<?php
/**
 * TPage class file
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.pradosoft.com/
 * @copyright Copyright &copy; 2005-2014 PradoSoft
 * @license http://www.pradosoft.com/license/
 * @package Prado\Web\UI
 */

namespace Prado\Web\UI;
use Prado\Collections\TList;
use Prado\Collections\TMap;
use Prado\Collections\TStack;
use Prado\Data\ActiveRecord\TActiveRecord;
use Prado\Exceptions\TConfigurationException;
use Prado\Exceptions\THttpException;
use Prado\Exceptions\TInvalidDataValueException;
use Prado\Exceptions\TInvalidDataTypeException;
use Prado\Exceptions\TInvalidOperationException;
use Prado\Prado;
use Prado\TPropertyValue;
use Prado\Web\Javascripts\TJavaScript;
use Prado\Web\UI\ActiveControls\TActivePageAdapter;
use Prado\Web\UI\ActiveControls\TCallbackClientScript;
use Prado\Web\UI\WebControls\THead;

Prado::using('System.Web.UI.*');
Prado::using('System.Web.UI.WebControls.*');

/**
 * TPage class
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package Prado\Web\UI
 * @since 3.0
 */
class TPage extends TTemplateControl
{
	/**
	 * system post fields
	 */
	const FIELD_POSTBACK_TARGET='PRADO_POSTBACK_TARGET';
	const FIELD_POSTBACK_PARAMETER='PRADO_POSTBACK_PARAMETER';
	const FIELD_LASTFOCUS='PRADO_LASTFOCUS';
	const FIELD_PAGESTATE='PRADO_PAGESTATE';
	const FIELD_CALLBACK_TARGET='PRADO_CALLBACK_TARGET';
	const FIELD_CALLBACK_PARAMETER='PRADO_CALLBACK_PARAMETER';

	/**
	 * @var array system post fields
	 */
	private static $_systemPostFields=array(
		'PRADO_POSTBACK_TARGET'=>true,
		'PRADO_POSTBACK_PARAMETER'=>true,
		'PRADO_LASTFOCUS'=>true,
		'PRADO_PAGESTATE'=>true,
		'PRADO_CALLBACK_TARGET'=>true,
		'PRADO_CALLBACK_PARAMETER'=>true
	);
	/**
	 * @var TForm form instance
	 */
	private $_form;
	/**
	 * @var THead head instance
	 */
	private $_head;
	/**
	 * @var array list of registered validators
	 */
	private $_validators=array();
	/**
	 * @var boolean if validation has been performed
	 */
	private $_validated=false;
	/**
	 * @var TTheme page theme
	 */
	private $_theme;
	/**
	 * @var string page title set when Head is not in page yet
	 */
	private $_title;
	/**
	 * @var TTheme page stylesheet theme
	 */
	private $_styleSheet;
	/**
	 * @var TClientScriptManager client script manager
	 */
	private $_clientScript;
	/**
	 * @var TMap data post back by user
	 */
	protected $_postData;
	/**
	 * @var TMap postback data that is not handled during first invocation of LoadPostData.
	 */
	protected $_restPostData;
	/**
	 * @var array list of controls whose data have been changed due to the postback
	 */
	protected $_controlsPostDataChanged=array();
	/**
	 * @var array list of controls that need to load post data in the current request
	 */
	protected $_controlsRequiringPostData=array();
	/**
	 * @var array list of controls that need to load post data in the next postback
	 */
	protected $_controlsRegisteredForPostData=array();
	/**
	 * @var TControl control that needs to raise postback event
	 */
	private $_postBackEventTarget;
	/**
	 * @var string postback event parameter
	 */
	private $_postBackEventParameter;
	/**
	 * @var boolean whether the form has been rendered
	 */
	protected $_formRendered=false;
	/**
	 * @var boolean whether the current rendering is within a form
	 */
	protected $_inFormRender=false;
	/**
	 * @var TControl|string the control or the ID of the element on the page to be focused when the page is sent back to user
	 */
	private $_focus;
	/**
	 * @var string page path to this page
	 */
	private $_pagePath='';
	/**
	 * @var boolean whether page state should be HMAC validated
	 */
	private $_enableStateValidation=true;
	/**
	 * @var boolean whether page state should be encrypted
	 */
	private $_enableStateEncryption=false;
	/**
	 * @var boolean whether page state should be compressed
	 * @since 3.1.6
	 */
	private $_enableStateCompression=true;
	/**
	 * @var string page state persister class name
	 */
	private $_statePersisterClass='\Prado\Web\UI\TPageStatePersister';
	/**
	 * @var mixed page state persister
	 */
	private $_statePersister;
	/**
	 * @var TStack stack used to store currently active caching controls
	 */
	private $_cachingStack;
	/**
	 * @var string state string to be stored on the client side
	 */
	private $_clientState='';
	/**
	 * @var boolean true if loading post data.
	 */
	protected $_isLoadingPostData=false;
	/**
	 * @var boolean whether client supports javascript
	 */
	private $_enableJavaScript=true;
	/**
	 * @var THtmlWriter current html render writer
	 */
	private $_writer;

