<?php
/**
 * TButton 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\WebControls
 */

namespace Prado\Web\UI\WebControls;

/**
 * TButton class
 *
 * TButton creates a click button on the page. It is mainly used to submit data to a page.
 *
 * TButton raises two server-side events, {@link onClick OnClick} and {@link onCommand OnCommand},
 * when it is clicked on the client-side. The difference between these two events
 * is that the event {@link onCommand OnCommand} is bubbled up to the button's ancestor controls.
 * And within the event parameter for {@link onCommand OnCommand} contains the reference
 * to the {@link setCommandName CommandName} and {@link setCommandParameter CommandParameter}
 * property values that are set for the button object. This allows you to create multiple TButton
 * components on a Web page and programmatically determine which one is clicked
 * with what parameter.
 *
 * Clicking on button can also trigger form validation, if
 * {@link setCausesValidation CausesValidation} is true.
 * The validation may be restricted within a certain group of validator
 * controls by setting {@link setValidationGroup ValidationGroup} property.
 * If validation is successful, the data will be post back to the same page.
 *
 * TButton displays the {@link setText Text} property as the button caption.
 *
 * TButton can be one of three {@link setButtonType ButtonType}: Submit, Button and Reset.
 * By default, it is a Submit button and the form submission uses the browser's
 * default submission capability. If it is Button or Reset, postback may occur
 * if one of the following conditions is met:
 * - an event handler is attached to {@link onClick OnClick} event;
 * - an event handler is attached to {@link onCommand OnCommand} event;
 * - the button is in a non-empty validation group.
 * In addition, clicking on a Reset button will clear up all input fields
 * if the button does not cause a postback.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package Prado\Web\UI\WebControls
 * @since 3.0
 */
class TButton extends TWebControl implements IPostBackEventHandler, IButtonControl, IDataRenderer
{
	/**
	 * @return string tag name of the button
	 */
	protected function getTagName()
	{
		return 'input';
	}

	/**
	 * @return boolean whether to render javascript.
	 */
	public function getEnableClientScript()
	{
		return $this->getViewState('EnableClientScript',true);
	}

	/**
	 * @param boolean whether to render javascript.
	 */
	public function setEnableClientScript($value)
	{
		$this->setViewState('EnableClientScript',TPropertyValue::ensureBoolean($value),true);
	}

	/**
	 * Adds attribute name-value pairs to renderer.
	 * This overrides the parent implementation with additional button specific attributes.
	 * @param THtmlWriter the writer used for the rendering purpose
	 */
	protected function addAttributesToRender($writer)
	{
		$page=$this->getPage();
		$page->ensureRenderInForm($this);
		$writer->addAttribute('type',strtolower($this->getButtonType()));
		if(($uniqueID=$this->getUniqueID())!=='')
			$writer->addAttribute('name',$uniqueID);
		$writer->addAttribute('value',$this->getText());
		if($this->getEnabled(true))
		{
			if($this->getEnableClientScript() && $this->needPostBackScript())
				$this->renderClientControlScript($writer);
		}
		else if($this->getEnabled()) // in this case, parent will not render 'disabled'
			$writer->addAttribute('disabled','disabled');

		parent::addAttributesToRender($writer);
	}

	/**
	 * Renders the client-script code.
	 */
	protected function renderClientControlScript($writer)
	{
		$writer->addAttribute('id',$this->getClientID());
		$this->getPage()->getClientScript()->registerPostBackControl($this->getClientClassName(),$this->getPostBackOptions());
	}

	/**
	 * Gets the name of the javascript class responsible for performing postback for this control.
	 * This method overrides the parent implementation.
	 * @return string the javascript class name
	 */
	protected function getClientClassName()
	{
		return 'Prado.WebUI.TButton';
	}

	/**
	 * @return boolean whether to perform validation if the button is clicked
	 */
	protected function canCauseValidation()
	{
		if($this->getCausesValidation())
		{
			$group=$this->getValidationGroup();
			return $this->getPage()->getValidators($group)->getCount()>0;
		}
		else
			return false;
	}

	/**
	 * @param boolean set by a panel to register this button as the default button for the panel.
	 */
	public function setIsDefaultButton($value)
	{
		$this->setViewState('IsDefaultButton', TPropertyValue::ensureBoolean($value),false);
	}

	/**
	 * @return boolean true if this button is registered as a default button for a panel.
	 */
	public function getIsDefaultButton()
	{
		return $this->getViewState('IsDefaultButton', false);
	}

	/**
	 * @return boolean whether the button needs javascript to do postback
	 */
	protected function needPostBackScript()
	{
		return $this->canCauseValidation() || ($this->getButtonType()!==TButtonType::Submit &&
			($this->hasEventHandler('OnClick') || $this->hasEventHandler('OnCommand')))
			|| $this->getIsDefaultButton();
	}

