<?php

/**

 * PHPExcel

 *

 * Copyright (c) 2006 - 2014 PHPExcel

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 *

 * @category   PHPExcel

 * @package    PHPExcel_Shared_Trend

 * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)

 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt	LGPL

 * @version    1.8.0, 2014-03-02

 */





require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/linearBestFitClass.php';

require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/logarithmicBestFitClass.php';

require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/exponentialBestFitClass.php';

require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/powerBestFitClass.php';

require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/polynomialBestFitClass.php';





/**

 * PHPExcel_trendClass

 *

 * @category   PHPExcel

 * @package    PHPExcel_Shared_Trend

 * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)

 */

class trendClass

{

	const TREND_LINEAR				= 'Linear';

	const TREND_LOGARITHMIC			= 'Logarithmic';

	const TREND_EXPONENTIAL			= 'Exponential';

	const TREND_POWER				= 'Power';

	const TREND_POLYNOMIAL_2		= 'Polynomial_2';

	const TREND_POLYNOMIAL_3		= 'Polynomial_3';

	const TREND_POLYNOMIAL_4		= 'Polynomial_4';

	const TREND_POLYNOMIAL_5		= 'Polynomial_5';

	const TREND_POLYNOMIAL_6		= 'Polynomial_6';

	const TREND_BEST_FIT			= 'Bestfit';

	const TREND_BEST_FIT_NO_POLY	= 'Bestfit_no_Polynomials';



	/**

	 * Names of the best-fit trend analysis methods

	 *

	 * @var string[]

	 **/

	private static $_trendTypes = array( self::TREND_LINEAR,

										 self::TREND_LOGARITHMIC,

										 self::TREND_EXPONENTIAL,

										 self::TREND_POWER

									   );

	/**

	 * Names of the best-fit trend polynomial orders

	 *

	 * @var string[]

	 **/

	private static $_trendTypePolyOrders = array( self::TREND_POLYNOMIAL_2,

												  self::TREND_POLYNOMIAL_3,

												  self::TREND_POLYNOMIAL_4,

												  self::TREND_POLYNOMIAL_5,

												  self::TREND_POLYNOMIAL_6

											    );



	/**

	 * Cached results for each method when trying to identify which provides the best fit

	 *

	 * @var PHPExcel_Best_Fit[]

	 **/

	private static $_trendCache = array();





	public static function calculate($trendType=self::TREND_BEST_FIT, $yValues, $xValues=array(), $const=True) {

		//	Calculate number of points in each dataset

		$nY = count($yValues);

		$nX = count($xValues);



		//	Define X Values if necessary

		if ($nX == 0) {

			$xValues = range(1,$nY);

			$nX = $nY;

		} elseif ($nY != $nX) {

			//	Ensure both arrays of points are the same size

			trigger_error("trend(): Number of elements in coordinate arrays do not match.", E_USER_ERROR);

		}



		$key = md5($trendType.$const.serialize($yValues).serialize($xValues));

		//	Determine which trend method has been requested

		switch ($trendType) {

			//	Instantiate and return the class for the requested trend method

			case self::TREND_LINEAR :

			case self::TREND_LOGARITHMIC :

			case self::TREND_EXPONENTIAL :

			case self::TREND_POWER :

				if (!isset(self::$_trendCache[$key])) {

					$className = 'PHPExcel_'.$trendType.'_Best_Fit';

					self::$_trendCache[$key] = new $className($yValues,$xValues,$const);

				}

				return self::$_trendCache[$key];

				break;

			case self::TREND_POLYNOMIAL_2	:

			case self::TREND_POLYNOMIAL_3	:

			case self::TREND_POLYNOMIAL_4	:

			case self::TREND_POLYNOMIAL_5	:

			case self::TREND_POLYNOMIAL_6	:

				if (!isset(self::$_trendCache[$key])) {

					$order = substr($trendType,-1);

					self::$_trendCache[$key] = new PHPExcel_Polynomial_Best_Fit($order,$yValues,$xValues,$const);

				}

				return self::$_trendCache[$key];

				break;

			case self::TREND_BEST_FIT			:

			case self::TREND_BEST_FIT_NO_POLY	:

				//	If the request is to determine the best fit regression, then we test each trend line in turn

				//	Start by generating an instance of each available trend method

				foreach(self::$_trendTypes as $trendMethod) {

					$className = 'PHPExcel_'.$trendMethod.'BestFit';

					$bestFit[$trendMethod] = new $className($yValues,$xValues,$const);

					$bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();

				}

				if ($trendType != self::TREND_BEST_FIT_NO_POLY) {

					foreach(self::$_trendTypePolyOrders as $trendMethod) {

						$order = substr($trendMethod,-1);

						$bestFit[$trendMethod] = new PHPExcel_Polynomial_Best_Fit($order,$yValues,$xValues,$const);

						if ($bestFit[$trendMethod]->getError()) {

							unset($bestFit[$trendMethod]);

						} else {

							$bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();

						}

					}

				}

				//	Determine which of our trend lines is the best fit, and then we return the instance of that trend class

				arsort($bestFitValue);

				$bestFitType = key($bestFitValue);

				return $bestFit[$bestFitType];

				break;

			default	:

				return false;

		}

	}	//	function calculate()



}	//	class trendClass