<?php

declare(strict_types=1);

namespace App\Services\TenantConfiguration;

use App\Models\ManagedEnvironment;
use App\Models\ManagedEnvironmentPermission;
use App\Models\ProviderConnection;
use App\Support\Providers\ProviderReasonCodes;
use Illuminate\Support\Carbon;
use Throwable;

final class ExchangePowerShellPermissionEvidenceEvaluator
{
    private const string PERMISSION_KEY = 'Exchange.ManageAsApp';

    private const string TRUSTED_EVIDENCE_SOURCE = 'provider_verification';

    private const string EVIDENCE_EVALUATOR = 'exchange_powershell_permission_evidence';

    private const string EVIDENCE_EVALUATOR_VERSION = 'v1';

    public function evaluate(ManagedEnvironment $environment, ProviderConnection $connection): ExchangePowerShellGateResult
    {
        if (trim((string) $connection->provider) !== 'microsoft') {
            return $this->blocked(
                failureCode: 'permission_evidence_blocked_unsupported_provider',
                stateKey: 'permission_evidence_state',
                state: 'unsupported_provider',
                context: ['provider' => 'unsupported'],
            );
        }

        $permission = ManagedEnvironmentPermission::query()
            ->where('workspace_id', (int) $environment->workspace_id)
            ->where('managed_environment_id', (int) $environment->getKey())
            ->where('permission_key', self::PERMISSION_KEY)
            ->orderByDesc('last_checked_at')
            ->orderByDesc('id')
            ->first();

        if (! $permission instanceof ManagedEnvironmentPermission) {
            return $this->blocked('permission_evidence_blocked_missing', 'permission_evidence_state', 'missing');
        }

        $details = is_array($permission->details) ? $permission->details : [];
        $status = $this->normalizedStatus($permission->status);

        if ($status !== 'granted') {
            return match ($status) {
                'missing', 'absent', 'revoked' => $this->blocked('permission_evidence_blocked_absent', 'permission_evidence_state', 'absent', $permission),
                'unknown', 'error' => $this->blocked('permission_evidence_blocked_unknown', 'permission_evidence_state', 'unknown', $permission),
                default => $this->blocked('permission_evidence_blocked_unvalidated', 'permission_evidence_state', 'unvalidated', $permission),
            };
        }

        $metadata = $this->validatedEvidenceMetadata($details);

        if ($metadata === null) {
            return $this->blocked('permission_evidence_blocked_unvalidated', 'permission_evidence_state', 'unvalidated', $permission);
        }

        if ($this->permissionEvidenceIsStale($permission, $metadata)) {
            return $this->blocked('permission_evidence_blocked_stale', 'permission_evidence_state', 'stale', $permission);
        }

        $scopeIds = $this->validatedScopeIds($details);

        if ($scopeIds === null) {
            return $this->blocked('permission_evidence_blocked_unvalidated', 'permission_evidence_state', 'unvalidated', $permission);
        }

        if ($scopeIds['workspace_id'] !== (int) $connection->workspace_id) {
            return $this->blocked('permission_evidence_blocked_wrong_workspace', 'permission_evidence_state', 'wrong_workspace', $permission);
        }

        if ($scopeIds['managed_environment_id'] !== (int) $connection->managed_environment_id) {
            return $this->blocked('permission_evidence_blocked_wrong_environment', 'permission_evidence_state', 'wrong_environment', $permission);
        }

        if (trim((string) ($details['provider'] ?? '')) !== 'microsoft'
            || trim((string) ($details['provider'] ?? '')) !== trim((string) $connection->provider)
        ) {
            return $this->blocked('permission_evidence_blocked_unsupported_provider', 'permission_evidence_state', 'unsupported_provider', $permission);
        }

        if ($scopeIds['provider_connection_id'] !== (int) $connection->getKey()) {
            return $this->blocked('permission_evidence_blocked_wrong_provider_connection', 'permission_evidence_state', 'wrong_provider_connection', $permission);
        }

        return ExchangePowerShellGateResult::allowed([
            'permission_evidence_state' => 'verified',
            'permission_key' => self::PERMISSION_KEY,
            'permission_evidence_id' => (int) $permission->getKey(),
            'last_checked_at' => $permission->last_checked_at?->toJSON(),
            'permission_currentness_days' => $this->currentnessDays(),
            'permission_evidence_source' => $metadata['source'],
            'permission_observed_at' => $metadata['observed_at'],
            'permission_verified_at' => $metadata['verified_at'],
            'permission_evidence_evaluator' => $metadata['evaluator'],
            'permission_evidence_evaluator_version' => $metadata['evaluator_version'],
        ]);
    }

    private function currentnessDays(): int
    {
        $configured = config('tenantpilot.exchange_powershell.permission_evidence.currentness_days', 30);

        return max(1, (int) $configured);
    }

    private function normalizedStatus(mixed $status): string
    {
        if (! is_string($status) || trim($status) === '') {
            return 'unknown';
        }

        $status = strtolower(trim($status));

        return in_array($status, ['granted', 'missing', 'absent', 'revoked', 'blocked', 'unknown', 'error'], true)
            ? $status
            : 'unknown';
    }

