<?php

namespace TablePress\PhpOffice\PhpSpreadsheet\Calculation\Statistical;

use TablePress\PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Exception;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Functions;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
use TablePress\PhpOffice\PhpSpreadsheet\Shared\Trend\Trend;

class Trends
{
	use ArrayEnabled;

	private static function filterTrendValues(array &$array1, array &$array2): void
	{
		foreach ($array1 as $key => $value) {
			if ((is_bool($value)) || (is_string($value)) || ($value === null)) {
				unset($array1[$key], $array2[$key]);
			}
		}
	}

	/**
	 * @param mixed $array1 should be array, but scalar is made into one
	 * @param mixed $array2 should be array, but scalar is made into one
	 */
	private static function checkTrendArrays(&$array1, &$array2): void
	{
		if (!is_array($array1)) {
			$array1 = [$array1];
		}
		if (!is_array($array2)) {
			$array2 = [$array2];
		}

		$array1 = Functions::flattenArray($array1);
		$array2 = Functions::flattenArray($array2);

		self::filterTrendValues($array1, $array2);
		self::filterTrendValues($array2, $array1);

		// Reset the array indexes
		$array1 = array_merge($array1);
		$array2 = array_merge($array2);
	}

	protected static function validateTrendArrays(array $yValues, array $xValues): void
	{
		$yValueCount = count($yValues);
		$xValueCount = count($xValues);

		if (($yValueCount === 0) || ($yValueCount !== $xValueCount)) {
			throw new Exception(ExcelError::NA());
		} elseif ($yValueCount === 1) {
			throw new Exception(ExcelError::DIV0());
		}
	}

	/**
	 * CORREL.
	 *
	 * Returns covariance, the average of the products of deviations for each data point pair.
	 *
	 * @param mixed $yValues array of mixed Data Series Y
	 * @param null|mixed $xValues array of mixed Data Series X
	 *
	 * @return float|string
	 */
	public static function CORREL($yValues, $xValues = null)
	{
		if (($xValues === null) || (!is_array($yValues)) || (!is_array($xValues))) {
			return ExcelError::VALUE();
		}

		try {
			self::checkTrendArrays($yValues, $xValues);
			self::validateTrendArrays($yValues, $xValues);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		$bestFitLinear = Trend::calculate(Trend::TREND_LINEAR, $yValues, $xValues);

		return $bestFitLinear->getCorrelation();
	}

	/**
	 * COVAR.
	 *
	 * Returns covariance, the average of the products of deviations for each data point pair.
	 *
	 * @param mixed $yValues array of mixed Data Series Y
	 * @param mixed $xValues array of mixed Data Series X
	 *
	 * @return float|string
	 */
	public static function COVAR($yValues, $xValues)
	{
		try {
			self::checkTrendArrays($yValues, $xValues);
			self::validateTrendArrays($yValues, $xValues);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		$bestFitLinear = Trend::calculate(Trend::TREND_LINEAR, $yValues, $xValues);

		return $bestFitLinear->getCovariance();
	}

	/**
	 * FORECAST.
	 *
	 * Calculates, or predicts, a future value by using existing values.
	 * The predicted value is a y-value for a given x-value.
	 *
	 * @param mixed $xValue Float value of X for which we want to find Y
	 *                      Or can be an array of values
	 * @param mixed $yValues array of mixed Data Series Y
	 * @param mixed $xValues of mixed Data Series X
	 *
	 * @return array|bool|float|string
	 *         If an array of numbers is passed as an argument, then the returned result will also be an array
	 *            with the same dimensions
	 */
	public static function FORECAST($xValue, $yValues, $xValues)
	{
		if (is_array($xValue)) {
			return self::evaluateArrayArgumentsSubset([self::class, __FUNCTION__], 1, $xValue, $yValues, $xValues);
		}

		try {
			$xValue = StatisticalValidations::validateFloat($xValue);
			self::checkTrendArrays($yValues, $xValues);
			self::validateTrendArrays($yValues, $xValues);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		$bestFitLinear = Trend::calculate(Trend::TREND_LINEAR, $yValues, $xValues);

		return $bestFitLinear->getValueOfYForX($xValue);
	}

	/**
	 * GROWTH.
	 *
	 * Returns values along a predicted exponential Trend
	 *
	 * @param mixed[] $yValues Data Series Y
	 * @param mixed[] $xValues Data Series X
	 * @param mixed[] $newValues Values of X for which we want to find Y
	 * @param mixed $const A logical (boolean) value specifying whether to force the intersect to equal 0 or not
	 *
	 * @return float[]
	 */
	public static function GROWTH($yValues, $xValues = [], $newValues = [], $const = true)
	{
		$yValues = Functions::flattenArray($yValues);
		$xValues = Functions::flattenArray($xValues);
		$newValues = Functions::flattenArray($newValues);
		$const = ($const === null) ? true : (bool) Functions::flattenSingleValue($const);

