<?php

namespace App\Services\Intune;

use App\Models\BackupItem;
use App\Models\Tenant;
use App\Services\Graph\GraphClientInterface;
use App\Services\Graph\GraphContractRegistry;
use Illuminate\Support\Collection;

class FoundationMappingService
{
    public function __construct(
        private readonly GraphClientInterface $graphClient,
        private readonly GraphContractRegistry $contracts,
        private readonly FoundationSnapshotService $snapshotService,
    ) {}

    /**
     * @param  Collection<int, BackupItem>  $items
     * @return array{entries: array<int, array<string, mixed>>, mapping: array<string, string>, failed: int, skipped: int}
     */
    public function map(Tenant $tenant, Collection $items, bool $execute = false): array
    {
        $entries = [];
        $mapping = [];
        $failed = 0;
        $skipped = 0;

        if ($items->isEmpty()) {
            return [
                'entries' => $entries,
                'mapping' => $mapping,
                'failed' => $failed,
                'skipped' => $skipped,
            ];
        }

        $itemsByType = $items->groupBy('policy_type');

        foreach ($itemsByType as $foundationType => $typeItems) {
            $foundationType = (string) $foundationType;
            $existingOutcome = $this->snapshotService->fetchAll($tenant, $foundationType);
            $existingFailures = $existingOutcome['failures'] ?? [];

            if (! empty($existingFailures)) {
                $reason = $existingFailures[0]['reason'] ?? 'Unable to list foundation resources.';

                foreach ($typeItems as $item) {
                    $entries[] = $this->failureEntry($foundationType, $item, $reason);
                    $failed++;
                }

                continue;
            }

            $existing = $existingOutcome['items'] ?? [];
            $existingByName = $this->indexExistingByName($existing);
            $existingNames = array_keys($existingByName);

            foreach ($typeItems as $item) {
                $sourceId = $item->policy_identifier;
                $sourceName = $item->resolvedDisplayName();

                if ($sourceName === '') {
                    $entries[] = $this->skipEntry($foundationType, $sourceId, null, 'Missing display name.');
                    $skipped++;

                    continue;
                }

                $normalizedName = strtolower($sourceName);
                $matches = $existingByName[$normalizedName] ?? [];

                if (count($matches) === 1) {
                    $match = $matches[0];
                    $targetId = $match['source_id'] ?? null;
                    $targetName = $match['display_name'] ?? null;

                    if (is_string($targetId) && $targetId !== '') {
                        $mapping[$sourceId] = $targetId;
                    }

                    $entries[] = $this->decisionEntry(
                        $foundationType,
                        $sourceId,
                        $sourceName,
                        'mapped_existing',
                        $targetId,
                        $targetName,
                        null
                    );

                    continue;
                }

                $builtIn = $this->isBuiltInScopeTag($foundationType, $item);

                if ($builtIn) {
                    $entries[] = $this->skipEntry(
                        $foundationType,
                        $sourceId,
                        $sourceName,
                        'Built-in scope tag cannot be created.'
                    );
                    $skipped++;

                    continue;
                }

                $decision = count($matches) > 1 ? 'created_copy' : 'created';
                $targetName = $decision === 'created_copy'
                    ? $this->resolveCopyName($sourceName, $existingNames)
                    : $sourceName;

                if (! $execute) {
                    $entries[] = $this->decisionEntry(
                        $foundationType,
                        $sourceId,
                        $sourceName,
                        $decision,
                        null,
                        $targetName,
                        count($matches) > 1 ? 'Multiple matches found by name.' : null
                    );

                    continue;
                }

                $createOutcome = $this->createFoundation(
                    tenant: $tenant,
                    foundationType: $foundationType,
                    item: $item,
                    targetName: $targetName
                );

                if ($createOutcome['success'] ?? false) {
                    $targetId = $createOutcome['target_id'] ?? null;
                    $createdName = $createOutcome['target_name'] ?? $targetName;

                    if (is_string($targetId) && $targetId !== '') {
                        $mapping[$sourceId] = $targetId;
                    }

                    $entries[] = $this->decisionEntry(
                        $foundationType,
                        $sourceId,
                        $sourceName,
                        $decision,
                        $targetId,
                        $createdName,
                        null
                    );

                    continue;
                }

                $entries[] = $this->failureEntry(
                    $foundationType,
                    $item,
                    $createOutcome['reason'] ?? 'Failed to create foundation resource.'
                );
                $failed++;
            }
        }

        return [
            'entries' => $entries,
            'mapping' => $mapping,
            'failed' => $failed,
            'skipped' => $skipped,
        ];
    }

