<?php
/**
 * @package     FrameworkOnFramework
 * @subpackage  view
 * @copyright   Copyright (C) 2010 - 2015 Nicholas K. Dionysopoulos / Akeeba Ltd. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */
// Protect from unauthorized access
defined('FOF_INCLUDED') or die;

/**
 * FrameworkOnFramework JSON View class. Renders the data as a JSON object or
 * array. It can optionally output HAL links as well.
 *
 * @package  FrameworkOnFramework
 * @since    2.0
 */
class FOFViewJson extends FOFViewHtml
{
	/**
	 * When set to true we'll add hypermedia to the output, implementing the
	 * HAL specification (http://stateless.co/hal_specification.html)
	 *
	 * @var   boolean
	 */
	public $useHypermedia = false;

	/**
	 * Public constructor
	 *
	 * @param   array  $config  The component's configuration array
	 */
	public function __construct($config = array())
	{
		parent::__construct($config);

		if (isset($config['use_hypermedia']))
		{
			$this->useHypermedia = (bool) $config['use_hypermedia'];
		}
	}

	/**
	 * The event which runs when we are displaying the record list JSON view
	 *
	 * @param   string  $tpl  The view sub-template to use
	 *
	 * @return  boolean  True to allow display of the view
	 */
	protected function onDisplay($tpl = null)
	{
		// Load the model
		$model = $this->getModel();

		$items = $model->getItemList();
		$this->items = $items;

		$document = FOFPlatform::getInstance()->getDocument();

		if ($document instanceof JDocument)
		{
			if ($this->useHypermedia)
			{
				$document->setMimeEncoding('application/hal+json');
			}
			else
			{
				$document->setMimeEncoding('application/json');
			}
		}

		if (is_null($tpl))
		{
			$tpl = 'json';
		}

		FOFPlatform::getInstance()->setErrorHandling(E_ALL, 'ignore');

		$hasFailed = false;

		try
		{
			$result = $this->loadTemplate($tpl, true);

			if ($result instanceof Exception)
			{
				$hasFailed = true;
			}
		}
		catch (Exception $e)
		{
			$hasFailed = true;
		}

		if ($hasFailed)
		{
			// Default JSON behaviour in case the template isn't there!
			if ($this->useHypermedia)
			{
				$haldocument = $this->_createDocumentWithHypermedia($items, $model);
				$json = $haldocument->render('json');
			}
			else
			{
				$json = json_encode($items);
			}

			// JSONP support
			$callback = $this->input->getVar('callback', null);

			if (!empty($callback))
			{
				echo $callback . '(' . $json . ')';
			}
			else
			{
				$defaultName = $this->input->getCmd('view', 'joomla');
				$filename = $this->input->getCmd('basename', $defaultName);

				$document->setName($filename);
				echo $json;
			}

			return false;
		}
		else
		{
			echo $result;

			return false;
		}
	}

	/**
	 * The event which runs when we are displaying a single item JSON view
	 *
	 * @param   string  $tpl  The view sub-template to use
	 *
	 * @return  boolean  True to allow display of the view
	 */
	protected function onRead($tpl = null)
	{
		$model = $this->getModel();

		$item = $model->getItem();
		$this->item = $item;

		$document = FOFPlatform::getInstance()->getDocument();

		if ($document instanceof JDocument)
		{
			if ($this->useHypermedia)
			{
				$document->setMimeEncoding('application/hal+json');
			}
			else
			{
				$document->setMimeEncoding('application/json');
			}
		}

		if (is_null($tpl))
		{
			$tpl = 'json';
		}

    	FOFPlatform::getInstance()->setErrorHandling(E_ALL, 'ignore');

		$hasFailed = false;

		try
		{
			$result = $this->loadTemplate($tpl, true);

            if ($result instanceof Exception)
            {
                $hasFailed = true;
            }
		}
		catch (Exception $e)
		{
			$hasFailed = true;
		}

		if ($hasFailed)
		{
			// Default JSON behaviour in case the template isn't there!

			if ($this->useHypermedia)
			{
				$haldocument = $this->_createDocumentWithHypermedia($item, $model);
				$json = $haldocument->render('json');
			}
			else
			{
				$json = json_encode($item);
			}

