<?php

namespace YaySMTP\Aws3\Aws;

use YaySMTP\Aws3\Aws\Api\Parser\Exception\ParserException;
use YaySMTP\Aws3\GuzzleHttp\Promise;
use YaySMTP\Aws3\Psr\Http\Message\RequestInterface;
use YaySMTP\Aws3\Psr\Http\Message\ResponseInterface;

/**
 * Converts an HTTP handler into a Command HTTP handler.
 *
 * HTTP handlers have the following signature:
 *     function(RequestInterface $request, array $options) : PromiseInterface
 *
 * The promise returned form an HTTP handler must resolve to a PSR-7 response
 * object when fulfilled or an error array when rejected. The error array
 * can contain the following data:
 *
 * - exception: (required, Exception) Exception that was encountered.
 * - response: (ResponseInterface) PSR-7 response that was received (if a
 *   response) was received.
 * - connection_error: (bool) True if the error is the result of failing to
 *   connect.
 */
class WrappedHttpHandler {
  private $httpHandler;
  private $parser;
  private $errorParser;
  private $exceptionClass;
  private $collectStats;
  /**
   * @param callable $httpHandler    Function that accepts a request and array
   *                                 of request options and returns a promise
   *                                 that fulfills with a response or rejects
   *                                 with an error array.
   * @param callable $parser         Function that accepts a response object
   *                                 and returns an AWS result object.
   * @param callable $errorParser    Function that parses a response object
   *                                 into AWS error data.
   * @param string   $exceptionClass Exception class to throw.
   * @param bool     $collectStats   Whether to collect HTTP transfer
   *                                 information.
   */
  public function __construct(callable $httpHandler, callable $parser, callable $errorParser, $exceptionClass = 'YaySMTP\\Aws3\\Aws\\Exception\\AwsException', $collectStats = false) {
    $this->httpHandler = $httpHandler;
    $this->parser = $parser;
    $this->errorParser = $errorParser;
    $this->exceptionClass = $exceptionClass;
    $this->collectStats = $collectStats;
  }
  /**
   * Calls the simpler HTTP specific handler and wraps the returned promise
   * with AWS specific values (e.g., a result object or AWS exception).
   *
   * @param CommandInterface $command Command being executed.
   * @param RequestInterface $request Request to send.
   *
   * @return Promise\PromiseInterface
   */
  public function __invoke(\YaySMTP\Aws3\Aws\CommandInterface $command, \YaySMTP\Aws3\Psr\Http\Message\RequestInterface $request) {
    $fn = $this->httpHandler;
    $options = $command['@http'] ?: [];
    $stats = [];
    if ($this->collectStats) {
      $options['http_stats_receiver'] = static function (array $transferStats) use (&$stats) {
        $stats = $transferStats;
      };
    } elseif (isset($options['http_stats_receiver'])) {
      throw new \InvalidArgumentException('Providing a custom HTTP stats' . ' receiver to Aws\\WrappedHttpHandler is not supported.');
    }
    return \YaySMTP\Aws3\GuzzleHttp\Promise\promise_for($fn($request, $options))->then(function (\YaySMTP\Aws3\Psr\Http\Message\ResponseInterface $res) use ($command, $request, &$stats) {
      return $this->parseResponse($command, $request, $res, $stats);
    }, function ($err) use ($request, $command, &$stats) {
      if (is_array($err)) {
        $err = $this->parseError($err, $request, $command, $stats);
      }
      return new \YaySMTP\Aws3\GuzzleHttp\Promise\RejectedPromise($err);
    });
  }
  /**
   * @param CommandInterface  $command
   * @param RequestInterface  $request
   * @param ResponseInterface $response
   * @param array             $stats
   *
   * @return ResultInterface
   */
  private function parseResponse(\YaySMTP\Aws3\Aws\CommandInterface $command, \YaySMTP\Aws3\Psr\Http\Message\RequestInterface $request, \YaySMTP\Aws3\Psr\Http\Message\ResponseInterface $response, array $stats) {
    $parser = $this->parser;
    $status = $response->getStatusCode();
    $result = $status < 300 ? $parser($command, $response) : new \YaySMTP\Aws3\Aws\Result();
    $metadata = ['statusCode' => $status, 'effectiveUri' => (string) $request->getUri(), 'headers' => [], 'transferStats' => []];
    if (!empty($stats)) {
      $metadata['transferStats']['http'] = [$stats];
    }
    // Bring headers into the metadata array.
    foreach ($response->getHeaders() as $name => $values) {
      $metadata['headers'][strtolower($name)] = $values[0];
    }
    $result['@metadata'] = $metadata;
    return $result;
  }
  /**
   * Parses a rejection into an AWS error.
   *
   * @param array            $err     Rejection error array.
   * @param RequestInterface $request Request that was sent.
   * @param CommandInterface $command Command being sent.
   * @param array            $stats   Transfer statistics
   *
   * @return \Exception
   */
  private function parseError(array $err, \YaySMTP\Aws3\Psr\Http\Message\RequestInterface $request, \YaySMTP\Aws3\Aws\CommandInterface $command, array $stats) {
    if (!isset($err['exception'])) {
      throw new \RuntimeException('The HTTP handler was rejected without an "exception" key value pair.');
    }
    $serviceError = "AWS HTTP error: " . $err['exception']->getMessage();
    if (!isset($err['response'])) {
      $parts = ['response' => null];
    } else {
      try {
        $parts = call_user_func($this->errorParser, $err['response']);
        $serviceError .= " {$parts['code']} ({$parts['type']}): " . "{$parts['message']} - " . $err['response']->getBody();
      } catch (ParserException $e) {
        $parts = [];
        $serviceError .= ' Unable to parse error information from ' . "response - {$e->getMessage()}";
      }
      $parts['response'] = $err['response'];
    }
    $parts['exception'] = $err['exception'];
    $parts['request'] = $request;
    $parts['connection_error'] = !empty($err['connection_error']);
    $parts['transfer_stats'] = $stats;
    return new $this->exceptionClass(sprintf('Error executing "%s" on "%s"; %s', $command->getName(), $request->getUri(), $serviceError), $command, $parts, $err['exception']);
  }
}