	/**
	 * Constructor.
	 * Sets the page object to itself.
	 * Derived classes must call parent implementation.
	 */
	public function __construct()
	{
		$this->setPage($this);
	}

	/**
	 * Runs through the page lifecycles.
	 * @param THtmlTextWriter the HTML writer
	 */
	public function run($writer)
	{
		Prado::trace("Running page life cycles",'Prado\Web\UI\TPage');
		$this->_writer = $writer;

		$this->determinePostBackMode();

		if($this->getIsPostBack())
		{
			if($this->getIsCallback())
				$this->processCallbackRequest($writer);
			else
				$this->processPostBackRequest($writer);
		}
		else
			$this->processNormalRequest($writer);

		$this->_writer = null;
	}

	protected function processNormalRequest($writer)
	{
		Prado::trace("Page onPreInit()",'Prado\Web\UI\TPage');
		$this->onPreInit(null);

		Prado::trace("Page initRecursive()",'Prado\Web\UI\TPage');
		$this->initRecursive();

		Prado::trace("Page onInitComplete()",'Prado\Web\UI\TPage');
		$this->onInitComplete(null);

		Prado::trace("Page onPreLoad()",'Prado\Web\UI\TPage');
		$this->onPreLoad(null);
		Prado::trace("Page loadRecursive()",'Prado\Web\UI\TPage');
		$this->loadRecursive();
		Prado::trace("Page onLoadComplete()",'Prado\Web\UI\TPage');
		$this->onLoadComplete(null);

		Prado::trace("Page preRenderRecursive()",'Prado\Web\UI\TPage');
		$this->preRenderRecursive();
		Prado::trace("Page onPreRenderComplete()",'Prado\Web\UI\TPage');
		$this->onPreRenderComplete(null);

		Prado::trace("Page savePageState()",'Prado\Web\UI\TPage');
		$this->savePageState();
		Prado::trace("Page onSaveStateComplete()",'Prado\Web\UI\TPage');
		$this->onSaveStateComplete(null);

		Prado::trace("Page renderControl()",'Prado\Web\UI\TPage');
		$this->renderControl($writer);
		Prado::trace("Page unloadRecursive()",'Prado\Web\UI\TPage');
		$this->unloadRecursive();
	}

	protected function processPostBackRequest($writer)
	{
		Prado::trace("Page onPreInit()",'Prado\Web\UI\TPage');
		$this->onPreInit(null);

		Prado::trace("Page initRecursive()",'Prado\Web\UI\TPage');
		$this->initRecursive();

		Prado::trace("Page onInitComplete()",'Prado\Web\UI\TPage');
		$this->onInitComplete(null);

		$this->_restPostData=new TMap;
		Prado::trace("Page loadPageState()",'Prado\Web\UI\TPage');
		$this->loadPageState();
		Prado::trace("Page processPostData()",'Prado\Web\UI\TPage');
		$this->processPostData($this->_postData,true);
		Prado::trace("Page onPreLoad()",'Prado\Web\UI\TPage');
		$this->onPreLoad(null);
		Prado::trace("Page loadRecursive()",'Prado\Web\UI\TPage');
		$this->loadRecursive();
		Prado::trace("Page processPostData()",'Prado\Web\UI\TPage');
		$this->processPostData($this->_restPostData,false);
		Prado::trace("Page raiseChangedEvents()",'Prado\Web\UI\TPage');
		$this->raiseChangedEvents();
		Prado::trace("Page raisePostBackEvent()",'Prado\Web\UI\TPage');
		$this->raisePostBackEvent();
		Prado::trace("Page onLoadComplete()",'Prado\Web\UI\TPage');
		$this->onLoadComplete(null);

		Prado::trace("Page preRenderRecursive()",'Prado\Web\UI\TPage');
		$this->preRenderRecursive();
		Prado::trace("Page onPreRenderComplete()",'Prado\Web\UI\TPage');
		$this->onPreRenderComplete(null);

		Prado::trace("Page savePageState()",'Prado\Web\UI\TPage');
		$this->savePageState();
		Prado::trace("Page onSaveStateComplete()",'Prado\Web\UI\TPage');
		$this->onSaveStateComplete(null);

		Prado::trace("Page renderControl()",'Prado\Web\UI\TPage');
		$this->renderControl($writer);
		Prado::trace("Page unloadRecursive()",'Prado\Web\UI\TPage');
		$this->unloadRecursive();
	}

	protected static function decodeUTF8($data, $enc)
	{
		if(is_array($data))
		{
			foreach($data as $k=>$v)
				$data[$k]=self::decodeUTF8($v, $enc);
			return $data;
		} elseif(is_string($data)) {
			return iconv('UTF-8',$enc.'//IGNORE',$data);
		} else {
			return $data;
		}
	}

