<?php

/**
 * Class PasswordResetModel
 *
 * Handles all the stuff that is related to the password-reset process
 */
class PasswordResetModel
{
	/**
	 * Perform the necessary actions to send a password reset mail
	 *
	 * @param $user_name_or_email string Username or user's email
	 *
	 * @return bool success status
	 */
	public static function requestPasswordReset($user_name_or_email)
	{
		if (empty($user_name_or_email)) {
			Session::add('feedback_negative', Text::get('FEEDBACK_USERNAME_EMAIL_FIELD_EMPTY'));
			return false;
		}

		// check if that username exists
		$result = UserModel::getUserDataByUserNameOrEmail($user_name_or_email);
		if (!$result) {
			Session::add('feedback_negative', Text::get('FEEDBACK_USER_DOES_NOT_EXIST'));
			return false;
		}

		// generate integer-timestamp (to see when exactly the user (or an attacker) requested the password reset mail)
		// generate random hash for email password reset verification (40 char string)
		$temporary_timestamp = time();
		$user_password_reset_hash = sha1(uniqid(mt_rand(), true));

		// set token (= a random hash string and a timestamp) into database ...
		$token_set = PasswordResetModel::setPasswordResetDatabaseToken($result->user_name, $user_password_reset_hash, $temporary_timestamp);
		if (!$token_set) {
			return false;
		}

		// ... and send a mail to the user, containing a link with username and token hash string
		$mail_sent = PasswordResetModel::sendPasswordResetMail($result->user_name, $user_password_reset_hash, $result->user_email);
		if ($mail_sent) {
			return true;
		}

		// default return
		return false;
	}

	/**
	 * Set password reset token in database (for DEFAULT user accounts)
	 *
	 * @param string $user_name username
	 * @param string $user_password_reset_hash password reset hash
	 * @param int $temporary_timestamp timestamp
	 *
	 * @return bool success status
	 */
	public static function setPasswordResetDatabaseToken($user_name, $user_password_reset_hash, $temporary_timestamp)
	{
		$database = DatabaseFactory::getFactory()->getConnection();

		$sql = "UPDATE users
                SET user_password_reset_hash = :user_password_reset_hash, user_password_reset_timestamp = :user_password_reset_timestamp
                WHERE user_name = :user_name AND user_provider_type = :provider_type LIMIT 1";
		$query = $database->prepare($sql);
		$query->execute(array(
			':user_password_reset_hash' => $user_password_reset_hash, ':user_name' => $user_name,
			':user_password_reset_timestamp' => $temporary_timestamp, ':provider_type' => 'DEFAULT'
		));

		// check if exactly one row was successfully changed
		if ($query->rowCount() == 1) {
			return true;
		}

		// fallback
		Session::add('feedback_negative', Text::get('FEEDBACK_PASSWORD_RESET_TOKEN_FAIL'));
		return false;
	}

	/**
	 * Send the password reset mail
	 *
	 * @param string $user_name username
	 * @param string $user_password_reset_hash password reset hash
	 * @param string $user_email user email
	 *
	 * @return bool success status
	 */
	public static function sendPasswordResetMail($user_name, $user_password_reset_hash, $user_email)
	{
		// create email body
		$body = Config::get('EMAIL_PASSWORD_RESET_CONTENT') . ' ' . Config::get('URL') .
		        Config::get('EMAIL_PASSWORD_RESET_URL') . '/' . urlencode($user_name) . '/' . urlencode($user_password_reset_hash);

		// create instance of Mail class, try sending and check
		$mail = new Mail;
		$mail_sent = $mail->sendMail($user_email, Config::get('EMAIL_PASSWORD_RESET_FROM_EMAIL'), 
            Config::get('EMAIL_PASSWORD_RESET_FROM_NAME'), Config::get('EMAIL_PASSWORD_RESET_SUBJECT'), $body
		);

		if ($mail_sent) {
			Session::add('feedback_positive', Text::get('FEEDBACK_PASSWORD_RESET_MAIL_SENDING_SUCCESSFUL'));
			return true;
		}

		Session::add('feedback_negative', Text::get('FEEDBACK_PASSWORD_RESET_MAIL_SENDING_ERROR') . $mail->getError() );
		return false;
	}

	/**
	 * Verifies the password reset request via the verification hash token (that's only valid for one hour)
	 * @param string $user_name Username
	 * @param string $verification_code Hash token
	 * @return bool Success status
	 */
	public static function verifyPasswordReset($user_name, $verification_code)
	{
		$database = DatabaseFactory::getFactory()->getConnection();

		// check if user-provided username + verification code combination exists
		$sql = "SELECT user_id, user_password_reset_timestamp
                  FROM users
                 WHERE user_name = :user_name
                       AND user_password_reset_hash = :user_password_reset_hash
                       AND user_provider_type = :user_provider_type
                 LIMIT 1";
		$query = $database->prepare($sql);
		$query->execute(array(
			':user_password_reset_hash' => $verification_code, ':user_name' => $user_name,
			':user_provider_type' => 'DEFAULT'
		));

