<?php

/**
 * @file
 * Functions to handle the NodeSquirrel backup destination.
 */

define('NODESQUIRREL_SECRET_KEY_PATTERN', '/^[0-9a-f]{32}\:?[0-9a-f]{32}$/');

/**
 * Checks that a nodesquirel key is valid.
 */
function backup_migrate_nodesquirrel_check_secret_key($secret_key) {
  if ($destination = backup_migrate_nodesquirrel_get_destination($secret_key)) {
    if ($destination->confirm_destination()) {
      return $destination;
    }
  }
  return FALSE;
}

/**
 * Gets the NS destination for the given key.
 */
function backup_migrate_nodesquirrel_get_destination($secret_key) {
  if ($secret_key) {
    backup_migrate_include('destinations');
    $destination = backup_migrate_create_destination('nodesquirrel', array('machine_name' => 'nodesquirrel'));
    $destination->settings['secret_key'] = $secret_key;
    return $destination;
  }
  return NULL;
}

/**
 * Gets a helper link to activate a site and create a tree.
 */
function backup_migrate_nodesquirrel_get_activate_help_text() {
  $activate_link = backup_migrate_nodesquirrel_get_activate_link();
  return array(
    '#type' => 'item',
    '#title' => t('Need a Secret Key?'),
    '#markup' => t('Visit !nodesquirrel.', array('!nodesquirrel' => $activate_link)),
    '#description' => t("Don't worry if you don't have an account yet. You can create one when you get there."),
  );
}

/**
 * Gets a helper link to activate a site and create a tree.
 */
function backup_migrate_nodesquirrel_get_activate_link() {
  $activate_link = l('nodesquirrel.com/activate', variable_get('nodesquirrel_activate_url', 'https://manage.nodesquirrel.com/activate'), array(
    'query' => array(
      'url' => url('', array('absolute' => TRUE)),
      'email' => variable_get('site_mail', ''),
      'configure' => url($_GET['q'], array('absolute' => TRUE)),
    ),
  ));
  return $activate_link;
}

/**
 * Gets a helper link to activate a site and create a tree.
 */
function backup_migrate_nodesquirrel_get_manage_link($destination) {
  $url = variable_get('nodesquirrel_manage_url', 'https://manage.nodesquirrel.com') . '/backups/' . $destination->_get_destination();
  return l($url, $url);
}

/**
 * Gets a helper link to activate a site and create a tree.
 */
function backup_migrate_nodesquirrel_get_plan_link() {
  $url = variable_get('nodesquirrel_manage_url', 'https://manage.nodesquirrel.com') . '/plan';
  return l($url, $url);
}

/**
 * Gets the path to the nodesquirrel settings tab.
 */
function backup_migrate_nodesquirrel_settings_path() {
  $path = BACKUP_MIGRATE_MENU_PATH . '/settings/destinations/nodesquirrel/edit';
  return $path;
}

/**
 * NodeSquirrel settings page callback.
 */
function backup_migrate_nodesquirrel_settings() {
  return drupal_get_form('backup_migrate_nodesquirrel_settings_form');
}

/**
 * NodeSquirrel settings form.
 */
function backup_migrate_nodesquirrel_credentials_settings_form($key = '', $status) {
  $collapse = !empty($status);
  $form['nodesquirrel_credentials'] = array(
    '#type' => 'fieldset',
    '#title' => t('NodeSquirrel Credentials'),
    '#collapsible' => $collapse,
    '#collapsed' => $collapse,
  );

  $form['nodesquirrel_credentials']['nodesquirrel_secret_key'] = array(
    '#type' => 'textfield',
    '#title' => t('Secret Key'),
    '#size' => 80,
    '#default_value' => $key,
  );
  if (empty($key)) {
    $form['nodesquirrel_credentials']['secret_key_help'] = backup_migrate_nodesquirrel_get_activate_help_text();
  }

  $form['nodesquirrel_credentials']['nodesquirrel_failover'] = array(
    '#type' => 'checkbox',
    '#title' => t('Connection failover by disabling SSL certification validation'),
    '#description' => t("If normal connections to NodeSquirrel fail due incompatibility between this server's PHP installation and the destination server, use this option to disable validating the destination's SSL certificate.<br />Note: <em>this has security implications</em> and should be the last option taken; it probably would be safer to update the server's PHP."),
    '#default_value' => variable_get('nodesquirrel_failover', FALSE),
  );

  return $form;
}

/**
 * Return a form element with some help text describing NodeSquirrel.
 */
function backup_migrate_nodesquirrel_info_form() {
  $form = array();

  $form['nodesquirrel_info'] = array(
    '#type' => 'fieldset',
    '#title' => t('What is NodeSquirrel?'),
  );

