<?php

declare(strict_types=1);

/**
 * SPDX-FileCopyrightText: Sebastian Krupinski <krupinski01@gmail.com>
 * SPDX-License-Identifier: AGPL-3.0-or-later
 */

namespace KTXM\ProviderMailSystem\Providers;

use InvalidArgumentException;
use KTXC\Resource\ProviderManager;
use KTXF\Mail\Provider\ProviderBaseInterface;
use KTXF\Mail\Provider\ProviderServiceMutateInterface;
use KTXF\Resource\Provider\ResourceServiceMutateInterface;
use KTXM\ProviderMailSystem\Stores\ServiceStore;

/**
 * System Mail Provider
 *
 * Rule-based routing provider for system-generated mail. Owns the reserved
 * "@system" address namespace: each service is a route that maps a logical
 * system address (e.g. authentication@system) to a backing service on a real
 * mail provider, with the sender identity rewritten on submission. A
 * "*@system" route acts as the tenant-wide default (catch-all).
 *
 * Routes are tenant scoped and resolvable only under the reserved system
 * user context.
 *
 * @since 2026.07.01
 */
class Provider implements ProviderBaseInterface, ProviderServiceMutateInterface
{

    protected const PROVIDER_IDENTIFIER  = 'system';
    protected const PROVIDER_LABEL       = 'System Mail Provider';
    protected const PROVIDER_DESCRIPTION = 'Routes system-generated mail to configured mail services';
    protected const PROVIDER_ICON        = 'mdi-email-lock';

    protected const ADDRESS_DOMAIN_SUFFIX = '@system';

    protected array $providerAbilities = [
        self::CAPABILITY_SERVICE_LIST    => true,
        self::CAPABILITY_SERVICE_FETCH   => true,
        self::CAPABILITY_SERVICE_EXTANT  => true,
        self::CAPABILITY_SERVICE_CREATE  => true,
        self::CAPABILITY_SERVICE_MODIFY  => true,
        self::CAPABILITY_SERVICE_DESTROY => true,
    ];

    public function __construct(
        private readonly ServiceStore $serviceStore,
        private readonly ProviderManager $providerManager,
    ) {}

    public function jsonSerialize(): array
    {
        return [
            self::PROPERTY_TYPE         => self::JSON_TYPE,
            self::PROPERTY_IDENTIFIER   => self::PROVIDER_IDENTIFIER,
            self::PROPERTY_LABEL        => self::PROVIDER_LABEL,
            self::PROPERTY_CAPABILITIES => $this->providerAbilities,
        ];
    }

    public function jsonDeserialize(array|string $data): static
    {
        return $this;
    }

    public function type(): string
    {
        return self::TYPE_MAIL;
    }

    public function identifier(): string
    {
        return self::PROVIDER_IDENTIFIER;
    }

    public function label(): string
    {
        return self::PROVIDER_LABEL;
    }

    public function description(): string
    {
        return self::PROVIDER_DESCRIPTION;
    }

    public function icon(): string
    {
        return self::PROVIDER_ICON;
    }

    public function capable(string $value): bool
    {
        return !empty($this->providerAbilities[$value]);
    }

    public function capabilities(): array
    {
        return $this->providerAbilities;
    }

    public function serviceList(string $tenantId, string $userId, array $filter = []): array
    {
        // routes are tenant scoped and only visible in the system user context,
        // keeping them out of regular user account listings
        if ($userId !== self::USER_SYSTEM) {
            return [];
        }

        $list = [];
        foreach ($this->serviceStore->list($tenantId, $filter ?: null) as $serviceData) {
            $serviceInstance = $this->serviceFresh()->fromStore($serviceData);
            $list[$serviceInstance->identifier()] = $serviceInstance;
        }
        return $list;
    }

    public function serviceFetch(string $tenantId, string $userId, string|int $identifier): ?Service
    {
        if ($userId !== self::USER_SYSTEM) {
            return null;
        }

        $serviceData = $this->serviceStore->fetch($tenantId, $identifier);
        if ($serviceData === null) {
            return null;
        }
        return $this->serviceFresh()->fromStore($serviceData);
    }

