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

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    header('Location: index.php');
    exit();
}

$username = trim($_POST['username'] ?? '');
$password = $_POST['password'] ?? '');
$confirm_password = $_POST['confirm_password'] ?? '');

// Basic validation
if (empty($username) || empty($password)) {
    header('Location: index.php?reg_error=Username and password are required.#register');
    exit();
}

if ($password !== $confirm_password) {
    header('Location: index.php?reg_error=Passwords do not match.#register');
    exit();
}

if (strlen($password) < 6) {
    header('Location: index.php?reg_error=Password must be at least 6 characters long.#register');
    exit();
}

try {
    $pdo = db();

    // Check if username already exists
    $stmt = $pdo->prepare("SELECT id FROM users WHERE username = ?");
    $stmt->execute([$username]);
    if ($stmt->rowCount() > 0) {
        header('Location: index.php?reg_error=Username already taken.#register');
        exit();
    }

    // Hash password and insert user
    $password_hash = password_hash($password, PASSWORD_DEFAULT);
    $stmt = $pdo->prepare("INSERT INTO users (username, password_hash) VALUES (?, ?)");
    $stmt->execute([$username, $password_hash]);

    header('Location: index.php?reg_success=1#login');
    exit();

} catch (PDOException $e) {
    // In a real app, log the error
    header('Location: index.php?reg_error=A database error occurred.#register');
    exit();
}
?>