<?php
require_once '../db/config.php';
require_once '../stripe/config.php'; // for $subscriptions

header('Content-Type: application/json');

$data = json_decode(file_get_contents('php://input'), true);

$coupon_code = $data['coupon_code'] ?? null;
$plan_id = $data['plan_id'] ?? null;

if (!$coupon_code || !$plan_id) {
    echo json_encode(['success' => false, 'error' => 'Missing coupon code or plan ID']);
    exit;
}

global $subscriptions;
if (!isset($subscriptions[$plan_id])) {
    echo json_encode(['success' => false, 'error' => 'Invalid plan']);
    exit;
}
$plan = $subscriptions[$plan_id];

// Fetch coupon details
$stmt = db()->prepare('SELECT * FROM discounts WHERE code = ? AND is_active = 1');
$stmt->execute([$coupon_code]);
$coupon = $stmt->fetch();

if (!$coupon) {
    echo json_encode(['success' => false, 'error' => 'Invalid or inactive coupon']);
    exit;
}

// Check date validity
if (($coupon['start_date'] && strtotime($coupon['start_date']) > time()) || ($coupon['end_date'] && strtotime($coupon['end_date']) < time())) {
    echo json_encode(['success' => false, 'error' => 'Coupon is not valid at this time']);
    exit;
}

// Check usage limit
if ($coupon['uses_limit'] !== null && $coupon['times_used'] >= $coupon['uses_limit']) {
    echo json_encode(['success' => false, 'error' => 'Coupon has reached its usage limit']);
    exit;
}

// Calculate discounted price
$original_price = $plan['price'] / 100;
$discounted_price = 0;

if ($coupon['type'] === 'percentage') {
    $discounted_price = $original_price - ($original_price * ($coupon['value'] / 100));
} else { // fixed
    $discounted_price = $original_price - $coupon['value'];
}

if ($discounted_price < 0) {
    $discounted_price = 0;
}

echo json_encode(['success' => true, 'discounted_price' => $discounted_price]);