Percentage calculator

src/PercentCalculator.php

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+<?php
+
+declare(strict_types=1);
+
+namespace Brick\Math;
+
+use Brick\Math\Exception\MathException;
+use DivisionByZeroError;
+
+/**
+ * Class PercentCalculator
+ *
+ * This class defines constants for various types of percentages used in calculations.
+ * These constants can be used to specify the type of percentage calculation to be performed.
+ */
+class PercentCalculator
+{
+    /**
+     * Represents an increase percentage.
+     */
+    const INCREASE = 'increase';
+
+    /**
+     * Represents a decrease percentage.
+     */
+    const DECREASE = 'decrease';
+
+    /**
+     * Represents a total percentage.
+     */
+    const TOTAL_PERCENTAGE = 'total_percentage';
+
+    /**
+     * Represents a reference percentage.
+     */
+    const REFERENCE_PERCENTAGE = 'reference_percentage';
+
+    /**
+     * Represents an average percentage.
+     */
+    const AVERAGE_PERCENTAGE = 'average_percentage';
+
+    /**
+     * Represents a margin percentage.
+     */
+    const MARGIN_PERCENTAGE = 'margin_percentage';
+
+    /**
+     * Represents an interest percentage.
+     */
+    const INTEREST_PERCENTAGE = 'interest_percentage';
+
+    /**
+     * Represents a participation percentage.
+     */
+    const PARTICIPATION_PERCENTAGE = 'participation_percentage';
+
+    /**
+     * Calculates the percentage based on the given type and numbers.
+     *
+     * @param string $type The type of percentage calculation to perform.
+     * @param mixed ...$numbers The numbers to use for the calculation.
+     * @return float The calculated percentage.
+     */
+    public static function calculatePercentage($type, ...$numbers)
+    {
+        try {
+            switch ($type) {
+                case self::INCREASE:
+                    return self::calculateIncrease(...$numbers);
+                    break;
+                case self::DECREASE:
+                    return self::calculateDecrease(...$numbers);
+                    break;
+                case self::TOTAL_PERCENTAGE:
+                    return self::calculateTotalPercentage(...$numbers);
+                    break;
+                case self::REFERENCE_PERCENTAGE:
+                    return self::calculateReferencePercentage(...$numbers);
+                    break;
+                case self::AVERAGE_PERCENTAGE:
+                    return self::calculateAveragePercentage(...$numbers);
+                    break;
+                case self::MARGIN_PERCENTAGE:
+                    return self::calculateMarginPercentage(...$numbers);
+                    break;
+                case self::INTEREST_PERCENTAGE:
+                    return self::calculateInterestPercentage(...$numbers);
+                    break;
+                case self::PARTICIPATION_PERCENTAGE:
+                    return self::calculateParticipationPercentage(...$numbers);
+                    break;
+                default:
+                    throw new MathException("Invalid percentage calculation type '$type'. Only the following types are supported: increase, decrease, total_percentage, reference_percentage, average_percentage, margin_percentage, interest_percentage, participation_percentage.");
+            }
+        } catch (DivisionByZeroError) {
+            return 0;
+        }
+
+
+    }
+
+    /**
+     * Calculates the percentage increase between two values.
+     *
+     * @param float $startValue The starting value.
+     * @param float $endValue The ending value.
+     * @return float The percentage increase.
+     */
+    private static function calculateIncrease($startValue, $endValue): float
+    {
+        return (($endValue - $startValue) / $startValue) * 100;
+    }
+
+    /**
+     * Calculates the percentage decrease between two values.
+     *
+     * @param float $startValue The starting value.
+     * @param float $endValue The ending value.
+     * @return float The percentage decrease.
+     */
+    private static function calculateDecrease($startValue, $endValue): float
+    {
+        return (($startValue - $endValue) / $startValue) * 100;
+    }
+
+    /**
+     * Calculates the percentage of a part relative to a total.
+     *
+     * @param float $part The part value.
+     * @param float $total The total value.
+     * @return float The percentage of the part.
+     */
+    private static function calculateTotalPercentage($part, $total): float
+    {
+        return ($part / $total) * 100;
+    }
+
+    /**
+     * Calculates the percentage of a value relative to a reference value.
+     *
+     * @param float $value The value.
+     * @param float $reference The reference value.
+     * @return float The percentage of the value.
+     */
+    private static function calculateReferencePercentage($value, $reference): float
+    {
+        return ($value / $reference) * 100;
+    }
+
+    /**
+     * Calculates the average percentage of a list of numbers.
+     *
+     * @param float ...$numbers The numbers.
+     * @return float The average percentage.
+     */
+    private static function calculateAveragePercentage(...$numbers): float
+    {
+        $total = array_sum($numbers);
+        $count = count($numbers);
+        return ($total / $count) * 100;
+    }
+
+    /**
+     * Calculates the margin percentage between a cost price and a selling price.
+     *
+     * @param float $costPrice The cost price.
+     * @param float $sellingPrice The selling price.
+     * @return float The margin percentage.
+     */
+    private static function calculateMarginPercentage($firstNumber, $secondNumber): float
+    {
+        return (($secondNumber - $firstNumber) / abs($firstNumber)) * 100;
+    }
+
+    /**
+     * Calculates the interest amount based on a principal and an interest rate.
+     *
+     * @param float $principal The principal amount.
+     * @param float $interestRate The interest rate.
+     * @return float The interest amount.
+     */
+    private static function calculateInterestPercentage($principal, $interestRate): float
+    {
+        return $principal * ($interestRate / 100);
+    }
+
+    /**
+     * Calculates the percentage of own shares relative to total shares.
+     *
+     * @param float $ownShares The number of own shares.
+     * @param float $totalShares The total number of shares.
+     * @return float The percentage of own shares.
+     */
+    private static function calculateParticipationPercentage($ownShares, $totalShares): float
+    {
+        return ($ownShares / $totalShares) * 100;
+    }
+}