    /**
     * @param  array<int, array{source_id:string,display_name:?string}>  $existing
     * @return array<string, array<int, array{source_id:string,display_name:?string}>>
     */
    private function indexExistingByName(array $existing): array
    {
        $index = [];

        foreach ($existing as $item) {
            $name = $item['display_name'] ?? null;

            if (! is_string($name) || $name === '') {
                continue;
            }

            $index[strtolower($name)][] = [
                'source_id' => $item['source_id'],
                'display_name' => $name,
            ];
        }

        return $index;
    }

    private function resolveCopyName(string $baseName, array $existingNames): string
    {
        $suffix = ' (Copy)';
        $candidate = $baseName.$suffix;
        $normalized = array_map('strtolower', $existingNames);

        if (! in_array(strtolower($candidate), $normalized, true)) {
            return $candidate;
        }

        $counter = 2;

        while (true) {
            $candidate = sprintf('%s (Copy %d)', $baseName, $counter);

            if (! in_array(strtolower($candidate), $normalized, true)) {
                return $candidate;
            }

            $counter++;
        }
    }

    private function isBuiltInScopeTag(string $foundationType, BackupItem $item): bool
    {
        if ($foundationType !== 'roleScopeTag') {
            return false;
        }

        if ($item->policy_identifier === '0') {
            return true;
        }

        $payload = is_array($item->payload) ? $item->payload : [];

        return (bool) ($payload['isBuiltIn'] ?? false);
    }

    /**
     * @return array{success: bool, target_id: ?string, target_name: ?string, reason: ?string}
     */
    private function createFoundation(
        Tenant $tenant,
        string $foundationType,
        BackupItem $item,
        string $targetName
    ): array {
        $resource = $this->contracts->resourcePath($foundationType);

        if (! $resource) {
            return [
                'success' => false,
                'target_id' => null,
                'target_name' => null,
                'reason' => 'Graph contract resource missing for foundation type.',
            ];
        }

        $contract = $this->contracts->get($foundationType);
        $method = strtoupper((string) ($contract['create_method'] ?? 'POST'));
        $payload = $this->contracts->sanitizeUpdatePayload($foundationType, is_array($item->payload) ? $item->payload : []);
        $payload = $this->applyDisplayName($payload, $targetName);

        if ($payload === []) {
            return [
                'success' => false,
                'target_id' => null,
                'target_name' => null,
                'reason' => 'Foundation payload could not be sanitized.',
            ];
        }

        $response = $this->graphClient->request(
            $method,
            $resource,
            ['json' => $payload] + $tenant->graphOptions()
        );

        if ($response->failed()) {
            return [
                'success' => false,
                'target_id' => null,
                'target_name' => null,
                'reason' => $response->meta['error_message'] ?? 'Graph create failed.',
            ];
        }

        $data = $response->data;
        $targetId = is_array($data) ? ($data['id'] ?? null) : null;
        $targetName = is_array($data) ? ($data['displayName'] ?? $data['name'] ?? $targetName) : $targetName;

        return [
            'success' => true,
            'target_id' => is_string($targetId) ? $targetId : null,
            'target_name' => is_string($targetName) ? $targetName : $targetName,
            'reason' => null,
        ];
    }

    /**
     * @param  array<string, mixed>  $payload
     * @return array<string, mixed>
     */
    private function applyDisplayName(array $payload, string $targetName): array
    {
        if (array_key_exists('displayName', $payload)) {
            $payload['displayName'] = $targetName;

            return $payload;
        }

        if (array_key_exists('name', $payload)) {
            $payload['name'] = $targetName;

            return $payload;
        }

        $payload['displayName'] = $targetName;

        return $payload;
    }

    private function decisionEntry(
        string $foundationType,
        string $sourceId,
        string $sourceName,
        string $decision,
        ?string $targetId,
        ?string $targetName,
        ?string $reason
    ): array {
        return array_filter([
            'type' => $foundationType,
            'sourceId' => $sourceId,
            'sourceName' => $sourceName,
            'decision' => $decision,
            'targetId' => $targetId,
            'targetName' => $targetName,
            'reason' => $reason,
        ], static fn ($value) => $value !== null);
    }

    private function skipEntry(
        string $foundationType,
        string $sourceId,
        ?string $sourceName,
        string $reason
    ): array {
        return $this->decisionEntry(
            $foundationType,
            $sourceId,
            $sourceName ?? $sourceId,
            'skipped',
            null,
            null,
            $reason
        );
    }

    private function failureEntry(string $foundationType, BackupItem $item, string $reason): array
    {
        $sourceName = $item->resolvedDisplayName();

        return $this->decisionEntry(
            $foundationType,
            $item->policy_identifier,
            $sourceName,
            'failed',
            null,
            null,
            $reason
        );
    }
}