	/**
	 * Sets Adapter to TActivePageAdapter and calls apter to process the
	 * callback request.
	 */
	protected function processCallbackRequest($writer)
	{
		Prado::using('Prado\Web\UI\ActiveControls\TActivePageAdapter');

		$this->setAdapter(new TActivePageAdapter($this));

		$callbackEventParameter = $this->getRequest()->itemAt(TPage::FIELD_CALLBACK_PARAMETER);
		if(strlen($callbackEventParameter) > 0)
			$this->_postData[TPage::FIELD_CALLBACK_PARAMETER]=TJavaScript::jsonDecode((string)$callbackEventParameter);

		// Decode Callback postData from UTF-8 to current Charset
		if (($g=$this->getApplication()->getGlobalization(false))!==null &&
			strtoupper($enc=$g->getCharset())!='UTF-8')
				foreach ($this->_postData as $k=>$v)
					$this->_postData[$k]=self::decodeUTF8($v, $enc);

		Prado::trace("Page onPreInit()",'Prado\Web\UI\TPage');
		$this->onPreInit(null);

		Prado::trace("Page initRecursive()",'Prado\Web\UI\TPage');
		$this->initRecursive();

		Prado::trace("Page onInitComplete()",'Prado\Web\UI\TPage');
		$this->onInitComplete(null);

		$this->_restPostData=new TMap;
		Prado::trace("Page loadPageState()",'Prado\Web\UI\TPage');
		$this->loadPageState();
		Prado::trace("Page processPostData()",'Prado\Web\UI\TPage');
		$this->processPostData($this->_postData,true);
		Prado::trace("Page onPreLoad()",'Prado\Web\UI\TPage');
		$this->onPreLoad(null);
		Prado::trace("Page loadRecursive()",'Prado\Web\UI\TPage');
		$this->loadRecursive();

		Prado::trace("Page processPostData()",'Prado\Web\UI\TPage');
		$this->processPostData($this->_restPostData,false);

		Prado::trace("Page raiseChangedEvents()",'Prado\Web\UI\TPage');
		$this->raiseChangedEvents();


		$this->getAdapter()->processCallbackEvent($writer);

/*
		Prado::trace("Page raisePostBackEvent()",'Prado\Web\UI\TPage');
		$this->raisePostBackEvent();
*/
		Prado::trace("Page onLoadComplete()",'Prado\Web\UI\TPage');
		$this->onLoadComplete(null);

		Prado::trace("Page preRenderRecursive()",'Prado\Web\UI\TPage');
		$this->preRenderRecursive();
		Prado::trace("Page onPreRenderComplete()",'Prado\Web\UI\TPage');
		$this->onPreRenderComplete(null);

		Prado::trace("Page savePageState()",'Prado\Web\UI\TPage');
		$this->savePageState();
		Prado::trace("Page onSaveStateComplete()",'Prado\Web\UI\TPage');
		$this->onSaveStateComplete(null);

/*
		Prado::trace("Page renderControl()",'Prado\Web\UI\TPage');
		$this->renderControl($writer);
*/
		$this->getAdapter()->renderCallbackResponse($writer);

		Prado::trace("Page unloadRecursive()",'Prado\Web\UI\TPage');
		$this->unloadRecursive();
	}

	/**
	 * Gets the callback client script handler that allows javascript functions
	 * to be executed during the callback response.
	 * @return TCallbackClientScript interface to client-side javascript code.
	 */
	public function getCallbackClient()
	{
		if($this->getAdapter() !== null)
			return $this->getAdapter()->getCallbackClientHandler();
		else
			return new TCallbackClientScript();
	}

	/**
	 * Set a new callback client handler.
	 * @param TCallbackClientScript new callback client script handler.
	 */
	public function setCallbackClient($client)
	{
		$this->getAdapter()->setCallbackClientHandler($client);
	}

	/**
	 * @return TControl the control responsible for the current callback event,
	 * null if nonexistent
	 */
	public function getCallbackEventTarget()
	{
		return $this->getAdapter()->getCallbackEventTarget();
	}

	/**
	 * Registers a control to raise callback event in the current request.
	 * @param TControl control registered to raise callback event.
	 */
	public function setCallbackEventTarget(TControl $control)
	{
		$this->getAdapter()->setCallbackEventTarget($control);
	}

	/**
	 * Callback parameter is decoded assuming JSON encoding.
	 * @return string callback event parameter
	 */
	public function getCallbackEventParameter()
	{
		return $this->getAdapter()->getCallbackEventParameter();
	}

	/**
	 * @param mixed callback event parameter
	 */
	public function setCallbackEventParameter($value)
	{
		$this->getAdapter()->setCallbackEventParameter($value);
	}

	/**
	 * @return TForm the form on the page
	 */
	public function getForm()
	{
		return $this->_form;
	}

	/**
	 * Registers a TForm instance to the page.
	 * Note, a page can contain at most one TForm instance.
	 * @param TForm the form on the page
	 * @throws TInvalidOperationException if this method is invoked twice or more.
	 */
	public function setForm(TForm $form)
	{
		if($this->_form===null)
			$this->_form=$form;
		else
			throw new TInvalidOperationException('page_form_duplicated');
	}

