<?php

declare(strict_types=1);

namespace KTXT\Unit\Preview;

use DateTimeImmutable;
use KTXC\Models\Tenant\TenantConfiguration;
use KTXC\Models\Tenant\TenantObject;
use KTXC\Preview\PreviewManager;
use KTXC\Resource\ProviderManager;
use KTXC\Service\TenantService;
use KTXC\SystemStore\SystemStoreManager;
use KTXF\Preview\PreviewGenerationException;
use KTXF\Preview\PreviewRequest;
use KTXF\Preview\PreviewResult;
use KTXF\Preview\PreviewSource;
use KTXF\Preview\Provider\PreviewProviderInterface;
use KTXF\Resource\BinaryResource;
use KTXF\Resource\Provider\ProviderInterface;
use KTXF\SystemStore\BlobInfo;
use KTXF\SystemStore\Provider\ProviderBaseInterface;
use KTXF\SystemStore\Service\SystemStoreServiceInterface;
use PHPUnit\Framework\Attributes\Test;
use PHPUnit\Framework\MockObject\MockObject;
use PHPUnit\Framework\MockObject\Stub;
use PHPUnit\Framework\TestCase;
use Psr\Log\LoggerInterface;

final class PreviewManagerTest extends TestCase
{
    #[Test]
    public function returnsAValidCacheHitWithoutGenerating(): void
    {
        $source = $this->source();
        $provider = $this->provider();
        $request = $this->request();
        $key = $this->cacheKey($source, $request);
        $blob = $this->blob($this->physicalKey($key));
        $service = $this->createMock(SystemStoreServiceInterface::class);
        $service->expects(self::once())->method('stat')->willReturn($blob);
        $service->expects(self::once())->method('read')->willReturn($this->resource());
        $service->expects(self::never())->method('write');
        $provider->expects(self::never())->method('generate');

        $cached = $this->manager($provider, $service)->fetch('tenant-a', $source);

        self::assertSame($blob->etag, $cached?->etag);
        self::assertSame(7, $cached?->size);
    }

    #[Test]
    public function generatesStoresAndReturnsAPreviewOnCacheMiss(): void
    {
        $source = $this->source();
        $provider = $this->provider();
        $request = $this->request();
        $key = $this->cacheKey($source, $request);
        $result = new PreviewResult($this->resource(), 320, 200);
        $blob = $this->blob($this->physicalKey($key));
        $provider->expects(self::once())->method('generate')->with($source, self::isInstanceOf(PreviewRequest::class))->willReturn($result);
        $service = $this->createMock(SystemStoreServiceInterface::class);
        $service->expects(self::once())->method('stat')->willReturn(null);
        $service->expects(self::once())->method('write')->with(
            $this->physicalKey($key),
            $result->resource,
            ['width' => 320, 'height' => 200],
            null,
        )->willReturn($blob);
        $service->expects(self::once())->method('read')->willReturn($this->resource());

        $cached = $this->manager($provider, $service)->fetch('tenant-a', $source);

        self::assertSame($blob->etag, $cached?->etag);
    }

    #[Test]
    public function disabledOrOversizedSourcesDoNotReachProviders(): void
    {
        $configuration = (new TenantConfiguration())->jsonDeserialize([
            'preview' => ['enabled' => false],
        ]);
        $providerManager = $this->createMock(ProviderManager::class);
        $providerManager->expects(self::never())->method('providers');
        $service = $this->createMock(SystemStoreServiceInterface::class);
        $service->expects(self::never())->method('stat');
        $provider = $this->provider();
        $provider->expects(self::never())->method('generate');

        self::assertNull($this->manager(
            $provider,
            $service,
            $configuration,
            $providerManager,
        )->fetch('tenant-a', $this->source()));
    }

    #[Test]
    public function generationFailuresBecomePreviewUnavailable(): void
    {
        $source = $this->source();
        $provider = $this->provider();
        $provider->expects(self::once())->method('generate')->willThrowException(new \RuntimeException('decode failed'));
        $service = $this->createMock(SystemStoreServiceInterface::class);
        $service->expects(self::once())->method('stat')->willReturn(null);
        $logger = $this->createMock(LoggerInterface::class);
        $logger->expects(self::once())->method('warning')->with('Preview unavailable', self::arrayHasKey('exception'));

        self::assertNull($this->manager($provider, $service, logger: $logger)->fetch('tenant-a', $source));
    }

