<?php

/**
 * @package KantPHP
 * @author  Zhenqiang Zhang <zhenqiang.zhang@hotmail.com>
 * @copyright (c) KantPHP Studio, All rights reserved.
 * @license http://www.opensource.org/licenses/BSD-3-Clause  The BSD 3-Clause License
 */
namespace Kant\Rest;

use Kant\Kant;
use Kant\Exception\InvalidConfigException;
use Kant\Database\ActiveRecordInterface;
use Kant\Exception\NotFoundHttpException;

/**
 * Action is the base class for action classes that implement RESTful API.
 *
 * For more details and usage information on Action, see the [guide article on rest controllers](guide:rest-controllers).
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class Action extends \Kant\Action\Action
{

    /**
     *
     * @var string class name of the model which will be handled by this action.
     *      The model class must implement [[ActiveRecordInterface]].
     *      This property must be set.
     */
    public $modelClass;

    /**
     *
     * @var callable a PHP callable that will be called to return the model corresponding
     *      to the specified primary key value. If not set, [[findModel()]] will be used instead.
     *      The signature of the callable should be:
     *     
     *      ```php
     *      function ($id, $action) {
     *      // $id is the primary key value. If composite primary key, the key values
     *      // will be separated by comma.
     *      // $action is the action object currently running
     *      }
     *      ```
     *     
     *      The callable should return the model found, or throw an exception if not found.
     */
    public $findModel;

    /**
     *
     * @var callable a PHP callable that will be called when running an action to determine
     *      if the current user has the permission to execute the action. If not set, the access
     *      check will not be performed. The signature of the callable should be as follows,
     *     
     *      ```php
     *      function ($action, $model = null) {
     *      // $model is the requested model instance.
     *      // If null, it means no specific model (e.g. IndexAction)
     *      }
     *      ```
     */
    public $checkAccess;

    /**
     * @inheritdoc
     */
    public function init()
    {
        if ($this->modelClass === null) {
            throw new InvalidConfigException(get_class($this) . '::$modelClass must be set.');
        }
    }

    /**
     * Returns the data model based on the primary key given.
     * If the data model is not found, a 404 HTTP exception will be raised.
     * 
     * @param string $id
     *            the ID of the model to be loaded. If the model has a composite primary key,
     *            the ID must be a string of the primary key values separated by commas.
     *            The order of the primary key values should follow that returned by the `primaryKey()` method
     *            of the model.
     * @return ActiveRecordInterface the model found
     * @throws NotFoundHttpException if the model cannot be found
     */
    public function findModel($id)
    {
        if ($this->findModel !== null) {
            return call_user_func($this->findModel, $id, $this);
        }
        
        /* @var $modelClass ActiveRecordInterface */
        $modelClass = $this->modelClass;
        
        $keys = $modelClass::primaryKey();
        
        if (count($keys) > 1) {
            $values = explode(',', $id);
            if (count($keys) === count($values)) {
                $model = $modelClass::findOne(array_combine($keys, $values));
            }
        } elseif ($id !== null) {
            $model = $modelClass::findOne($id);
        }
        
        if (isset($model)) {
            return $model;
        } else {
            throw new NotFoundHttpException("Object not found: $id");
        }
    }
}
