<?php

declare(strict_types=1);

namespace App\Services\Runbooks;

use App\Jobs\BackfillFindingLifecycleJob;
use App\Jobs\BackfillFindingLifecycleWorkspaceJob;
use App\Models\Finding;
use App\Models\OperationRun;
use App\Models\PlatformUser;
use App\Models\Tenant;
use App\Models\Workspace;
use App\Notifications\OperationRunCompleted;
use App\Services\Alerts\AlertDispatchService;
use App\Services\Auth\BreakGlassSession;
use App\Services\Intune\AuditLogger;
use App\Services\OperationRunService;
use App\Services\System\AllowedTenantUniverse;
use App\Support\OperationRunOutcome;
use App\Support\OperationRunStatus;
use App\Support\System\SystemOperationRunLinks;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;
use Throwable;

class FindingsLifecycleBackfillRunbookService
{
    public const string RUNBOOK_KEY = 'findings.lifecycle.backfill';

    public function __construct(
        private readonly AllowedTenantUniverse $allowedTenantUniverse,
        private readonly BreakGlassSession $breakGlassSession,
        private readonly OperationRunService $operationRunService,
        private readonly AuditLogger $auditLogger,
        private readonly AlertDispatchService $alertDispatchService,
    ) {}

    /**
     * @return array{affected_count: int, total_count: int, estimated_tenants?: int|null}
     */
    public function preflight(FindingsLifecycleBackfillScope $scope): array
    {
        $result = $this->computePreflight($scope);

        $this->auditSafely(
            action: 'platform.ops.runbooks.preflight',
            scope: $scope,
            operationRunId: null,
            context: [
                'preflight' => $result,
            ],
        );

        return $result;
    }

    public function start(
        FindingsLifecycleBackfillScope $scope,
        ?PlatformUser $initiator,
        ?RunbookReason $reason,
        string $source,
    ): OperationRun {
        $source = trim($source);

        if ($source === '') {
            throw ValidationException::withMessages([
                'source' => 'A run source is required.',
            ]);
        }

        $isBreakGlassActive = $this->breakGlassSession->isActive();

        if ($scope->isAllTenants() || $isBreakGlassActive) {
            if (! $reason instanceof RunbookReason) {
                throw ValidationException::withMessages([
                    'reason' => 'A reason is required for this run.',
                ]);
            }
        }

        $preflight = $this->computePreflight($scope);

        if (($preflight['affected_count'] ?? 0) <= 0) {
            throw ValidationException::withMessages([
                'preflight.affected_count' => 'Nothing to do for this scope.',
            ]);
        }

        $platformTenant = $this->platformTenant();
        $workspace = $platformTenant->workspace;

        if (! $workspace instanceof Workspace) {
            throw new \RuntimeException('Platform tenant is missing its workspace.');
        }

        if ($scope->isAllTenants()) {
            $lockKey = sprintf('tenantpilot:runbooks:%s:workspace:%d', self::RUNBOOK_KEY, (int) $workspace->getKey());
            $lock = Cache::lock($lockKey, 900);

            if (! $lock->get()) {
                throw ValidationException::withMessages([
                    'scope' => 'Another run is already in progress for this scope.',
                ]);
            }

            try {
                return $this->startAllTenants(
                    workspace: $workspace,
                    initiator: $initiator,
                    reason: $reason,
                    preflight: $preflight,
                    source: $source,
                    isBreakGlassActive: $isBreakGlassActive,
                );
            } finally {
                $lock->release();
            }
        }

        return $this->startSingleTenant(
            tenantId: (int) $scope->tenantId,
            initiator: $initiator,
            reason: $reason,
            preflight: $preflight,
            source: $source,
            isBreakGlassActive: $isBreakGlassActive,
        );
    }

    public function maybeFinalize(OperationRun $run): void
    {
        $run->refresh();

        if ($run->status !== OperationRunStatus::Completed->value) {
            return;
        }

        $context = is_array($run->context) ? $run->context : [];

        if ((string) data_get($context, 'runbook.key') !== self::RUNBOOK_KEY) {
            return;
        }

        $lockKey = sprintf('tenantpilot:runbooks:%s:finalize:%d', self::RUNBOOK_KEY, (int) $run->getKey());
        $lock = Cache::lock($lockKey, 86400);

        if (! $lock->get()) {
            return;
        }

        try {
            $this->auditSafely(
                action: $run->outcome === OperationRunOutcome::Failed->value
                    ? 'platform.ops.runbooks.failed'
                    : 'platform.ops.runbooks.completed',
                scope: $this->scopeFromRunContext($context),
                operationRunId: (int) $run->getKey(),
                context: [
                    'status' => (string) $run->status,
                    'outcome' => (string) $run->outcome,
                    'is_break_glass' => (bool) data_get($context, 'platform_initiator.is_break_glass', false),
                    'reason_code' => data_get($context, 'reason.reason_code'),
                    'reason_text' => data_get($context, 'reason.reason_text'),
                ],
            );

