<?php
declare(strict_types=1);

require_once __DIR__ . '/../includes/bootstrap.php';
require_once __DIR__ . '/../includes/StripeClient.php';
require_once __DIR__ . '/../includes/FreeTier.php';

dbnToolsRequireMethod('POST');
dbnToolsRequireAuth();

$user = dbnToolsAuthenticatedUser();
$userId = (int)($user['user_id'] ?? 0);
$email  = (string)($user['email'] ?? '');
if ($userId <= 0 || $email === '') {
    dbnToolsError('User session missing user_id or email.', 401, 'bad_session');
}

$input = dbnToolsJsonInput(2000);
$sku = StripeClient::canonicalSku((string)($input['sku'] ?? ''));

if (!StripeClient::isSubscriptionSku($sku) && !StripeClient::isTopupSku($sku)) {
    dbnToolsError('Unknown SKU.', 400, 'unknown_sku');
}

try {
    $stripe = new StripeClient();
    $customerId = $stripe->ensureCustomer($email, $userId);

    $baseUrl = (dbnToolsIsHttps() ? 'https://' : 'http://') . ($_SERVER['HTTP_HOST'] ?? 'tools.dobetternorge.no');
    $successUrl = $baseUrl . '/billing.php?status=success&session_id={CHECKOUT_SESSION_ID}';
    $cancelUrl  = $baseUrl . '/pricing.php?status=canceled';

    $isSub = StripeClient::isSubscriptionSku($sku);
    $credits = $isSub ? 0 : StripeClient::topupCredits($sku);
    $metadata = [
        'user_id' => (string)$userId,
        'sku' => $sku,
        'catalog_version' => PricingCatalog::VERSION,
    ];
    if ($isSub) {
        $metadata['tier'] = $sku;
    } else {
        $metadata['credits'] = (string)$credits;
    }

    $params = [
        'mode' => $isSub ? 'subscription' : 'payment',
        'customer' => $customerId,
        'success_url' => $successUrl,
        'cancel_url'  => $cancelUrl,
        'line_items' => [[
            'price'    => StripeClient::priceId($sku),
            'quantity' => 1,
        ]],
        'metadata' => $metadata,
        'allow_promotion_codes' => true,
        'billing_address_collection' => 'auto',
        'locale' => 'auto',
        'automatic_tax' => ['enabled' => false],
    ];

    if ($isSub) {
        FreeTier::ensureRow($userId);
        $detail = FreeTier::balanceDetail($userId);
        $params['subscription_data'] = [
            'metadata' => $metadata,
        ];
        $trialDays = PricingCatalog::planTrialDays($sku);
        if ($trialDays > 0 && empty($detail['trial_started_at'])) {
            $params['subscription_data']['trial_period_days'] = $trialDays;
            $params['subscription_data']['trial_settings'] = [
                'end_behavior' => ['missing_payment_method' => 'cancel'],
            ];
        }
        $params['payment_method_collection'] = 'always';
    } else {
        $params['payment_intent_data'] = [
            'metadata' => $metadata,
        ];
    }

    $session = $stripe->createCheckoutSession($params);
    $url = (string)($session['url'] ?? '');
    if ($url === '') {
        dbnToolsError('Stripe did not return a checkout URL.', 502, 'stripe_no_url');
    }

    dbnToolsRespond(['ok' => true, 'url' => $url, 'session_id' => (string)($session['id'] ?? '')]);
} catch (Throwable $e) {
    error_log('[stripe-checkout] ' . $e->getMessage());
    dbnToolsError('Could not start checkout: ' . $e->getMessage(), 500, 'stripe_failed');
}