<?php
/**
 * TPagedList, TPagedListFetchDataEventParameter, TPagedListPageChangedEventParameter class file
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link https://github.com/pradosoft/prado
 * @copyright Copyright &copy; 2005-2016 The PRADO Group
 * @license https://github.com/pradosoft/prado/blob/master/COPYRIGHT
 * @package System.Collections
 */

/**
 * TPagedList class
 *
 * TPagedList implements a list with paging functionality.
 *
 * TPagedList works in one of two modes, managed paging or customized paging,
 * specified by {@link setCustomPaging CustomPaging}.
 * - Managed paging ({@link setCustomPaging CustomPaging}=false) :
 *   the list is assumed to contain all data and it will manage which page
 *   of data are available to user.
 * - Customized paging ({@link setCustomPaging CustomPaging}=true) :
 *   the list is assumed to contain only one page of data. An  {@link onFetchData OnFetchData}
 *   event will be raised if the list changes to a different page.
 *   Developers can attach a handler to the event and supply the needed data.
 *   The event handler can be written as follows,
 * <code>
 *  public function fetchData($sender,$param)
 *  {
 *    $offset=$param->Offset; // beginning index of the data needed
 *    $limit=$param->Limit;   // maximum number of data items needed
 *    // get data according to the above two parameters
 *    $param->Data=$data;
 *  }
 * </code>
 *
 * Data in TPagedList can be accessed like an integer-indexed array and can
 * be traversed using foreach. For example,
 * <code>
 * $count=$list->Count;
 * for($index=0;$index<$count;++$index)
 *     echo $list[$index];
 * foreach($list as $index=>$item) // traverse each item in the list
 * </code>
 *
 * The {@link setPageSize PageSize} property specifies the number of items in each page.
 * To access different page of data in the list, set {@link setCurrentPageIndex CurrentPageIndex}
 * or call {@link nextPage()}, {@link previousPage()}, or {@link gotoPage()}.
 * The total number of pages can be obtained by {@link getPageCount() PageCount}.
 *
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package System.Collections
 * @since 3.0
 */
class TPagedList extends TList
{
	/**
	 * @var boolean whether to allow custom paging
	 */
	private $_customPaging=false;
	/**
	 * @var integer number of items in each page
	 */
	private $_pageSize=10;
	/**
	 * @var integer current page index
	 */
	private $_currentPageIndex=-1;
	/**
	 * @var integer user-assigned number of items in data source
	 */
	private $_virtualCount=-1;

	/**
	 * Constructor.
	 * @param array|Iterator the initial data. Default is null, meaning no initialization.
	 * @param boolean whether the list is read-only. Always true for paged list.
	 */
	public function __construct($data=null,$readOnly=false)
	{
		parent::__construct($data,true);
	}

	/**
	 * @return boolean whether to use custom paging. Defaults to false.
	 */
	public function getCustomPaging()
	{
		return $this->_customPaging;
	}

	/**
	 * @param boolean whether to allow custom paging
	 */
	public function setCustomPaging($value)
	{
		$this->_customPaging=TPropertyValue::ensureBoolean($value);
	}

	/**
	 * @return integer number of items in each page. Defaults to 10.
	 */
	public function getPageSize()
	{
		return $this->_pageSize;
	}

	/**
	 * @param integer number of items in each page
	 */
	public function setPageSize($value)
	{
		if(($value=TPropertyValue::ensureInteger($value))>0)
			$this->_pageSize=$value;
		else
			throw new TInvalidDataValueException('pagedlist_pagesize_invalid');
	}

	/**
	 * @return integer current page index. Defaults to 0.
	 */
	public function getCurrentPageIndex()
	{
		return $this->_currentPageIndex;
	}

	/**
	 * @param integer current page index
	 * @throws TInvalidDataValueException if the page index is out of range
	 */
	public function setCurrentPageIndex($value)
	{
		if($this->gotoPage($value=TPropertyValue::ensureInteger($value))===false)
			throw new TInvalidDataValueException('pagedlist_currentpageindex_invalid');
	}