            $this->notifyInitiatorSafely($run);

            if ($run->outcome === OperationRunOutcome::Failed->value) {
                $this->dispatchFailureAlertSafely($run);
            }
        } finally {
            $lock->release();
        }
    }

    /**
     * @return array{affected_count: int, total_count: int, estimated_tenants?: int|null}
     */
    private function computePreflight(FindingsLifecycleBackfillScope $scope): array
    {
        if ($scope->isSingleTenant()) {
            $tenant = Tenant::query()->whereKey((int) $scope->tenantId)->firstOrFail();
            $this->allowedTenantUniverse->ensureAllowed($tenant);

            return $this->computeTenantPreflight($tenant);
        }

        $platformTenant = $this->platformTenant();
        $workspaceId = (int) ($platformTenant->workspace_id ?? 0);

        $tenants = $this->allowedTenantUniverse
            ->query()
            ->where('workspace_id', $workspaceId)
            ->orderBy('id')
            ->get();

        $affected = 0;
        $total = 0;

        foreach ($tenants as $tenant) {
            if (! $tenant instanceof Tenant) {
                continue;
            }

            $counts = $this->computeTenantPreflight($tenant);

            $affected += (int) ($counts['affected_count'] ?? 0);
            $total += (int) ($counts['total_count'] ?? 0);
        }

        return [
            'affected_count' => $affected,
            'total_count' => $total,
            'estimated_tenants' => $tenants->count(),
        ];
    }

    /**
     * @return array{affected_count: int, total_count: int}
     */
    private function computeTenantPreflight(Tenant $tenant): array
    {
        $query = Finding::query()->where('tenant_id', (int) $tenant->getKey());

        $total = (int) (clone $query)->count();

        $affected = 0;

        (clone $query)
            ->orderBy('id')
            ->chunkById(500, function ($findings) use (&$affected): void {
                foreach ($findings as $finding) {
                    if (! $finding instanceof Finding) {
                        continue;
                    }

                    if ($this->findingNeedsBackfill($finding)) {
                        $affected++;
                    }
                }
            });

        $affected += $this->countDriftDuplicateConsolidations($tenant);

        return [
            'affected_count' => $affected,
            'total_count' => $total,
        ];
    }

    private function findingNeedsBackfill(Finding $finding): bool
    {
        if ($finding->first_seen_at === null || $finding->last_seen_at === null) {
            return true;
        }

        if ($finding->last_seen_at !== null && $finding->first_seen_at !== null) {
            if ($finding->last_seen_at->lt($finding->first_seen_at)) {
                return true;
            }
        }

        $timesSeen = is_numeric($finding->times_seen) ? (int) $finding->times_seen : 0;

        if ($timesSeen < 1) {
            return true;
        }

        if ($finding->status === Finding::STATUS_ACKNOWLEDGED) {
            return true;
        }

        if (Finding::isOpenStatus((string) $finding->status)) {
            if ($finding->sla_days === null || $finding->due_at === null) {
                return true;
            }
        }

        if ($finding->finding_type === Finding::FINDING_TYPE_DRIFT) {
            $recurrenceKey = $finding->recurrence_key !== null ? trim((string) $finding->recurrence_key) : '';

            if ($recurrenceKey === '') {
                $scopeKey = trim((string) ($finding->scope_key ?? ''));
                $subjectType = trim((string) ($finding->subject_type ?? ''));
                $subjectExternalId = trim((string) ($finding->subject_external_id ?? ''));

                if ($scopeKey !== '' && $subjectType !== '' && $subjectExternalId !== '') {
                    $evidence = is_array($finding->evidence_jsonb) ? $finding->evidence_jsonb : [];
                    $kind = data_get($evidence, 'summary.kind');

                    if (is_string($kind) && trim($kind) !== '') {
                        return true;
                    }
                }
            }
        }

        return false;
    }

    private function countDriftDuplicateConsolidations(Tenant $tenant): int
    {
        $rows = Finding::query()
            ->where('tenant_id', (int) $tenant->getKey())
            ->where('finding_type', Finding::FINDING_TYPE_DRIFT)
            ->whereNotNull('recurrence_key')
            ->select(['recurrence_key', DB::raw('COUNT(*) as count')])
            ->groupBy('recurrence_key')
            ->havingRaw('COUNT(*) > 1')
            ->get();

