<?php

namespace App\Services;

use Brick\Math\BigDecimal;
use Brick\Math\RoundingMode;
use Illuminate\Validation\ValidationException;

class QuotationPricing
{
    /** Discount applies to the unit price before VAT; the net unit is rounded once to cents.
     * @return array{gross_unit_minor: int, discount_type: string, discount_value: string, net_unit_minor: int}
     */
    public function unit(string $price, string $type = 'none', string $value = '0'): array
    {
        $gross = BigDecimal::of($price)->multipliedBy(100)->toInt();
        $discount = BigDecimal::of($value);
        if ($gross < 1 || $discount->isNegative() || ! in_array($type, ['none', 'percent', 'amount'], true) ||
            ($type === 'none' && ! $discount->isZero()) || ($type === 'percent' && $discount->isGreaterThan(100))) {
            throw ValidationException::withMessages(['items' => 'Indique um desconto unitário válido: percentagem ou valor em MZN, antes do IVA.']);
        }
        $reduction = match ($type) {
            'percent' => BigDecimal::of($gross)->multipliedBy($discount)->dividedBy(100, 4),
            'amount' => $discount->multipliedBy(100),
            default => BigDecimal::zero(),
        };
        $net = BigDecimal::of($gross)->minus($reduction)->toScale(0, RoundingMode::HalfUp)->toInt();
        if ($net < 1) {
            throw ValidationException::withMessages(['items' => 'O preço unitário após desconto deve ser pelo menos 0,01 MZN.']);
        }

        return ['gross_unit_minor' => $gross, 'discount_type' => $type, 'discount_value' => (string) $discount->toScale(2), 'net_unit_minor' => $net];
    }
}