<?php

namespace DeliciousBrains\WP_Offload_Media\Aws3\Aws\Credentials;

use DeliciousBrains\WP_Offload_Media\Aws3\Aws\Exception\CredentialsException;
use DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Psr7\Request;
use DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Promise\PromiseInterface;
use DeliciousBrains\WP_Offload_Media\Aws3\Psr\Http\Message\ResponseInterface;
/**
 * Credential provider that fetches credentials with GET request.
 * ECS environment variable is used in constructing request URI.
 */
class EcsCredentialProvider
{
    const SERVER_URI = 'http://169.254.170.2';
    const ENV_URI = "AWS_CONTAINER_CREDENTIALS_RELATIVE_URI";
    /** @var callable */
    private $client;
    /**
     *  The constructor accepts following options:
     *  - timeout: (optional) Connection timeout, in seconds, default 1.0
     *  - client: An EcsClient to make request from
     *
     * @param array $config Configuration options
     */
    public function __construct(array $config = [])
    {
        $this->timeout = isset($config['timeout']) ? $config['timeout'] : 1.0;
        $this->client = isset($config['client']) ? $config['client'] : \DeliciousBrains\WP_Offload_Media\Aws3\Aws\default_http_handler();
    }
    /**
     * Load ECS credentials
     *
     * @return PromiseInterface
     */
    public function __invoke()
    {
        $client = $this->client;
        $request = new \DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Psr7\Request('GET', self::getEcsUri());
        return $client($request, ['timeout' => $this->timeout, 'proxy' => ''])->then(function (\DeliciousBrains\WP_Offload_Media\Aws3\Psr\Http\Message\ResponseInterface $response) {
            $result = $this->decodeResult((string) $response->getBody());
            return new \DeliciousBrains\WP_Offload_Media\Aws3\Aws\Credentials\Credentials($result['AccessKeyId'], $result['SecretAccessKey'], $result['Token'], strtotime($result['Expiration']));
        })->otherwise(function ($reason) {
            $reason = is_array($reason) ? $reason['exception'] : $reason;
            $msg = $reason->getMessage();
            throw new \DeliciousBrains\WP_Offload_Media\Aws3\Aws\Exception\CredentialsException("Error retrieving credential from ECS ({$msg})");
        });
    }
    /**
     * Fetch credential URI from ECS environment variable
     *
     * @return string Returns ECS URI
     */
    private function getEcsUri()
    {
        $creds_uri = getenv(self::ENV_URI);
        return self::SERVER_URI . $creds_uri;
    }
    private function decodeResult($response)
    {
        $result = json_decode($response, true);
        if (!isset($result['AccessKeyId'])) {
            throw new \DeliciousBrains\WP_Offload_Media\Aws3\Aws\Exception\CredentialsException('Unexpected ECS credential value');
        }
        return $result;
    }
}