<?php

namespace App\Services\Intune;

use App\Models\BackupItem;
use App\Models\BackupSet;
use App\Models\Policy;
use App\Models\RestoreRun;
use App\Models\Tenant;
use App\Services\Graph\GraphClientInterface;
use App\Services\Graph\GraphErrorMapper;
use App\Services\Graph\GraphLogger;
use Carbon\CarbonImmutable;
use Illuminate\Support\Collection;
use Throwable;

class RestoreService
{
    public function __construct(
        private readonly GraphClientInterface $graphClient,
        private readonly GraphLogger $graphLogger,
        private readonly AuditLogger $auditLogger,
        private readonly VersionService $versionService,
        private readonly SnapshotValidator $snapshotValidator,
    ) {}

    /**
     * Build a preview describing intended restore actions.
     *
     * @param  array<int>|null  $selectedItemIds
     */
    public function preview(Tenant $tenant, BackupSet $backupSet, ?array $selectedItemIds = null): array
    {
        $this->assertActiveContext($tenant, $backupSet);

        $items = $this->loadItems($backupSet, $selectedItemIds);

        return $items->map(function (BackupItem $item) use ($tenant) {
            $existing = Policy::query()
                ->where('tenant_id', $tenant->id)
                ->where('external_id', $item->policy_identifier)
                ->where('policy_type', $item->policy_type)
                ->first();

            return [
                'backup_item_id' => $item->id,
                'policy_identifier' => $item->policy_identifier,
                'policy_type' => $item->policy_type,
                'platform' => $item->platform,
                'action' => $existing ? 'update' : 'create',
                'conflict' => false,
                'validation_warning' => BackupItem::odataTypeWarning(
                    is_array($item->payload) ? $item->payload : [],
                    $item->policy_type,
                    $item->platform
                ) ?? ($this->snapshotValidator->validate(is_array($item->payload) ? $item->payload : [])['warnings'][0] ?? null),
            ];
        })->all();
    }

    /**
     * Execute restore or dry-run for selected items.
     *
     * @param  array<int>|null  $selectedItemIds
     */
    public function execute(
        Tenant $tenant,
        BackupSet $backupSet,
        ?array $selectedItemIds = null,
        bool $dryRun = true,
        ?string $actorEmail = null,
        ?string $actorName = null,
    ): RestoreRun {
        $this->assertActiveContext($tenant, $backupSet);

        $tenantIdentifier = $tenant->tenant_id ?? $tenant->external_id;
        $items = $this->loadItems($backupSet, $selectedItemIds);
        $preview = $this->preview($tenant, $backupSet, $selectedItemIds);

        $restoreRun = RestoreRun::create([
            'tenant_id' => $tenant->id,
            'backup_set_id' => $backupSet->id,
            'requested_by' => $actorEmail,
            'is_dry_run' => $dryRun,
            'status' => 'running',
            'requested_items' => $selectedItemIds,
            'preview' => $preview,
            'started_at' => CarbonImmutable::now(),
            'metadata' => [],
        ]);

        $results = [];
        $failures = 0;

        foreach ($items as $item) {
            $context = [
                'tenant' => $tenantIdentifier,
                'policy_type' => $item->policy_type,
                'policy_id' => $item->policy_identifier,
                'backup_item_id' => $item->id,
            ];

            $odataValidation = BackupItem::validateODataType(
                is_array($item->payload) ? $item->payload : [],
                $item->policy_type,
                $item->platform
            );

            if (! $odataValidation['matches']) {
                $results[] = $context + [
                    'status' => 'failed',
                    'reason' => BackupItem::odataTypeWarning(
                        is_array($item->payload) ? $item->payload : [],
                        $item->policy_type,
                        $item->platform
                    ) ?? 'Snapshot type mismatch',
                    'code' => 'odata_mismatch',
                ];
                $failures++;

                continue;
            }

            if ($dryRun) {
                $results[] = $context + ['status' => 'dry_run'];

                continue;
            }

            $this->graphLogger->logRequest('apply_policy', $context);

            try {
                $payload = $this->sanitizePayload($item->payload);