  $form['nodesquirrel_info']['intro'] = array(
    '#type' => 'markup',
    '#markup' => t('<p>NodeSquirrel is the cloud backup service built by the maintainers of Backup and Migrate.</p></p>NodeSquirrel is now free for all Drupal sites, courtesy of Pantheon.</p><p>Create your free account at !signup</p>', array(
      '!nodesquirrel' => l('nodesquirrel.com', 'http://www.nodesquirrel.com'),
      '!signup' => backup_migrate_nodesquirrel_get_activate_link(),
    )),
  );
  return $form;
}

/**
 * Display the NodeSquirrel status on the configuration form.
 */
function backup_migrate_nodesquirrel_status_form($key, $destination, $status) {
  $form = array();

  $form['nodesquirrel_status'] = array(
    '#type' => 'fieldset',
    '#title' => t('NodeSquirrel Status'),
  );
  $form['nodesquirrel_status']['status'] = array(
    '#type' => 'item',
    '#title' => t('NodeSquirrel Status'),
    '#markup' => t('Not Configured. Enter your Secret Key below to get started.'),
  );

  // Warn the user if the key they entered is invalid.
  if ($key && empty($status)) {
    $form['nodesquirrel_status']['status']['#markup'] = t('Your secret key does not seem to be valid. Please check that you entered it correctly or visit !ns to generate a new key.', array('!ns' => backup_migrate_nodesquirrel_get_activate_link()));
  }
  elseif (!empty($destination) && is_array($status)) {
    if (!empty($status['lifetime_backups_used']) && !empty($status['lifetime_backups']) && $status['lifetime_backups_used'] >= $status['lifetime_backups']) {
      $form['nodesquirrel_status']['status']['#markup'] = t('Your !num backup trial has expired. Visit !link to continue backing up.', array('!num' => $status['lifetime_backups'], '!link' => backup_migrate_nodesquirrel_get_plan_link()));
    }
    else {
      $form['nodesquirrel_status']['status']['#markup'] = t('Ready to Backup');
      if (user_access('perform backup')) {
        $form['nodesquirrel_status']['status']['#markup'] .= ' ' . l('(' . t('backup now') . ')', BACKUP_MIGRATE_MENU_PATH);
      }
    }
    if (!empty($status['plan_name'])) {
      $form['nodesquirrel_status']['plan_name'] = array(
        '#type' => 'item',
        '#title' => t('Current Plan'),
        '#markup' => check_plain($status['plan_name']),
      );

      if (!empty($status['lifetime_backups']) && isset($status['lifetime_backups_used'])) {
        $remains = $status['lifetime_backups'] - $status['lifetime_backups_used'];
        $remains = $remains > 0 ? $remains : t('none');
        $form['nodesquirrel_status']['plan_name']['#markup'] .= ' ' . t('(@remains remaining of @backups backup trial)', array('@backups' => $status['lifetime_backups'], '@remains' => $remains));
      }

      if (!empty($status['lifespan']) && isset($status['age']) && $status['lifespan'] > 0) {
        $remains = ceil(($status['lifespan'] - $status['age']) / 86400);
        if ($remains <= 0) {
          $form['nodesquirrel_status']['plan_name']['#markup'] .= ' ' . t('(Your !span day trial has expired.)', array('!span' => ceil($status['lifespan'] / 86400)));
        }
        else {
          $form['nodesquirrel_status']['plan_name']['#markup'] .= ' ' . format_plural($remains, '(1 day remaining)', '(!span days remaining)', array('!span' => ceil($remains)));
        }
      }

    }

    if (isset($status['backups_used'])) {
      $form['nodesquirrel_status']['backups_used'] = array(
        '#type' => 'item',
        '#title' => t('Number of Stored Backups'),
        '#markup' => $status['backups_used'] == 0 ? t('None') : number_format($status['backups_used']),
      );
    }

    if (isset($status['last_backup'])) {
      $form['nodesquirrel_status']['last_backup'] = array(
        '#type' => 'item',
        '#title' => t('Last Backup'),
        '#markup' => empty($status['last_backup']) ? t('Never') : t('!date (!ago ago)', array(
          '!date' => format_date($status['last_backup'], 'small'),
          '!ago' => format_interval(time() - $status['last_backup'], 1),
        )),
      );
    }
    if ($status['bytes_per_locker']) {
      if (isset($status['bytes_used'])) {
        $form['nodesquirrel_status']['space'] = array(
          '#type' => 'item',
          '#title' => t('Storage Space'),
          '#markup' => t('!used used of !total (!remaining remaining)', array(
            '!used' => backup_migrate_format_size($status['bytes_used']),
            '!total' => backup_migrate_format_size($status['bytes_per_locker']),
            '!remaining' => backup_migrate_format_size(max(0, $status['bytes_per_locker'] - $status['bytes_used'])),
          )),
        );
      }
      else {
        $form['nodesquirrel_status']['space'] = array(
          '#type' => 'item',
          '#title' => t('Total Storage Space'),
          '#markup' => t('!total', array('!total' => backup_migrate_format_size($status['bytes_per_locker']))),
        );
      }
    }
    $form['nodesquirrel_status']['manage'] = array(
      '#type' => 'item',
      '#title' => t('Management Console'),
      '#markup' => backup_migrate_nodesquirrel_get_manage_link($destination),
      '#description' => t('You can use the NodeSquirrel management console to add and edit your sites, reset your secret key, download and delete backups, and modify your NodeSquirrel account.'),
    );

