<?php

declare(strict_types=1);

namespace KTXC\SystemStore;

use KTXC\Resource\ProviderManager;
use KTXC\Service\TenantService;
use KTXF\Resource\BinaryResource;
use KTXF\Resource\Provider\ProviderInterface;
use KTXF\Resource\SystemIdentity;
use KTXF\SystemStore\BlobInfo;
use KTXF\SystemStore\InvalidKeyException;
use KTXF\SystemStore\Provider\ProviderBaseInterface;
use KTXF\SystemStore\Service\SystemStoreServiceInterface;
use KTXF\SystemStore\StoreReference;
use KTXF\SystemStore\SystemStoreException;
use KTXF\SystemStore\SystemStoreManagerInterface;
use KTXF\SystemStore\WriteCondition;

final readonly class SystemStoreManager implements SystemStoreManagerInterface
{
    public function __construct(
        private TenantService $tenants,
        private ProviderManager $providers,
    ) {
    }

    public function stat(string $tenantId, string $store, string $key): ?BlobInfo
    {
        [$service, $reference] = $this->resolve($tenantId, $store);
        $info = $service->stat($this->qualify($reference, $key));

        return $info === null ? null : $this->logicalInfo($info, $reference);
    }

    public function read(string $tenantId, string $store, string $key): ?BinaryResource
    {
        [$service, $reference] = $this->resolve($tenantId, $store);
        return $service->read($this->qualify($reference, $key));
    }

    public function write(
        string $tenantId,
        string $store,
        string $key,
        BinaryResource $content,
        array $metadata = [],
        ?WriteCondition $condition = null,
    ): BlobInfo {
        [$service, $reference] = $this->resolve($tenantId, $store);
        $info = $service->write(
            $this->qualify($reference, $key),
            $content,
            $metadata,
            $condition,
        );

        return $this->logicalInfo($info, $reference);
    }

    public function delete(
        string $tenantId,
        string $store,
        string $key,
        ?WriteCondition $condition = null,
    ): bool {
        [$service, $reference] = $this->resolve($tenantId, $store);
        return $service->delete($this->qualify($reference, $key), $condition);
    }

    public function list(string $tenantId, string $store, string $prefix = ''): iterable
    {
        [$service, $reference] = $this->resolve($tenantId, $store);
        $physicalPrefix = $reference->namespace . '/';
        if ($prefix !== '') {
            $physicalPrefix .= $this->normalizeKey($prefix, true);
        }

        return $this->logicalItems($service->list($physicalPrefix), $reference);
    }

    /** @return array{SystemStoreServiceInterface, StoreReference} */
    private function resolve(string $tenantId, string $store): array
    {
        $tenant = $this->tenants->fetchById($tenantId);
        if ($tenant === null) {
            throw new SystemStoreException("Tenant '{$tenantId}' was not found");
        }

        $reference = $tenant->getConfiguration()->stores()->store($store);
        if ($reference === null) {
            throw new SystemStoreException("System store '{$store}' is not configured for tenant '{$tenantId}'");
        }

        $provider = $this->providers->resolve(ProviderInterface::TYPE_SYSTEM_STORE, $reference->provider);
        if (!$provider instanceof ProviderBaseInterface) {
            throw new SystemStoreException("System-store provider '{$reference->provider}' is unavailable or incompatible");
        }

        $service = $provider->serviceFetch($tenantId, SystemIdentity::USER, $reference->service);
        if (!$service instanceof SystemStoreServiceInterface) {
            throw new SystemStoreException("System-store service '{$reference->service}' is unavailable or incompatible");
        }

        return [$service, $reference];
    }

    private function qualify(StoreReference $reference, string $key): string
    {
        return $reference->namespace . '/' . $this->normalizeKey($key);
    }

    private function normalizeKey(string $key, bool $allowTrailingSlash = false): string
    {
        if (
            $key === ''
            || str_starts_with($key, '/')
            || (!$allowTrailingSlash && str_ends_with($key, '/'))
            || str_contains($key, '\\')
            || str_contains($key, "\0")
        ) {
            throw new InvalidKeyException('System-store keys must be non-empty normalized relative keys');
        }

        $segments = explode('/', $key);
        if ($allowTrailingSlash && end($segments) === '') {
            array_pop($segments);
        }
        if (in_array('', $segments, true) || in_array('.', $segments, true) || in_array('..', $segments, true)) {
            throw new InvalidKeyException('System-store keys cannot contain empty or traversal segments');
        }

        return $key;
    }

    private function logicalInfo(BlobInfo $info, StoreReference $reference): BlobInfo
    {
        $prefix = $reference->namespace . '/';
        if (!str_starts_with($info->key, $prefix)) {
            throw new SystemStoreException('System-store provider returned a blob outside the configured namespace');
        }

        return new BlobInfo(
            key: substr($info->key, strlen($prefix)),
            mimeType: $info->mimeType,
            size: $info->size,
            etag: $info->etag,
            modifiedAt: $info->modifiedAt,
            attributes: $info->attributes,
        );
    }

    /**
     * @param iterable<BlobInfo> $items
     * @return iterable<BlobInfo>
     */
    private function logicalItems(iterable $items, StoreReference $reference): iterable
    {
        foreach ($items as $item) {
            if (!$item instanceof BlobInfo) {
                throw new SystemStoreException('System-store provider returned invalid listing metadata');
            }
            yield $this->logicalInfo($item, $reference);
        }
    }
}