Api PHP

index.php

<?php

include_once('sql.php');
include_once('request.php');
include_once('response.php');

header('Content-Type: application/json');

$request  = Request::auto_construct();
$response = new Response($request);

$response->respond();

request.php

<?php

class Request {

	protected static $allowed_verbes  = array("GET");
	protected static $allowed_items   = array('games', 'companies', 'keywords');
	protected static $allowed_fields  = array('id', 'slug');
	protected static $max_limit       = 100;

	public $error      = false;
	public $error_msg  = null;

	public $item       = null;
	public $limit      = null;
	public $verbe      = null;
	public $pagination = null;
	public $fields     = null;

	function __construct($verbe, $item, $fields, $limit = 20, $pagination = 0)
	{
		$this->verbe      = $verbe;
		$this->item       = $item;
		$this->limit      = $limit;
		$this->fields     = $fields;
		$this->pagination = $pagination;

		$this->validate();
	}

	function validate()
	{
		if(!in_array($this->verbe, get_called_class()::$allowed_verbes)) {
			$this->error = true;
			$this->error_msg = 'HTTP verbe "' . $this->verbe . '" unauthorized.';
		}
		elseif(!in_array($this->item, get_called_class()::$allowed_items)) {
			$this->error = true;
			$this->error_msg = 'Item type "' . $this->item . '" unauthorized.';
		}
		elseif($this->limit > get_called_class()::$max_limit) {
			$this->error = true;
			$this->error_msg = 'Limit ' . $this->limit . ' too high, max: ' . $this->max_limit;
		}
		else {
			foreach($this->fields as $field) {
				if(!in_array($field, get_called_class()::$allowed_fields)) {
					$this->error = true;
					$this->error_msg = 'Fields "' . join(', ', $this->fields) . '" contains unauthorized fields.';
					continue;
				}
			}
		}

		return $this->error;
	}


	static function from_array($array)
	{
		return new self(
			$array['HTTP_METHOD'],
			$array['REQUEST']['item'],
			explode(',', $array['REQUEST']['fields']),
			$array['REQUEST']['limit'],
			$array['REQUEST']['pagination']
		);
	}

	static function auto_construct()
	{
		$verbe  = $_SERVER['REQUEST_METHOD'];

		if(isset($_REQUEST['item'])) {
			$item   = $_REQUEST['item'];
		} else {
			$item = null;
		}

		if(isset($_REQUEST['fields'])) {
			$fields = explode(',', $_REQUEST['fields']);
		} else {
			$fields = null;
		}
		if(isset($_REQUEST['limit'])) {
			$limit  = $_REQUEST['limit'];
		} else {
			$limit = null;
		}
		if(isset($_REQUEST['pagination'])) {
			$pagin  = $_REQUEST['pagination'];
		} else {
			$pagin = null;
		}

		if($item == 'games') {
			return new GamesRequest($verbe, $fields, $limit, $pagin);
		}
		elseif($item == 'companies') {
			return new CompaniesRequest($verbe, $fields, $limit, $pagin);
		}
		elseif($item == 'keywords') {
			return new KeywordsRequest($verbe, $fields, $limit, $pagin);
		}
		else {
			return new self($verbe, $item, $fields, $limit, $pagin);
		}
	}
}


class GamesRequest extends Request{

	protected static $allowed_fields = array('id', 'name', 'slug', 'popularity');
	protected static $allowed_items    = array('games');

	function __construct($verbe, $fields, $limit = 20, $pagination = 0)
	{
		parent::__construct($verbe, 'games', $fields, $limit, $pagination);
	}
}

class CompaniesRequest extends Request{

	protected static $allowed_fields = array('id', 'name', 'slug');
	protected static $allowed_items    = array('companies');

	function __construct($verbe, $fields, $limit = 20, $pagination = 0)
	{
		parent::__construct($verbe, 'companies', $fields, $limit, $pagination);
	}
}

class KeywordsRequest extends Request{

	protected static $allowed_fields = array('id', 'name', 'slug');
	protected static $allowed_items    = array('keywords');
	protected static $max_limit      = 400;

	function __construct($verbe, $fields, $limit = 20, $pagination = 0)
	{
		parent::__construct($verbe, 'keywords', $fields, $limit, $pagination);
	}
}

response.php

<?php

class Response {

	public $error       = false;
	public $http_status = 200;
	public $request     = null;
	public $data        = array();

	function __construct($request)
	{
		$this->request = $request;

		if($this->request->error === true) {
			$this->http_status = 400;
		}

		$this->db = new Database('localhost', 'root', 'root', 'igdb');
	}


	function get_data()
	{
		$query = $this->db->compute_query(
			$this->request->item, 
			$this->request->fields, 
			$this->request->limit, 
			$this->request->pagination
		);
		return array(
			"data" => $this->db->execute($query),
			"error" => false,
			"_query" => $query
		);
	}

	function respond()
	{
		if($this->request->error) {
			echo(json_encode(array("error" => true, "message" => $this->request->error_msg)));
		}
		else {
			echo(json_encode($this->get_data()));
		}
	}
}

sql.php

<?php

class Database {

	function __construct($hostname, $username, $password, $database)
	{
		$this->db = new mysqli($hostname, $username, $password, $database);
	}

	function compute_query($item, $fields, $limit, $pagination)
	{
		$sql_fields = join(', ', $fields);
		$offset = $pagination * $limit;
		return "SELECT $sql_fields FROM $item LIMIT $offset, $limit";
	}

	function execute($query)
	{
		return $this->db->query($query)->fetch_all();
	}
}