action.php

<?php

// Open connection to DB by including conn.php
include_once "conn.php";
// Connection is On.

/* Functions */
function email_is_persent($con,$email)
{
	$temp = $email;
	$conn = $con;
	$sql = "SELECT user_email FROM users WHERE user_email = ? ;";

	$stmt = mysqli_stmt_init($conn);
	mysqli_stmt_prepare($stmt,$sql);
	mysqli_stmt_bind_param($stmt,'s',$temp);

	if(!mysqli_stmt_execute($stmt)){
		echo "Error on executing stmt of email function";
		exit();
	}else{
		$result = mysqli_stmt_get_result($stmt);
		if(mysqli_num_rows($result) <= 0){
			return false;
		}else{
			return true;
		}
	}
	mysqli_stmt_close($stmt);
}

function username_is_persent($con,$user)
{
	$temp = $user;
	$conn = $con;
	$sql = "SELECT user_uid FROM users WHERE user_uid = ? ;";

	$stmt = mysqli_stmt_init($conn);
	mysqli_stmt_prepare($stmt,$sql);
	mysqli_stmt_bind_param($stmt,'s',$temp);

	if(!mysqli_stmt_execute($stmt)){
		echo "Error on executing stmt of username function";
		exit();
	}else{
		$result = mysqli_stmt_get_result($stmt);
		if(mysqli_num_rows($result) <= 0){
			return false;
		}else{
			return true;
		}
	}
	mysqli_stmt_close($stmt);
}

function password_is_strong($password)
{
	$temp = $password;
	$isStrong = true;

	if( strlen($temp) < 8 || !preg_match("/[A-Z]+/", $temp))
	{
		$isStrong = false;
	}


	return $isStrong;
}

function Signup_InsertData($con,$var_firstname,$var_lastname,$var_email,$var_phone,$var_username,$var_password)
{
	$first = $var_firstname;
	$last =$var_lastname;
	$email = $var_email;
	$phone = $var_phone;
	$username = $var_username;
	$password = $var_password;
	$conn = $con;

	// Hashing Password For Security
	$password = password_hash($password, PASSWORD_DEFAULT);

	$sql = "INSERT INTO users (user_first,user_last,user_email,user_phone,user_uid,user_pwd) VALUES (?,?,?,?,?,?);";
	$stmt = mysqli_stmt_init($conn);
	mysqli_stmt_prepare($stmt,$sql);
	mysqli_stmt_bind_param($stmt,'ssssss',$first,$last,$email,$phone,$username,$password);

	if( !mysqli_stmt_execute($stmt) )
	{
		return false;
	}
	else
	{
		return true;
	}

	mysqli_stmt_close($stmt);
}
/* Functions */

// Handles if accessing page without submit clicking
if(!isset($_POST['SignUpSubmit'])){
	header("Location: index.php?Error=InvalidPage");
	exit();
}
else // If user click Submit else works
{

	// Storing user inputs and escaping them to aviod speical characters using mysqli_real function
	$firstname = mysqli_real_escape_string($conn,$_POST['FirstName']);
	$lastname = mysqli_real_escape_string($conn,$_POST['LastName']);
	$email = mysqli_real_escape_string($conn,$_POST['Email']);
	$phone = mysqli_real_escape_string($conn,$_POST['Phone']);
	$username = mysqli_real_escape_string($conn,$_POST['UserName']);
	$password = mysqli_real_escape_string($conn,$_POST['Password']);


	// Checking if all fields are filled
	if( empty($firstname) or empty($lastname) or empty($email) or empty($phone) or empty($username) or empty($password) )
	{
		// Including all inputs (except for password) , back on the URL to retrieve them using $_GET[] at index.php
		header("Location: index.php?Error=EmptyField&firstname=$firstname&lastname=$lastname&email=$email&phone=$phone&username=$username");
		exit();
	}
	else // if all fields arn't empty else works
	{

		if( !preg_match("/^[A-Za-z]+$/", $firstname) or !preg_match("/^[A-Za-z]+$/", $lastname) ) // Validating FirstName and LastName Formats
		{
			header("Location: index.php?Error=InvalidName&firstname=$firstname&lastname=$lastname&email=$email&phone=$phone&username=$username");
			exit();
		}
		else // if FirstName and LastName are valid else works
		{

			if( !filter_var($email,FILTER_VALIDATE_EMAIL) ) // Validate Email Format
			{
				header("Location: index.php?Error=InvalidEmail&firstname=$firstname&lastname=$lastname&email=&phone=$phone&username=$username");
				exit();
			}
			else // if Email is valid format else works
			{

				if( email_is_persent($conn,$email)) // Check if email is already persent on DB
				{
					header("Location: index.php?Error=PersentEmail&firstname=$firstname&lastname=$lastname&email=&phone=$phone&username=$username");
					exit();
				}
				else // if Email is not persent at DB else works
				{

					if( !preg_match("/^01[0-9]{8}$/", $phone) ) // Checks if phone format is valid
					{
						header("Location: index.php?Error=InvalidPhone&firstname=$firstname&lastname=$lastname&email=$email&phone=&username=$username");
						exit();
					}
					else // if phone format is valid else works
					{

						if( username_is_persent($conn,$username) ) // Checks if username is already persent on DB
						{
							header("Location: index.php?Error=PersentUsername&firstname=$firstname&lastname=$lastname&email=$email&phone=$phone&username=");
							exit();
						}
						else // if username is not persent at DB else works
						{

							if( !password_is_strong($password) ) // Check password Strength
							{
								header("Location: index.php?Error=WeakPassword&firstname=$firstname&lastname=$lastname&email=$email&phone=$phone&username=$username");
								exit();
							}
							else // if password is strong else works
							{

								if( !Signup_InsertData($conn,$firstname,$lastname,$email,$phone,$username,$password) ) // Function to Complete Signup
								{
									header("Location: index.php?Error=Signup&firstname=$firstname&lastname=$lastname&email=$email&phone=$phone&username=$username");
									exit();
								}
								else // if Signup is successfull else works
								{
									echo "Your Signed Up Successfully!";
									mysql_close($conn);
								}

							}
						}
					}
				}
			}
		}
	}
}