		$bestFitExponential = Trend::calculate(Trend::TREND_EXPONENTIAL, $yValues, $xValues, $const);
		if (empty($newValues)) {
			$newValues = $bestFitExponential->getXValues();
		}

		$returnArray = [];
		foreach ($newValues as $xValue) {
			$returnArray[0][] = [$bestFitExponential->getValueOfYForX($xValue)];
		}

		return $returnArray; //* @phpstan-ignore-line
	}

	/**
	 * INTERCEPT.
	 *
	 * Calculates the point at which a line will intersect the y-axis by using existing x-values and y-values.
	 *
	 * @param mixed[] $yValues Data Series Y
	 * @param mixed[] $xValues Data Series X
	 *
	 * @return float|string
	 */
	public static function INTERCEPT($yValues, $xValues)
	{
		try {
			self::checkTrendArrays($yValues, $xValues);
			self::validateTrendArrays($yValues, $xValues);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		$bestFitLinear = Trend::calculate(Trend::TREND_LINEAR, $yValues, $xValues);

		return $bestFitLinear->getIntersect();
	}

	/**
	 * LINEST.
	 *
	 * Calculates the statistics for a line by using the "least squares" method to calculate a straight line
	 *     that best fits your data, and then returns an array that describes the line.
	 *
	 * @param mixed[] $yValues Data Series Y
	 * @param null|mixed[] $xValues Data Series X
	 * @param mixed $const A logical (boolean) value specifying whether to force the intersect to equal 0 or not
	 * @param mixed $stats A logical (boolean) value specifying whether to return additional regression statistics
	 *
	 * @return array|int|string The result, or a string containing an error
	 */
	public static function LINEST($yValues, $xValues = null, $const = true, $stats = false)
	{
		$const = ($const === null) ? true : (bool) Functions::flattenSingleValue($const);
		$stats = ($stats === null) ? false : (bool) Functions::flattenSingleValue($stats);
		if ($xValues === null) {
			$xValues = $yValues;
		}

		try {
			self::checkTrendArrays($yValues, $xValues);
			self::validateTrendArrays($yValues, $xValues);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		$bestFitLinear = Trend::calculate(Trend::TREND_LINEAR, $yValues, $xValues, $const);

		if ($stats === true) {
			return [
				[
					$bestFitLinear->getSlope(),
					$bestFitLinear->getIntersect(),
				],
				[
					$bestFitLinear->getSlopeSE(),
					($const === false) ? ExcelError::NA() : $bestFitLinear->getIntersectSE(),
				],
				[
					$bestFitLinear->getGoodnessOfFit(),
					$bestFitLinear->getStdevOfResiduals(),
				],
				[
					$bestFitLinear->getF(),
					$bestFitLinear->getDFResiduals(),
				],
				[
					$bestFitLinear->getSSRegression(),
					$bestFitLinear->getSSResiduals(),
				],
			];
		}

		return [
			$bestFitLinear->getSlope(),
			$bestFitLinear->getIntersect(),
		];
	}

	/**
	 * LOGEST.
	 *
	 * Calculates an exponential curve that best fits the X and Y data series,
	 *        and then returns an array that describes the line.
	 *
	 * @param mixed[] $yValues Data Series Y
	 * @param null|mixed[] $xValues Data Series X
	 * @param mixed $const A logical (boolean) value specifying whether to force the intersect to equal 0 or not
	 * @param mixed $stats A logical (boolean) value specifying whether to return additional regression statistics
	 *
	 * @return array|int|string The result, or a string containing an error
	 */
	public static function LOGEST($yValues, $xValues = null, $const = true, $stats = false)
	{
		$const = ($const === null) ? true : (bool) Functions::flattenSingleValue($const);
		$stats = ($stats === null) ? false : (bool) Functions::flattenSingleValue($stats);
		if ($xValues === null) {
			$xValues = $yValues;
		}

		try {
			self::checkTrendArrays($yValues, $xValues);
			self::validateTrendArrays($yValues, $xValues);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		foreach ($yValues as $value) {
			if ($value < 0.0) {
				return ExcelError::NAN();
			}
		}

