<?php

namespace App\Filament\Pages;

use App\Filament\Resources\FindingResource;
use App\Filament\Resources\InventorySyncRunResource;
use App\Jobs\GenerateDriftFindingsJob;
use App\Models\BulkOperationRun;
use App\Models\Finding;
use App\Models\InventorySyncRun;
use App\Models\OperationRun;
use App\Models\Tenant;
use App\Models\User;
use App\Services\BulkOperationService;
use App\Services\Drift\DriftRunSelector;
use App\Services\OperationRunService;
use App\Support\OperationRunLinks;
use App\Support\RunIdempotency;
use BackedEnum;
use Filament\Actions\Action;
use Filament\Notifications\Notification;
use Filament\Pages\Page;
use UnitEnum;

class DriftLanding extends Page
{
    protected static string|BackedEnum|null $navigationIcon = 'heroicon-o-arrows-right-left';

    protected static string|UnitEnum|null $navigationGroup = 'Drift';

    protected static ?string $navigationLabel = 'Drift';

    protected string $view = 'filament.pages.drift-landing';

    public ?string $state = null;

    public ?string $message = null;

    public ?string $scopeKey = null;

    public ?int $baselineRunId = null;

    public ?int $currentRunId = null;

    public ?string $baselineFinishedAt = null;

    public ?string $currentFinishedAt = null;

    public ?int $operationRunId = null;

    public ?int $bulkOperationRunId = null;

    /** @var array<string, int>|null */
    public ?array $statusCounts = null;

    public static function canAccess(): bool
    {
        return FindingResource::canAccess();
    }

    public function mount(): void
    {
        $tenant = Tenant::current();

        $user = auth()->user();
        if (! $user instanceof User) {
            abort(403, 'Not allowed');
        }

        $latestSuccessful = InventorySyncRun::query()
            ->where('tenant_id', $tenant->getKey())
            ->where('status', InventorySyncRun::STATUS_SUCCESS)
            ->whereNotNull('finished_at')
            ->orderByDesc('finished_at')
            ->first();

        if (! $latestSuccessful instanceof InventorySyncRun) {
            $this->state = 'blocked';
            $this->message = 'No successful inventory runs found yet.';

            return;
        }

        $scopeKey = (string) $latestSuccessful->selection_hash;
        $this->scopeKey = $scopeKey;

        $selector = app(DriftRunSelector::class);
        $comparison = $selector->selectBaselineAndCurrent($tenant, $scopeKey);

        if ($comparison === null) {
            $this->state = 'blocked';
            $this->message = 'Need at least 2 successful runs for this scope to calculate drift.';

            return;
        }

        $baseline = $comparison['baseline'];
        $current = $comparison['current'];

        $this->baselineRunId = (int) $baseline->getKey();
        $this->currentRunId = (int) $current->getKey();

        $this->baselineFinishedAt = $baseline->finished_at?->toDateTimeString();
        $this->currentFinishedAt = $current->finished_at?->toDateTimeString();

        $existingOperationRun = OperationRun::query()
            ->where('tenant_id', $tenant->getKey())
            ->where('type', 'drift.generate')
            ->where('context->scope_key', $scopeKey)
            ->where('context->baseline_run_id', (int) $baseline->getKey())
            ->where('context->current_run_id', (int) $current->getKey())
            ->latest('id')
            ->first();

        if ($existingOperationRun instanceof OperationRun) {
            $this->operationRunId = (int) $existingOperationRun->getKey();
        }

        $idempotencyKey = RunIdempotency::buildKey(
            tenantId: (int) $tenant->getKey(),
            operationType: 'drift.generate',
            targetId: $scopeKey,
            context: [
                'scope_key' => $scopeKey,
                'baseline_run_id' => (int) $baseline->getKey(),
                'current_run_id' => (int) $current->getKey(),
            ],
        );

        $exists = Finding::query()
            ->where('tenant_id', $tenant->getKey())
            ->where('finding_type', Finding::FINDING_TYPE_DRIFT)
            ->where('scope_key', $scopeKey)
            ->where('baseline_run_id', $baseline->getKey())
            ->where('current_run_id', $current->getKey())
            ->exists();

        if ($exists) {
            $this->state = 'ready';
            $newCount = (int) Finding::query()
                ->where('tenant_id', $tenant->getKey())
                ->where('finding_type', Finding::FINDING_TYPE_DRIFT)
                ->where('scope_key', $scopeKey)
                ->where('baseline_run_id', $baseline->getKey())
                ->where('current_run_id', $current->getKey())
                ->where('status', Finding::STATUS_NEW)
                ->count();

            $this->statusCounts = [Finding::STATUS_NEW => $newCount];

            return;
        }

        $latestRun = BulkOperationRun::query()
            ->where('tenant_id', $tenant->getKey())
            ->where('idempotency_key', $idempotencyKey)
            ->latest('id')
            ->first();

