class ChangePassword{

    private $_errors = array();

    public function __construct(){

        require_once 'PasswordHash.php';
        require_once 'ValidateData.php';
        require_once 'SqlQueryController.php';

        if(isset($_POST['resetPassword'])){
            /**
            * @param associative array
            * stripAllWhiteSpaces will remove ALL white spaces.
            * example: $stringBefore = ' this is an example';
            *          $stringAfter  = 'thisisanexample';
            */
            $credentials = ValidateData::stripAllWhiteSpaces(array('passwordCurrent' => $_POST['passwordCurrent'],
                                                                   'passwordNew'     => $_POST['passwordNew'],
                                                                   'passwordNewAgain'=> $_POST['passwordNewAgain']
                                                                  )
                                                            );
            $this->doResetPassword($credentials);
        }
    }

    public function doResetPassword($credentials){
        /**
        * @bool  returns true if value is empty
        */
        if(ValidateData::isEmpty($credentials)){

            $_errors[] = '<p>Some fields are empty</p>';

        } else {

            if($credentials['passwordNew'] != $credentials['passwordNewAgain']){
                $_errors[] = '<p>Passwords do not match.</p>';
            }

            if($credentials['passwordNew'] == $credentials['passwordCurrent']){
                $_errors[] = '<p>Your new password cannot be the same as your old password.</p>';
            }

            /**
            * @bool
            * Example of valid password: Thequickbrown200!
            */
            if( ! ValidateData::pregMatch('/^(?=.*d)(?=.*[A-Za-z])[0-9A-Za-z!@#$%]{5,200}$/', $credentials['passwordNew'])){
                $_errors[] = '<p>The password must be between 5 and 200 characters long, must contain at least one number, at least one letter and at least one non Alphanumeric character.</p>';
            }

        }

        if( ! empty($_errors)){
                foreach($_errors as $error){
                    echo $error;
            }
            return;
        }

        $this->insertPassword($credentials);
        $_SESSION = array();
        session_destroy();
    }

    public function insertPassword($credentials){

        $passwordHash = new PasswordHash();

        $hashedPassword = $passwordHash->hashPassword($credentials['passwordNew']);

        $usernameId = $_SESSION['id'];

        $sqlQueryController = new SqlQueryController();

        $query = "UPDATE users_table
                 SET login_password=:passwordNew
                 WHERE login_id=:usernameId";

        $array = array(':passwordNew' => $hashedPassword,
                       ':usernameId'  => $usernameId);

        if($sqlQueryController->runQueryExecute($query, $array)){
            echo '<p>Successfully changed the password</p>';
        } else {
            echo '<p>An error occurred while changing the password</p>';
        }

    }

}

<?php

class Login{
    public function __construct(){

        require_once 'PasswordHash.php';
        require_once 'SqlQueryController.php';
        require_once 'ValidateData.php';

        if(isset($_POST['login'])){
            /**
            * @param associative array
            * stripAllWhiteSpaces will remove ALL white spaces.
            * example: $stringBefore = ' this is an example';
            *          $stringAfter  = 'thisisanexample';
            */
            $credentials = ValidateData::stripAllWhiteSpaces(array('username' => $_POST['username'],
                                                                   'password' => $_POST['password']
                                                                  )
                                                            );

            $this->doLogin($credentials);
        }
    }

    /**
    * Log in with post data
    */
    public function doLogin($credentials){
        if( ! ValidateData::isEmpty($credentials)){

            $passwordHash = new PasswordHash();

            $sqlQueryController = new SqlQueryController();

            $query = "SELECT login_password
                      FROM users_table
                      WHERE login_username=:username
                      LIMIT 1";

            $array = array(':username' => $credentials['username']);
            /**
            * @param associative array
            * return an associative array using PDO's fetch();
            */
            $hash = $sqlQueryController->runQueryFetch($query, $array);

            /**
            * @bool
            * verifies password based on the $hash
            * and the password provided by the user
            */
            $passwordVerify = $passwordHash->verifyPassword($credentials['password'], $hash['login_password']);

            $query = "SELECT login_username, login_id
                      FROM users_table
                      WHERE login_username=:username LIMIT 1";

            $array = array(':username' => $credentials['username']);

            $userVerify = $sqlQueryController->runQueryFetch($query, $array);

            if(($passwordVerify == 1) && ($userVerify['login_username'] == $credentials['username'])){

