<?php
/**
 * Joomla! Content Management System
 *
 * @copyright  (C) 2020 Open Source Matters, Inc. <https://www.joomla.org>
 * @license    GNU General Public License version 2 or later; see LICENSE.txt
 */

namespace Joomla\CMS\MVC\View\Event;

\defined('_JEXEC') or die;

use BadMethodCallException;
use Joomla\CMS\Event\AbstractImmutableEvent;

/**
 * Event for getting extra API Fields and Relations to render with an entity
 *
 * @since  4.0.0
 */
final class OnGetApiFields extends AbstractImmutableEvent
{
	/**
	 * List of types of view supported
	 *
	 * @since  4.0.0
	 */
	const LIST = 'list';

	/**
	 * List of types of view supported
	 *
	 * @since  4.0.0
	 */
	const ITEM = 'item';

	/**
	 * List of names of properties that will be rendered as relations
	 *
	 * @var    string[]
	 * @since  4.0.0
	 */
	private $extraRelations = [];

	/**
	 * List of names of properties that will be rendered as data
	 *
	 * @var    string[]
	 * @since  4.0.0
	 */
	private $extraAttributes = [];

	/**
	 * Constructor.
	 *
	 * Mandatory arguments:
	 * type         string          The type of the field. Should be a constant from static::VIEW_TYPE
	 * fields       fields          The list of fields that will be rendered in the API.
	 *
	 * @param   string  $name       The event name.
	 * @param   array   $arguments  The event arguments.
	 *
	 * @throws  BadMethodCallException
	 */
	public function __construct($name, array $arguments = array())
	{
		if (!\array_key_exists('type', $arguments))
		{
			throw new BadMethodCallException("Argument 'type' is required for event $name");
		}

		if (!\array_key_exists('fields', $arguments))
		{
			throw new BadMethodCallException("Argument 'fields' is required for event $name");
		}

		if (!\array_key_exists('context', $arguments))
		{
			throw new BadMethodCallException("Argument 'context' is required for event $name");
		}

		parent::__construct($name, $arguments);
	}

	/**
	 * Setter for the type argument
	 *
	 * @param   integer  $value  The constant from VIEW_TYPE
	 *
	 * @return  mixed
	 *
	 * @throws  BadMethodCallException  if the argument is not of the expected type
	 */
	protected function setType($value)
	{
		if (!in_array($value, [static::ITEM, static::LIST]))
		{
			throw new BadMethodCallException("Argument 'type' of event {$this->name} must be a valid value");
		}

		return $value;
	}

	/**
	 * Setter for the fields argument
	 *
	 * @param   mixed  $value  The value to set
	 *
	 * @return  array
	 *
	 * @throws  BadMethodCallException  if the argument is not a non-empty array
	 */
	protected function setFields($value)
	{
		if (!\is_array($value) || is_array($value) && empty($value))
		{
			throw new BadMethodCallException("Argument 'fields' of event {$this->name} must be be an array and not empty");
		}

		return $value;
	}

	/**
	 * Setter for the relations argument
	 *
	 * @param   mixed  $value  The value to set
	 *
	 * @return  array
	 *
	 * @throws  BadMethodCallException  if the argument is not a non-empty array
	 */
	protected function setRelations($value)
	{
		if (!\is_array($value))
		{
			throw new BadMethodCallException("Argument 'relations' of event {$this->name} must be be an array");
		}

		return $value;
	}

	/**
	 * Allows the user to add names of properties that will be interpreted as relations
	 * Note that if there is an existing data property it will also be displayed as well
	 * as the relation due to the internal implementation (this behaviour is not part of this API
	 * however and should not be guaranteed)
	 *
	 * @param   string[]  $fields  The array of additional fields to add to the data of the attribute
	 *
	 * @return  void
	 */
	public function addFields(array $fields): void
	{
		$this->extraAttributes = array_merge($this->extraAttributes, $fields);
	}

	/**
	 * Allows the user to add names of properties that will be interpreted as relations
	 * Note that if there is an existing data property it will also be displayed as well
	 * as the relation due to the internal implementation (this behaviour is not part of this API
	 * however and should not be guaranteed)
	 *
	 * @param   string[]  $fields  The array of additional fields to add as relations
	 *
	 * @return  void
	 */
	public function addRelations(array $fields): void
	{
		$this->extraRelations = array_merge($this->extraRelations, $fields);
	}

	/**
	 * Get properties to render.
	 *
	 * @return  array
	 */
	public function getAllPropertiesToRender(): array
	{
		return array_merge($this->getArgument('fields'), $this->extraAttributes);
	}

	/**
	 * Get properties to render.
	 *
	 * @return  array
	 */
	public function getAllRelationsToRender(): array
	{
		return array_merge($this->getArgument('relations'), $this->extraRelations);
	}
}
