From 7d3bc3104c06404d864844377d177221322a3b8d Mon Sep 17 00:00:00 2001
From: Alex Tselegidis <alextselegidis@gmail.com>
Date: Tue, 2 Nov 2021 10:44:37 +0100
Subject: [PATCH] Created new library that handles common API functionality.

---
 application/libraries/Api.php | 226 ++++++++++++++++++++++++++++++++++
 1 file changed, 226 insertions(+)
 create mode 100644 application/libraries/Api.php

diff --git a/application/libraries/Api.php b/application/libraries/Api.php
new file mode 100644
index 00000000..8496d8f5
--- /dev/null
+++ b/application/libraries/Api.php
@@ -0,0 +1,226 @@
+<?php defined('BASEPATH') or exit('No direct script access allowed');
+
+/* ----------------------------------------------------------------------------
+ * Easy!Appointments - Open Source Web Scheduler
+ *
+ * @package     EasyAppointments
+ * @author      A.Tselegidis <alextselegidis@gmail.com>
+ * @copyright   Copyright (c) 2013 - 2020, Alex Tselegidis
+ * @license     http://opensource.org/licenses/GPL-3.0 - GPLv3
+ * @link        http://easyappointments.org
+ * @since       v1.5.0
+ * ---------------------------------------------------------------------------- */
+
+
+/**
+ * Api library.
+ *
+ * Handles API related functionality.
+ *
+ * @package Libraries
+ */
+class Api {
+    /**
+     * @var EA_Controller
+     */
+    protected $CI;
+
+    /**
+     * @var int
+     */
+    private $default_length = 20;
+
+    /**
+     * Api constructor.
+     */
+    public function __construct()
+    {
+        $this->CI =& get_instance();
+
+        $this->CI->load->library('accounts');
+    }
+
+    public function authorize()
+    {
+        try
+        {
+            // Bearer token. 
+            $api_token = setting('api_token');
+
+            if ( ! empty($api_token) && $api_token === $this->get_bearer_token())
+            {
+                return;
+            }
+
+            if ( ! isset($_SERVER['PHP_AUTH_USER']))
+            {
+                return;
+            }
+
+            // Basic auth.  
+            $username = $_SERVER['PHP_AUTH_USER'];
+
+            $password = $_SERVER['PHP_AUTH_PW'];
+
+            if ( ! $this->CI->accounts->check_login($username, $password))
+            {
+                throw new RuntimeException('The provided credentials do not match any admin user!', 401, 'Unauthorized');
+            }
+        }
+        catch (Throwable $e)
+        {
+            $this->request_authentication();
+        }
+    }
+
+    /**
+     * Returns the bearer token value.
+     *
+     * @return string
+     */
+    protected function get_bearer_token(): ?string
+    {
+        $headers = $this->get_authorization_header();
+
+        // HEADER: Get the access token from the header
+
+        if ( ! empty($headers))
+        {
+            if (preg_match('/Bearer\s(\S+)/', $headers, $matches))
+            {
+                return $matches[1];
+            }
+        }
+
+        return NULL;
+    }
+
+    /**
+     * Returns the authorization header.
+     *
+     * @return string|null
+     */
+    protected function get_authorization_header(): ?string
+    {
+        $headers = NULL;
+
+        if (isset($_SERVER['Authorization']))
+        {
+            $headers = trim($_SERVER['Authorization']);
+        }
+        else
+        {
+            if (isset($_SERVER['HTTP_AUTHORIZATION']))
+            {
+                // Nginx or fast CGI
+                $headers = trim($_SERVER['HTTP_AUTHORIZATION']);
+            }
+            elseif (function_exists('apache_request_headers'))
+            {
+                $requestHeaders = apache_request_headers();
+
+                // Server-side fix for bug in old Android versions (a nice side effect of this fix means we don't care
+                // about capitalization for Authorization).
+                $requestHeaders = array_combine(array_map('ucwords', array_keys($requestHeaders)), array_values($requestHeaders));
+
+                if (isset($requestHeaders['Authorization']))
+                {
+                    $headers = trim($requestHeaders['Authorization']);
+                }
+            }
+        }
+
+        return $headers;
+    }
+
+    /**
+     * Sets request authentication headers.
+     */
+    public function request_authentication()
+    {
+        header('WWW-Authenticate: Basic realm="Easy!Appointments"');
+        header('HTTP/1.0 401 Unauthorized');
+        exit('You are not authorized to use the API.');
+    }
+
+    /**
+     * Get the search keyword value of the current request.
+     *
+     * @return string|null
+     */
+    public function request_keyword(): ?string
+    {
+        return request('q');
+    }
+
+    /**
+     * Get the limit value of the current request.
+     *
+     * @return int|null
+     */
+    public function request_limit(): ?int
+    {
+        return request('length', $this->default_length);
+    }
+
+    /**
+     * Get the limit value of the current request.
+     *
+     * @return int|null
+     */
+    public function request_offset(): ?int
+    {
+        $page = request('page', 1);
+
+        $length = request('length', $this->default_length);
+
+        return ($page - 1) * $length;
+    }
+
+    /**
+     * Get the order by value of the current request.
+     *
+     * @return string|null
+     */
+    public function request_order_by(): ?string
+    {
+        $sort = request('sort');
+
+        if ( ! $sort)
+        {
+            return NULL;
+        }
+
+        $sort_tokens = explode(',', $sort);
+
+        $order_by = [];
+
+        foreach ($sort_tokens as $sort_token)
+        {
+            $field = substr($sort_token, 1);
+
+            $direction = substr($sort_token, 0, 1) === '-' ? 'DESC' : 'ASC';
+
+            $order_by[] = $field . ' ' . $direction;
+        }
+
+        return implode(', ', $order_by);
+    }
+
+    /**
+     * Get the chosen fields array of the current request.
+     *
+     * @return array|null
+     */
+    public function request_fields(): ?array
+    {
+        $fields = request('fields');
+
+        if ( ! $fields)
+        {
+            return NULL;
+        }
+
+        return explode(',', $fields);
+    }
+}