<?php

namespace TablePress\PhpOffice\PhpSpreadsheet\Calculation\Statistical\Distributions;

use TablePress\PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Exception;
use TablePress\PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;

class Weibull
{
	use ArrayEnabled;

	/**
	 * WEIBULL.
	 *
	 * Returns the Weibull distribution. Use this distribution in reliability
	 * analysis, such as calculating a device's mean time to failure.
	 *
	 * @param mixed $value Float value for the distribution
	 *                      Or can be an array of values
	 * @param mixed $alpha Float alpha Parameter
	 *                      Or can be an array of values
	 * @param mixed $beta Float beta Parameter
	 *                      Or can be an array of values
	 * @param mixed $cumulative Boolean value indicating if we want the cdf (true) or the pdf (false)
	 *                      Or can be an array of values
	 *
	 * @return array|float|string (string if result is an error)
	 *         If an array of numbers is passed as an argument, then the returned result will also be an array
	 *            with the same dimensions
	 */
	public static function distribution($value, $alpha, $beta, $cumulative)
	{
		if (is_array($value) || is_array($alpha) || is_array($beta) || is_array($cumulative)) {
			return self::evaluateArrayArguments([self::class, __FUNCTION__], $value, $alpha, $beta, $cumulative);
		}

		try {
			$value = DistributionValidations::validateFloat($value);
			$alpha = DistributionValidations::validateFloat($alpha);
			$beta = DistributionValidations::validateFloat($beta);
			$cumulative = DistributionValidations::validateBool($cumulative);
		} catch (Exception $e) {
			return $e->getMessage();
		}

		if (($value < 0) || ($alpha <= 0) || ($beta <= 0)) {
			return ExcelError::NAN();
		}

		if ($cumulative) {
			return 1 - exp(0 - ($value / $beta) ** $alpha);
		}

		return ($alpha / $beta ** $alpha) * $value ** ($alpha - 1) * exp(0 - ($value / $beta) ** $alpha);
	}
}