        $duplicates = 0;

        foreach ($rows as $row) {
            $count = is_numeric($row->count ?? null) ? (int) $row->count : 0;

            if ($count > 1) {
                $duplicates += ($count - 1);
            }
        }

        return $duplicates;
    }

    private function startAllTenants(
        Workspace $workspace,
        ?PlatformUser $initiator,
        ?RunbookReason $reason,
        array $preflight,
        string $source,
        bool $isBreakGlassActive,
    ): OperationRun {
        $run = $this->operationRunService->ensureWorkspaceRunWithIdentity(
            workspace: $workspace,
            type: self::RUNBOOK_KEY,
            identityInputs: [
                'runbook' => self::RUNBOOK_KEY,
                'scope' => FindingsLifecycleBackfillScope::MODE_ALL_TENANTS,
            ],
            context: $this->buildRunContext(
                workspaceId: (int) $workspace->getKey(),
                scope: FindingsLifecycleBackfillScope::allTenants(),
                initiator: $initiator,
                reason: $reason,
                preflight: $preflight,
                source: $source,
                isBreakGlassActive: $isBreakGlassActive,
            ),
            initiator: null,
        );

        if ($initiator instanceof PlatformUser && $run->wasRecentlyCreated) {
            $run->update(['initiator_name' => $initiator->name ?: $initiator->email]);
            $run->refresh();
        }

        $this->auditSafely(
            action: 'platform.ops.runbooks.start',
            scope: FindingsLifecycleBackfillScope::allTenants(),
            operationRunId: (int) $run->getKey(),
            context: [
                'preflight' => $preflight,
                'is_break_glass' => $isBreakGlassActive,
            ] + ($reason instanceof RunbookReason ? $reason->toArray() : []),
        );

        if (! $run->wasRecentlyCreated) {
            return $run;
        }

        $this->operationRunService->dispatchOrFail($run, function () use ($run, $workspace): void {
            BackfillFindingLifecycleWorkspaceJob::dispatch(
                operationRunId: (int) $run->getKey(),
                workspaceId: (int) $workspace->getKey(),
            );
        });

        return $run;
    }

    private function startSingleTenant(
        int $tenantId,
        ?PlatformUser $initiator,
        ?RunbookReason $reason,
        array $preflight,
        string $source,
        bool $isBreakGlassActive,
    ): OperationRun {
        $tenant = Tenant::query()->whereKey($tenantId)->firstOrFail();
        $this->allowedTenantUniverse->ensureAllowed($tenant);

        $run = $this->operationRunService->ensureRunWithIdentity(
            tenant: $tenant,
            type: self::RUNBOOK_KEY,
            identityInputs: [
                'tenant_id' => (int) $tenant->getKey(),
                'trigger' => 'backfill',
            ],
            context: $this->buildRunContext(
                workspaceId: (int) $tenant->workspace_id,
                scope: FindingsLifecycleBackfillScope::singleTenant((int) $tenant->getKey()),
                initiator: $initiator,
                reason: $reason,
                preflight: $preflight,
                source: $source,
                isBreakGlassActive: $isBreakGlassActive,
            ),
            initiator: null,
        );

        if ($initiator instanceof PlatformUser && $run->wasRecentlyCreated) {
            $run->update(['initiator_name' => $initiator->name ?: $initiator->email]);
            $run->refresh();
        }

        $this->auditSafely(
            action: 'platform.ops.runbooks.start',
            scope: FindingsLifecycleBackfillScope::singleTenant((int) $tenant->getKey()),
            operationRunId: (int) $run->getKey(),
            context: [
                'preflight' => $preflight,
                'is_break_glass' => $isBreakGlassActive,
            ] + ($reason instanceof RunbookReason ? $reason->toArray() : []),
        );

        if (! $run->wasRecentlyCreated) {
            return $run;
        }

        $this->operationRunService->dispatchOrFail($run, function () use ($tenant): void {
            BackfillFindingLifecycleJob::dispatch(
                tenantId: (int) $tenant->getKey(),
                workspaceId: (int) $tenant->workspace_id,
                initiatorUserId: null,
            );
        });

        return $run;
    }

    private function platformTenant(): Tenant
    {
        $tenant = Tenant::query()->where('external_id', 'platform')->first();

        if (! $tenant instanceof Tenant) {
            throw new \RuntimeException('Platform tenant is missing.');
        }

