phly/http
=========

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`phly/http` is a PHP package containing implementations of the [proposed PSR HTTP message interfaces](https://github.com/php-fig/fig-standards/blob/master/proposed/http-message.md), as well as a "server" implementation similar to [node's http.Server](http://nodejs.org/api/http.html).

This package exists:

- to provide a proof-of-concept of the proposed PSR HTTP message interfaces with relation to server-side applications.
- to provide a node-like paradigm for PHP front controllers.
- to provide a common methodology for marshaling a request from the server environment.

Installation and Requirements
-----------------------------

Install this library using composer:

```console
$ composer require phly/http
```

`phly/http` has the following dependencies (which are managed by Composer):

- `psr/http-message`, which defines interfaces for HTTP messages, including requests and responses. `phly/http` provides implementations of each of these.

Contributing
------------

- Please write unit tests for any features or bug reports you have.
- Please run unit tests before opening a pull request. You can do so using `./vendor/bin/phpunit`.
- Please run CodeSniffer before opening a pull request, and correct any issues. Use the following to run it: `./vendor/bin/phpcs --standard=PSR2 --ignore=test/Bootstrap.php src test`.

Usage
-----

Usage will differ based on whether you are writing an HTTP client, or a server-side application.

For HTTP client purposes, you will create and populate a `Request` instance, and the client should return a `Response` instance.

For server-side applications, you will create a `ServerRequest` instance, and populate and return a `Response` instance.

### HTTP Clients

A client will _send_ a request, and _return_ a response. As a developer, you will _create_ and _populate_ the request, and then _introspect_ the response.  Both requests and responses are immutable; if you make changes -- e.g., by calling setter methods -- you must capture the return value, as it is a new instance.

```php
// Create a request
$request = (new Phly\Http\Request())
    ->withUri(new Phly\Http\Uri('http://example.com'))
    ->withMethod('PATCH')
    ->withAddedHeader('Authorization', 'Bearer ' . $token)
    ->withAddedHeader('Content-Type', 'application/json');

// OR:
$request = new Phly\Http\Request(
    'http://example.com',
    'PATCH',
    'php://memory',
    [
        'Authorization' => 'Bearer ' . $token,
        'Content-Type'  => 'application/json',
    ]
);

// If you want to set a non-origin-form request target, set the
// request-target explicitly:
$request = $request->withRequestTarget((string) $uri);       // absolute-form
$request = $request->withRequestTarget($uri->getAuthority(); // authority-form
$request = $request->withRequestTarget('*');                 // asterisk-form

// Once you have the instance:
$request->getBody()->write(json_encode($data));
$response = $client->send($request);

printf("Response status: %d (%s)\n", $response->getStatusCode(), $response->getReasonPhrase());
printf("Headers:\n");
foreach ($response->getHeaders() as $header => $values) {
  printf("    %s: %s\n", $header, implode(', ', $values));
}
printf("Message:\n%s\n", $response->getBody());
```

(Note: phly/http does NOT ship with a client implementation; the above is just an illustration of a possible implementation.)

### Server-Side Applications

Server-side applications will need to marshal the incoming request based on superglobals, and will then populate and send a response.

#### Marshaling an incoming request

PHP contains a plethora of information about the incoming request, and keeps that information in a variety of locations. `Phly\Http\ServerRequestFactory::fromGlobals()` can simplify marshaling that information into a request instance.

You can call the factory method with or without the following arguments, in the following order:

- `$server`, typically `$_SERVER`
- `$query`, typically `$_GET`
- `$body`, typically `$_POST`
- `$cookies`, typically `$_COOKIE`
- `$files`, typically `$_FILES`

The method will then return a `Phly\Http\ServerRequest` instance. If any argument is omitted, the associated superglobal will be used.

```php
$request = Phly\Http\ServerRequestFactory::fromGlobals(
  $_SERVER,
  $_GET,
  $_POST,
  $_COOKIE,
  $_FILES
);
```

#### Manipulating the response

Use the response object to add headers and provide content for the response.  Writing to the body does not create a state change in the response, so it can be done without capturing the return value. Manipulating headers does, however.

```php
$response = new Phly\Http\Response();

// Write to the response body:
$response->getBody()->write("some content\n");

// Multiple calls to write() append:
$response->getBody()->write("more content\n"); // now "some content\nmore content\n"

// Add headers
// Note: headers do not need to be added before data is written to the body!
$response = $response
    ->withHeader('Content-Type', 'text/plain')
    ->withAddedHeader('X-Show-Something', 'something');
```

#### "Serving" an application

`Phly\Http\Server` mimics a portion of the API of node's `http.Server` class. It invokes a callback, passing it an `ServerRequest`, an `Response`, and optionally a callback to use for incomplete/unhandled requests.