		// if this user with exactly this verification hash code does NOT exist
		if ($query->rowCount() != 1) {
			Session::add('feedback_negative', Text::get('FEEDBACK_PASSWORD_RESET_COMBINATION_DOES_NOT_EXIST'));
			return false;
		}

		// get result row (as an object)
		$result_user_row = $query->fetch();

		// 3600 seconds are 1 hour
		$timestamp_one_hour_ago = time() - 3600;

		// if password reset request was sent within the last hour (this timeout is for security reasons)
		if ($result_user_row->user_password_reset_timestamp > $timestamp_one_hour_ago) {
			// verification was successful
			Session::add('feedback_positive', Text::get('FEEDBACK_PASSWORD_RESET_LINK_VALID'));
			return true;
		} else {
			Session::add('feedback_negative', Text::get('FEEDBACK_PASSWORD_RESET_LINK_EXPIRED'));
			return false;
		}
	}

	/**
	 * Writes the new password to the database
	 *
	 * @param string $user_name username
	 * @param string $user_password_hash
	 * @param string $user_password_reset_hash
	 *
	 * @return bool
	 */
	public static function saveNewUserPassword($user_name, $user_password_hash, $user_password_reset_hash)
	{
		$database = DatabaseFactory::getFactory()->getConnection();

		$sql = "UPDATE users SET user_password_hash = :user_password_hash, user_password_reset_hash = NULL,
                       user_password_reset_timestamp = NULL
                 WHERE user_name = :user_name AND user_password_reset_hash = :user_password_reset_hash
                       AND user_provider_type = :user_provider_type LIMIT 1";
		$query = $database->prepare($sql);
		$query->execute(array(
			':user_password_hash' => $user_password_hash, ':user_name' => $user_name,
			':user_password_reset_hash' => $user_password_reset_hash, ':user_provider_type' => 'DEFAULT'
		));

		// if one result exists, return true, else false. Could be written even shorter btw.
		return ($query->rowCount() == 1 ? true : false);
	}

	/**
	 * Set the new password (for DEFAULT user, FACEBOOK-users don't have a password)
	 * Please note: At this point the user has already pre-verified via verifyPasswordReset() (within one hour),
	 * so we don't need to check again for the 60min-limit here. In this method we authenticate
	 * via username & password-reset-hash from (hidden) form fields.
	 *
	 * @param string $user_name
	 * @param string $user_password_reset_hash
	 * @param string $user_password_new
	 * @param string $user_password_repeat
	 *
	 * @return bool success state of the password reset
	 */
	public static function setNewPassword($user_name, $user_password_reset_hash, $user_password_new, $user_password_repeat)
	{
		// validate the password
		if (!self::validateNewPassword($user_name, $user_password_reset_hash, $user_password_new, $user_password_repeat)) {
			return false;
		}

		// crypt the password (with the PHP 5.5+'s password_hash() function, result is a 60 character hash string)
		$user_password_hash = password_hash($user_password_new, PASSWORD_DEFAULT);

		// write the password to database (as hashed and salted string), reset user_password_reset_hash
		if (PasswordResetModel::saveNewUserPassword($user_name, $user_password_hash, $user_password_reset_hash)) {
			Session::add('feedback_positive', Text::get('FEEDBACK_PASSWORD_CHANGE_SUCCESSFUL'));
			return true;
		} else {
			Session::add('feedback_negative', Text::get('FEEDBACK_PASSWORD_CHANGE_FAILED'));
			return false;
		}
	}

	/**
	 * Validate the password submission
	 *
	 * @param $user_name
	 * @param $user_password_reset_hash
	 * @param $user_password_new
	 * @param $user_password_repeat
	 *
	 * @return bool
	 */
	public static function validateNewPassword($user_name, $user_password_reset_hash, $user_password_new, $user_password_repeat)
	{
		if (empty($user_name)) {
			Session::add('feedback_negative', Text::get('FEEDBACK_USERNAME_FIELD_EMPTY'));
			return false;
		} else if (empty($user_password_reset_hash)) {
			Session::add('feedback_negative', Text::get('FEEDBACK_PASSWORD_RESET_TOKEN_MISSING'));
			return false;
		} else if (empty($user_password_new) || empty($user_password_repeat)) {
			Session::add('feedback_negative', Text::get('FEEDBACK_PASSWORD_FIELD_EMPTY'));
			return false;
		} else if ($user_password_new !== $user_password_repeat) {
			Session::add('feedback_negative', Text::get('FEEDBACK_PASSWORD_REPEAT_WRONG'));
			return false;
		} else if (strlen($user_password_new) < 6) {
			Session::add('feedback_negative', Text::get('FEEDBACK_PASSWORD_TOO_SHORT'));
			return false;
		}

		return true;
	}
}