  }

  return $form;
}

function backup_migrate_nodesquirrel_schedule_settings_form($destination, $status) {
  backup_migrate_include('sources', 'schedules', 'profiles');

  // If the schedule has been overriden it must be edited in the schedule tab.
  $schedule = backup_migrate_crud_get_item('schedule', 'nodesquirrel');

  $default = 60 * 60 * 24;

  $form = array();
  $form['nodesquirrel_schedule'] = array(
    '#type' => 'fieldset',
    '#title' => t('Backup Schedule'),
    '#description' => t('Set up a schedule to back up your site to NodeSquirrel. You can customize this schedule or add additional schedules in the !schedule.', array(
      '!schedule' => l(t('Schedules tab'), BACKUP_MIGRATE_MENU_PATH . '/schedule'),
      '!cron' => l(t('cron'), 'http://drupal.org/cron'),
    )),
  );

  $key = 'nodesquirrel_schedule';
  $form['nodesquirrel_schedule'][$key] = array();
  $defaults = array(
    'period' => empty($schedule) ? variable_get('nodesquirrel_schedule', 60 * 60 * 24) : $schedule->get('period'),
    'enabled' => empty($schedule) ? variable_get('nodesquirrel_schedule_enabled', TRUE) : $schedule->get('enabled'),
    'source_id' => empty($schedule) ? variable_get('nodesquirrel_schedule_source_id', 'db') : $schedule->get('source_id'),
    'keep' => empty($schedule) ? variable_get('nodesquirrel_schedule_keep', BACKUP_MIGRATE_SMART_DELETE) : $schedule->get('keep'),
  );

  $form['nodesquirrel_schedule'][$key]['nodesquirrel_schedule_enabled'] = array(
    '#type' => 'checkbox',
    '#title' => t('Automatically backup to NodeSquirrel'),
    '#default_value' => $defaults['enabled'],
  );
  $form['nodesquirrel_schedule'][$key]['settings'] = array(
    '#type' => 'backup_migrate_dependent',
    '#dependencies' => array(
      'nodesquirrel_schedule_enabled' => TRUE,
    ),
  );
  $form['nodesquirrel_schedule'][$key]['settings']['nodesquirrel_schedule_source_id'] = _backup_migrate_get_source_pulldown($defaults['source_id']);
  $options = array(
    (60 * 60)       => t('Once an hour'),
    (60 * 60 * 24)    => t('Once a day'),
    (60 * 60 * 24 * 7)  => t('Once a week'),
  );
  $period = $defaults['period'];
  if (!isset($options[$period])) {
    $options[$period] = empty($schedule) ? t('Custom') : $schedule->get('frequency_description');
  }
  $form['nodesquirrel_schedule'][$key]['settings']['nodesquirrel_schedule'] = array(
    '#type' => 'select',
    '#title' => t('Schedule Frequency'),
    '#options' => $options,
    '#default_value' => $period,
  );
  $form['nodesquirrel_schedule'][$key]['settings']['nodesquirrel_schedule_keep'] = array(
    '#type' => 'checkbox',
    '#title' => t('Automatically delete old backups'),
    '#return_value' => $defaults['keep'] == BACKUP_MIGRATE_KEEP_ALL ? BACKUP_MIGRATE_SMART_DELETE : $defaults['keep'],
    '#default_value' => $defaults['keep'],
  );
  return $form;
}

/**
 * NodeSquirrel settings form.
 */
function backup_migrate_nodesquirrel_settings_form($form_state) {
  _backup_migrate_message_callback('_backup_migrate_message_browser');

  $form = array();

  $key = variable_get('nodesquirrel_secret_key', '');
  $status = array();
  if ($destination = backup_migrate_nodesquirrel_get_destination($key)) {
    $status = $destination->check_limits();
  }

  $form += backup_migrate_nodesquirrel_info_form();
  $form += backup_migrate_nodesquirrel_status_form($key, $destination, $status);
  $form += backup_migrate_nodesquirrel_credentials_settings_form($key, $status);
  $form += backup_migrate_nodesquirrel_schedule_settings_form($destination, $status);

  return system_settings_form($form);
}

/**
 * A destination for sending database backups to the NodeSquirel backup service.
 *
 * @ingroup backup_migrate_destinations
 */
class backup_migrate_destination_nodesquirrel extends backup_migrate_destination {
  public $supported_ops = array(
    'scheduled backup',
    'manual backup',
    'remote backup',
    'restore',
    'list files',
    'configure',
    'delete',
  );
  public $cache_files = TRUE;
  /**
   * Don't generate a metadata file as NodeSquirrel can save metadata natively.
   */
  public $save_metadata = FALSE;
  public function __construct($params = array()) {
    parent::__construct($params + array('name' => t('NodeSquirrel')));
  }

