signup.php

<?php
session_start();
$conn = new mysqli("localhost", "root", "", "health_advice_group");

if ($conn->connect_error) {
    die("Database connection failed: " . $conn->connect_error);
}

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Get form data
    $first_name = trim($_POST['first_name']);
    $last_name = trim($_POST['last_name']);
    $email = trim($_POST['email']);
    $password = $_POST['password'];
    $confirm_password = $_POST['confirm_password'];

    // Validate fields
    if (empty($first_name) || empty($last_name) || empty($email) || empty($password) || empty($confirm_password)) {
        echo "<script>alert('All fields are required.'); window.location.href='signup.html';</script>";
        exit();
    }

    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        echo "<script>alert('Invalid email format.'); window.location.href='signup.html';</script>";
        exit();
    }

    if ($password !== $confirm_password) {
        echo "<script>alert('Passwords do not match.'); window.location.href='signup.html';</script>";
        exit();
    }

    // Check if the email already exists
    $stmt = $conn->prepare("SELECT id FROM users WHERE email = ?");
    $stmt->bind_param("s", $email);
    $stmt->execute();
    $stmt->store_result();

    if ($stmt->num_rows > 0) {
        echo "<script>alert('Email already registered. Try logging in.'); window.location.href='signup.html';</script>";
        exit();
    }
    $stmt->close();

    // Hash the password
    $hashed_password = password_hash($password, PASSWORD_DEFAULT);

    // Insert into database
    $stmt = $conn->prepare("INSERT INTO users (first_name, last_name, email, password) VALUES (?, ?, ?, ?)");
    $stmt->bind_param("ssss", $first_name, $last_name, $email, $hashed_password);

    if ($stmt->execute()) {
        $_SESSION["user_id"] = $stmt->insert_id;
        $_SESSION["email"] = $email;
        echo "<script>alert('Signup successful! Redirecting to dashboard.'); window.location.href='dashboard.php';</script>";
        exit();
    } else {
        echo "<script>alert('Error: Could not complete signup.'); window.location.href='signup.html';</script>";
    }

    $stmt->close();
}
$conn->close();
?>