<?php

declare(strict_types=1);

namespace Domain\Models\ValueObjects;

use Money\Money;
use Webmozart\Assert\Assert;

/**
 * Taux de remise exprimé en points de base (1 bp = 0,01 %), pour éviter toute imprécision en virgule flottante.
 */
final readonly class DiscountRate implements \Stringable
{
    public const MAX_BASIS_POINTS = 10000;

    public function __construct(
        private int $basisPoints
    ) {
        Assert::range($basisPoints, 0, self::MAX_BASIS_POINTS, 'Discount rate has to be between 0 and 100 percent.');
    }

    public static function zero(): self
    {
        return new self(0);
    }

    public static function fromBasisPoints(int $basisPoints): self
    {
        return new self($basisPoints);
    }

    /** @param  int|float  $percentage  Percentage between 0 and 100 (ex: 15 for 15 %) */
    public static function fromPercentage(int | float $percentage): self
    {
        return new self((int) round($percentage * 100));
    }

    /** @param  float  $ratio  Ratio between 0 and 1 (ex: 0.15 for 15 %) */
    public static function fromRatio(float $ratio): self
    {
        return new self((int) round($ratio * self::MAX_BASIS_POINTS));
    }

    /**
     * Computes the effective rate represented by a fixed discount amount on a base price.
     * The result is capped at 100 %.
     */
    public static function fromAmounts(Money $discountAmount, Money $basePrice): self
    {
        if (! $basePrice->isPositive() || ! $discountAmount->isPositive()) {
            return self::zero();
        }

        $basisPoints = intdiv(
            ((int) $discountAmount->getAmount() * self::MAX_BASIS_POINTS * 2) + (int) $basePrice->getAmount(),
            (int) $basePrice->getAmount() * 2
        );

        return new self(min($basisPoints, self::MAX_BASIS_POINTS));
    }

    public function basisPoints(): int
    {
        return $this->basisPoints;
    }

    /** Ratio between 0.0 and 1.0 */
    public function ratio(): float
    {
        return $this->basisPoints / self::MAX_BASIS_POINTS;
    }

    /** Percentage between 0.0 and 100.0 */
    public function percentage(): float
    {
        return $this->basisPoints / 100;
    }

    public function isZero(): bool
    {
        return $this->basisPoints === 0;
    }

    public function equals(self $other): bool
    {
        return $this->basisPoints === $other->basisPoints;
    }

    /**
     * Returns the discount amount produced by this rate on the given amount.
     *
     * @param  Money::ROUND_*  $roundingMode
     */
    public function applyTo(Money $amount, int $roundingMode = Money::ROUND_UP): Money
    {
        return $amount->multiply((string) $this->basisPoints)->divide(self::MAX_BASIS_POINTS, $roundingMode);
    }

    #[\Override]
    public function __toString(): string
    {
        return rtrim(rtrim(number_format($this->percentage(), 2, '.', ''), '0'), '.') . ' %';
    }
}