	/**
	 * Returns a list of registered validators.
	 * If validation group is specified, only the validators in that group will be returned.
	 * @param string validation group
	 * @return TList registered validators in the requested group. If the group is null, all validators will be returned.
	 */
	public function getValidators($validationGroup=null)
	{
		if(!$this->_validators)
			$this->_validators=new TList;
		if(empty($validationGroup) === true)
			return $this->_validators;
		else
		{
			$list=new TList;
			foreach($this->_validators as $validator)
				if($validator->getValidationGroup()===$validationGroup)
					$list->add($validator);
			return $list;
		}
	}

	/**
	 * Performs input validation.
	 * This method will invoke the registered validators to perform the actual validation.
	 * If validation group is specified, only the validators in that group will be invoked.
	 * @param string validation group. If null, all validators will perform validation.
	 */
	public function validate($validationGroup=null)
	{
		Prado::trace("Page validate()",'Prado\Web\UI\TPage');
		$this->_validated=true;
		if($this->_validators && $this->_validators->getCount())
		{
			if($validationGroup===null)
			{
				foreach($this->_validators as $validator)
					$validator->validate();
			}
			else
			{
				foreach($this->_validators as $validator)
				{
					if($validator->getValidationGroup()===$validationGroup)
						$validator->validate();
				}
			}
		}
	}

	/**
	 * Returns whether user input is valid or not.
	 * This method must be invoked after {@link validate} is called.
	 * @return boolean whether the user input is valid or not.
	 * @throws TInvalidOperationException if {@link validate} is not invoked yet.
	 */
	public function getIsValid()
	{
		if($this->_validated)
		{
			if($this->_validators && $this->_validators->getCount())
			{
				foreach($this->_validators as $validator)
					if(!$validator->getIsValid())
						return false;
			}
			return true;
		}
		else
			throw new TInvalidOperationException('page_isvalid_unknown');
	}

	/**
	 * @return TTheme the theme used for the page. Defaults to null.
	 */
	public function getTheme()
	{
		if(is_string($this->_theme))
			$this->_theme=$this->getService()->getThemeManager()->getTheme($this->_theme);
		return $this->_theme;
	}

	/**
	 * Sets the theme to be used for the page.
	 * @param string|TTheme the theme name or the theme object to be used for the page.
	 */
	public function setTheme($value)
	{
		$this->_theme=empty($value)?null:$value;
	}


	/**
	 * @return TTheme the stylesheet theme used for the page. Defaults to null.
	 */
	public function getStyleSheetTheme()
	{
		if(is_string($this->_styleSheet))
			$this->_styleSheet=$this->getService()->getThemeManager()->getTheme($this->_styleSheet);
		return $this->_styleSheet;
	}

	/**
	 * Sets the stylesheet theme to be used for the page.
	 * @param string|TTheme the stylesheet theme name or the stylesheet theme object to be used for the page.
	 */
	public function setStyleSheetTheme($value)
	{
		$this->_styleSheet=empty($value)?null:$value;
	}

	/**
	 * Applies a skin in the current theme to a control.
	 * This method should only be used by framework developers.
	 * @param TControl a control to be applied skin with
	 */
	public function applyControlSkin($control)
	{
		if(($theme=$this->getTheme())!==null)
			$theme->applySkin($control);
	}

	/**
	 * Applies a stylesheet skin in the current theme to a control.
	 * This method should only be used by framework developers.
	 * @param TControl a control to be applied stylesheet skin with
	 */
	public function applyControlStyleSheet($control)
	{
		if(($theme=$this->getStyleSheetTheme())!==null)
			$theme->applySkin($control);
	}

	/**
	 * @return TClientScriptManager client script manager
	 */
	public function getClientScript()
	{
		if(!$this->_clientScript) {
			$className = $classPath = $this->getService()->getClientScriptManagerClass();
			Prado::using($className);

			if($className!=='\Prado\Web\UI\TClientScriptManager' && !is_subclass_of($className,'\Prado\Web\UI\TClientScriptManager'))
				throw new THttpException(404,'page_csmanagerclass_invalid',$className);

			$this->_clientScript=new $className($this);
		}
		return $this->_clientScript;
	}

	/**
	 * Raises OnPreInit event.
	 * This method is invoked right before {@link onInit OnInit} stage.
	 * You may override this method to provide additional initialization that
	 * should be done before {@link onInit OnInit} (e.g. setting {@link setTheme Theme} or
	 * {@link setStyleSheetTheme StyleSheetTheme}).
	 * Remember to call the parent implementation to ensure OnPreInit event is raised.
	 * @param mixed event parameter
	 */
	public function onPreInit($param)
	{
		$this->raiseEvent('OnPreInit',$this,$param);
	}

