<?php

class Segment_Consumer_Socket extends Segment_QueueConsumer {
  protected $type = "Socket";
  private $socket_failed;

  /**
   * Creates a new socket consumer for dispatching async requests immediately
   * @param string $secret
   * @param array  $options
   *     number   "timeout" - the timeout for connecting
   *     function "error_handler" - function called back on errors.
   *     boolean  "debug" - whether to use debug output, wait for response.
   */
  public function __construct($secret, $options = array()) {
    if (!isset($options["timeout"])) {
      $options["timeout"] = 5;
    }

    if (!isset($options["host"])) {
      $options["host"] = "api.segment.io";
    }

    parent::__construct($secret, $options);
  }

  //define getter method for consumer type
  public function getConsumer() {
    return $this->type;
  }

  public function flushBatch($batch) {
    $socket = $this->createSocket();

    if (!$socket) {
      return;
    }

    $payload = $this->payload($batch);
    $payload = json_encode($payload);

    $body = $this->createBody($this->options["host"], $payload);
    if (false === $body) {
      return false;
    }

    return $this->makeRequest($socket, $body);
  }

  private function createSocket() {
    if ($this->socket_failed) {
      return false;
    }

    $protocol = $this->ssl() ? "ssl" : "tcp";
    $host = $this->options["host"];
    $port = $this->ssl() ? 443 : 80;
    $timeout = $this->options["timeout"];

    try {
      // Open our socket to the API Server.
      // Since we're try catch'ing prevent PHP logs.
      $socket = @pfsockopen(
        $protocol . "://" . $host,
        $port,
        $errno,
        $errstr,
        $timeout
      );

      // If we couldn't open the socket, handle the error.
      if (false === $socket) {
        $this->handleError($errno, $errstr);
        $this->socket_failed = true;

        return false;
      }

      return $socket;
    } catch (Exception $e) {
      $this->handleError($e->getCode(), $e->getMessage());
      $this->socket_failed = true;

      return false;
    }
  }

  /**
   * Attempt to write the request to the socket, wait for response if debug
   * mode is enabled.
   * @param  stream  $socket the handle for the socket
   * @param  string  $req    request body
   * @param  boolean $retry
   * @return boolean $success
   */
  private function makeRequest($socket, $req, $retry = true) {
    $bytes_written = 0;
    $bytes_total = strlen($req);
    $closed = false;
    $success = true;

    // Retries with exponential backoff until success
    $backoff = 100;   // Set initial waiting time to 100ms

    while (true) {
      // Send request to server
      while (!$closed && $bytes_written < $bytes_total) {
        try {
          // Since we're try catch'ing prevent PHP logs.
          $written = @fwrite($socket, substr($req, $bytes_written));
        } catch (Exception $e) {
          $this->handleError($e->getCode(), $e->getMessage());
          $closed = true;
        }
        if (!isset($written) || !$written) {
          $closed = true;
        } else {
          $bytes_written += $written;
        }
      }

      // Get response for request
      $statusCode = 0;
      $errorMessage = "";

      if (!$closed) {
        $res = $this->parseResponse(fread($socket, 2048));
        $statusCode = (int)$res["status"];
        $errorMessage = $res["message"];
      }
      fclose($socket);

      // If status code is 200, return true
      if (200 == $statusCode) {
        return true;
      }

      // If status code is greater than 500 and less than 600, it indicates server error
      // Error code 429 indicates rate limited.
      // Retry uploading in these cases.
      if (($statusCode >= 500 && $statusCode <= 600) || 429 == $statusCode || 0 == $statusCode) {
        if ($backoff >= $this->maximum_backoff_duration) {
          break;
        }

        usleep($backoff * 1000);
      } elseif ($statusCode >= 400) {
        if ($this->debug()) {
          $this->handleError($res["status"], $res["message"]);
        }

        break;
      }

      // Retry uploading...
      $backoff *= 2;
      $socket = $this->createSocket();
    }

    return $success;
  }

  /**
   * Create the body to send as the post request.
   * @param  string $host
   * @param  string $content
   * @return string body
   */
  private function createBody($host, $content) {
    $req = "";
    $req.= "POST /v1/batch HTTP/1.1\r\n";
    $req.= "Host: " . $host . "\r\n";
    $req.= "Content-Type: application/json\r\n";
    $req.= "Authorization: Basic " . base64_encode($this->secret . ":") . "\r\n";
    $req.= "Accept: application/json\r\n";

    // Send user agent in the form of {library_name}/{library_version} as per RFC 7231.
    $content_json = json_decode($content, true);
    $library = $content_json['batch'][0]['context']['library'];
    $libName = $library['name'];
    $libVersion = $library['version'];
    $req.= "User-Agent: ${libName}/${libVersion}\r\n";

    // Compress content if compress_request is true
    if ($this->compress_request) {
      $content = gzencode($content);

      $req.= "Content-Encoding: gzip\r\n";
    }

    $req.= "Content-length: " . strlen($content) . "\r\n";
    $req.= "\r\n";
    $req.= $content;

    // Verify message size is below than 32KB
    if (strlen($req) >= 32 * 1024) {
      $msg = "Message size is larger than 32KB";
      error_log("[Analytics][" . $this->type . "] " . $msg);

      return false;
    }

    return $req;
  }

  /**
   * Parse our response from the server, check header and body.
   * @param  string $res
   * @return array
   *     string $status  HTTP code, e.g. "200"
   *     string $message JSON response from the api
   */
  private function parseResponse($res) {
    $contents = explode("\n", $res);

    // Response comes back as HTTP/1.1 200 OK
    // Final line contains HTTP response.
    $status = explode(" ", $contents[0], 3);
    $result = $contents[count($contents) - 1];

    return array(
      "status"  => isset($status[1]) ? $status[1] : null,
      "message" => $result
    );
  }
}