	/**
	 * Raises <b>OnPageIndexChanged</b> event.
	 * This event is raised each time when the list changes to a different page.
	 * @param TPagedListPageChangedEventParameter event parameter
	 */
	public function onPageIndexChanged($param)
	{
		$this->raiseEvent('OnPageIndexChanged',$this,$param);
	}

	/**
	 * Raises <b>OnFetchData</b> event.
	 * This event is raised each time when the list changes to a different page
	 * and needs the new page of data. This event can only be raised when
	 * {@link setCustomPaging CustomPaging} is true.
	 * @param TPagedListFetchDataEventParameter event parameter
	 */
	public function onFetchData($param)
	{
		$this->raiseEvent('OnFetchData',$this,$param);
	}

	/**
	 * Changes to a page with the specified page index.
	 * @param integer page index
	 * @return integer|boolean the new page index, false if page index is out of range.
	 */
	public function gotoPage($pageIndex)
	{
		if($pageIndex===$this->_currentPageIndex)
			return $pageIndex;
		if($this->_customPaging)
		{
			if($pageIndex>=0 && ($this->_virtualCount<0 || $pageIndex<$this->getPageCount()))
			{
				$param=new TPagedListFetchDataEventParameter($pageIndex,$this->_pageSize*$pageIndex,$this->_pageSize);
				$this->onFetchData($param);
				if(($data=$param->getData())!==null)
				{
					$this->setReadOnly(false);
					$this->copyFrom($data);
					$this->setReadOnly(true);
					$oldPage=$this->_currentPageIndex;
					$this->_currentPageIndex=$pageIndex;
					$this->onPageIndexChanged(new TPagedListPageChangedEventParameter($oldPage));
					return $pageIndex;
				}
				else
					return false;
			}
			else
				return false;
		}
		else
		{
			if($pageIndex>=0 && $pageIndex<$this->getPageCount())
			{
				$this->_currentPageIndex=$pageIndex;
				$this->onPageIndexChanged(null);
				return $pageIndex;
			}
			else
				return false;
		}
	}

	/**
	 * Switches to the next page.
	 * @return integer|boolean the new page index, false if next page is not available.
	 */
	public function nextPage()
	{
		return $this->gotoPage($this->_currentPageIndex+1);
	}

	/**
	 * Switches to the previous page.
	 * @return integer|boolean the new page index, false if previous page is not available.
	 */
	public function previousPage()
	{
		return $this->gotoPage($this->_currentPageIndex-1);
	}

	/**
	 * @return integer user-assigned number of items in data source. Defaults to 0.
	 */
	public function getVirtualCount()
	{
		return $this->_virtualCount;
	}

	/**
	 * @param integer user-assigned number of items in data source
	 */
	public function setVirtualCount($value)
	{
		if(($value=TPropertyValue::ensureInteger($value))<0)
			$value=-1;
		$this->_virtualCount=$value;
	}

	/**
	 * @return integer number of pages, -1 if under custom paging mode and {@link setVirtualCount VirtualCount} is not set.
	 */
	public function getPageCount()
	{
		if($this->_customPaging)
		{
			if($this->_virtualCount>=0)
				return (int)(($this->_virtualCount+$this->_pageSize-1)/$this->_pageSize);
			else
				return -1;
		}
		else
			return (int)((parent::getCount()+$this->_pageSize-1)/$this->_pageSize);
	}

	/**
	 * @return boolean whether the current page is the first page
	 */
	public function getIsFirstPage()
	{
		return $this->_currentPageIndex===0;
	}

	/**
	 * @return boolean whether the current page is the last page
	 */
	public function getIsLastPage()
	{
		return $this->_currentPageIndex===$this->getPageCount()-1;
	}

	/**
	 * @return integer the number of items in current page
	 */
	public function getCount()
	{
		if($this->_customPaging)
			return parent::getCount();
		else
		{
			if($this->_currentPageIndex===$this->getPageCount()-1)
				return parent::getCount()-$this->_pageSize*$this->_currentPageIndex;
			else
				return $this->_pageSize;
		}
	}

	/**
	 * @return Iterator iterator
	 */
	public function getIterator()
	{
		if($this->_customPaging)
			return parent::getIterator();
		else
		{
			$data=$this->toArray();
			return new ArrayIterator($data);
		}
	}

