CodeIgniter OAuth controller example

gistfile1.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Oauth extends CI_Controller {

	private $oauth;

	public function __construct()
	{
		parent::__construct();

		$this->load->model('authdb');
		$this->authServer = new Oauth2\Authentication\Server();
		
		$this->authServer->registerDbAbstractor($this->authdb);
	}

	public function index()
	{
		try {

			$params = $this->authServer->checkClientAuthoriseParams();

		}

		catch (Oauth2\Authentication\ClientException $e)
		{
			show_error('<strong>Client exception (' . $this->authServer->exceptionCodes[$e->getCode()] . '):</strong> ' . $e->getMessage());
		}

		catch (Oauth2\Authentication\UserException $e)
		{
			show_error('<strong>User exception (' . $this->authServer->exceptionCodes[$e->getCode()] . '):</strong> ' . $e);
		}

		catch (Oauth2\Authentication\ServerException $e)
		{
			show_error('<strong>Server exception (' . $this->authServer->exceptionCodes[$e->getCode()] . '):</strong> ' . $e);
		}

		catch (Exception $e)
		{
			show_error('<strong>General exception:</strong> ' . $e->getMessage());
		}

		$this->session->set_userdata('oauth', $params);
		redirect(site_url('oauth/signin'));
		
	}

	public function signin()
	{
		$user_id	= $this->session->userdata('user_id');
		$oauth		= $this->session->userdata('oauth');

		// If the user is already signed in then redirect them
		if ($user_id !== FALSE && $oauth !== FALSE)
		{
			redirect(site_url('oauth/authorise'));
		}

		if ($oauth === FALSE)
		{
			show_error('No OAuth session initiated or the request parameters haven\'t been saved properly');
		}

		$data = array();
		
		if ($this->input->post('username') && $this->input->post('password'))
		{
			$u = $this->input->post('username');
			$p = $this->input->post('password');

			if ($user_id = $this->auth->check($u, $p))
			{
				$this->session->set_userdata('user_id', $user_id);
				redirect(site_url('oauth/authorise'));
			}

			else
			{
				$data['error'] = 'Invalid username/password';
			}
		}

		$this->load->view('oauth/signin', $data);
	}

	public function authorise()
	{
		$user_id	= $this->session->userdata('user_id');
		$oauth		= $this->session->userdata('oauth');

		if ($user_id === FALSE)
		{
			redirect(site_url('oauth/signin'));
		}

		if ($oauth === FALSE)
		{
			show_error('No OAuth session initiated or the request parameters haven\'t been saved properly');
		}

		if ($state = $this->input->post('state'))
		{
			switch ($state)
			{
				case 'approve':

					$code = $authserver->newAuthoriseRequest('user', $user_id, $oauth);

					// Redirect the user back to the client with the authorization code
					redirect($authserver->redirectUri($oauth['redirect_uri'], array(
						'code'	=>	$code,
						'state'	=>	isset($oauth['state']) ? $oauth['state'] : ''
					)));

				break;

				case 'deny':

					redirect($authserver->redirectUri($oauth['redirect_uri'], array(
						'error'	=>	$authserver->exceptionCodes[2],
						'error_message'	=>	$authserver->errors[$authserver->exceptionCodes[2]], 
						'state'	=>	isset($oauth['state']) ? $oauth['state'] : ''
					)));

				break;
			}
		}

		else
		{
			$this->load->view('oauth/authorise');
		}
	}

	public function access_token()
	{
		try {

			$response = $authserver->issueAccessToken();

		}

		catch (Oauth2\Authentication\ClientException $e)
		{
			$response = array(
				'error'	=>	$authserver->exceptionCodes[$e->getCode()],
				'error_description'	=> $e->getMessage()
			);
		}

		catch (Oauth2\Authentication\ServerException $e)
		{
			$response = array(
				'error'	=>	$authserver->exceptionCodes[$e->getCode()],
				'error_description'	=> $e->getMessage()
			);
		}

		catch (Oauth2\Authentication\Exception $e)
		{
			$response = array(
				'error'	=>	$authserver->exceptionCodes[$e->getCode()],
				'error_description'	=> $e->getMessage()
			);
		}

		catch (Exception $e)
		{
			$response = array(
				'error'	=>	'undefined_error',
				'error_description'	=> $e->getMessage()
			);
		}

		header('Content-type: application/json');
		echo json_encode($response);

	}

}