	/**
	 * Raises OnInitComplete event.
	 * This method is invoked right after {@link onInit OnInit} stage and before {@link onLoad OnLoad} stage.
	 * You may override this method to provide additional initialization that
	 * should be done after {@link onInit OnInit}.
	 * Remember to call the parent implementation to ensure OnInitComplete event is raised.
	 * @param mixed event parameter
	 */
	public function onInitComplete($param)
	{
		$this->raiseEvent('OnInitComplete',$this,$param);
	}

	/**
	 * Raises OnPreLoad event.
	 * This method is invoked right before {@link onLoad OnLoad} stage.
	 * You may override this method to provide additional page loading logic that
	 * should be done before {@link onLoad OnLoad}.
	 * Remember to call the parent implementation to ensure OnPreLoad event is raised.
	 * @param mixed event parameter
	 */
	public function onPreLoad($param)
	{
		$this->raiseEvent('OnPreLoad',$this,$param);
	}

	/**
	 * Raises OnLoadComplete event.
	 * This method is invoked right after {@link onLoad OnLoad} stage.
	 * You may override this method to provide additional page loading logic that
	 * should be done after {@link onLoad OnLoad}.
	 * Remember to call the parent implementation to ensure OnLoadComplete event is raised.
	 * @param mixed event parameter
	 */
	public function onLoadComplete($param)
	{
		$this->raiseEvent('OnLoadComplete',$this,$param);
	}

	/**
	 * Raises OnPreRenderComplete event.
	 * This method is invoked right after {@link onPreRender OnPreRender} stage.
	 * You may override this method to provide additional preparation for page rendering
	 * that should be done after {@link onPreRender OnPreRender}.
	 * Remember to call the parent implementation to ensure OnPreRenderComplete event is raised.
	 * @param mixed event parameter
	 */
	public function onPreRenderComplete($param)
	{
		$this->raiseEvent('OnPreRenderComplete',$this,$param);
		$cs=$this->getClientScript();
		$theme=$this->getTheme();
		if($theme instanceof ITheme)
		{
			foreach($theme->getStyleSheetFiles() as $url)
				$cs->registerStyleSheetFile($url,$url,$this->getCssMediaType($url));
			foreach($theme->getJavaScriptFiles() as $url)
				$cs->registerHeadScriptFile($url,$url);
		}
		$styleSheet=$this->getStyleSheetTheme();
		if($styleSheet instanceof ITheme)
		{
			foreach($styleSheet->getStyleSheetFiles() as $url)
				$cs->registerStyleSheetFile($url,$url,$this->getCssMediaType($url));
			foreach($styleSheet->getJavaScriptFiles() as $url)
				$cs->registerHeadScriptFile($url,$url);
		}

		if($cs->getRequiresHead() && $this->getHead()===null)
			throw new TConfigurationException('page_head_required');
	}

	/**
	 * Determines the media type of the CSS file.
	 * The media type is determined according to the following file name pattern:
	 *        xxx.media-type.extension
	 * For example, 'mystyle.print.css' means its media type is 'print'.
	 * @param string CSS URL
	 * @return string media type of the CSS file
	 */
	private function getCssMediaType($url)
	{
		$segs=explode('.',basename($url));
		if(isset($segs[2]))
			return $segs[count($segs)-2];
		else
			return '';
	}

	/**
	 * Raises OnSaveStateComplete event.
	 * This method is invoked right after {@link onSaveState OnSaveState} stage.
	 * You may override this method to provide additional logic after page state is saved.
	 * Remember to call the parent implementation to ensure OnSaveStateComplete event is raised.
	 * @param mixed event parameter
	 */
	public function onSaveStateComplete($param)
	{
		$this->raiseEvent('OnSaveStateComplete',$this,$param);
	}

	/**
	 * Determines whether the current page request is a postback.
	 * Call {@link getIsPostBack} to get the result.
	 */
	private function determinePostBackMode()
	{
		$postData=$this->getRequest();
		if($postData->contains(self::FIELD_PAGESTATE) || $postData->contains(self::FIELD_POSTBACK_TARGET))
			$this->_postData=$postData;
	}

	/**
	 * @return boolean whether the current page request is a postback
	 */
	public function getIsPostBack()
	{
		return $this->_postData!==null;
	}

	/**
	 * @return boolean whether this is a callback request
	 */
	public function getIsCallback()
	{
		return $this->getIsPostBack() && $this->getRequest()->contains(self::FIELD_CALLBACK_TARGET);
	}

	/**
	 * This method is invoked when control state is to be saved.
	 * You can override this method to do last step state saving.
	 * Parent implementation must be invoked.
	 */
	public function saveState()
	{
		parent::saveState();
		$this->setViewState('ControlsRequiringPostBack',$this->_controlsRegisteredForPostData,array());
	}

	/**
	 * This method is invoked right after the control has loaded its state.
	 * You can override this method to initialize data from the control state.
	 * Parent implementation must be invoked.
	 */
	public function loadState()
	{
		parent::loadState();
		$this->_controlsRequiringPostData=$this->getViewState('ControlsRequiringPostBack',array());
	}