                /**
                * Great, the user's logged in
                * Time to set the session and redirect him
                */
                $_SESSION['id']       = $userVerify['login_id'];
                $_SESSION['username'] = $userVerify['login_username'];

                #session_write_close();
                header('Location: logged_in.php');
                die();
            } else {
                echo '<p> The username or password do not match any registered users.</p>';
            }
        } else {
            echo '<p> You must fill in all fields.</p>';
        }
    }
}

<?php

class RecoverPassword{

    public function __construct(){

        require_once 'PasswordHash.php';
        require_once 'SendMailRecoverPassword.php';
        require_once 'ValidateData.php';
        require_once 'SqlQueryController.php';

        if(isset($_POST['recoverPassword'])){
            /**
            * @param associative array
            * stripAllWhiteSpaces will remove ALL white spaces.
            * example: $stringBefore = ' this is an example';
            *          $stringAfter  = 'thisisanexample';
            */
            $credentials = ValidateData::stripAllWhiteSpaces(array('email' => $_POST['email']
                                                                   )
                                                            );
            $this->doRecoverPassword($credentials);
        }
    }

    public function doRecoverPassword($credentials){

        if(ValidateData::validateEmail($credentials['email'])){

            $sqlQueryController = new SqlQueryController();

            $query = "SELECT login_email
                      FROM users_table
                      WHERE login_email=:email LIMIT 1";
            $array = array(':email' => $credentials['email']);

            $emailExist = $sqlQueryController->runQueryFetchAssoc($query, $array);

            if($emailExist){

                /**
                * If a proper SMTP is not configured, the password
                * will not be changed and the page will die
                * with a user friendly error.
                * A more useful error can be found in the log fiels
                * The __construct() of the class is built
                * in such a way that it will throw the exception and die
                * after. Point is, don't move this further down the page
                * or the password WILL be changed but the email will NOT
                * be sent if the SMTP is not configured!
                */
                $swift = new SendMailRecoverPassword();

                $passwordHash = new PasswordHash();

                /*
                * Create a random string of letteres and numbers
                * This will be the users new password
                */
                $randomPassword = str_shuffle('abcdefghijklmnopqrstqwxz0123456789ABCDEFGHIJKLMNOPQRSTWXZ');

                /**
                * Hash the random string
                */
                $newPassword = $passwordHash->hashPassword($randomPassword);

                /**
                * Update the new hashed password
                * replacing the old password
                */
                $query = "UPDATE users_table
                          SET login_password=:password
                          WHERE login_email=:email LIMIT 1";
                $array = array(':password' => $newPassword,
                               ':email'    => $credentials['email']);

                $sqlQueryController->runQueryExecute($query, $array);

                /**
                * Create the message
                */
                $swift->createMessage($randomPassword, $credentials['email']);

                /**
                * Return the newly created message
                */
                $message = $swift->getMessage();

                /**
                * Send the message
                */
                if($swift->sendMessage($message)){
                    echo '<p>Check your inbox for the new password. Your old password will no longer work</p>';
                }

            } else {
                echo '<p>Email doesn't exist!</p>';
            }

        } else {
            echo '<p>Email is invalid</p>';
        }

    }
}

/**
            * Create the message
            */
            $swift->createMessage($randomPassword, $credentials['email']);

            /**
            * Return the newly created message
            */
            $message = $swift->getMessage();

            /**
            * Send the message
            */
            if($swift->sendMessage($message)){
                echo '<p>Check your inbox for the new password. Your old password will no longer work</p>';
            }

/**
* @param associative array
* stripAllWhiteSpaces will remove ALL white spaces.
* example: $stringBefore = ' this is an example';
*          $stringAfter  = 'thisisanexample';
*/
$credentials = ValidateData::stripAllWhiteSpaces(.....

/**
* @bool  returns true if value is empty
*/
if(ValidateData::isEmpty($credentials)){

public static function doRecoverPassword($credentials) {
    if (!ValidateData::validateEmail(…)) {
        echo '<p>Email is invalid</p>';
        return;
    }
    $sqlQueryController = …;
    …
    if (!$emailExist) {
        echo "<p>Email doesn't exist!</p>";
        return;
    }
    …
    if (!$swift->sendMessage($message)) {
        echo '<p>Failed to send message</p>';
        return;
    }
    echo '<p>Check your inbox…</p>';
}