Register.php // Project Crazy

<?php
// Include config file
require_once 'config.php';

// Define variables and initialize with empty values
$username = $password = $confirm_password = $email = $toon = "";
$username_err = $password_err = $confirm_password_err = $email_err = $toon_err = "";

// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){

    // Validate username
    if(empty(trim($_POST["username"]))){
        $username_err = "Please enter a username.";
    } else{
        // Prepare a select statement
        $sql = "SELECT id FROM users WHERE username = ?";

        if($stmt = mysqli_prepare($link, $sql)){

          // Set parameters
           $param_username = $username;

            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "s", $username);


            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                /* store result */
                mysqli_stmt_store_result($stmt);

                if(mysqli_stmt_num_rows($stmt) == 1){
                    $username_err = "This username is already taken.";
                } else{
                    $username = trim($_POST["username"]);
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }

    // Validate password
    if(empty(trim($_POST['password']))){
        $password_err = "Please enter a password.";
    } elseif(strlen(trim($_POST['password'])) < 6){
        $password_err = "Password must have atleast 6 characters.";
    } else{
        $password = trim($_POST['password']);
    }

    // Validate confirm password
    if(empty(trim($_POST["confirm_password"]))){
        $confirm_password_err = 'Please confirm password.';
    } else{
        $confirm_password = trim($_POST['confirm_password']);
        if($password != $confirm_password){
            $confirm_password_err = 'Password did not match.';
        }
    }

    // Validate email
    if(empty(trim($_POST["email"]))){
        $email_err = "Please enter your email.";
    } else{
        // Prepare a select statement
        $sql = "SELECT id FROM users WHERE email = ?";

        if($stmt = mysqli_prepare($link, $sql)){
          // Set parameters
        $param_email = $email;

            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "s", $email);



            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                /* store result */
                mysqli_stmt_store_result($stmt);

                if(mysqli_stmt_num_rows($stmt) == 1){
                    $email_err = "This email is already taken.";
                } else{
                    $email = trim($_POST["email"]);
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }

    // Validate toon
    if(empty(trim($_POST['toon']))){
        $toon_err = "Please enter a toon name.";
    } else{
        $toon = trim($_POST['toon']);
    }
    // Check input errors before inserting in database
    if(empty($username_err) && empty($password_err) && empty($confirm_password_err) && empty($email_err) && empty($toon_err)){

        // Prepare an insert statement
        $sql = "INSERT INTO users (username, password, email, toon) VALUES (?, ?, ?, ?)";

        if($stmt = mysqli_prepare($link, $sql)){
          // Set parameters
          $param_username = $username;
          $param_password = password_hash($password, PASSWORD_DEFAULT); // Creates a password hash
          $param_email = $email;
          $param_toon = $toon;

            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "ss", $username, $password, $email, $toon);

            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                // Redirect to login page
                header("location: login.php");
            } else{
                echo "Something went wrong. Please try again later.";
            }
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }

    // Close connection
    mysqli_close($link);
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Sign Up</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.css">
    <style type="text/css">
        body{ font: 14px sans-serif; }
        .wrapper{ width: 350px; padding: 20px; }
    </style>
</head>
<body>
    <div class="wrapper">
        <h2>Sign Up</h2>
        <p>Please fill this form to create an account.</p>
        <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
            <div class="form-group <?php echo (!empty($username_err)) ? 'has-error' : ''; ?>">
                <label>Username</label>
                <input type="text" name="username"class="form-control" value="<?php echo $username; ?>">
                <span class="help-block"><?php echo $username_err; ?></span>
            </div>
            <div class="form-group <?php echo (!empty($password_err)) ? 'has-error' : ''; ?>">
                <label>Password</label>
                <input type="password" name="password" class="form-control" value="<?php echo $password; ?>">
                <span class="help-block"><?php echo $password_err; ?></span>
            </div>
            <div class="form-group <?php echo (!empty($confirm_password_err)) ? 'has-error' : ''; ?>">
                <label>Confirm Password</label>
                <input type="password" name="confirm_password" class="form-control" value="<?php echo $confirm_password; ?>">
                <span class="help-block"><?php echo $confirm_password_err; ?></span>
            </div>
            <div class="form-group <?php echo (!empty($email_err)) ? 'has-error' : ''; ?>">
                <label>Email</label>
                <input type="email" name="email" class="form-control" value="<?php echo $email; ?>">
                <span class="help-block"><?php echo $email_err; ?></span>
            </div>
            <div class="form-group <?php echo (!empty($toon_err)) ? 'has-error' : ''; ?>">
                <label>Toon</label>
                <input type="text" name="toon" class="form-control" value="<?php echo $toon; ?>">
                <span class="help-block"><?php echo $toon_err; ?></span>
            </div>
            <div class="form-group">
                <input type="submit" class="btn btn-primary" value="Submit">
                <input type="reset" class="btn btn-default" value="Reset">
            </div>
            <p>Already have an account? <a href="login.php">Login here</a>.</p>
        </form>
    </div>
</body>
</html>