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<?php
    if(empty($_POST['firstname'])){
        $error['firstname'] = 'Firstname is empty!';
    }
    if(empty($_POST['lastname'])){
        $error['lastname'] = 'Lastname is empty!';
    }
    if(empty($_POST['email'])){
        $error['email'] = 'Email is empty!';
    }
    if(empty($_POST['password'])){
        $error['password'] = 'Password is empty!';
    }
    if(empty($_POST['password-confirm'])){
        $error['password-confirm'] = 'Password and password confirmation not match!';
    }
    if(empty($_POST['password-confirm'])){
        $error['password-confirm'] = 'Password confirmation is empty!';
    }
    if(!empty($_POST['password-confirm']) && !empty($_POST['password']) ){
        if($_POST['password-confirm'] == $_POST['password']){
            $error['password-confirm'] = 'Password confirmation and password is not match!';
        }
    }

?>
<!DOCTYPE html>
<html lang="en" dir="ltr">
  <head>
    <meta charset="utf-8">
    <title>Form Validation</title>
    <link rel="stylesheet" href="css/bootstrap.min.css">
    <link rel="stylesheet" href="css/fontawesome-all.min.css">
  </head>
  <body>
    <div class="container py-5">
      <div class="col-8 offset-2">
          <h1>Form Validation</h1>
          <form action="" method="post">
            <div class="form-group">
                <label for="firstname">First Name</label>
                <input type="text" name="firstname" id="firstname" class="form-control" autofocus placeholder="First Name">
                <?php if(!empty($_POST) && !empty($error['firstname'])): ?>
                    <div class="alert alert-danger" role="alert">
                        <?php echo $error['firstname'] ?>
                    </div>
                <?php endif; ?>
            </div>
            <div class="form-group">
                <label for="lastname">Last Name</label>
                <input type="text" name="lastname" id="lastname" class="form-control" placeholder="Last Name">
                <?php if(!empty($_POST) && !empty($error['lastname'])): ?>
                    <div class="alert alert-danger" role="alert">
                        <?php echo $error['lastname'] ?>
                    </div>
                <?php endif; ?>
            </div>
            <div class="form-group">
                <label for="email">Email</label>
                <input type="email" name="email" id="email" class="form-control"  placeholder="Email">
                <?php if(!empty($_POST)  && !empty($error['email'])): ?>
                    <div class="alert alert-danger" role="alert">
                        <?php echo $error['email'] ?>
                    </div>
                <?php endif; ?>
            </div>
            <div class="form-group">
                <label for="password">Password</label>
                <input type="password" name="password" id="password" class="form-control" placeholder="Password">
                <?php if(!empty($_POST) && !empty($error['password'])): ?>
                    <div class="alert alert-danger" role="alert">
                        <?php echo $error['password'] ?>
                    </div>
                <?php endif; ?>
            </div>
            <div class="form-group">
                <label for="password-confirm">Password Confirmation</label>
                <input type="password" name="password-confirm" id="password-confirm" class="form-control" placeholder="Password Confirmation">
                <?php if(!empty($_POST) && !empty($error['password-confirm'])): ?>
                    <div class="alert alert-danger" role="alert">
                        <?php echo $error['password-confirm'] ?>
                    </div>
                <?php endif; ?>
            </div>
            <button class="btn btn-info">Send</button>
        </form>
      </div>
    </div>
  </body>
</html>