		$bestFitExponential = Trend::calculate(Trend::TREND_EXPONENTIAL, $yValues, $xValues, $const);

		if ($stats === true) {
			return [
				[
					$bestFitExponential->getSlope(),
					$bestFitExponential->getIntersect(),
				],
				[
					$bestFitExponential->getSlopeSE(),
					($const === false) ? ExcelError::NA() : $bestFitExponential->getIntersectSE(),
				],
				[
					$bestFitExponential->getGoodnessOfFit(),
					$bestFitExponential->getStdevOfResiduals(),
				],
				[
					$bestFitExponential->getF(),
					$bestFitExponential->getDFResiduals(),
				],
				[
					$bestFitExponential->getSSRegression(),
					$bestFitExponential->getSSResiduals(),
				],
			];
		}

		return [
			$bestFitExponential->getSlope(),
			$bestFitExponential->getIntersect(),
		];
	}

	/**
	 * RSQ.
	 *
	 * Returns the square of the Pearson product moment correlation coefficient through data points
	 *     in known_y's and known_x's.
	 *
	 * @param mixed[] $yValues Data Series Y
	 * @param mixed[] $xValues Data Series X
	 *
	 * @return float|string The result, or a string containing an error
	 */
	public static function RSQ($yValues, $xValues)
	{
		try {
			self::checkTrendArrays($yValues, $xValues);
			self::validateTrendArrays($yValues, $xValues);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		$bestFitLinear = Trend::calculate(Trend::TREND_LINEAR, $yValues, $xValues);

		return $bestFitLinear->getGoodnessOfFit();
	}

	/**
	 * SLOPE.
	 *
	 * Returns the slope of the linear regression line through data points in known_y's and known_x's.
	 *
	 * @param mixed[] $yValues Data Series Y
	 * @param mixed[] $xValues Data Series X
	 *
	 * @return float|string The result, or a string containing an error
	 */
	public static function SLOPE($yValues, $xValues)
	{
		try {
			self::checkTrendArrays($yValues, $xValues);
			self::validateTrendArrays($yValues, $xValues);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		$bestFitLinear = Trend::calculate(Trend::TREND_LINEAR, $yValues, $xValues);

		return $bestFitLinear->getSlope();
	}

	/**
	 * STEYX.
	 *
	 * Returns the standard error of the predicted y-value for each x in the regression.
	 *
	 * @param mixed[] $yValues Data Series Y
	 * @param mixed[] $xValues Data Series X
	 *
	 * @return float|string
	 */
	public static function STEYX($yValues, $xValues)
	{
		try {
			self::checkTrendArrays($yValues, $xValues);
			self::validateTrendArrays($yValues, $xValues);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		$bestFitLinear = Trend::calculate(Trend::TREND_LINEAR, $yValues, $xValues);

		return $bestFitLinear->getStdevOfResiduals();
	}

	/**
	 * TREND.
	 *
	 * Returns values along a linear Trend
	 *
	 * @param mixed[] $yValues Data Series Y
	 * @param mixed[] $xValues Data Series X
	 * @param mixed[] $newValues Values of X for which we want to find Y
	 * @param mixed $const A logical (boolean) value specifying whether to force the intersect to equal 0 or not
	 *
	 * @return float[]
	 */
	public static function TREND($yValues, $xValues = [], $newValues = [], $const = true)
	{
		$yValues = Functions::flattenArray($yValues);
		$xValues = Functions::flattenArray($xValues);
		$newValues = Functions::flattenArray($newValues);
		$const = ($const === null) ? true : (bool) Functions::flattenSingleValue($const);

		$bestFitLinear = Trend::calculate(Trend::TREND_LINEAR, $yValues, $xValues, $const);
		if (empty($newValues)) {
			$newValues = $bestFitLinear->getXValues();
		}

		$returnArray = [];
		foreach ($newValues as $xValue) {
			$returnArray[0][] = [$bestFitLinear->getValueOfYForX($xValue)];
		}

		return $returnArray; //* @phpstan-ignore-line
	}
}