                $response = $this->graphClient->applyPolicy(
                    $item->policy_type,
                    $item->policy_identifier,
                    $payload,
                    [
                        'tenant' => $tenantIdentifier,
                        'client_id' => $tenant->app_client_id,
                        'client_secret' => $tenant->app_client_secret,
                        'platform' => $item->platform,
                    ]
                );
            } catch (Throwable $throwable) {
                $mapped = GraphErrorMapper::fromThrowable($throwable, $context);
                $results[] = $context + [
                    'status' => 'failed',
                    'reason' => $mapped->getMessage(),
                    'code' => $mapped->status,
                ];
                $failures++;

                continue;
            }

            $this->graphLogger->logResponse('apply_policy', $response, $context);

            if ($response->failed()) {
                $results[] = $context + [
                    'status' => 'failed',
                    'reason' => 'Graph apply failed',
                    'code' => $response->status,
                ];
                $failures++;

                continue;
            }

            $results[] = $context + ['status' => 'applied'];

            $policy = Policy::query()
                ->where('tenant_id', $tenant->id)
                ->where('external_id', $item->policy_identifier)
                ->where('policy_type', $item->policy_type)
                ->first();

            if ($policy) {
                $this->versionService->captureVersion(
                    policy: $policy,
                    payload: $item->payload,
                    createdBy: $actorEmail,
                    metadata: [
                        'source' => 'restore',
                        'restore_run_id' => $restoreRun->id,
                        'backup_item_id' => $item->id,
                    ]
                );
            }
        }

        $status = $dryRun
            ? 'previewed'
            : (match (true) {
                $failures === count($results) => 'failed',
                $failures > 0 => 'partial',
                default => 'completed',
            });

        $restoreRun->update([
            'status' => $status,
            'results' => $results,
            'completed_at' => CarbonImmutable::now(),
            'metadata' => [
                'failed' => $failures,
                'total' => count($results),
            ],
        ]);

        $this->auditLogger->log(
            tenant: $tenant,
            action: $dryRun ? 'restore.previewed' : 'restore.executed',
            context: [
                'metadata' => [
                    'restore_run_id' => $restoreRun->id,
                    'backup_set_id' => $backupSet->id,
                    'status' => $status,
                    'dry_run' => $dryRun,
                ],
            ],
            actorEmail: $actorEmail,
            actorName: $actorName,
            resourceType: 'restore_run',
            resourceId: (string) $restoreRun->id,
            status: $status === 'completed' || $status === 'previewed' ? 'success' : 'partial'
        );

        return $restoreRun->refresh();
    }

    /**
     * @param  array<int>|null  $selectedItemIds
     */
    private function loadItems(BackupSet $backupSet, ?array $selectedItemIds = null): Collection
    {
        $query = $backupSet->items()->getQuery();

        if ($selectedItemIds !== null) {
            $query->whereIn('id', $selectedItemIds);
        }

        return $query->orderBy('id')->get();
    }

    /**
     * Strip read-only/metadata fields before sending payload back to Graph.
     */
    private function sanitizePayload(array $payload): array
    {
        $readOnlyKeys = [
            '@odata.context',
            'id',
            'createdDateTime',
            'lastModifiedDateTime',
            'version',
            'supportsScopeTags',
            'roleScopeTagIds',
        ];

        $clean = [];

        foreach ($payload as $key => $value) {
            // Drop read-only/meta keys except @odata.type which we keep for type hinting
            if (in_array($key, $readOnlyKeys, true)) {
                continue;
            }

            // Keep @odata.type for Graph type resolution
            if ($key === '@odata.type') {
                $clean[$key] = $value;

                continue;
            }

            if (is_array($value)) {
                $clean[$key] = $this->sanitizePayload($value);

                continue;
            }

            $clean[$key] = $value;
        }

        return $clean;
    }

    private function assertActiveContext(Tenant $tenant, BackupSet $backupSet): void
    {
        if (! $tenant->isActive()) {
            throw new \RuntimeException('Tenant is archived or inactive.');
        }

        if ($backupSet->trashed()) {
            throw new \RuntimeException('Backup set is archived.');
        }
    }
}