        return $tenant;
    }

    /**
     * @return array<string, mixed>
     */
    private function buildRunContext(
        int $workspaceId,
        FindingsLifecycleBackfillScope $scope,
        ?PlatformUser $initiator,
        ?RunbookReason $reason,
        array $preflight,
        string $source,
        bool $isBreakGlassActive,
    ): array {
        $context = [
            'workspace_id' => $workspaceId,
            'runbook' => [
                'key' => self::RUNBOOK_KEY,
                'scope' => $scope->mode,
                'target_tenant_id' => $scope->tenantId,
                'source' => $source,
            ],
            'preflight' => [
                'affected_count' => (int) ($preflight['affected_count'] ?? 0),
                'total_count' => (int) ($preflight['total_count'] ?? 0),
                'estimated_tenants' => $preflight['estimated_tenants'] ?? null,
            ],
        ];

        if ($reason instanceof RunbookReason) {
            $context['reason'] = $reason->toArray();
        }

        if ($initiator instanceof PlatformUser) {
            $context['platform_initiator'] = [
                'platform_user_id' => (int) $initiator->getKey(),
                'email' => (string) $initiator->email,
                'name' => (string) $initiator->name,
                'is_break_glass' => $isBreakGlassActive,
            ];
        }

        return $context;
    }

    private function scopeFromRunContext(array $context): FindingsLifecycleBackfillScope
    {
        $scope = data_get($context, 'runbook.scope');
        $tenantId = data_get($context, 'runbook.target_tenant_id');

        if ($scope === FindingsLifecycleBackfillScope::MODE_SINGLE_TENANT && is_numeric($tenantId)) {
            return FindingsLifecycleBackfillScope::singleTenant((int) $tenantId);
        }

        return FindingsLifecycleBackfillScope::allTenants();
    }

    /**
     * @param  array<string, mixed>  $context
     */
    private function auditSafely(
        string $action,
        FindingsLifecycleBackfillScope $scope,
        ?int $operationRunId,
        array $context = [],
    ): void {
        try {
            $platformTenant = $this->platformTenant();

            $actor = auth('platform')->user();

            $actorId = null;
            $actorEmail = null;
            $actorName = null;

            if ($actor instanceof PlatformUser) {
                $actorId = (int) $actor->getKey();
                $actorEmail = (string) $actor->email;
                $actorName = (string) $actor->name;
            }

            $metadata = [
                'runbook_key' => self::RUNBOOK_KEY,
                'scope' => $scope->mode,
                'target_tenant_id' => $scope->tenantId,
                'operation_run_id' => $operationRunId,
                'ip' => request()->ip(),
                'user_agent' => request()->userAgent(),
            ];

            $this->auditLogger->log(
                tenant: $platformTenant,
                action: $action,
                context: [
                    'metadata' => array_filter($metadata, static fn (mixed $value): bool => $value !== null),
                ] + $context,
                actorId: $actorId,
                actorEmail: $actorEmail,
                actorName: $actorName,
                status: 'success',
                resourceType: 'operation_run',
                resourceId: $operationRunId !== null ? (string) $operationRunId : null,
            );
        } catch (Throwable) {
            // Audit is fail-safe (must not crash runbooks).
        }
    }

    private function notifyInitiatorSafely(OperationRun $run): void
    {
        try {
            $platformUserId = data_get($run->context, 'platform_initiator.platform_user_id');

            if (! is_numeric($platformUserId)) {
                return;
            }

            $platformUser = PlatformUser::query()->whereKey((int) $platformUserId)->first();

            if (! $platformUser instanceof PlatformUser) {
                return;
            }

            $platformUser->notify(new OperationRunCompleted($run));
        } catch (Throwable) {
            // Notifications must not crash the runbook.
        }
    }

    private function dispatchFailureAlertSafely(OperationRun $run): void
    {
        try {
            $platformTenant = $this->platformTenant();
            $workspace = $platformTenant->workspace;

            if (! $workspace instanceof Workspace) {
                return;
            }

            $this->alertDispatchService->dispatchEvent($workspace, [
                'tenant_id' => (int) $platformTenant->getKey(),
                'event_type' => 'operations.run.failed',
                'severity' => 'high',
                'title' => 'Operation failed: Findings lifecycle backfill',
                'body' => 'A findings lifecycle backfill run failed.',
                'metadata' => [
                    'operation_run_id' => (int) $run->getKey(),
                    'operation_type' => (string) $run->type,
                    'scope' => (string) data_get($run->context, 'runbook.scope', ''),
                    'view_run_url' => SystemOperationRunLinks::view($run),
                ],
            ]);
        } catch (Throwable) {
            // Alerts must not crash the runbook.
        }
    }
}