	/**
	 * Loads page state from persistent storage.
	 */
	protected function loadPageState()
	{
		Prado::trace("Loading state",'Prado\Web\UI\TPage');
		$state=$this->getStatePersister()->load();
		$this->loadStateRecursive($state,$this->getEnableViewState());
	}

	/**
	 * Saves page state from persistent storage.
	 */
	protected function savePageState()
	{
		Prado::trace("Saving state",'Prado\Web\UI\TPage');
		$state=&$this->saveStateRecursive($this->getEnableViewState());
		$this->getStatePersister()->save($state);
	}

	/**
	 * @param string the field name
	 * @return boolean whether the specified field is a system field in postback data
	 */
	protected function isSystemPostField($field)
	{
		return isset(self::$_systemPostFields[$field]);
	}

	/**
	 * Registers a control for loading post data in the next postback.
	 * This method needs to be invoked if the control to load post data
	 * may not have a post variable in some cases. For example, a checkbox,
	 * if not checked, will not have a post value.
	 * @param TControl control registered for loading post data
	 */
	public function registerRequiresPostData($control)
	{
		$id=is_string($control)?$control:$control->getUniqueID();
		$this->_controlsRegisteredForPostData[$id]=true;
		$params=func_get_args();
		foreach($this->getCachingStack() as $item)
			$item->registerAction('Page','registerRequiresPostData',array($id));
	}

	/**
	 * @return TControl the control responsible for the current postback event, null if nonexistent
	 */
	public function getPostBackEventTarget()
	{
		if($this->_postBackEventTarget===null && $this->_postData!==null)
		{
			$eventTarget=$this->_postData->itemAt(self::FIELD_POSTBACK_TARGET);
			if(!empty($eventTarget))
				$this->_postBackEventTarget=$this->findControl($eventTarget);
		}
		return $this->_postBackEventTarget;
	}

	/**
	 * Registers a control to raise postback event in the current request.
	 * @param TControl control registered to raise postback event.
	 */
	public function setPostBackEventTarget(TControl $control)
	{
		$this->_postBackEventTarget=$control;
	}

	/**
	 * @return string postback event parameter
	 */
	public function getPostBackEventParameter()
	{
		if($this->_postBackEventParameter===null && $this->_postData!==null)
		{
			if(($this->_postBackEventParameter=$this->_postData->itemAt(self::FIELD_POSTBACK_PARAMETER))===null)
				$this->_postBackEventParameter='';
		}
		return $this->_postBackEventParameter;
	}

	/**
	 * @param string postback event parameter
	 */
	public function setPostBackEventParameter($value)
	{
		$this->_postBackEventParameter=$value;
	}

	/**
	 * Processes post data.
	 * @param TMap post data to be processed
	 * @param boolean whether this method is invoked before {@link onLoad OnLoad}.
	 */
	protected function processPostData($postData,$beforeLoad)
	{
		$this->_isLoadingPostData=true;
		if($beforeLoad)
			$this->_restPostData=new TMap;
		foreach($postData as $key=>$value)
		{
			if($this->isSystemPostField($key))
				continue;
			else if($control=$this->findControl($key))
			{
				if($control instanceof \Prado\Web\UI\IPostBackDataHandler)
				{
					if($control->loadPostData($key,$postData))
						$this->_controlsPostDataChanged[]=$control;
				}
				else if($control instanceof IPostBackEventHandler &&
					empty($this->_postData[self::FIELD_POSTBACK_TARGET]))
				{
					$this->_postData->add(self::FIELD_POSTBACK_TARGET,$key);  // not calling setPostBackEventTarget() because the control may be removed later
				}
				unset($this->_controlsRequiringPostData[$key]);
			}
			else if($beforeLoad)
				$this->_restPostData->add($key,$value);
		}

		foreach($this->_controlsRequiringPostData as $key=>$value)
		{
			if($control=$this->findControl($key))
			{
				if($control instanceof \Prado\Web\UI\IPostBackDataHandler)
				{
					if($control->loadPostData($key,$this->_postData))
						$this->_controlsPostDataChanged[]=$control;
				}
				else
					throw new TInvalidDataValueException('page_postbackcontrol_invalid',$key);
				unset($this->_controlsRequiringPostData[$key]);
			}
		}
		$this->_isLoadingPostData=false;
	}

	/**
	 * @return boolean true if loading post data.
	 */
	public function getIsLoadingPostData()
	{
		return $this->_isLoadingPostData;
	}

	/**
	 * Raises OnPostDataChangedEvent for controls whose data have been changed due to the postback.
	 */
	protected function raiseChangedEvents()
	{
		foreach($this->_controlsPostDataChanged as $control)
			$control->raisePostDataChangedEvent();
	}

	/**
	 * Raises PostBack event.
	 */
	protected function raisePostBackEvent()
	{
		if(($postBackHandler=$this->getPostBackEventTarget())===null)
			$this->validate();
		else if($postBackHandler instanceof IPostBackEventHandler)
			$postBackHandler->raisePostBackEvent($this->getPostBackEventParameter());
	}