    #[Test]
    public function selectsACompatibleProviderByPriorityThenRegistryIdentifier(): void
    {
        $source = $this->source();
        $alpha = $this->candidate('alpha', 20, true);
        $zeta = $this->candidate('zeta', 20, true);
        $low = $this->candidate('low', 10, true);
        $rejecting = $this->candidate('rejecting', 100, false);
        $providerManager = $this->createMock(ProviderManager::class);
        $providerManager->expects(self::once())
            ->method('providers')
            ->with(ProviderInterface::TYPE_PREVIEW)
            ->willReturn([
                'rejecting' => $rejecting,
                'zeta' => $zeta,
                'low' => $low,
                'alpha' => $alpha,
            ]);

        $key = $this->cacheKey($source, $this->request());
        $result = new PreviewResult($this->resource(), 320, 200);
        $alpha->expects(self::once())->method('generate')->willReturn($result);
        $zeta->expects(self::never())->method('generate');
        $low->expects(self::never())->method('generate');
        $rejecting->expects(self::never())->method('generate');
        $service = $this->createMock(SystemStoreServiceInterface::class);
        $blob = $this->blob($this->physicalKey($key));
        $service->expects(self::once())->method('stat')->with($this->physicalKey($key))->willReturn(null);
        $service->expects(self::once())->method('write')->willReturn($blob);
        $service->expects(self::once())->method('read')->willReturn($this->resource());

        $cached = $this->manager($alpha, $service, providerManager: $providerManager)->fetch('tenant-a', $source);

        self::assertSame($blob->etag, $cached?->etag);
    }

    #[Test]
    public function unsupportedRequestsBecomePreviewUnavailable(): void
    {
        $provider = $this->candidate('pdf', 10, false);
        $providerManager = $this->createMock(ProviderManager::class);
        $providerManager->expects(self::once())->method('providers')->willReturn(['pdf' => $provider]);
        $service = $this->createMock(SystemStoreServiceInterface::class);
        $service->expects(self::once())->method('stat')->willReturn(null);
        $logger = $this->createMock(LoggerInterface::class);
        $logger->expects(self::once())->method('warning')->with(
            'Preview unavailable',
            self::callback(static fn(array $context): bool =>
                ($context['exception'] ?? null) instanceof PreviewGenerationException
            ),
        );

        self::assertNull($this->manager(
            $provider,
            $service,
            providerManager: $providerManager,
            logger: $logger,
        )->fetch('tenant-a', $this->source()));
    }

    #[Test]
    public function cacheKeysAreDeterministicOpaqueAndChangeWithSourceIdentity(): void
    {
        $provider = $this->provider();
        $provider->expects(self::never())->method('generate');
        $providerManager = $this->createMock(ProviderManager::class);
        $providerManager->expects(self::never())->method('providers');
        $observedKeys = [];
        $service = $this->createMock(SystemStoreServiceInterface::class);
        $service->expects(self::exactly(3))->method('stat')->willReturnCallback(
            function (string $key) use (&$observedKeys): BlobInfo {
                $observedKeys[] = $key;
                return $this->blob($key);
            },
        );
        $service->expects(self::exactly(3))->method('read')->willReturnCallback(fn() => $this->resource());
        $manager = $this->manager($provider, $service, providerManager: $providerManager);
        $source = $this->source();
        $changedSource = new PreviewSource(
            'document',
            'quarterly-report',
            'revision-2',
            'image/jpeg',
            1234,
            fn(): BinaryResource => $this->resource('image/jpeg'),
        );

        self::assertNotNull($manager->fetch('tenant-a', $source));
        self::assertNotNull($manager->fetch('tenant-a', $source));
        self::assertNotNull($manager->fetch('tenant-a', $changedSource));

        self::assertSame($observedKeys[0], $observedKeys[1]);
        self::assertNotSame($observedKeys[0], $observedKeys[2]);
        self::assertMatchesRegularExpression(
            '~^tenant-previews/generated/document/[a-f0-9]{2}/[a-f0-9]{64}$~',
            $observedKeys[0],
        );
        self::assertStringNotContainsString('tenant-a', $observedKeys[0]);
        self::assertStringNotContainsString('quarterly-report', $observedKeys[0]);
    }

    #[Test]
    public function invalidCachedMetadataIsTreatedAsAMiss(): void
    {
        $provider = $this->provider();
        $provider->expects(self::once())->method('generate')->willThrowException(new \RuntimeException('stop after miss'));
        $service = $this->createMock(SystemStoreServiceInterface::class);
        $service->expects(self::once())->method('stat')->willReturnCallback(
            fn(string $key): BlobInfo => $this->blob($key, ['width' => 900, 'height' => 200]),
        );
        $service->expects(self::never())->method('read');
        $service->expects(self::never())->method('write');

        self::assertNull($this->manager($provider, $service)->fetch('tenant-a', $this->source()));
    }

