<?php

/**
 * git statu class that holds many important numeric constants.
 *
 * @author Andreu Correa Casablanca <castarco@litipk.com>
 */
final class DecimalConstants
{
    private static $ZERO;
    private static $ONE;
    private static $NEGATIVE_ONE;
    private static $HUNDRED;

    private static $PI;
    private static $EulerMascheroni;

    private static $GoldenRatio;

    private static $LightSpeed;

    /**
     * Private constructor.
     */
    private function __construct()
    {
    }

    /**
     * Private clone method.
     */
    private function __clone()
    {
    }

    public static function zero()
    {
        if (self::$ZERO === null) {
            self::$ZERO = Decimal::fromInteger(0);
        }

        return self::$ZERO;
    }

    public static function one()
    {
        if (self::$ONE === null) {
            self::$ONE = Decimal::fromInteger(1);
        }

        return self::$ONE;
    }

    public static function negativeOne()
    {
        if (self::$NEGATIVE_ONE === null) {
            self::$NEGATIVE_ONE = Decimal::fromInteger(-1);
        }

        return self::$NEGATIVE_ONE;
    }

    public static function hundred()
    {
        if (self::$HUNDRED === null) {
            self::$HUNDRED = Decimal::fromInteger(100);
        }

        return self::$HUNDRED;
    }

    /**
     * Returns the Pi number.
     *
     * @return Decimal
     */
    public static function pi()
    {
        if (self::$PI === null) {
            self::$PI = Decimal::fromString(
                '3.14159265358979323846264338327950'
            );
        }

        return self::$PI;
    }

    /**
     * Returns the Euler's E number.
     *
     * @param int $scale
     *
     * @return Decimal
     */
    public static function e($scale = 32)
    {
        if (!is_int($scale)) {
            throw new InvalidArgumentTypeException(['integer'], gettype($scale));
        }
        if ($scale < 0) {
            throw new \InvalidArgumentException('$scale must be positive.');
        }

        return self::$ONE->exp($scale);
    }

    /**
     * Returns the Euler-Mascheroni constant.
     *
     * @return Decimal
     */
    public static function eulerMascheroni()
    {
        if (self::$EulerMascheroni === null) {
            self::$EulerMascheroni = Decimal::fromString(
                '0.57721566490153286060651209008240'
            );
        }

        return self::$EulerMascheroni;
    }

    /**
     * Returns the Golden Ration, also named Phi.
     *
     * @return Decimal
     */
    public static function goldenRatio()
    {
        if (self::$GoldenRatio === null) {
            self::$GoldenRatio = Decimal::fromString(
                '1.61803398874989484820458683436564'
            );
        }

        return self::$GoldenRatio;
    }

    /**
     * Returns the Light of Speed measured in meters / second.
     *
     * @return Decimal
     */
    public static function lightSpeed()
    {
        if (self::$LightSpeed === null) {
            self::$LightSpeed = Decimal::fromInteger(299792458);
        }

        return self::$LightSpeed;
    }
}