<?php
session_start();
require_once __DIR__ . '/db/config.php';

// 1. Check if user is logged in
if (!isset($_SESSION['user_id'])) {
    header('Location: login.php');
    exit();
}

// 2. Get the plan from the URL
$plan = $_GET['plan'] ?? null;
if ($plan !== 'monthly' && $plan !== 'yearly') {
    // Redirect if plan is invalid
    header('Location: pricing.php');
    exit();
}

$user_id = $_SESSION['user_id'];
$start_date = new DateTime();
$end_date = new DateTime();

if ($plan === 'monthly') {
    $end_date->modify('+1 month');
} elseif ($plan === 'yearly') {
    $end_date->modify('+1 year');
}

$db = db();

// 3. Update user's subscription status
$stmt_user = $db->prepare("UPDATE users SET subscription_status = 'premium' WHERE id = ?");
$user_updated = $stmt_user->execute([$user_id]);

// 4. Create a record in the subscriptions table
$stmt_sub = $db->prepare("INSERT INTO subscriptions (user_id, plan, start_date, end_date) VALUES (?, ?, ?, ?)");
$subscription_created = $stmt_sub->execute([
    $user_id,
    $plan,
    $start_date->format('Y-m-d H:i:s'),
    $end_date->format('Y-m-d H:i:s')
]);

if ($user_updated && $subscription_created) {
    // 5. Update session and redirect with success message
    $_SESSION['subscription_status'] = 'premium';
    $_SESSION['success_message'] = 'Welcome to Premium! You now have access to all courses.';
} else {
    $_SESSION['error_message'] = 'There was an error processing your subscription. Please try again.';
}

header('Location: dashboard.php');
exit();