	/**
	 * Returns postback specifications for the button.
	 * This method is used by framework and control developers.
	 * @return array parameters about how the button defines its postback behavior.
	 */
	protected function getPostBackOptions()
	{
		$options['ID']=$this->getClientID();
		$options['CausesValidation']=$this->getCausesValidation();
		$options['EventTarget'] = $this->getUniqueID();
		$options['ValidationGroup']=$this->getValidationGroup();

		return $options;
	}

	/**
	 * Renders the body content enclosed between the control tag.
	 * This overrides the parent implementation with nothing to be rendered.
	 * @param THtmlWriter the writer used for the rendering purpose
	 */
	public function renderContents($writer)
	{
	}

	/**
	 * This method is invoked when the button is clicked.
	 * The method raises 'OnClick' event to fire up the event handlers.
	 * If you override this method, be sure to call the parent implementation
	 * so that the event handler can be invoked.
	 * @param TEventParameter event parameter to be passed to the event handlers
	 */
	public function onClick($param)
	{
		$this->raiseEvent('OnClick',$this,$param);
	}

	/**
	 * This method is invoked when the button is clicked.
	 * The method raises 'OnCommand' event to fire up the event handlers.
	 * If you override this method, be sure to call the parent implementation
	 * so that the event handlers can be invoked.
	 * @param TCommandEventParameter event parameter to be passed to the event handlers
	 */
	public function onCommand($param)
	{
		$this->raiseEvent('OnCommand',$this,$param);
		$this->raiseBubbleEvent($this,$param);
	}

	/**
	 * Raises the postback event.
	 * This method is required by {@link IPostBackEventHandler} interface.
	 * If {@link getCausesValidation CausesValidation} is true, it will
	 * invoke the page's {@link TPage::validate validate} method first.
	 * It will raise {@link onClick OnClick} and {@link onCommand OnCommand} events.
	 * This method is mainly used by framework and control developers.
	 * @param TEventParameter the event parameter
	 */
	public function raisePostBackEvent($param)
	{
		if($this->getCausesValidation())
			$this->getPage()->validate($this->getValidationGroup());
		$this->onClick(null);
		$this->onCommand(new TCommandEventParameter($this->getCommandName(),$this->getCommandParameter()));
	}

	/**
	 * @return string caption of the button
	 */
	public function getText()
	{
		return $this->getViewState('Text','');
	}

	/**
	 * @param string caption of the button
	 */
	public function setText($value)
	{
		$this->setViewState('Text',$value,'');
	}

	/**
	 * Returns the caption of the button.
	 * This method is required by {@link IDataRenderer}.
	 * It is the same as {@link getText()}.
	 * @return string caption of the button.
	 * @see getText
	 * @since 3.1.0
	 */
	public function getData()
	{
		return $this->getText();
	}

	/**
	 * Sets the caption of the button.
	 * This method is required by {@link IDataRenderer}.
	 * It is the same as {@link setText()}.
	 * @param string caption of the button
	 * @see setText
	 * @since 3.1.0
	 */
	public function setData($value)
	{
		$this->setText($value);
	}

	/**
	 * @return boolean whether postback event trigger by this button will cause input validation, default is true
	 */
	public function getCausesValidation()
	{
		return $this->getViewState('CausesValidation',true);
	}

	/**
	 * @param boolean whether postback event trigger by this button will cause input validation
	 */
	public function setCausesValidation($value)
	{
		$this->setViewState('CausesValidation',TPropertyValue::ensureBoolean($value),true);
	}

	/**
	 * @return string the command name associated with the {@link onCommand OnCommand} event.
	 */
	public function getCommandName()
	{
		return $this->getViewState('CommandName','');
	}

	/**
	 * @param string the command name associated with the {@link onCommand OnCommand} event.
	 */
	public function setCommandName($value)
	{
		$this->setViewState('CommandName',$value,'');
	}

	/**
	 * @return string the parameter associated with the {@link onCommand OnCommand} event
	 */
	public function getCommandParameter()
	{
		return $this->getViewState('CommandParameter','');
	}

	/**
	 * @param string the parameter associated with the {@link onCommand OnCommand} event.
	 */
	public function setCommandParameter($value)
	{
		$this->setViewState('CommandParameter',$value,'');
	}

	/**
	 * @return string the group of validators which the button causes validation upon postback
	 */
	public function getValidationGroup()
	{
		return $this->getViewState('ValidationGroup','');
	}

	/**
	 * @param string the group of validators which the button causes validation upon postback
	 */
	public function setValidationGroup($value)
	{
		$this->setViewState('ValidationGroup',$value,'');
	}

	/**
	 * @return TButtonType the type of the button. Defaults to TButtonType::Submit.
	 */
	public function getButtonType()
	{
		return $this->getViewState('ButtonType',TButtonType::Submit);
	}

	/**
	 * @param TButtonType the type of the button.
	 */
	public function setButtonType($value)
	{
		$this->setViewState('ButtonType',TPropertyValue::ensureEnum($value,'TButtonType'),TButtonType::Submit);
	}
}