        $activeRun = RunIdempotency::findActiveBulkOperationRun((int) $tenant->getKey(), $idempotencyKey);
        if ($activeRun instanceof BulkOperationRun) {
            $this->state = 'generating';
            $this->bulkOperationRunId = (int) $activeRun->getKey();

            return;
        }

        if ($latestRun instanceof BulkOperationRun && $latestRun->status === 'completed') {
            $this->state = 'ready';
            $this->bulkOperationRunId = (int) $latestRun->getKey();

            $newCount = (int) Finding::query()
                ->where('tenant_id', $tenant->getKey())
                ->where('finding_type', Finding::FINDING_TYPE_DRIFT)
                ->where('scope_key', $scopeKey)
                ->where('baseline_run_id', $baseline->getKey())
                ->where('current_run_id', $current->getKey())
                ->where('status', Finding::STATUS_NEW)
                ->count();

            $this->statusCounts = [Finding::STATUS_NEW => $newCount];

            if ($newCount === 0) {
                $this->message = 'No drift findings for this comparison. If you changed settings after the current run, run Inventory Sync again to capture a newer snapshot.';
            }

            return;
        }

        if ($latestRun instanceof BulkOperationRun && in_array($latestRun->status, ['failed', 'aborted'], true)) {
            $this->state = 'error';
            $this->message = 'Drift generation failed for this comparison. See the run for details.';
            $this->bulkOperationRunId = (int) $latestRun->getKey();

            return;
        }

        if (! $user->canSyncTenant($tenant)) {
            $this->state = 'blocked';
            $this->message = 'You can view existing drift findings and run history, but you do not have permission to generate drift.';

            return;
        }

        // --- Phase 3: Canonical Operation Run Start ---
        /** @var OperationRunService $opService */
        $opService = app(OperationRunService::class);
        $opRun = $opService->ensureRun(
            tenant: $tenant,
            type: 'drift.generate',
            inputs: [
                'scope_key' => $scopeKey,
                'baseline_run_id' => (int) $baseline->getKey(),
                'current_run_id' => (int) $current->getKey(),
            ],
            initiator: $user
        );

        $this->operationRunId = (int) $opRun->getKey();

        if (! $opRun->wasRecentlyCreated && in_array($opRun->status, ['queued', 'running'])) {
            $this->state = 'generating'; // Reflect generating state in UI if idempotency hit
            // Optionally, we could find the related BulkOpRun to link, but the UI might just need state.

            Notification::make()
                ->title('Drift generation already active')
                ->body('This operation is already queued or running.')
                ->warning()
                ->actions([
                    Action::make('view_run')
                        ->label('View Run')
                        ->url(OperationRunLinks::view($opRun, $tenant)),
                ])
                ->send();

            return;
        }
        // ----------------------------------------------

        $bulkOperationService = app(BulkOperationService::class);
        $run = $bulkOperationService->createRun(
            tenant: $tenant,
            user: $user,
            resource: 'drift',
            action: 'generate',
            itemIds: [
                'scope_key' => $scopeKey,
                'baseline_run_id' => (int) $baseline->getKey(),
                'current_run_id' => (int) $current->getKey(),
            ],
            totalItems: 1,
        );

        $run->update(['idempotency_key' => $idempotencyKey]);

        $this->state = 'generating';
        $this->bulkOperationRunId = (int) $run->getKey();

        /** @var OperationRunService $opService */
        $opService = app(OperationRunService::class);
        $opService->dispatchOrFail($opRun, function () use ($tenant, $user, $baseline, $current, $scopeKey, $run, $opRun): void {
            GenerateDriftFindingsJob::dispatch(
                tenantId: (int) $tenant->getKey(),
                userId: (int) $user->getKey(),
                baselineRunId: (int) $baseline->getKey(),
                currentRunId: (int) $current->getKey(),
                scopeKey: $scopeKey,
                bulkOperationRunId: (int) $run->getKey(),
                operationRun: $opRun
            );
        });

        Notification::make()
            ->title('Drift generation queued')
            ->body('Drift generation has been queued. Monitor progress in Monitoring → Operations.')
            ->success()
            ->actions([
                Action::make('view_run')
                    ->label('View run')
                    ->url(OperationRunLinks::view($opRun, $tenant)),
            ])
            ->sendToDatabase($user)
            ->send();
    }

    public function getFindingsUrl(): string
    {
        return FindingResource::getUrl('index', tenant: Tenant::current());
    }

    public function getBaselineRunUrl(): ?string
    {
        if (! is_int($this->baselineRunId)) {
            return null;
        }

        return InventorySyncRunResource::getUrl('view', ['record' => $this->baselineRunId], tenant: Tenant::current());
    }

    public function getCurrentRunUrl(): ?string
    {
        if (! is_int($this->currentRunId)) {
            return null;
        }

        return InventorySyncRunResource::getUrl('view', ['record' => $this->currentRunId], tenant: Tenant::current());
    }

    public function getOperationRunUrl(): ?string
    {
        if (! is_int($this->operationRunId)) {
            return null;
        }

        return OperationRunLinks::view($this->operationRunId, Tenant::current());
    }
}