	/**
	 * @return boolean Whether form rendering is in progress
	 */
	public function getInFormRender()
	{
		return $this->_inFormRender;
	}

	/**
	 * Ensures the control is rendered within a form.
	 * @param TControl the control to be rendered
	 * @throws TConfigurationException if the control is outside of the form
	 */
	public function ensureRenderInForm($control)
	{
		if(!$this->getIsCallback() && !$this->_inFormRender)
			throw new TConfigurationException('page_control_outofform',get_class($control), $control ? $control->getUniqueID() : null);
	}

	/**
	 * @internal This method is invoked by TForm at the beginning of its rendering
	 */
	public function beginFormRender($writer)
	{
		if($this->_formRendered)
			throw new TConfigurationException('page_form_duplicated');
		$this->_formRendered=true;
		$this->getClientScript()->registerHiddenField(self::FIELD_PAGESTATE,$this->getClientState());
		$this->_inFormRender=true;
	}

	/**
	 * @internal This method is invoked by TForm  at the end of its rendering
	 */
	public function endFormRender($writer)
	{
		if($this->_focus)
		{
			if(($this->_focus instanceof TControl) && $this->_focus->getVisible(true))
				$focus=$this->_focus->getClientID();
			else
				$focus=$this->_focus;
			$this->getClientScript()->registerFocusControl($focus);
		}
		else if($this->_postData && ($lastFocus=$this->_postData->itemAt(self::FIELD_LASTFOCUS))!==null)
			$this->getClientScript()->registerFocusControl($lastFocus);
		$this->_inFormRender=false;
	}

	/**
	 * Sets input focus on a control after the page is rendered to users.
	 * @param TControl|string control to receive focus, or the ID of the element on the page to receive focus
	 */
	public function setFocus($value)
	{
		$this->_focus=$value;
	}

	/**
	 * @return boolean whether client supports javascript. Defaults to true.
	 */
	public function getClientSupportsJavaScript()
	{
		return $this->_enableJavaScript;
	}

	/**
	 * @param boolean whether client supports javascript. If false, javascript will not be generated for controls.
	 */
	public function setClientSupportsJavaScript($value)
	{
		$this->_enableJavaScript=TPropertyValue::ensureBoolean($value);
	}

	/**
	 * @return THead page head, null if not available
	 */
	public function getHead()
	{
		return $this->_head;
	}

	/**
	 * @param THead page head
	 * @throws TInvalidOperationException if a head already exists
	 */
	public function setHead(THead $value)
	{
		if($this->_head)
			throw new TInvalidOperationException('page_head_duplicated');
		$this->_head=$value;
		if($this->_title!==null)
		{
			$this->_head->setTitle($this->_title);
			$this->_title=null;
		}
	}

	/**
	 * @return string page title.
	 */
	public function getTitle()
	{
		if($this->_head)
			return $this->_head->getTitle();
		else
			return $this->_title===null ? '' : $this->_title;
	}

	/**
	 * Sets the page title.
	 * Note, a {@link THead} control needs to place on the page
	 * in order that this title be rendered.
	 * @param string page title. This will override the title set in {@link getHead Head}.
	 */
	public function setTitle($value)
	{
		if($this->_head)
			$this->_head->setTitle($value);
		else
			$this->_title=$value;
	}

	/**
	 * Returns the state to be stored on the client side.
	 * This method should only be used by framework and control developers.
	 * @return string the state to be stored on the client side
	 */
	public function getClientState()
	{
		return $this->_clientState;
	}

	/**
	 * Sets the state to be stored on the client side.
	 * This method should only be used by framework and control developers.
	 * @param string the state to be stored on the client side
	 */
	public function setClientState($state)
	{
		$this->_clientState=$state;
	}

	/**
	 * @return string the state postback from client side
	 */
	public function getRequestClientState()
	{
		return $this->getRequest()->itemAt(self::FIELD_PAGESTATE);
	}

	/**
	 * @return string class name of the page state persister. Defaults to TPageStatePersister.
	 */
	public function getStatePersisterClass()
	{
		return $this->_statePersisterClass;
	}

	/**
	 * @param string class name of the page state persister.
	 */
	public function setStatePersisterClass($value)
	{
		$this->_statePersisterClass=$value;
	}

	/**
	 * @return IPageStatePersister page state persister
	 */
	public function getStatePersister()
	{
		if($this->_statePersister===null)
		{
			$this->_statePersister=Prado::createComponent($this->_statePersisterClass);
			if(!($this->_statePersister instanceof IPageStatePersister))
				throw new TInvalidDataTypeException('page_statepersister_invalid');
			$this->_statePersister->setPage($this);
		}
		return $this->_statePersister;
	}

	/**
	 * @return boolean whether page state should be HMAC validated. Defaults to true.
	 */
	public function getEnableStateValidation()
	{
		return $this->_enableStateValidation;
	}

	/**
	 * @param boolean whether page state should be HMAC validated.
	 */
	public function setEnableStateValidation($value)
	{
		$this->_enableStateValidation=TPropertyValue::ensureBoolean($value);
	}