    #[Test]
    public function refusesGeneratedContentWithTheWrongMimeType(): void
    {
        $provider = $this->provider();
        $provider->expects(self::once())->method('generate')->willReturn(
            new PreviewResult($this->resource('image/png'), 320, 200),
        );
        $service = $this->createMock(SystemStoreServiceInterface::class);
        $service->expects(self::once())->method('stat')->willReturn(null);
        $service->expects(self::never())->method('write');
        $logger = $this->createMock(LoggerInterface::class);
        $logger->expects(self::once())->method('warning')->with(
            'Preview unavailable',
            self::callback(static fn(array $context): bool =>
                ($context['exception'] ?? null) instanceof PreviewGenerationException
            ),
        );

        self::assertNull($this->manager($provider, $service, logger: $logger)->fetch('tenant-a', $this->source()));
    }

    private function manager(
        PreviewProviderInterface $provider,
        SystemStoreServiceInterface $service,
        ?TenantConfiguration $configuration = null,
        ?ProviderManager $providerManager = null,
        ?LoggerInterface $logger = null,
    ): PreviewManager {
        $effectiveConfiguration = $configuration ?? new TenantConfiguration();
        if ($configuration === null) {
            $effectiveConfiguration->jsonDeserialize([
                'stores' => [
                    'previews' => [
                        'provider' => 'storage-provider',
                        'service' => 'preview-storage',
                        'namespace' => 'tenant-previews',
                    ],
                ],
            ]);
        }
        $tenant = (new TenantObject())
            ->setIdentifier('tenant-a')
            ->setConfiguration($effectiveConfiguration);
        $tenants = $this->createStub(TenantService::class);
        $tenants->method('fetchById')->willReturn($tenant);

        if ($providerManager === null) {
            $providerManager = $this->createStub(ProviderManager::class);
            $providerManager->method('providers')->willReturn(['imagemagick' => $provider]);
        }

        $storageProvider = $this->createStub(ProviderBaseInterface::class);
        $storageProvider->method('serviceFetch')->willReturn($service);
        $systemProviders = $this->createStub(ProviderManager::class);
        $systemProviders->method('resolve')->willReturn($storageProvider);

        return new PreviewManager(
            $tenants,
            $providerManager,
            new SystemStoreManager($tenants, $systemProviders),
            $logger ?? $this->createStub(LoggerInterface::class),
        );
    }

    private function provider(): PreviewProviderInterface&MockObject
    {
        $provider = $this->createMock(PreviewProviderInterface::class);
        $provider->method('identifier')->willReturn('imagemagick');
        $provider->method('supports')->willReturn(true);
        $provider->method('priority')->willReturn(100);
        return $provider;
    }

    private function candidate(
        string $identifier,
        int $priority,
        bool $supports,
    ): PreviewProviderInterface&MockObject {
        $provider = $this->createMock(PreviewProviderInterface::class);
        $provider->method('identifier')->willReturn($identifier);
        $provider->method('supports')->willReturn($supports);
        $provider->method('priority')->willReturn($priority);
        return $provider;
    }

    private function source(): PreviewSource
    {
        return new PreviewSource(
            'document',
            'quarterly-report',
            'revision-1',
            'image/jpeg',
            1234,
            fn(): BinaryResource => $this->resource('image/jpeg'),
        );
    }

    private function request(): PreviewRequest
    {
        return new PreviewRequest(640, 640, 'image/webp', 80);
    }

    private function resource(string $mimeType = 'image/webp'): BinaryResource
    {
        return new BinaryResource(
            'preview.bin',
            $mimeType,
            (static function (): \Generator { yield 'preview'; })(),
        );
    }

    private function blob(string $key, array $attributes = ['width' => 320, 'height' => 200]): BlobInfo
    {
        return new BlobInfo(
            key: $key,
            mimeType: 'image/webp',
            size: 7,
            etag: 'etag-1',
            modifiedAt: new DateTimeImmutable('2026-08-29T12:00:00+00:00'),
            attributes: $attributes,
        );
    }

    private function physicalKey(string $key): string
    {
        return 'tenant-previews/' . $key;
    }

    private function cacheKey(
        PreviewSource $source,
        PreviewRequest $request,
    ): string {
        $canonical = json_encode([
            'tenantId' => 'tenant-a',
            'source' => [
                'type' => $source->sourceType,
                'identity' => $source->identity,
                'signature' => $source->signature,
                'mimeType' => $source->mimeType,
            ],
            'request' => [
                'maxWidth' => $request->maxWidth,
                'maxHeight' => $request->maxHeight,
                'preferredMimeType' => $request->preferredMimeType,
                'quality' => $request->quality,
            ],
        ], JSON_THROW_ON_ERROR | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_PRESERVE_ZERO_FRACTION);
        $digest = hash('sha256', $canonical);

        return "generated/{$source->sourceType}/" . substr($digest, 0, 2) . "/{$digest}";
    }
}