<?php

namespace App\Services\Intune;

use App\Models\Policy;
use App\Models\PolicyVersion;
use App\Models\Tenant;
use App\Services\Graph\AssignmentFetcher;
use App\Services\Graph\GroupResolver;
use Illuminate\Support\Facades\Log;

/**
 * Orchestrates policy capture with assignments and scope tags.
 * 
 * Ensures PolicyVersion is the source of truth, with BackupItem as restore copy.
 */
class PolicyCaptureOrchestrator
{
    public function __construct(
        private readonly VersionService $versionService,
        private readonly PolicySnapshotService $snapshotService,
        private readonly AssignmentFetcher $assignmentFetcher,
        private readonly GroupResolver $groupResolver,
    ) {}

    /**
     * Capture policy snapshot with optional assignments/scope tags.
     * 
     * @param Policy $policy
     * @param Tenant $tenant
     * @param bool $includeAssignments
     * @param bool $includeScopeTags
     * @param string|null $createdBy
     * @param array $metadata
     * @return array ['version' => PolicyVersion, 'captured' => array]
     */
    public function capture(
        Policy $policy,
        Tenant $tenant,
        bool $includeAssignments = false,
        bool $includeScopeTags = false,
        ?string $createdBy = null,
        array $metadata = []
    ): array {
        // 1. Fetch policy snapshot
        $snapshot = $this->snapshotService->fetch($tenant, $policy, $createdBy);

        if (isset($snapshot['failure'])) {
            throw new \RuntimeException($snapshot['failure']['reason'] ?? 'Unable to fetch policy snapshot');
        }

        $payload = $snapshot['payload'];
        $assignments = null;
        $scopeTags = null;
        $captureMetadata = [];

        // 2. Fetch assignments if requested
        if ($includeAssignments) {
            try {
                $rawAssignments = $this->assignmentFetcher->fetch($tenant->id, $policy->external_id);

                if (!empty($rawAssignments)) {
                    $assignments = $rawAssignments;

                    // Resolve groups for orphaned detection
                    $groupIds = collect($rawAssignments)
                        ->pluck('target.groupId')
                        ->filter()
                        ->unique()
                        ->values()
                        ->toArray();

                    if (!empty($groupIds)) {
                        $resolvedGroups = $this->groupResolver->resolve($tenant->id, $groupIds);
                        $captureMetadata['has_orphaned_assignments'] = !empty($resolvedGroups['orphaned']);
                    }

                    $captureMetadata['assignments_count'] = count($rawAssignments);
                }
            } catch (\Throwable $e) {
                $captureMetadata['assignments_fetch_failed'] = true;
                $captureMetadata['assignments_fetch_error'] = $e->getMessage();
                
                Log::warning('Failed to fetch assignments during capture', [
                    'tenant_id' => $tenant->id,
                    'policy_id' => $policy->id,
                    'error' => $e->getMessage(),
                ]);
            }
        }

        // 3. Fetch scope tags if requested
        if ($includeScopeTags) {
            $scopeTags = [
                'ids' => $payload['roleScopeTagIds'] ?? ['0'],
                'names' => ['Default'], // Could fetch from Graph if needed
            ];
        }

        // 4. Check if PolicyVersion with same snapshot already exists
        $snapshotHash = hash('sha256', json_encode($payload));
        
        // Find existing version by comparing snapshot content (database-agnostic)
        $existingVersion = PolicyVersion::where('policy_id', $policy->id)
            ->get()
            ->first(function ($version) use ($snapshotHash) {
                return hash('sha256', json_encode($version->snapshot)) === $snapshotHash;
            });

        if ($existingVersion && $includeAssignments && is_null($existingVersion->assignments)) {
            // Backfill existing version with assignments (idempotent)
            $existingVersion->update([
                'assignments' => $assignments,
                'scope_tags' => $scopeTags,
                'assignments_hash' => $assignments ? hash('sha256', json_encode($assignments)) : null,
                'scope_tags_hash' => $scopeTags ? hash('sha256', json_encode($scopeTags)) : null,
            ]);

