<?php 
  session_start(); 
  require("BotDetect.php"); 


  $form_page = "index.php";
	$view_page = "Messages.php";
	
	// directly accessing this script is an error
	if (!$_SERVER['REQUEST_METHOD'] == "POST") {
    header("Location: ${form_page}");
    exit;
	}

	// sumbitted data
	$name = $_REQUEST['Name'];
	$email = $_REQUEST['Email'];
	$message = $_REQUEST['Message'];
	$form_page = $form_page . "?Name=" . urlencode($name) . "&Email=" . urlencode($email) . "&Message=" . urlencode($message);

	// total form validation result
	$isPageValid = true;

  
  // Captcha validation 
  $FormCaptcha = new Captcha("FormCaptcha");
	$FormCaptcha->UserInputID = "CaptchaCode";
	if (!$FormCaptcha->IsSolved) {
		$isHuman = $FormCaptcha->Validate();
		$isPageValid = $isPageValid && $isHuman;
		$form_page = $form_page . "&captchaValid=" . $isHuman;
	}
	
	// name validation
	$isNameValid = ValidateName($name);
	$isPageValid = $isPageValid && $isNameValid;
	$form_page = $form_page . "&nameValid=" . $isNameValid;
	
	// email validation
	$isEmailValid = ValidateEmail($email);
	$isPageValid = $isPageValid && $isEmailValid;
	$form_page = $form_page . "&emailValid=" . $isEmailValid;
	
	// message validation
	$isMessageValid = ValidateMessage($message);
	$isPageValid = $isPageValid && $isMessageValid;
	$form_page = $form_page . "&messageValid=" . $isMessageValid;
	
	if (!$isPageValid) { 
		// form validation failed, show error message
		header("Location: ${form_page}");
    exit;
	}
	
	// keep a collection of submitted valid messages in Session state
	SaveMessage($name, $email, $message);
  $FormCaptcha->Reset(); // each message requires a new Captcha challenge
	header("Location: ${view_page}");
  exit;
	
  
	// name validation
	function ValidateName($name) {
	  $result = false;
		if (strlen($name) > 2 && strlen($name) < 30) {
		  $result = true;
		}
	  return $result;
	}
	
	// email validaton
	function ValidateEmail($email) {
	  $result = false;
		if (strlen($email) < 5 || strlen($email) > 100) {
		  $result = false;
		} else {
		  $result = (1 == preg_match('/^(.+)@(.+)\.(.+)$/', $email));
		}
		return $result;
	}
	
	// message validation
  function ValidateMessage($message) {
	  $result = false;
		if (strlen($message) > 2 && strlen($message) < 255) {
		  $result = true;
		}
	  return $result;
	}
	
	// data storage
	function SaveMessage($name, $email, $message) {
	  // we want to keep the sample code simple, so we'll store the messages in Session state despite it being unfit for real-world use in such scenarios;
    // using a database or another appropriate persistence medium would complicate the sample code
		$_SESSION['Message_' . $FormCaptcha->InstanceId] = htmlentities($name) . ' (' . htmlentities($email) . ') says: ' . htmlentities($message);
	}
  
?>