  /**
   * Gets the menu items for manipulating this type.
   */
  public function get_menu_items() {
    $items = array();
    $path = BACKUP_MIGRATE_MENU_PATH . '/nodesquirrel';
    $items[$path] = array(
      'title' => t('NodeSquirrel'),
      'page callback' => 'backup_migrate_menu_callback',
      'page arguments' => array('destinations.nodesquirrel', 'backup_migrate_nodesquirrel_settings'),
      'access arguments' => array('administer backup and migrate'),
      'weight' => 10,
      'type' => MENU_LOCAL_TASK,
    );
    return $items;
  }

  /**
   * Declares any MySQL databases defined in the settings.php file as a possible destination.
   */
  public function destinations() {
    $out = array();
    $out['nodesquirrel'] = backup_migrate_create_destination('nodesquirrel', array('machine_name' => 'nodesquirrel'));
    if ($secret_key = variable_get('nodesquirrel_secret_key', '')) {
      $out['nodesquirrel']->settings['secret_key'] = $secret_key;
    }
    else {
      $out['nodesquirrel']->supported_ops = array('manual backup', 'remote backup');
    }
    return $out;
  }

  /**
   * Returns a form to be completed before saving to the destination can be complete.
   */
  public function before_backup_form($settings) {
    $form = array();
    $key = $this->settings('secret_key');
    if (empty($key)) {
      $form += backup_migrate_nodesquirrel_info_form();
      $form += backup_migrate_nodesquirrel_credentials_settings_form();
    }
    return $form;
  }

  /**
   * Validates the before_backup_form form.
   */
  public function before_backup_form_validate($settings, $form, $form_state) {
    if (isset($form_state['values']['nodesquirrel_secret_key'])) {
      $key = trim($form_state['values']['nodesquirrel_secret_key']);
      if ($error = $this->vaidate_key($key)) {
        form_set_error('secret_key', $error);
      }
    }
  }

  /**
   * Submits the before_backup_form form.
   */
  public function before_backup_form_submit($settings, $form, $form_state) {
    if (isset($form_state['values']['nodesquirrel_secret_key'])) {
      $this->settings['secret_key'] = $form_state['values']['nodesquirrel_secret_key'];
      variable_set('nodesquirrel_secret_key', $this->settings['secret_key']);
    }
  }

  /**
   * Saves to the NodeSquirrel destination.
   */
  public function save_file($file, $settings) {
    if ($destination = $this->_get_destination()) {
      srand((double) microtime() * 1000000);

      $filename = $file->filename();
      $filesize = filesize($file->filepath());
      $ticket = $this->_xmlrpc('backups.getUploadTicket', array(
        $destination,
        $filename,
        $filesize,
        $file->file_info,
      ));

      if ($ticket) {

        $url = $ticket['url'];

        // If the ticket requires authentication add our username/password to
        // the url.
        if (!empty($ticket['auth']) && $ticket['auth'] = 'basic') {
          $parts = parse_url($ticket['url']);
          list($parts['user'], $parts['pass']) = $this->get_user_pass();
          $url = $this->glue_url($parts, FALSE);
        }

        $out = $this->_post_file($url, 'POST', $ticket['params'], $file);

        if ($out->code == 200) {
          // Confirm the upload.
          $confirm = $this->_xmlrpc('backups.confirmUpload', array(
            $destination,
            $filename,
            $filesize,
          ));

          if ($confirm['success']) {
            // Set a message with a link to the manage console.
            _backup_migrate_message('Your backup has been saved to your NodeSquirrel account. View it at !account', array('!account' => backup_migrate_nodesquirrel_get_manage_link($this)));
            return $file;
          }
          else {
            _backup_migrate_message('The backup file never made it to the NodeSquirrel backup server. There may have been a network problem. Please try again later');
          }
        }
        else {
          $error = !empty($out->headers['x-bams-error']) ? $out->headers['x-bams-error'] : $out->error;
          _backup_migrate_message('The NodeSquirrel server returned the following error: %err', array('%err' => $error), 'error');
        }
      }
      elseif ($err = xmlrpc_error()) {
        // XMLRPC errors are already handled by the server function below.
      }
      else {
        _backup_migrate_message('The NodeSquirrel server refused the backup but did not specify why. Maybe the server is down.');
      }
    }
    return NULL;
  }

  /**
   * Loads from the NodeSquirrel destination.
   */
  public function load_file($file_id) {
    if ($destination = $this->_get_destination()) {
      backup_migrate_include('files');
      $file = new backup_file(array('filename' => $file_id));