    /**
     * Finds the route that handles a logical system address
     *
     * Only addresses in the reserved "@system" namespace are considered, and
     * only when asked in the reserved system user context — real users can
     * not resolve (and therefore not send through) system routes. An exact
     * address match always wins over the "*@system" catch-all.
     */
    public function serviceFindByAddress(string $tenantId, string $userId, string $address): ?Service
    {
        $address = strtolower(trim($address));
        if (!str_ends_with($address, self::ADDRESS_DOMAIN_SUFFIX)) {
            return null;
        }
        if ($userId !== self::USER_SYSTEM) {
            return null;
        }

        $catchAll = null;
        /** @var Service $service */
        foreach ($this->serviceList($tenantId, $userId) as $service) {
            if (!$service->getEnabled()) {
                continue;
            }
            if ($service->hasAddressExact($address)) {
                return $service;
            }
            if ($catchAll === null && $service->hasAddressPattern($address)) {
                $catchAll = $service;
            }
        }

        return $catchAll;
    }

    public function serviceExtant(string $tenantId, string $userId, string|int ...$identifiers): array
    {
        if ($userId !== self::USER_SYSTEM) {
            return array_fill_keys(array_map('strval', $identifiers), false);
        }

        return $this->serviceStore->extant($tenantId, $identifiers);
    }

    public function serviceFresh(): Service
    {
        return new Service($this->providerManager);
    }

    public function serviceCreate(string $tenantId, string $userId, ResourceServiceMutateInterface $service): string
    {
        $this->assertSystemContext($userId);
        if (!($service instanceof Service)) {
            throw new InvalidArgumentException('Service must be an instance of System Mail Service');
        }
        $this->validateRoute($service);

        $created = $this->serviceStore->create($tenantId, $service);
        return (string)$created['sid'];
    }

    public function serviceModify(string $tenantId, string $userId, ResourceServiceMutateInterface $service): string
    {
        $this->assertSystemContext($userId);
        if (!($service instanceof Service)) {
            throw new InvalidArgumentException('Service must be an instance of System Mail Service');
        }
        $this->validateRoute($service);

        $this->serviceStore->modify($tenantId, $service);
        return (string)$service->identifier();
    }

    public function serviceDestroy(string $tenantId, string $userId, ResourceServiceMutateInterface $service): bool
    {
        $this->assertSystemContext($userId);
        if (!($service instanceof Service)) {
            return false;
        }

        return $this->serviceStore->delete($tenantId, $service->identifier());
    }

    /**
     * Ensures the operation runs in the reserved system user context
     *
     * @throws InvalidArgumentException
     */
    protected function assertSystemContext(string $userId): void
    {
        if ($userId !== self::USER_SYSTEM) {
            throw new InvalidArgumentException('System mail routes can only be managed in the system user context');
        }
    }

    /**
     * Validates route configuration before persisting
     *
     * @throws InvalidArgumentException
     */
    protected function validateRoute(Service $service): void
    {
        $address = strtolower(trim($service->getPrimaryAddress()->getAddress()));
        if ($address === '' || !str_ends_with($address, self::ADDRESS_DOMAIN_SUFFIX)) {
            throw new InvalidArgumentException('Route address must be within the reserved "@system" namespace (e.g. authentication@system or *@system)');
        }
        foreach ($service->getSecondaryAddresses() as $secondary) {
            $secondaryAddress = strtolower(trim($secondary->getAddress()));
            if ($secondaryAddress === '' || !str_ends_with($secondaryAddress, self::ADDRESS_DOMAIN_SUFFIX)) {
                throw new InvalidArgumentException('Route alias addresses must be within the reserved "@system" namespace');
            }
        }

        if ($service->getTargetProvider() === '' || $service->getTargetService() === '') {
            throw new InvalidArgumentException('Route requires a delivery target (provider and service)');
        }
        if ($service->getTargetProvider() === self::PROVIDER_IDENTIFIER) {
            throw new InvalidArgumentException('Route cannot target the system provider itself');
        }

        $fromAddress = $service->getFromAddress();
        if ($fromAddress === '' || filter_var($fromAddress, FILTER_VALIDATE_EMAIL) === false) {
            throw new InvalidArgumentException('Route requires a valid sender (from) address');
        }
    }

}