Simple Rest

ApiController.php

<?php

/**
 * Class ApiController
 *
 * File Location : application/core/ApiController.php
 *
 * @property CI_Input $input
 * @property CI_Output $output
 */
class ApiController extends CI_Controller {

    protected $identity;
    const TOKEN_KEY = 'token';
    const TOKEN_PREFIX = 'token ';

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

    /**
     * @return bool
     */
    public function is_guest(){
        return $this->get_identity() === null;
    }

    public function get_identity(){
        if($this->identity === null && (($token = $this->get_token()) != null)){
            /*
             * todo: query builder get user by token
             * example :
             * $row = $this->db->get_where('user',array(
             *  'active' => 0,
             *  'token' => $token
             * ));
             * if($row->num_rows() > 0){
             *      $this->identity = $row->row();
             * }
             */

            /*
             * todo: delete ini hanya contoh hapus kalau tidak perlu
             */
            if($token === '1234') {
                $this->identity = (object)array(
                    'user_id' => 1,
                    'name' => 'user'
                );
            }
        }

        return $this->identity;
    }

    /**
     * @return mixed|null
     */
    protected function get_token(){
        $headers = $this->input->request_headers();
        $token = isset($headers[static::TOKEN_KEY]) ? $headers[static::TOKEN_KEY] : null;
        return !is_null($token) && !empty($token) ? str_replace(static::TOKEN_PREFIX,'', $token) : null;
    }

    protected function response($response, $code = 200){
        $this->output
            ->set_status_header($code)
            ->set_content_type('application/json')
            ->set_output(json_encode($response));
    }

    protected function unauthorized(){
        return $this->response(array(
            'message' => 'Authorize failed'
        ), 401);
    }
}

Main.php

<?php
/*
 * File Location : application/controllers/Main.php
 */
require_once APPPATH.'core/ApiController.php';

class Main extends ApiController {

    public function __construct() {
        parent::__construct();
        $this->get_identity();
    }

    public function tes(){
        if($this->is_guest()) {
            $this->unauthorized();
        }else{
            $this->response(array(
                'status' => 'success',
                'data' => $this->get_identity()
            ));
        }
    }

}

Test call

GET http://localhost/ci/index.php/main/tes
Accept: */*
Cache-Control: no-cache
token: token 1234