You can create a server in one of three ways:

```php
// Direct instantiation, with a callback handler, request, and response
$server = new Phly\Http\Server(
    function ($request, $response, $done) {
        $response->getBody()->write("Hello world!");
    },
    $request,
    $response
);

// Using the createServer factory, providing it with the various superglobals:
$server = Phly\Http\Server::createServer(
    function ($request, $response, $done) {
        $response->getBody()->write("Hello world!");
    },
    $_SERVER,
    $_GET,
    $_POST,
    $_COOKIE,
    $_FILES
);

// Using the createServerFromRequest factory, and providing it a request:
$server = Phly\Http\Server::createServerfromRequest(
  function ($request, $response, $done) {
      $response->getBody()->write("Hello world!");
  },
  $request
);
```

Server callbacks can expect up to three arguments, in the following order:

- `$request` - the request object
- `$response` - the response object
- `$done` - an optional callback to call when complete

Once you have your server instance, you must instruct it to listen:

```php
$server->listen();
```

At this time, you can optionally provide a callback to `listen()`; this will be passed to the handler as the third argument (`$done`):

```php
$server->listen(function ($request, $response, $error = null) {
    if (! $error) {
        return;
    }
    // do something with the error...
});
```

Typically, the `listen` callback will be an error handler, and can expect to
receive the request, response, and error as its arguments (though the error may
be null).

API
---

### Request Message

`Phly\Http\Request` implements `Psr\Http\Message\RequestInterface`, and is intended for client-side requests. It includes the following methods:

```php
class Request
{
    public function __construct(
        $uri = null,
        $method = null,
        $body = 'php://memory',
        array $headers = []
    );
    public function getRequestTarget();
    public function getMethod();
    public function getUri();
    public function getProtocolVersion();
    public function getBody();
    public function hasHeader($header);
    public function getHeader($header);
    public function getHeaderLines($header);
    public function getHeaders();
    public function withRequestTarget($requestTarget);
    public function withMethod($method);
    public function withUri(Psr\Http\Message\UriInterface $uri);
    public function withProtocolVersion($version);
    public function withHeader($header, $value);
    public function withAddedHeader($header, $value);
    public function withoutHeader($header);
    public function withBody(Psr\Http\Message\StreamableInterface $body);
}
```

Requests are immutable. Any methods that would change state -- those prefixed with `with` and `without` -- all return a new instance with the changes requested.

### ServerRequest Message

For server-side applications, `Phly\Http\ServerRequest` implements `Psr\Http\Message\ServerRequestInterface`, which provides access to the elements of an HTTP request, as well as uniform access to the various elements of incoming data. The methods included are:

```php
class ServerRequest
{
    public function __construct(
        array $serverParams = [],
        array $fileParams = [],
        $uri = null,
        $method = null,
        $body = 'php://input',
        array $headers = []
    );
    public function getRequestTarget();
    public function getMethod();
    public function getUri();
    public function getProtocolVersion();
    public function hasHeader($header);
    public function getHeader($header);
    public function getHeaderLines($header);
    public function getHeaders();
    public function getCookieParams();
    public function getQueryParams();
    public function getBody();
    public function getParsedBody();
    public function getAttribute($attribute, $default = NULL);
    public function getAttributes();
    public function getServerParams();
    public function getFileParams();
    public function hasHeader($header);

    public function withRequestTarget($requestTarget);
    public function withMethod($method);
    public function withUri(Psr\Http\Message\UriInterface $uri);
    public function withProtocolVersion($version);
    public function withHeader($header, $value);
    public function withAddedHeader($header, $value);
    public function withoutHeader($header);
    public function withCookieParams(array $cookies);
    public function withQueryParams(array $query);
    public function withBody(Psr\Http\Message\StreamableInterface $stream);
    public function withParsedBody(array $params);
    public function withAttribute($attribute, $value);
    public function withoutAttribute($attribute);
}
```

The `ServerRequest` is immutable. Any methods that would change state -- those prefixed with `with` and `without` -- all return a new instance with the changes requested. Two input sources, server and file parameters, are considered completely immutable, however, as they cannot be recalculated, and, rather, are the sources for other values.