            Log::info('Backfilled existing PolicyVersion with assignments', [
                'tenant_id' => $tenant->id,
                'policy_id' => $policy->id,
                'version_id' => $existingVersion->id,
                'version_number' => $existingVersion->version_number,
            ]);

            return [
                'version' => $existingVersion->fresh(),
                'captured' => [
                    'payload' => $payload,
                    'assignments' => $assignments,
                    'scope_tags' => $scopeTags,
                    'metadata' => $captureMetadata,
                ],
            ];
        }

        if ($existingVersion) {
            // Reuse existing version without modification
            Log::info('Reusing existing PolicyVersion', [
                'tenant_id' => $tenant->id,
                'policy_id' => $policy->id,
                'version_id' => $existingVersion->id,
                'version_number' => $existingVersion->version_number,
            ]);

            return [
                'version' => $existingVersion,
                'captured' => [
                    'payload' => $payload,
                    'assignments' => $assignments,
                    'scope_tags' => $scopeTags,
                    'metadata' => $captureMetadata,
                ],
            ];
        }

        // 5. Create new PolicyVersion with all captured data
        $metadata = array_merge(
            ['source' => 'orchestrated_capture'],
            $metadata,
            $captureMetadata
        );

        $version = $this->versionService->captureVersion(
            policy: $policy,
            payload: $payload,
            createdBy: $createdBy,
            metadata: $metadata,
            assignments: $assignments,
            scopeTags: $scopeTags,
        );

        Log::info('Policy captured via orchestrator', [
            'tenant_id' => $tenant->id,
            'policy_id' => $policy->id,
            'version_id' => $version->id,
            'version_number' => $version->version_number,
            'has_assignments' => !is_null($assignments),
            'has_scope_tags' => !is_null($scopeTags),
        ]);

        return [
            'version' => $version,
            'captured' => [
                'payload' => $payload,
                'assignments' => $assignments,
                'scope_tags' => $scopeTags,
                'metadata' => $captureMetadata,
            ],
        ];
    }

    /**
     * Ensure existing PolicyVersion has assignments if missing.
     * 
     * @param PolicyVersion $version
     * @param Tenant $tenant
     * @param Policy $policy
     * @param bool $includeAssignments
     * @param bool $includeScopeTags
     * @return PolicyVersion
     */
    public function ensureVersionHasAssignments(
        PolicyVersion $version,
        Tenant $tenant,
        Policy $policy,
        bool $includeAssignments = false,
        bool $includeScopeTags = false
    ): PolicyVersion {
        // If version already has assignments, don't overwrite (idempotent)
        if ($version->assignments !== null) {
            Log::debug('Version already has assignments, skipping', [
                'version_id' => $version->id,
            ]);
            
            return $version;
        }

        // Only fetch if requested
        if (!$includeAssignments && !$includeScopeTags) {
            return $version;
        }

        $assignments = null;
        $scopeTags = null;
        $metadata = $version->metadata ?? [];

        // Fetch assignments
        if ($includeAssignments) {
            try {
                $rawAssignments = $this->assignmentFetcher->fetch($tenant->id, $policy->external_id);

                if (!empty($rawAssignments)) {
                    $assignments = $rawAssignments;

                    // Resolve groups
                    $groupIds = collect($rawAssignments)
                        ->pluck('target.groupId')
                        ->filter()
                        ->unique()
                        ->values()
                        ->toArray();

                    if (!empty($groupIds)) {
                        $resolvedGroups = $this->groupResolver->resolve($tenant->id, $groupIds);
                        $metadata['has_orphaned_assignments'] = !empty($resolvedGroups['orphaned']);
                    }

                    $metadata['assignments_count'] = count($rawAssignments);
                }
            } catch (\Throwable $e) {
                $metadata['assignments_fetch_failed'] = true;
                $metadata['assignments_fetch_error'] = $e->getMessage();
                
                Log::warning('Failed to backfill assignments for version', [
                    'version_id' => $version->id,
                    'error' => $e->getMessage(),
                ]);
            }
        }

        // Fetch scope tags
        if ($includeScopeTags && $version->scope_tags === null) {
            // Try to get from snapshot
            $scopeTags = [
                'ids' => $version->snapshot['roleScopeTagIds'] ?? ['0'],
                'names' => ['Default'],
            ];
        }

        // Update version
        $version->update([
            'assignments' => $assignments,
            'scope_tags' => $scopeTags,
            'assignments_hash' => $assignments ? hash('sha256', json_encode($assignments)) : null,
            'scope_tags_hash' => $scopeTags ? hash('sha256', json_encode($scopeTags)) : null,
            'metadata' => $metadata,
        ]);

        Log::info('Version backfilled with assignments', [
            'version_id' => $version->id,
            'has_assignments' => !is_null($assignments),
            'has_scope_tags' => !is_null($scopeTags),
        ]);

        return $version->refresh();
    }
}