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

if (!isset($_SESSION['user_id'])) {
    header('Location: login.php');
    exit();
}

if ($_SERVER['REQUEST_METHOD'] !== 'POST' || !isset($_POST['reward'])) {
    header('Location: rewards.php');
    exit();
}

$user_id = $_SESSION['user_id'];
$reward = $_POST['reward'];

$rewards = [
    '5_off' => [
        'points' => 500,
        'discount' => 5,
        'type' => 'fixed'
    ]
];

if (!array_key_exists($reward, $rewards)) {
    $_SESSION['error_message'] = 'Invalid reward selected.';
    header('Location: rewards.php');
    exit();
}

$reward_details = $rewards[$reward];
$points_required = $reward_details['points'];

$pdo = db();

// Get user's current points
$stmt = $pdo->prepare("SELECT points FROM user_rewards WHERE user_id = ?");
$stmt->execute([$user_id]);
$user_reward = $stmt->fetch();

$current_points = $user_reward ? $user_reward['points'] : 0;

if ($current_points < $points_required) {
    $_SESSION['error_message'] = 'You do not have enough points to redeem this reward.';
    header('Location: rewards.php');
    exit();
}

// Deduct points and create coupon
try {
    $pdo->beginTransaction();

    // Deduct points
    $new_points = $current_points - $points_required;
    $stmt = $pdo->prepare("UPDATE user_rewards SET points = ? WHERE user_id = ?");
    $stmt->execute([$new_points, $user_id]);

    // Log history
    $stmt = $pdo->prepare("INSERT INTO reward_history (user_id, points_change, reason) VALUES (?, ?, ?)");
    $stmt->execute([$user_id, -$points_required, 'Redeemed ' . $reward]);

    // Create coupon
    $coupon_code = 'REWARD-' . strtoupper(bin2hex(random_bytes(4))) . '-' . $user_id;
    $stmt = $pdo->prepare("INSERT INTO coupons (code, type, value, expires_at, is_active) VALUES (?, ?, ?, DATE_ADD(NOW(), INTERVAL 30 DAY), 1)");
    $stmt->execute([$coupon_code, $reward_details['type'], $reward_details['discount']]);

    $pdo->commit();

    $_SESSION['success_message'] = 'Reward redeemed successfully! Your coupon code is: ' . $coupon_code;
    header('Location: rewards.php');
    exit();

} catch (Exception $e) {
    $pdo->rollBack();
    $_SESSION['error_message'] = 'There was an error redeeming your reward. Please try again.';
    error_log($e->getMessage());
    header('Location: rewards.php');
    exit();
}