### Response Message

`Phly\Http\Response` provides an implementation of `Psr\Http\Message\ResponseInterface`, an object to be used to aggregate response information for both HTTP clients and server-side applications, including headers and message body content. It includes the following:

```php
class Response
{
    public function __construct(
        $body = 'php://memory',
        $statusCode = 200,
        array $headers = []
    );
    public function getProtocolVersion();
    public function getStatusCode();
    public function getReasonPhrase();
    public function getHeader($header);
    public function getHeaderLines($header);
    public function getHeaders();
    public function getBody();
    public function hasHeader($header);
    public function withProtocolVersion($version);
    public function withStatus($code, $reasonPhrase = NULL);
    public function withHeader($header, $value);
    public function withAddedHeader($header, $value);
    public function withoutHeader($header);
    public function withBody(Psr\Http\Message\StreamableInterface $body);
}
```

Like the `Request` and `ServerRequest`, responses are immutable. Any methods that would change state -- those prefixed with `with` and `without` -- all return a new instance with the changes requested.

#### ServerRequestFactory

This static class can be used to marshal a `ServerRequest` instance from the PHP environment. The primary entry point is `Phly\Http\ServerRequestFactory::fromGlobals(array $server, array $query, array $body, array $cookies, array $files)`. This method will create a new `ServerRequest` instance with the data provided. Examples of usage are:

```php
// Returns new ServerRequest instance, using values from superglobals:
$request = ServerRequestFactory::fromGlobals();

// or

// Returns new ServerRequest instance, using values provided (in this
// case, equivalent to the previous!)
$request = RequestFactory::fromGlobals(
  $_SERVER,
  $_GET,
  $_POST,
  $_COOKIE,
  $_FILES
);
```

### URI

`Phly\Http\Uri` is an implementation of `Psr\Http\Message\UriInterface`, and models and validates URIs. It implements `__toString()`, allowing it to be represented as a string and `echo()`'d directly. The following methods are pertinent:

```php
class Uri
{
    public function __construct($uri = '');
    public function getScheme();
    public function getAuthority();
    public function getUserInfo();
    public function getHost();
    public function getPort();
    public function getPath();
    public function getQuery();
    public function getFragment();
    public function withScheme($scheme);
    public function withUserInfo($user, $password = null);
    public function withHost($host);
    public function withPort($port);
    public function withPath($path);
    public function withQuery($query);
    public function withFragment($fragment);
    public function __toString();
}
```

Like the various message objects, URIs are immutable. Any methods that would change state -- those prefixed with `with` and `without` -- all return a new instance with the changes requested.

### Stream

`Phly\Http\Stream` is an implementation of `Psr\Http\Message\StreamableInterface`, and provides a number of facilities around manipulating the composed PHP stream resource. The constructor accepts a stream, which may be either:

- a stream identifier; e.g., `php://input`, a filename, etc.
- a PHP stream resource

If a stream identifier is provided, an optional second parameter may be provided, the file mode by which to `fopen` the stream.

`ServerRequest` objects by default use a `php://input` stream set to read-only; `Response` objects by default use a `php://memory` with a mode of `wb+`, allowing binary read/write access.

In most cases, you will not interact with the Stream object directly.

### Server

`Phly\Http\Server` represents a server capable of executing a callback. It has four methods:

```php
class Server
{
    public function __construct(
        callable $callback,
        Psr\Http\Message\ServerRequestInterface $request,
        Psr\Http\Message\ResponseInterface $response
    );
    public static function createServer(
        callable $callback,
        array $server,  // usually $_SERVER
        array $query,   // usually $_GET
        array $body,    // usually $_POST
        array $cookies, // usually $_COOKIE
        array $files    // usually $_FILES
    );
    public static function createServerFromRequest(
        callable $callback,
        Psr\Http\Message\ServerRequestInterface $request,
        Psr\Http\Message\ResponseInterface $response = null
    );
    public function listen(callable $finalHandler = null);
}
```

You can create an instance of the `Server` using any of the constructor, `createServer()`, or `createServerFromRequest()` methods. If you wish to use the default request and response implementations, `createServer($middleware, $_SERVER, $_GET, $_POST, $_COOKIE, $_FILES)` is the recommended option, as this method will also marshal the `ServerRequest` object based on the PHP request environment.  If you wish to use your own implementations, pass them to the constructor or `createServerFromRequest()` method (the latter will create a default `Response` instance if you omit it).

`listen()` executes the callback. If a `$finalHandler` is provided, it will be passed as the third argument to the `$callback` registered with the server.