	/**
	 * Returns the item at the specified offset.
	 * This method is exactly the same as {@link offsetGet}.
	 * @param integer the index of the item
	 * @return mixed the item at the index
	 * @throws TInvalidDataValueException if the index is out of the range
	 */
	public function itemAt($index)
	{
		if($this->_customPaging)
			return parent::itemAt($index);
		else
			return parent::itemAt($this->_pageSize*$this->_currentPageIndex+$index);
	}

	/**
	 * @param mixed the item
	 * @return integer the index of the item in the list (0 based), -1 if not found.
	 */
	public function indexOf($item)
	{
		$c=$this->getCount();
		for($i=0;$i<$c;++$i)
			if($this->itemAt($i)===$item)
				return $i;
		return -1;
	}

	/**
	 * Returns whether there is an item at the specified offset.
	 * This method is required by the interface ArrayAccess.
	 * @param integer the offset to check on
	 * @return boolean
	 */
	public function offsetExists($offset)
	{
		return ($offset>=0 && $offset<$this->getCount());
	}

	/**
	 * Returns the item at the specified offset.
	 * This method is required by the interface ArrayAccess.
	 * @param integer the offset to retrieve item.
	 * @return mixed the item at the offset
	 * @throws TInvalidDataValueException if the offset is invalid
	 */
	public function offsetGet($offset)
	{
		return $this->itemAt($offset);
	}

	/**
	 * @return array the list of items in array
	 */
	public function toArray()
	{
		$c=$this->getCount();
		$array=array();
		for($i=0;$i<$c;++$i)
			$array[$i]=$this->itemAt($i);
		return $array;
	}
}

/**
 * TPagedListPageChangedEventParameter class.
 * TPagedListPageChangedEventParameter is used as the parameter for
 * {@link TPagedList::onPageChanged OnPageChanged} event.
 * To obtain the page index before it was changed, use {@link getOldPageIndex OldPageIndex}.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package System.Collections
 * @since 3.0
 */
class TPagedListPageChangedEventParameter extends TEventParameter
{
	private $_oldPage;

	/**
	 * Constructor.
	 * @param integer old page index
	 */
	public function __construct($oldPage)
	{
		$this->_oldPage=$oldPage;
	}

	/**
	 * @return integer the index of the page before the list changed to the new page
	 */
	public function getOldPageIndex()
	{
		return $this->_oldPage;
	}
}

/**
 * TPagedListFetchDataEventParameter class.
 *
 * TPagedListFetchDataEventParameter is used as the parameter for
 * {@link TPagedList::onFetchData OnFetchData} event.
 * To obtain the new page index, use {@link getNewPageIndex NewPageIndex}.
 * The {@link getOffset Offset} property refers to the index
 * of the first item in the new page, while {@link getLimit Limit}
 * specifies how many items are requested for the page.
 * Newly fetched data should be saved in {@link setData Data} property.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package System.Collections
 * @since 3.0
 */
class TPagedListFetchDataEventParameter extends TEventParameter
{
	private $_pageIndex;
	private $_offset;
	private $_limit;
	private $_data=null;

	/**
	 * Constructor.
	 * @param integer new page index
	 * @param integer offset of the first item in the new page
	 * @param integer number of items in the new page desired
	 */
	public function __construct($pageIndex,$offset,$limit)
	{
		$this->_pageIndex=$pageIndex;
		$this->_offset=$offset;
		$this->_limit=$limit;
	}

	/**
	 * @return integer the zero-based index of the new page
	 */
	public function getNewPageIndex()
	{
		return $this->_pageIndex;
	}

	/**
	 * @return integer offset of the first item in the new page
	 */
	public function getOffset()
	{
		return $this->_offset;
	}

	/**
	 * @return integer number of items in the new page
	 */
	public function getLimit()
	{
		return $this->_limit;
	}

	/**
	 * @return mixed new page data
	 */
	public function getData()
	{
		return $this->_data;
	}

	/**
	 * @param mixed new page data
	 */
	public function setData($value)
	{
		$this->_data=$value;
	}
}