      $ticket = $this->_xmlrpc('backups.getDownloadTicket', array($destination, $file_id));

      if ($ticket && $url = $ticket['url']) {
        // If the ticket requires authentication add our username/password to
        // the url.
        if (!empty($ticket['auth']) && $ticket['auth'] = 'basic') {
          $parts = parse_url($ticket['url']);
          $parts['user'] = @$this->dest_url['user'];
          $parts['pass'] = @$this->dest_url['pass'];
          $url = $this->glue_url($parts, FALSE);
        }

        $out = drupal_http_request($url);

        if ($out->code == 200) {
          file_put_contents($file->filepath(), $out->data);
          return $file;
        }
        else {
          $error = !empty($out->headers['x-bams-error']) ? $out->headers['x-bams-error'] : $out->error;
          _backup_migrate_message('The server returned the following error: %err', array('%err' => $error), 'error');
        }
      }
    }
    return NULL;
  }

  /**
   * Deletes from the NodeSquirrel destination.
   */
  public function delete_file($file_id) {
    if ($destination = $this->_get_destination()) {
      $result = $this->_xmlrpc('backups.deleteFile', array($destination, $file_id));
    }
  }

  /**
   * Lists the files in the remote destination.
   */
  public function _list_files() {
    $files = array();
    backup_migrate_include('files');

    if ($destination = $this->_get_destination()) {
      $file_list = $this->_xmlrpc('backups.listFiles', array($destination));
      foreach ((array) $file_list as $file) {
        $files[$file['filename']] = new backup_file($file);
      }
    }

    return $files;
  }

  /**
   * Lists the files in the remote destination.
   */
  public function check_limits() {
    if (empty($this->limits)) {
      $this->limits = $this->_xmlrpc('backups.getLimits', array($this->_get_destination()));
    }
    return $this->limits;
  }

  /**
   * Checks that a destination is valid.
   */
  public function confirm_destination() {
    return $this->check_limits();
  }

  /**
   * Gets the form for the settings for this destination.
   */
  public function edit_form() {
    $form = parent::edit_form();

    // If this is a new destination but the default NS destination has not been
    // created yet, redirect to the NS config screen.
    if (!$this->get_id() && !variable_get('nodesquirrel_secret_key', '')) {
      drupal_goto(BACKUP_MIGRATE_MENU_PATH . '/nodesquirrel');
    }

    $form['settings'] = array('#tree' => TRUE);
    $activate_link = backup_migrate_nodesquirrel_get_activate_link();

    // Retrieve the key from the settings or get it from the get string if this
    // is an auto-config action.
    $key = $this->settings('secret_key');
    if (!empty($_GET['key']) && preg_match(NODESQUIRREL_SECRET_KEY_PATTERN, $_GET['key'])) {
      $key = $_GET['key'];
    }

    $form['settings']['secret_key'] = array(
      '#type' => 'textfield',
      '#title' => t('Secret Key'),
      '#default_value' => $key,
    );
    $form['settings']['location'] = array('#type' => 'value', '#value' => '');

    $form['settings']['secret_key_help'] = array(
      '#type' => 'item',
      '#title' => t('Need a Secret Key?'),
      '#markup' => t('Visit !nodesquirrel.', array('!nodesquirrel' => $activate_link)),
    );

    return $form;
  }

  /**
   * Submits the configuration form.
   *
   * Glue the url together and add the old password back if a new one was not
   * specified.
   */
  public function edit_form_validate($form, &$form_state) {
    $key = trim($form_state['values']['settings']['secret_key']);
    if ($error = $this->vaidate_key($key)) {
      form_set_error('secret_key', $error);
    }
  }

  /**
   * Validates a secret key.
   *
   * Returns error text if the key is invalid.
   */
  public function vaidate_key($key) {
    $error = FALSE;
    if ($key) {
      if (!preg_match(NODESQUIRREL_SECRET_KEY_PATTERN, $key)) {
        return 'The secret key you entered is not the right format. Please make sure you copy it exactly.';
      }
      $this->settings['secret_key'] = check_plain($key);

      $limits = $this->check_limits();

      if (!$limits) {
        $err = xmlrpc_error();
        if (!empty($err->code) && $err->code == '401') {
          return 'Could not log in to the NodeSquirrel server. Please check that your secret key is correct.';
        }
        else {
          return 'Your site could not be found on NodeSquirrel. Please check that your secret key is correct.';
        }
      }
    }
    else {
      return 'You must enter a NodeSquirrel secret key.';
    }
    return FALSE;
  }

  /**
   * Submits the configuration form.
   *
   * Glue the url together and add the old password back if a new one was not
   * specified.
   */
  public function edit_form_submit($form, &$form_state) {
    $form_state['values']['secret_key'] = check_plain($form_state['values']['settings']['secret_key']);
    parent::edit_form_submit($form, $form_state);
  }

  /**
   * Gets the destination id or warn the user that it has not been set.
   */
  public function _get_destination($warn = TRUE) {
    list($id, $key) = $this->get_user_pass();
    return $id;
  }