			// JSONP support
			$callback = $this->input->get('callback', null);

			if (!empty($callback))
			{
				echo $callback . '(' . $json . ')';
			}
			else
			{
				$defaultName = $this->input->getCmd('view', 'joomla');
				$filename = $this->input->getCmd('basename', $defaultName);
				$document->setName($filename);
				echo $json;
			}

			return false;
		}
		else
		{
			echo $result;

			return false;
		}
	}

	/**
	 * Creates a FOFHalDocument using the provided data
	 *
	 * @param   array     $data   The data to put in the document
	 * @param   FOFModel  $model  The model of this view
	 *
	 * @return  FOFHalDocument  A HAL-enabled document
	 */
	protected function _createDocumentWithHypermedia($data, $model = null)
	{
		// Create a new HAL document

		if (is_array($data))
		{
			$count = count($data);
		}
		else
		{
			$count = null;
		}

		if ($count == 1)
		{
			reset($data);
			$document = new FOFHalDocument(end($data));
		}
		else
		{
			$document = new FOFHalDocument($data);
		}

		// Create a self link
		$uri = (string) (JUri::getInstance());
		$uri = $this->_removeURIBase($uri);
		$uri = JRoute::_($uri);
		$document->addLink('self', new FOFHalLink($uri));

		// Create relative links in a record list context

		if (is_array($data) && ($model instanceof FOFModel))
		{
			$pagination = $model->getPagination();

			if ($pagination->get('pages.total') > 1)
			{
				// Try to guess URL parameters and create a prototype URL
				// NOTE: You are better off specialising this method
				$protoUri = $this->_getPrototypeURIForPagination();

				// The "first" link
				$uri = clone $protoUri;
				$uri->setVar('limitstart', 0);
				$uri = JRoute::_((string) $uri);

				$document->addLink('first', new FOFHalLink($uri));

				// Do we need a "prev" link?

				if ($pagination->get('pages.current') > 1)
				{
					$prevPage = $pagination->get('pages.current') - 1;
					$limitstart = ($prevPage - 1) * $pagination->limit;
					$uri = clone $protoUri;
					$uri->setVar('limitstart', $limitstart);
					$uri = JRoute::_((string) $uri);

					$document->addLink('prev', new FOFHalLink($uri));
				}

				// Do we need a "next" link?

				if ($pagination->get('pages.current') < $pagination->get('pages.total'))
				{
					$nextPage = $pagination->get('pages.current') + 1;
					$limitstart = ($nextPage - 1) * $pagination->limit;
					$uri = clone $protoUri;
					$uri->setVar('limitstart', $limitstart);
					$uri = JRoute::_((string) $uri);

					$document->addLink('next', new FOFHalLink($uri));
				}

				// The "last" link?
				$lastPage = $pagination->get('pages.total');
				$limitstart = ($lastPage - 1) * $pagination->limit;
				$uri = clone $protoUri;
				$uri->setVar('limitstart', $limitstart);
				$uri = JRoute::_((string) $uri);

				$document->addLink('last', new FOFHalLink($uri));
			}
		}

		return $document;
	}

	/**
	 * Convert an absolute URI to a relative one
	 *
	 * @param   string  $uri  The URI to convert
	 *
	 * @return  string  The relative URL
	 */
	protected function _removeURIBase($uri)
	{
		static $root = null, $rootlen = 0;

		if (is_null($root))
		{
			$root = rtrim(FOFPlatform::getInstance()->URIbase(), '/');
			$rootlen = strlen($root);
		}

		if (substr($uri, 0, $rootlen) == $root)
		{
			$uri = substr($uri, $rootlen);
		}

		return ltrim($uri, '/');
	}

	/**
	 * Returns a JUri instance with a prototype URI used as the base for the
	 * other URIs created by the JSON renderer
	 *
	 * @return  JUri  The prototype JUri instance
	 */
	protected function _getPrototypeURIForPagination()
	{
		$protoUri = new JUri('index.php');
		$protoUri->setQuery($this->input->getData());
		$protoUri->delVar('savestate');
		$protoUri->delVar('base_path');

		return $protoUri;
	}
}
