eveseat/services

<?php

/*
 * This file is part of SeAT
 *
 * Copyright (C) 2015 to present Leon Jacobs
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

namespace Seat\Services\Services;

use Seat\Services\Exceptions\InjectedRelationConflictException;

class InjectedRelationRegistry
{
    /**
     * Lookup table to search for injected relations.
     * Maps the result from getInjectionTargetKey to a class.
     *
     * @var array<string, string>
     */
    private array $relations = [];

    /**
     * Injects all relations from a class into a model.
     *
     * @param  string  $target_model  the model to inject relations into
     * @param  string  $extension_class  the class to take the relations from
     * @return void
     *
     * @throws InjectedRelationConflictException A conflict arises when trying to inject two relations with the same name into a target.
     */
    public function injectRelations(string $target_model, string $extension_class): void
    {
        $methods = get_class_methods($extension_class);

        foreach ($methods as $relation_name){
            $this->injectSingleRelation($target_model, $extension_class, $relation_name);
        }
    }

    /**
     * Injects a single relation into a model.
     *
     * @param  string  $model  the model to inject the relation into
     * @param  string  $extension_class  the class holding the relation function
     * @param  string  $relation  the name of the relation to be injected. The method providing the relation in $extension_class must have the same name, and the relation will be accessible under this name.
     * @return void
     *
     * @throws InjectedRelationConflictException A conflict arises when trying to inject two relations with the same name into a target.
     */
    public function injectSingleRelation(string $model, string $extension_class, string $relation): void
    {
        $key = $this->getInjectionTargetKey($model, $relation);

        // check for conflicts, as there can't be two relations with the same name
        if(array_key_exists($key, $this->relations)) {
            $conflict = $this->relations[$key];
            throw new InjectedRelationConflictException(sprintf('Relation \'%s\' from \'%s\' is name-conflicting with \'%s\'', $relation, $model, $conflict));
        }

        $this->relations[$key] = $extension_class;
    }

    /**
     * Searches for injected relations for a model.
     *
     * @param  string  $model  the model to search for
     * @param  string  $relation  the relation name to search for
     * @return string|null the class providing the injected relation, or null if there is no injected relation
     */
    public function getExtensionClassFor(string $model, string $relation): ?string
    {
        return $this->relations[$this->getInjectionTargetKey($model, $relation)] ?? null;
    }

    /**
     * Generates a key for $this->$relations.
     *
     * @param  string  $model  the injection target class
     * @param  string  $relation_name  the relation name
     * @return string a key to use with $this->$relations
     */
    private function getInjectionTargetKey(string $model, string $relation_name): string {
        return sprintf('%s.%s', $model, $relation_name);
    }
}