  /**
   * Gets the destination id or warn the user that it has not been set.
   */
  public function _get_private_key($warn = TRUE) {
    list($id, $key) = $this->get_user_pass();
    return $key;
  }

  /**
   * Breaks the secret key into the public/private key (user/pass).
   */
  public function get_user_pass() {
    $key = $this->settings('secret_key');
    // The username is the first 32 chars.
    $user = substr($key, 0, 32);
    // The pass is the last 32 chars. There may be a separating character.
    $pass = substr($key, strlen($key) - 32);
    return array($user, $pass);
  }

  public function get_display_location() {
    return t('NodeSquirrel.com');
  }

  public function add_scheme($url) {
    return 'https://' . $url;
  }

  /**
   * Gets the form for the settings for this destination.
   */
  public function _xmlrpc($method, $args = array()) {
    // Retrieve the severs or read them from a stored variable.
    $servers = $this->_get_endpoints();

    // Do the actual call.
    return $this->_xmlrpc_request($method, $args, $servers);
  }

  /**
   * Gets the form for the settings for this destination.
   */
  public function _xmlrpc_request($method, $args, $servers, $retry = 3) {
    if ($servers && --$retry > 0) {
      // Add the key authentication arguments if we can.
      if ($this->_sign_request($args)) {
        $url = reset($servers);
        // Try each available server in order.
        while ($url) {

          $url = $this->add_scheme($url);

          $options = array();
          // Optionally disable SSL certification validation. This may be
          // necessary if the server's SSL certificates are out of date because
          // and might be incompatible with PHP 5.6's OpenSSL implementation.
          // @see http://php.net/manual/en/migration56.openssl.php
          // @see http://php.net/manual/en/context.ssl.php#context.ssl.verify-peer
          if (variable_get('nodesquirrel_failover', FALSE)) {
            $opts = array(
              'ssl' => array(
                'verify_peer' => FALSE,
              ),
            );
            $options = array(
              'context' => stream_context_create($opts),
            );
          }

          $out = xmlrpc($url, array($method => $args), $options);

          // Check for errors.
          $err = xmlrpc_error();
          if ($err && $err->is_error) {
            switch ($err->code) {
              case '500':
              case '503':
              case '404':
                // Some sort of server error. Try the next one.
                $url = next($servers);

                // If we're at the end of the line then try refetching the urls.
                if (!$url) {
                  $servers = $this->_get_endpoints(TRUE, $retry);
                  return $this->_xmlrpc_request($method, $args, $servers, $retry);
                }
                break;

              case '300':
                // 'Multiple Choices' means that the existing server list needs
                // to be refreshed.
                $servers = $this->_get_endpoints(TRUE, $retry);
                return $this->_xmlrpc_request($method, $args, $servers, $retry);

              case '401':
              case '403':
                // Authentication failed.
                _backup_migrate_message('Couldn\'t log in to NodeSquirrel. The server error was: %err', array('%err' => $err->message), 'error');
                return FALSE;

              default:
                // Some sort of client error. Don't try the next server because
                // it'll probably say the same thing.
                _backup_migrate_message('The NodeSquirrel server returned the following error: %err', array('%err' => $err->message), 'error');
                return FALSE;
            }
          }
          // No error, return the result.
          else {
            return $out;
          }
        }
      }
    }
  }

  /**
   * Genrates a hash with a given secret key, timestamp and random value.
   */
  public function _get_hash($time, $nonce) {
    if ($private_key = $this->_get_private_key()) {
      $message = $time . ':' . $nonce . ':' . $private_key;
      // Use HMAC-SHA1 to authenticate the call.
      $hash = base64_encode(
        pack('H*', sha1((str_pad($private_key, 64, chr(0x00)) ^ (str_repeat(chr(0x5c), 64))) .
        pack('H*', sha1((str_pad($private_key, 64, chr(0x00)) ^ (str_repeat(chr(0x36), 64))) .
        $message))))
      );
      return $hash;
    }
    _backup_migrate_message('You must enter a valid secret key to use NodeSquirrel.', array(), 'error');
    return FALSE;
  }

  /**
   * Genrates a hash with a given secret key, timestamp and random value.
   */
  public function _sign_request(&$args) {
    $nonce = md5(mt_rand());
    $time = time();
    $hash = $this->_get_hash($time, $nonce);
    if ($hash) {
      array_unshift($args, $nonce);
      array_unshift($args, $time);
      array_unshift($args, $hash);
      return TRUE;
    }
    else {
      return FALSE;
    }
  }

  /**
   * Retrieves the list of servers.
   */
  public function _get_endpoints($refresh = FALSE, $retry = 3) {
    $servers = (array) variable_get('nodesquirrel_endpoint_urls', array());