	/**
	 * @return boolean whether page state should be encrypted. Defaults to false.
	 */
	public function getEnableStateEncryption()
	{
		return $this->_enableStateEncryption;
	}

	/**
	 * @param boolean whether page state should be encrypted.
	 */
	public function setEnableStateEncryption($value)
	{
		$this->_enableStateEncryption=TPropertyValue::ensureBoolean($value);
	}

	/**
	 * @return boolean whether page state should be compressed. Defaults to true.
	 * @since 3.1.6
	 */
	public function getEnableStateCompression()
	{
		return $this->_enableStateCompression;
	}

	/**
	 * @param boolean whether page state should be compressed.
	 * @since 3.1.6
	 */
	public function setEnableStateCompression($value)
	{
		$this->_enableStateCompression=TPropertyValue::ensureBoolean($value);
	}

	/**
	 * @return string the requested page path for this page
	 */
	public function getPagePath()
	{
		return $this->_pagePath;
	}

	/**
	 * @param string the requested page path for this page
	 */
	public function setPagePath($value)
	{
		$this->_pagePath=$value;
	}

	/**
	 * Registers an action associated with the content being cached.
	 * The registered action will be replayed if the content stored
	 * in the cache is served to end-users.
	 * @param string context of the action method. This is a property-path
	 * referring to the context object (e.g. Page, Page.ClientScript).
	 * @param string method name of the context object
	 * @param array list of parameters to be passed to the action method
	 */
	public function registerCachingAction($context,$funcName,$funcParams)
	{
		if($this->_cachingStack)
		{
			foreach($this->_cachingStack as $cache)
				$cache->registerAction($context,$funcName,$funcParams);
		}
	}

	/**
	 * @return TStack stack of {@link TOutputCache} objects
	 */
	public function getCachingStack()
	{
		if(!$this->_cachingStack)
			$this->_cachingStack=new TStack;
		return $this->_cachingStack;
	}

	/**
	 * Flushes output
	 */
	public function flushWriter()
	{
		if ($this->_writer)
			$this->Response->write($this->_writer->flush());
	}
		
	/**
	 * Function to update view controls with data in a given AR object.
	 * View controls and AR object need to have the same name in IDs and Attrs respectively.
	 * @param TActiveRecord $arObj
	 * @param Boolean $throwExceptions Wheter or not to throw exceptions
	 * @author Daniel Sampedro <darthdaniel85@gmail.com>
	 */
	public function tryToUpdateView($arObj, $throwExceptions = false)
	{
		$objAttrs = get_class_vars(get_class($arObj));
		foreach (array_keys($objAttrs) as $key)
		{
			try
			{
				if ($key != "RELATIONS")
				{
					$control = $this->{$key};
					if ($control instanceof \Prado\Web\UI\WebControls\TTextBox)
						$control->Text = $arObj->{$key};
					elseif ($control instanceof \Prado\Web\UI\WebControls\TCheckBox)
						$control->Checked = (boolean) $arObj->{$key};
					elseif ($control instanceof \Prado\Web\UI\WebControls\TDatePicker)
						$control->Date = $arObj->{$key};
				}
				else
				{
					foreach ($objAttrs["RELATIONS"] as $relKey => $relValues)
					{
						$relControl = $this->{$relKey};
						switch ($relValues[0])
						{
							case TActiveRecord::BELONGS_TO:
							case TActiveRecord::HAS_ONE:
								$relControl->Text = $arObj->{$relKey};
								break;
							case TActiveRecord::HAS_MANY:
								if ($relControl instanceof \Prado\Web\UI\WebControls\TListControl)
								{
									$relControl->DataSource = $arObj->{$relKey};
									$relControl->dataBind();
								}
								break;
						}
					}
					break;
				}
			} catch (\Exception $ex)
			{
				if ($throwExceptions)
					throw $ex;
			}
		}
	}

	/**
	 * Function to try to update an AR object with data in view controls.
	 * @param TActiveRecord $arObj
	 * @param Boolean $throwExceptions Wheter or not to throw exceptions
	 * @author Daniel Sampedro <darthdaniel85@gmail.com>
	 */
	public function tryToUpdateAR($arObj, $throwExceptions = false)
	{
		$objAttrs = get_class_vars(get_class($arObj));
		foreach (array_keys($objAttrs) as $key)
		{
			try
			{
				if ($key == "RELATIONS")
					break;
				$control = $this->{$key};
				if ($control instanceof \Prado\Web\UI\WebControls\TTextBox)
					$arObj->{$key} = $control->Text;
				elseif ($control instanceof \Prado\Web\UI\WebControls\TCheckBox)
					$arObj->{$key} = $control->Checked;
				elseif ($control instanceof \Prado\Web\UI\WebControls\TDatePicker)
					$arObj->{$key} = $control->Date;
			} catch (\Exception $ex)
			{
				if ($throwExceptions)
					throw $ex;
			}
		}
	}

}