<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\data;

use Yii;
use yii\base\Component;
use yii\base\InvalidParamException;

/**
 * BaseDataProvider provides a base class that implements the [[DataProviderInterface]].
 *
 * @property integer $count The number of data models in the current page. This property is read-only.
 * @property array $keys The list of key values corresponding to [[models]]. Each data model in [[models]] is
 * uniquely identified by the corresponding key value in this array.
 * @property array $models The list of data models in the current page.
 * @property Pagination|boolean $pagination The pagination object. If this is false, it means the pagination
 * is disabled. Note that the type of this property differs in getter and setter. See [[getPagination()]] and
 * [[setPagination()]] for details.
 * @property Sort|boolean $sort The sorting object. If this is false, it means the sorting is disabled. Note
 * that the type of this property differs in getter and setter. See [[getSort()]] and [[setSort()]] for details.
 * @property integer $totalCount Total number of possible data models.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
abstract class BaseDataProvider extends Component implements DataProviderInterface
{
	/**
	 * @var string an ID that uniquely identifies the data provider among all data providers.
	 * You should set this property if the same page contains two or more different data providers.
	 * Otherwise, the [[pagination]] and [[sort]] mainly not work properly.
	 */
	public $id;

	private $_sort;
	private $_pagination;
	private $_keys;
	private $_models;
	private $_totalCount;


	/**
	 * Prepares the data models that will be made available in the current page.
	 * @return array the available data models
	 */
	abstract protected function prepareModels();

	/**
	 * Prepares the keys associated with the currently available data models.
	 * @param array $models the available data models
	 * @return array the keys
	 */
	abstract protected function prepareKeys($models);

	/**
	 * Returns a value indicating the total number of data models in this data provider.
	 * @return integer total number of data models in this data provider.
	 */
	abstract protected function prepareTotalCount();

	/**
	 * Prepares the data models and keys.
	 *
	 * This method will prepare the data models and keys that can be retrieved via
	 * [[getModels()]] and [[getKeys()]].
	 *
	 * This method will be implicitly called by [[getModels()]] and [[getKeys()]] if it has not been called before.
	 *
	 * @param boolean $forcePrepare whether to force data preparation even if it has been done before.
	 */
	public function prepare($forcePrepare = false)
	{
		if ($forcePrepare || $this->_models === null) {
			$this->_models = $this->prepareModels();
		}
		if ($forcePrepare || $this->_keys === null) {
			$this->_keys = $this->prepareKeys($this->_models);
		}
	}

	/**
	 * Returns the data models in the current page.
	 * @return array the list of data models in the current page.
	 */
	public function getModels()
	{
		$this->prepare();
		return $this->_models;
	}

	/**
	 * Sets the data models in the current page.
	 * @param array $models the models in the current page
	 */
	public function setModels($models)
	{
		$this->_models = $models;
	}

	/**
	 * Returns the key values associated with the data models.
	 * @return array the list of key values corresponding to [[models]]. Each data model in [[models]]
	 * is uniquely identified by the corresponding key value in this array.
	 */
	public function getKeys()
	{
		$this->prepare();
		return $this->_keys;
	}

	/**
	 * Sets the key values associated with the data models.
	 * @param array $keys the list of key values corresponding to [[models]].
	 */
	public function setKeys($keys)
	{
		$this->_keys = $keys;
	}

	/**
	 * Returns the number of data models in the current page.
	 * @return integer the number of data models in the current page.
	 */
	public function getCount()
	{
		return count($this->getModels());
	}

	/**
	 * Returns the total number of data models.
	 * When [[pagination]] is false, this returns the same value as [[count]].
	 * Otherwise, it will call [[prepareTotalCount()]] to get the count.
	 * @return integer total number of possible data models.
	 */
	public function getTotalCount()
	{
		if ($this->getPagination() === false) {
			return $this->getCount();
		} elseif ($this->_totalCount === null) {
			$this->_totalCount = $this->prepareTotalCount();
		}
		return $this->_totalCount;
	}

	/**
	 * Sets the total number of data models.
	 * @param integer $value the total number of data models.
	 */
	public function setTotalCount($value)
	{
		$this->_totalCount = $value;
	}

	/**
	 * Returns the pagination object used by this data provider.
	 * Note that you should call [[prepare()]] or [[getModels()]] first to get correct values
	 * of [[Pagination::totalCount]] and [[Pagination::pageCount]].
	 * @return Pagination|boolean the pagination object. If this is false, it means the pagination is disabled.
	 */
	public function getPagination()
	{
		if ($this->_pagination === null) {
			$this->_pagination = new Pagination;
			if ($this->id !== null) {
				$this->_pagination->pageVar = $this->id . '-page';
			}
		}
		return $this->_pagination;
	}

	/**
	 * Sets the pagination for this data provider.
	 * @param array|Pagination|boolean $value the pagination to be used by this data provider.
	 * This can be one of the following:
	 *
	 * - a configuration array for creating the pagination object. The "class" element defaults
	 *   to 'yii\data\Pagination'
	 * - an instance of [[Pagination]] or its subclass
	 * - false, if pagination needs to be disabled.
	 *
	 * @throws InvalidParamException
	 */
	public function setPagination($value)
	{
		if (is_array($value)) {
			$config = array(
				'class' => Pagination::className(),
			);
			if ($this->id !== null) {
				$config['pageVar'] = $this->id . '-page';
			}
			$this->_pagination = Yii::createObject(array_merge($config, $value));
		} elseif ($value instanceof Pagination || $value === false) {
			$this->_pagination = $value;
		} else {
			throw new InvalidParamException('Only Pagination instance, configuration array or false is allowed.');
		}
	}

	/**
	 * @return Sort|boolean the sorting object. If this is false, it means the sorting is disabled.
	 */
	public function getSort()
	{
		if ($this->_sort === null) {
			$this->setSort(array());
		}
		return $this->_sort;
	}

	/**
	 * Sets the sort definition for this data provider.
	 * @param array|Sort|boolean $value the sort definition to be used by this data provider.
	 * This can be one of the following:
	 *
	 * - a configuration array for creating the sort definition object. The "class" element defaults
	 *   to 'yii\data\Sort'
	 * - an instance of [[Sort]] or its subclass
	 * - false, if sorting needs to be disabled.
	 *
	 * @throws InvalidParamException
	 */
	public function setSort($value)
	{
		if (is_array($value)) {
			$config = array(
				'class' => Sort::className(),
			);
			if ($this->id !== null) {
				$config['sortVar'] = $this->id . '-sort';
			}
			$this->_sort = Yii::createObject(array_merge($config, $value));
		} elseif ($value instanceof Sort || $value === false) {
			$this->_sort = $value;
		} else {
			throw new InvalidParamException('Only Sort instance, configuration array or false is allowed.');
		}
	}

	/**
	 * Refreshes the data provider.
	 * After calling this method, if [[getModels()]], [[getKeys()]] or [[getTotalCount()]] is called again,
	 * they will re-execute the query and return the latest data available.
	 */
	public function refresh()
	{
		$this->_totalCount = null;
		$this->_models = null;
		$this->_keys = null;
	}
}