    // No servers saved or a force refreshr required.
    if ($refresh || empty($servers)) {
      $servers = array_unique(array_merge($servers, variable_get('nodesquirrel_default_endpoint_urls', array('api.nodesquirrel.com/services/xmlrpc'))));
      // Call the get endpoints method but use the default or previous servers
      // to avoid infinite loops.
      $new_servers = $this->_xmlrpc_request('backups.getEndpoints', array($this->_get_destination(), 'xmlrpc'), $servers, $retry);
      if ($new_servers) {
        variable_set('nodesquirrel_endpoint_urls', $new_servers);
        $servers = $new_servers;
      }
    }
    return $servers;
  }

  /**
   * Posts a file via HTTP.
   *
   * This looks a lot like a clone of drupal_http_request() but it can post a
   * large file without reading the whole file into memory.
   */
  public function _post_file($url, $method = 'GET', $params = array(), $file = NULL, $retry = 3) {
    global $db_prefix;

    $result = new stdClass();

    // Parse the URL and make sure we can handle the schema.
    $uri = parse_url($url);

    if ($uri == FALSE) {
      $result->error = 'unable to parse URL';
      $result->code = -1001;
      return $result;
    }

    if (!isset($uri['scheme'])) {
      $result->error = 'missing schema';
      $result->code = -1002;
      return $result;
    }

    // Avoid some "undefined variable" errors.
    $errno = $errstr = NULL;

    switch ($uri['scheme']) {
      case 'http':
      case 'feed':
        $port = isset($uri['port']) ? $uri['port'] : 80;
        $host = $uri['host'] . ($port != 80 ? ':' . $port : '');
        $fp = @fsockopen($uri['host'], $port, $errno, $errstr, 15);
        break;

      case 'https':
        // Note: Only works for PHP 4.3+ compiled with OpenSSL.
        $port = isset($uri['port']) ? $uri['port'] : 443;
        $host = $uri['host'] . ($port != 443 ? ':' . $port : '');
        $fp = @fsockopen('ssl://' . $uri['host'], $port, $errno, $errstr, 20);

        // If fsockopen() doesn't work, try again after disabling SSL.
        // Optionally disable SSL certification validation. This may be
        // necessary if the server's SSL certificates are out of date and/or
        // might be incompatible with PHP 5.6's OpenSSL implementation.
        // @see http://php.net/manual/en/migration56.openssl.php
        // @see http://php.net/manual/en/context.ssl.php#context.ssl.verify-peer
        if (!$fp && variable_get('nodesquirrel_failover', FALSE)) {
          $opts = array(
            'ssl' => array(
              'verify_peer' => FALSE,
            ),
          );
          $context = stream_context_create($opts);
          $fp = stream_socket_client('ssl://' . $uri['host'] . ':' . $port, $errno, $errstr, 20, STREAM_CLIENT_CONNECT, $context);
        }
        break;

      default:
        $result->error = 'invalid schema ' . $uri['scheme'];
        $result->code = -1003;
        return $result;
    }

    // Make sure the socket opened properly.
    if (!$fp) {
      // When a network error occurs, we use a negative number so it does not
      // clash with the HTTP status codes.
      $result->code = -$errno;
      $result->error = trim($errstr);

      // Mark that this request failed. This will trigger a check of the web
      // server's ability to make outgoing HTTP requests the next time that
      // requirements checking is performed.
      // @see system_requirements()
      variable_set('drupal_http_request_fails', TRUE);

      return $result;
    }

    // Construct the path to act on.
    $path = isset($uri['path']) ? $uri['path'] : '/';
    if (isset($uri['query'])) {
      $path .= '?' . $uri['query'];
    }

    // Prepare the data payload.
    $boundary = '---------------------------' . substr(md5(rand(0, 32000)), 0, 10);
    $data_footer = "\r\n--$boundary--\r\n";

    $data_header = '';
    foreach ($params as $key => $value) {
      $data_header .= "--$boundary\r\n";
      $data_header .= "Content-Disposition: form-data; name=\"" . $key . "\"\r\n";
      $data_header .= "\r\n" . $value . "\r\n";
      $data_header .= "--$boundary\r\n";
    }

    // Add the file header to the post payload.
    $data_header .= "--$boundary\r\n";
    $data_header .= "Content-Disposition: form-data; name=\"file\"; filename=\"" . $file->filename() . "\"\r\n";
    $data_header .= "Content-Type: application/octet-stream;\r\n";
    $data_header .= "\r\n";

    // Calculate the content length.
    $content_length = strlen($data_header . $data_footer) + filesize($file->filepath());

    // file_get_contents($file->filepath()));
    // Create HTTP request.
    $defaults = array(
      // RFC 2616: "non-standard ports MUST, default ports MAY be included".
      // We don't add the port to prevent from breaking rewrite rules checking
      // the host that do not take into account the port number.
      'Host' => "Host: $host",
      'Content-type' => "Content-type: multipart/form-data, boundary=$boundary",
      'User-Agent' => 'User-Agent: NodeSquirrel Client/1.x (+http://www.nodesquirrel.com) (Drupal ' . VERSION . '; Backup and Migrate 2.x)',
      'Content-Length' => 'Content-Length: ' . $content_length,
    );