    /**
     * @param  array{source: string, observed_at: string, verified_at: string, evaluator: string, evaluator_version: string}  $metadata
     */
    private function permissionEvidenceIsStale(ManagedEnvironmentPermission $permission, array $metadata): bool
    {
        $freshSince = now()->subDays($this->currentnessDays());
        $observedAt = $this->safeTimestamp($metadata['observed_at']);
        $verifiedAt = $this->safeTimestamp($metadata['verified_at']);

        return ! $permission->last_checked_at
            || $permission->last_checked_at->lt($freshSince)
            || ! $observedAt instanceof Carbon
            || ! $verifiedAt instanceof Carbon
            || $observedAt->lt($freshSince)
            || $verifiedAt->lt($freshSince);
    }

    /**
     * @param  array<string, mixed>  $details
     * @return array{source: string, observed_at: string, verified_at: string, evaluator: string, evaluator_version: string}|null
     */
    private function validatedEvidenceMetadata(array $details): ?array
    {
        $source = $this->safeString($details['source'] ?? null);

        if ($source !== self::TRUSTED_EVIDENCE_SOURCE) {
            return null;
        }

        $observedAt = $this->safeTimestamp($details['observed_at'] ?? null);
        $verifiedAt = $this->safeTimestamp($details['verified_at'] ?? null);

        if (! $observedAt instanceof Carbon || ! $verifiedAt instanceof Carbon) {
            return null;
        }

        if ($observedAt->isFuture() || $verifiedAt->isFuture() || $verifiedAt->lt($observedAt)) {
            return null;
        }

        $evaluator = $this->safeString($details['evaluator'] ?? null);
        $evaluatorVersion = $this->safeString($details['evaluator_version'] ?? null);

        if ($evaluator !== self::EVIDENCE_EVALUATOR || $evaluatorVersion !== self::EVIDENCE_EVALUATOR_VERSION) {
            return null;
        }

        return [
            'source' => $source,
            'observed_at' => $observedAt->toJSON(),
            'verified_at' => $verifiedAt->toJSON(),
            'evaluator' => $evaluator,
            'evaluator_version' => $evaluatorVersion,
        ];
    }

    private function safeString(mixed $value): ?string
    {
        if (! is_string($value)) {
            return null;
        }

        $value = trim($value);

        if ($value === '') {
            return null;
        }

        return preg_match('/\A[A-Za-z0-9_.:-]{1,80}\z/', $value) === 1 ? $value : null;
    }

    private function safeTimestamp(mixed $value): ?Carbon
    {
        if (! is_string($value)) {
            return null;
        }

        $value = trim($value);

        if ($value === '') {
            return null;
        }

        $matches = [];

        if (preg_match('/\A(?<year>\d{4})-(?<month>0[1-9]|1[0-2])-(?<day>0[1-9]|[12]\d|3[01])T(?:[01]\d|2[0-3]):[0-5]\d:[0-5]\d(?:\.\d{1,6})?(?:Z|[+-](?:[01]\d|2[0-3]):[0-5]\d)\z/', $value, $matches) !== 1) {
            return null;
        }

        if (! checkdate((int) $matches['month'], (int) $matches['day'], (int) $matches['year'])) {
            return null;
        }

        try {
            return Carbon::parse($value);
        } catch (Throwable) {
            return null;
        }
    }

    /**
     * @param  array<string, mixed>  $details
     * @return array{workspace_id: int, managed_environment_id: int, provider_connection_id: int}|null
     */
    private function validatedScopeIds(array $details): ?array
    {
        $workspaceId = $this->safePositiveInteger($details['workspace_id'] ?? null);
        $environmentId = $this->safePositiveInteger($details['managed_environment_id'] ?? null);
        $providerConnectionId = $this->safePositiveInteger($details['provider_connection_id'] ?? null);

        if ($workspaceId === null || $environmentId === null || $providerConnectionId === null) {
            return null;
        }

        return [
            'workspace_id' => $workspaceId,
            'managed_environment_id' => $environmentId,
            'provider_connection_id' => $providerConnectionId,
        ];
    }

    private function safePositiveInteger(mixed $value): ?int
    {
        if (is_int($value)) {
            return $value > 0 ? $value : null;
        }

        if (! is_string($value)) {
            return null;
        }

        if ($value === '' || $value !== trim($value) || preg_match('/\A[1-9]\d{0,18}\z/', $value) !== 1) {
            return null;
        }

        $integer = filter_var($value, FILTER_VALIDATE_INT, ['options' => ['min_range' => 1]]);

        return is_int($integer) ? $integer : null;
    }

    private function blocked(
        string $failureCode,
        string $stateKey,
        string $state,
        ?ManagedEnvironmentPermission $permission = null,
        array $context = [],
    ): ExchangePowerShellGateResult {
        return ExchangePowerShellGateResult::blocked(
            reasonCode: ProviderReasonCodes::ProviderPermissionMissing,
            failureCode: $failureCode,
            message: 'Verified Exchange PowerShell permission evidence is required.',
            context: array_filter([
                $stateKey => $state,
                'permission_key' => self::PERMISSION_KEY,
                'permission_evidence_id' => $permission instanceof ManagedEnvironmentPermission ? (int) $permission->getKey() : null,
                'permission_currentness_days' => $this->currentnessDays(),
                ...$context,
            ], static fn (mixed $value): bool => $value !== null && $value !== ''),
        );
    }
}