++) {
            $response = $this->graphClient->request('GET', $path, $options);

            if (! $response->failed()) {
                $data = $response->data;
                if (is_array($data) && array_key_exists('value', $data) && is_array($data['value'])) {
                    return $data['value'];
                }

                if (is_array($data)) {
                    return $data;
                }

                return null;
            }

            $status = (int) ($response->status ?? 0);
            if (! in_array($status, [429, 503], true)) {
                break;
            }
        }

        $warning = [
            'type' => 'assignments_fetch_failed',
            'policy_id' => $externalId,
            'policy_type' => $policyType,
            'reason' => 'graph_assignments_list_failed',
        ];

        $warnings[] = $warning;
        Log::info('Failed to fetch policy assignments', $warning);

        return null;
    }

    private function resolveConfigurationPolicyType(array $policyData): string
    {
        $templateReference = $policyData['templateReference'] ?? null;
        $templateFamily = null;
        if (is_array($templateReference)) {
            $templateFamily = $templateReference['templateFamily'] ?? null;
        }

        if (is_string($templateFamily) && strcasecmp(trim($templateFamily), 'securityBaseline') === 0) {
            return 'securityBaselinePolicy';
        }

        if ($this->isEndpointSecurityConfigurationPolicy($policyData, $templateFamily)) {
            return 'endpointSecurityPolicy';
        }

        return 'settingsCatalogPolicy';
    }

    private function isEndpointSecurityConfigurationPolicy(array $policyData, ?string $templateFamily): bool
    {
        $technologies = $policyData['technologies'] ?? null;

        if (is_string($technologies) && strcasecmp(trim($technologies), 'endpointSecurity') === 0) {
            return true;
        }

        if (is_array($technologies)) {
            foreach ($technologies as $technology) {
                if (is_string($technology) && strcasecmp(trim($technology), 'endpointSecurity') === 0) {
                    return true;
                }
            }
        }

        return is_string($templateFamily) && str_starts_with(strtolower(trim($templateFamily)), 'endpointsecurity');
    }

    /**
     * @return array<string, array<string, mixed>>
     */
    private function supportedTypeConfigByType(): array
    {
        /** @var array<int, array<string, mixed>> $supported */
        $supported = config('tenantpilot.supported_policy_types', []);

        $byType = [];
        foreach ($supported as $config) {
            $type = $config['type'] ?? null;
            if (is_string($type) && $type !== '') {
                $byType[$type] = $config;
            }
        }

        return $byType;
    }

    private function selectionLockKey(Tenant $tenant, string $selectionHash): string
    {
        return sprintf('inventory_sync:tenant:%s:selection:%s', (string) $tenant->getKey(), $selectionHash);
    }

    /**
     * @param  array<string, mixed>  $selectionPayload
     */
    private function createSkippedRun(
        Tenant $tenant,
        string $selectionHash,
        array $selectionPayload,
        CarbonImmutable $now,
        string $errorCode,
    ): InventorySyncRun {
        return InventorySyncRun::query()->create([
            'tenant_id' => $tenant->getKey(),
            'user_id' => null,
            'selection_hash' => $selectionHash,
            'selection_payload' => $selectionPayload,
            'status' => InventorySyncRun::STATUS_SKIPPED,
            'had_errors' => true,
            'error_codes' => [$errorCode],
            'error_context' => null,
            'started_at' => $now,
            'finished_at' => $now,
            'items_observed_count' => 0,
            'items_upserted_count' => 0,
            'errors_count' => 0,
        ]);
    }

    private function markExistingRunSkipped(InventorySyncRun $run, CarbonImmutable $now, string $errorCode): InventorySyncRun
    {
        $run->update([
            'status' => InventorySyncRun::STATUS_SKIPPED,
            'had_errors' => true,
            'error_codes' => [$errorCode],
            'error_context' => null,
            'started_at' => $run->started_at ?? $now,
            'finished_at' => $now,
            'items_observed_count' => 0,
            'items_upserted_count' => 0,
            'errors_count' => 0,
        ]);

        return $run->refresh();
    }

    private function mapGraphFailureToErrorCode(GraphResponse $response): string
    {
        $status = (int) ($response->status ?? 0);

        return match ($status) {
            403 => 'graph_forbidden',
            429 => 'graph_throttled',
            503 => 'graph_transient',
            default => 'graph_transient',
        };
    }

    private function listPoliciesWithRetry(string $policyType, array $options): GraphResponse
    {
        $maxAttempts = 3;

        for ($attempt = 1; $attempt <= $maxAttempts; $attempt++) {
            $response = $this->graphClient->listPolicies($policyType, $options);

            if (! $response->failed()) {
                return $response;
            }

            $status = (int) ($response->status ?? 0);
            if (! in_array($status, [429, 503], true)) {
                return $response;
            }

            if ($attempt >= $maxAttempts) {
                return $response;
            }

            $baseMs = 250 * (2 ** ($attempt - 1));
            $jitterMs = random_int(0, 250);
            usleep(($baseMs + $jitterMs) * 1000);
        }

        return new GraphResponse(false, [], null, ['error' => ['code' => 'unexpected_exception', 'message' => 'retry loop failed']]);
    }

    /**
     * @return array<string, mixed>
     */
    private function safeErrorContext(Throwable $throwable): array
    {
        $message = $throwable->getMessage();

        $message = preg_replace('/Bearer\s+[A-Za-z0-9\-\._~\+\/]+=*/', 'Bearer [REDACTED]', (string) $message);
        $message = mb_substr((string) $message, 0, 500);

        return [
            'exception_class' => get_class($throwable),
            'message' => $message,
        ];
    }
}