    // If the server url has a user then attempt to use basic authentication.
    if (isset($uri['user'])) {
      $defaults['Authorization'] = 'Authorization: Basic ' . base64_encode($uri['user'] . (!empty($uri['pass']) ? ":" . $uri['pass'] : ''));
    }

    $request = $method . ' ' . $path . " HTTP/1.0\r\n";
    $request .= implode("\r\n", $defaults);
    $request .= "\r\n\r\n";
    $result->request = $request;

    $out = FALSE;
    // Write the headers and start of the headers
    if (($fp_in = fopen($file->filepath(), 'rb')) && fwrite($fp, $request) && fwrite($fp, $data_header)) {
      // Copy the file 1M at a time.
      do {
        $data = fread($fp_in, 1024 * 1024);
        $size = strlen($data);
        $sent = 0;
        while ($sent < $size && ($out = fwrite($fp, substr($data, $sent)))) {
          $sent += $out;
        }
      } while ($out && !feof($fp_in));

      // Finish the write.
      if ($out) {
        $out = fwrite($fp, $data_footer);
      }
    }
    @fclose($fp_in);

    // Check for errors.
    if (!$out) {
      watchdog('backup_migrate', 'NodeSquirrel: network write failed', NULL, WATCHDOG_ERROR);
      $result->code = -$errno;
      $result->error = trim($errstr);
      return $result;
    }

    // Fetch response.
    $response = '';
    while (!feof($fp) && $chunk = fread($fp, 1024)) {
      $response .= $chunk;
    }
    fclose($fp);

    if (variable_get('debug_http_request', FALSE)) {
      drupal_debug(date('r'));
      drupal_debug($request);
      drupal_debug($response);
    }

    // Parse response.
    list($split, $result->data) = explode("\r\n\r\n", $response, 2);
    $split = preg_split("/\r\n|\n|\r/", $split);

    list($protocol, $code, $status_message) = explode(' ', trim(array_shift($split)), 3);
    $result->protocol = $protocol;
    $result->status_message = $status_message;

    $result->headers = array();

    // Parse headers.
    while ($line = trim(array_shift($split))) {
      list($header, $value) = explode(':', $line, 2);
      if (isset($result->headers[$header]) && $header == 'Set-Cookie') {
        // RFC 2109: the Set-Cookie response header comprises the token Set-
        // Cookie:, followed by a comma-separated list of one or more cookies.
        $result->headers[$header] .= ',' . trim($value);
      }
      else {
        $result->headers[$header] = trim($value);
      }
    }

    $responses = array(
      100 => 'Continue',
      101 => 'Switching Protocols',
      200 => 'OK',
      201 => 'Created',
      202 => 'Accepted',
      203 => 'Non-Authoritative Information',
      204 => 'No Content',
      205 => 'Reset Content',
      206 => 'Partial Content',
      300 => 'Multiple Choices',
      301 => 'Moved Permanently',
      302 => 'Found',
      303 => 'See Other',
      304 => 'Not Modified',
      305 => 'Use Proxy',
      307 => 'Temporary Redirect',
      400 => 'Bad Request',
      401 => 'Unauthorized',
      402 => 'Payment Required',
      403 => 'Forbidden',
      404 => 'Not Found',
      405 => 'Method Not Allowed',
      406 => 'Not Acceptable',
      407 => 'Proxy Authentication Required',
      408 => 'Request Time-out',
      409 => 'Conflict',
      410 => 'Gone',
      411 => 'Length Required',
      412 => 'Precondition Failed',
      413 => 'Request Entity Too Large',
      414 => 'Request-URI Too Large',
      415 => 'Unsupported Media Type',
      416 => 'Requested range not satisfiable',
      417 => 'Expectation Failed',
      500 => 'Internal Server Error',
      501 => 'Not Implemented',
      502 => 'Bad Gateway',
      503 => 'Service Unavailable',
      504 => 'Gateway Time-out',
      505 => 'HTTP Version not supported',
    );
    // RFC 2616 states that all unknown HTTP codes must be treated the same as
    // the base code in their class.
    if (!isset($responses[$code])) {
      $code = floor($code / 100) * 100;
    }

    switch ($code) {
      case 200:
        // OK.
      case 304:
        // Not modified.
        break;

      case 301:
        // Moved permanently.
      case 302:
        // Moved temporarily.
      case 307:
        // Moved temporarily.
        $location = $result->headers['Location'];

        if ($retry) {
          $result = drupal_http_request($result->headers['Location'], $headers, $method, $data, --$retry);
          $result->redirect_code = $result->code;
        }
        $result->redirect_url = $location;

        break;

      default:
        $result->error = $status_message;
    }

    $result->code = $code;
    return $result;
  }

}