<?php
declare(strict_types=1);

namespace Gatecraft;

if (!defined('ABSPATH')) exit;

/*
 * Tax lines. Gatecraft Pro adds invoices on top of them.
 *
 * One tax rate applies to a booking, worked out once on the booking total after discounts, and rounded once. That is
 * how a Japanese qualified invoice (one rounding per rate per invoice) and an EU VAT invoice both expect it.
 *   none       no tax line (the default, and how every booking worked before this existed)
 *   inclusive  ticket prices already include tax: the total does not change, the tax inside it is shown
 *   exclusive  tax is added on top of the ticket prices
 *
 * The mode, rate and label are stored on each booking, so changing the settings never changes past bookings.
 */

add_filter('gatecraft_setting_defaults', fn(array $d) => $d + [
    'tax_mode' => 'none', 'tax_rate' => '10', 'tax_label' => 'Consumption tax', 'tax_reg_number' => '',
]);

add_filter('gatecraft_setting_rules', function (array $r, string $tab) {
    if ($tab !== 'checkout') return $r;
    return $r + [
        'tax_mode' => ['enum', ['none', 'inclusive', 'exclusive']], 'tax_rate' => ['rate'], 'tax_label' => ['text', 60],
        'tax_reg_number' => ['text', 40],
    ];
}, 10, 2);

/** The rate as people write it: 10, 8, 7.7, 19. */
function tax_rate_text(float $rate): string
{
    return rtrim(rtrim(number_format($rate, 2, '.', ''), '0'), '.') . '%';
}

/** Tax for a booking total (after discounts). Returns mode, rate, label, amount (minor units) and the total to charge. */
function tax_compute(int $total): array
{
    $mode = setting('tax_mode');
    $rate = (float)setting('tax_rate');
    $label = setting('tax_label') ?: 'Tax';
    if (!in_array($mode, ['inclusive', 'exclusive'], true) || $rate <= 0 || $total <= 0) {
        return ['mode' => 'none', 'rate' => null, 'label' => null, 'amount' => 0, 'total' => $total];
    }
    // Integer arithmetic on hundredths of a percent, so 7.7% and 19% round the same way every time (half up).
    $bp = (int)round($rate * 100);
    if ($mode === 'exclusive') {
        $tax = intdiv($total * $bp * 2 + 10000, 20000);
        return ['mode' => $mode, 'rate' => $rate, 'label' => $label, 'amount' => $tax, 'total' => $total + $tax];
    }
    $tax = intdiv($total * $bp * 2 + (10000 + $bp), 2 * (10000 + $bp));
    return ['mode' => $mode, 'rate' => $rate, 'label' => $label, 'amount' => $tax, 'total' => $total];
}

/** The line shown under the subtotal: "Consumption tax 10% (included)" or "VAT 20%". */
function tax_line_label(?string $mode, $rate, ?string $label): string
{
    if (!$mode || $mode === 'none' || $rate === null) return '';
    $t = ($label ?: 'Tax') . ' ' . tax_rate_text((float)$rate);
    return $mode === 'inclusive' ? $t . ' (included)' : $t;
}

function order_tax_label(array $o): string
{
    return tax_line_label($o['tax_mode'] ?? null, $o['tax_rate'] ?? null, $o['tax_label'] ?? null);
}