<?php
namespace Aws;
use Aws\Api\Service;
use Aws\Api\Validator;
use Aws\Credentials\CredentialsInterface;
use GuzzleHttp\Promise;
use GuzzleHttp\Psr7;
use GuzzleHttp\Psr7\LazyOpenStream;
use Psr\Http\Message\RequestInterface;
final class Middleware
{
/**
* Middleware used to allow a command parameter (e.g., "SourceFile") to
* be used to specify the source of data for an upload operation.
*
* @param Service $api
* @param string $bodyParameter
* @param string $sourceParameter
*
* @return callable
*/
public static function sourceFile(
Service $api,
$bodyParameter = 'Body',
$sourceParameter = 'SourceFile'
) {
return function (callable $handler) use (
$api,
$bodyParameter,
$sourceParameter
) {
return function (
CommandInterface $command,
RequestInterface $request = null)
use (
$handler,
$api,
$bodyParameter,
$sourceParameter
) {
$operation = $api->getOperation($command->getName());
$source = $command[$sourceParameter];
if ($source !== null
&& $operation->getInput()->hasMember($bodyParameter)
) {
$command[$bodyParameter] = new LazyOpenStream($source, 'r');
unset($command[$sourceParameter]);
}
return $handler($command, $request);
};
};
}
/**
* Adds a middleware that uses client-side validation.
*
* @param Service $api API being accessed.
*
* @return callable
*/
public static function validation(Service $api, Validator $validator = null)
{
$validator = $validator ?: new Validator();
return function (callable $handler) use ($api, $validator) {
return function (
CommandInterface $command,
RequestInterface $request = null
) use ($api, $validator, $handler) {
$operation = $api->getOperation($command->getName());
$validator->validate(
$command->getName(),
$operation->getInput(),
$command->toArray()
);
return $handler($command, $request);
};
};
}
/**
* Builds an HTTP request for a command.
*
* @param callable $serializer Function used to serialize a request for a
* command.
* @return callable
*/
public static function requestBuilder(callable $serializer)
{
return function (callable $handler) use ($serializer) {
return function (CommandInterface $command) use ($serializer, $handler) {
return $handler($command, $serializer($command));
};
};
}
/**
* Creates a middleware that signs requests for a command.
*
* @param callable $credProvider Credentials provider function that
* returns a promise that is resolved
* with a CredentialsInterface object.
* @param callable $signatureFunction Function that accepts a Command
* object and returns a
* SignatureInterface.
*
* @return callable
*/
public static function signer(callable $credProvider, callable $signatureFunction)
{
return function (callable $handler) use ($signatureFunction, $credProvider) {
return function (
CommandInterface $command,
RequestInterface $request
) use ($handler, $signatureFunction, $credProvider) {
$signer = $signatureFunction($command);
return $credProvider()->then(
function (CredentialsInterface $creds)
use ($handler, $command, $signer, $request) {
return $handler(
$command,
$signer->signRequest($request, $creds)
);
}
);
};
};
}
/**
* Creates a middleware that invokes a callback at a given step.
*
* The tap callback accepts a CommandInterface and RequestInterface as
* arguments but is not expected to return a new value or proxy to
* downstream middleware. It's simply a way to "tap" into the handler chain
* to debug or get an intermediate value.
*
* @param callable $fn Tap function
*
* @return callable
*/
public static function tap(callable $fn)
{
return function (callable $handler) use ($fn) {
return function (
CommandInterface $command,
RequestInterface $request = null
) use ($handler, $fn) {
$fn($command, $request);
return $handler($command, $request);
};
};
}
/**
* Middleware wrapper function that retries requests based on the boolean
* result of invoking the provided "decider" function.
*
* If no delay function is provided, a simple implementation of exponential
* backoff will be utilized.
*
* @param callable $decider Function that accepts the number of retries,
* a request, [result], and [exception] and
* returns true if the command is to be retried.
* @param callable $delay Function that accepts the number of retries and
* returns the number of milliseconds to delay.
*
* @return callable
*/
public static function retry(callable $decider = null, callable $delay = null)
{
$decider = $decider ?: RetryMiddleware::createDefaultDecider();
$delay = $delay ?: [RetryMiddleware::class, 'exponentialDelay'];
return function (callable $handler) use ($decider, $delay) {
return new RetryMiddleware($decider, $delay, $handler);
};
}
/**
* Middleware wrapper function that adds a Content-Type header to requests.
* This is only done when the Content-Type has not already been set, and the
* request body's URI is available. It then checks the file extension of the
* URI to determine the mime-type.
*
* @param array $operations Operations that Content-Type should be added to.
*
* @return callable
*/
public static function contentType(array $operations)
{
return function (callable $handler) use ($operations) {
return function (
CommandInterface $command,
RequestInterface $request = null
) use ($handler, $operations) {
if (!$request->hasHeader('Content-Type')
&& in_array($command->getName(), $operations, true)
&& ($uri = $request->getBody()->getMetadata('uri'))
) {
$request = $request->withHeader(
'Content-Type',
Psr7\mimetype_from_filename($uri) ?: 'application/octet-stream'
);
}
return $handler($command, $request);
};
};
}
/**
* Tracks command and request history using a history container.
*
* This is useful for testing.
*
* @param History $history History container to store entries.
*
* @return callable
*/
public static function history(History $history)
{
return function (callable $handler) use ($history) {
return function (
CommandInterface $command,
RequestInterface $request = null
) use ($handler, $history) {
$ticket = $history->start($command, $request);
return $handler($command, $request)
->then(
function ($result) use ($history, $ticket) {
$history->finish($ticket, $result);
return $result;
},
function ($reason) use ($history, $ticket) {
$history->finish($ticket, $reason);
return Promise\rejection_for($reason);
}
);
};
};
}
/**
* Creates a middleware that applies a map function to requests as they
* pass through the middleware.
*
* @param callable $f Map function that accepts a RequestInterface and
* returns a RequestInterface.
*
* @return callable
*/
public static function mapRequest(callable $f)
{
return function (callable $handler) use ($f) {
return function (
CommandInterface $command,
RequestInterface $request = null
) use ($handler, $f) {
return $handler($command, $f($request));
};
};
}
/**
* Creates a middleware that applies a map function to commands as they
* pass through the middleware.
*
* @param callable $f Map function that accepts a command and returns a
* command.
*
* @return callable
*/
public static function mapCommand(callable $f)
{
return function (callable $handler) use ($f) {
return function (
CommandInterface $command,
RequestInterface $request = null
) use ($handler, $f) {
return $handler($f($command), $request);
};
};
}
/**
* Creates a middleware that applies a map function to results.
*
* @param callable $f Map function that accepts an Aws\ResultInterface and
* returns an Aws\ResultInterface.
*
* @return callable
*/
public static function mapResult(callable $f)
{
return function (callable $handler) use ($f) {
return function (
CommandInterface $command,
RequestInterface $request = null
) use ($handler, $f) {
return $handler($command, $request)->then($f);
};
};
}
}
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