function callback($path = '', $blog_id = 0, $post_id = 0)
 {
     $blog_id = $this->api->switch_to_blog_and_validate_user($this->api->get_blog_id($blog_id));
     if (is_wp_error($blog_id)) {
         return $blog_id;
     }
     $args = $this->query_args();
     $input = $this->input(false);
     if (!is_array($input) || !$input) {
         return new WP_Error('invalid_input', 'Invalid request input', 400);
     }
     $post = get_post($post_id);
     if (!$post || is_wp_error($post)) {
         return new WP_Error('unknown_post', 'Unknown post', 404);
     }
     if (!current_user_can('edit_post', $post->ID)) {
         return new WP_Error('unauthorized', 'User cannot edit post', 403);
     }
     $post_data = array('post_ID' => $post_id, 'post_title' => $input['title'], 'post_content' => $input['content'], 'post_excerpt' => $input['excerpt']);
     $preview_url = add_query_arg('preview', 'true', get_permalink($post->ID));
     if (!wp_check_post_lock($post->ID) && get_current_user_id() == $post->post_author && ('auto-draft' == $post->post_status || 'draft' == $post->post_status)) {
         // Drafts and auto-drafts are just overwritten by autosave for the same user if the post is not locked
         $auto_ID = edit_post(wp_slash($post_data));
     } else {
         // Non drafts or other users drafts are not overwritten. The autosave is stored in a special post revision for each user.
         $auto_ID = wp_create_post_autosave(wp_slash($post_data));
         $nonce = wp_create_nonce('post_preview_' . $post->ID);
         $preview_url = add_query_arg(array('preview_id' => $auto_ID, 'preview_nonce' => $nonce), $preview_url);
     }
     $updated_post = get_post($auto_ID);
     if ($updated_post && $updated_post->ID && $updated_post->post_modified) {
         return array('ID' => $auto_ID, 'post_ID' => $post->ID, 'modified' => $this->format_date($updated_post->post_modified), 'preview_URL' => $preview_url);
     } else {
         return new WP_Error('autosave_error', __('Autosave encountered an unexpected error', 'jetpack'), 500);
     }
 }

 /**
  * create a autosave revision with this content
  *
  * @param $pid
  * @param $content
  */
 public function update_autosave_version($pid, $content)
 {
     $post = get_post($pid);
     // only when something has changed
     if ($post && normalize_whitespace($post->post_content) != normalize_whitespace($content)) {
         $post->post_content = $content;
         $post = $post->to_array();
         $post['post_ID'] = $pid;
         wp_create_post_autosave($post);
     }
 }

function wp_ajax_autosave()
{
    global $login_grace_period;
    define('DOING_AUTOSAVE', true);
    $nonce_age = check_ajax_referer('autosave', 'autosavenonce');
    $_POST['post_category'] = explode(",", $_POST['catslist']);
    if ($_POST['post_type'] == 'page' || empty($_POST['post_category'])) {
        unset($_POST['post_category']);
    }
    $do_autosave = (bool) $_POST['autosave'];
    $do_lock = true;
    $data = $alert = '';
    /* translators: draft saved date format, see http://php.net/date */
    $draft_saved_date_format = __('g:i:s a');
    /* translators: %s: date and time */
    $message = sprintf(__('Draft saved at %s.'), date_i18n($draft_saved_date_format));
    $supplemental = array();
    if (isset($login_grace_period)) {
        $alert .= sprintf(__('Your login has expired. Please open a new browser window and <a href="%s" target="_blank">log in again</a>. '), add_query_arg('interim-login', 1, wp_login_url()));
    }
    $id = $revision_id = 0;
    $post_ID = (int) $_POST['post_ID'];
    $_POST['ID'] = $post_ID;
    $post = get_post($post_ID);
    if ('auto-draft' == $post->post_status) {
        $_POST['post_status'] = 'draft';
    }
    if ($last = wp_check_post_lock($post->ID)) {
        $do_autosave = $do_lock = false;
        $last_user = get_userdata($last);
        $last_user_name = $last_user ? $last_user->display_name : __('Someone');
        $data = __('Autosave disabled.');
        $supplemental['disable_autosave'] = 'disable';
        $alert .= sprintf(__('%s is currently editing this article. If you update it, you will overwrite the changes.'), esc_html($last_user_name));
    }
    if ('page' == $post->post_type) {
        if (!current_user_can('edit_page', $post_ID)) {
            wp_die(__('You are not allowed to edit this page.'));
        }
    } else {
        if (!current_user_can('edit_post', $post_ID)) {
            wp_die(__('You are not allowed to edit this post.'));
        }
    }
    if ($do_autosave) {
        // Drafts and auto-drafts are just overwritten by autosave
        if ('auto-draft' == $post->post_status || 'draft' == $post->post_status) {
            $id = edit_post();
        } else {
            // Non drafts are not overwritten. The autosave is stored in a special post revision.
            $revision_id = wp_create_post_autosave($post->ID);
            if (is_wp_error($revision_id)) {
                $id = $revision_id;
            } else {
                $id = $post->ID;
            }
        }
        $data = $message;
    } else {
        if (!empty($_POST['auto_draft'])) {
            $id = 0;
        } else {
            $id = $post->ID;
        }
    }
    if ($do_lock && empty($_POST['auto_draft']) && $id && is_numeric($id)) {
        $lock_result = wp_set_post_lock($id);
        $supplemental['active-post-lock'] = implode(':', $lock_result);
    }
    if ($nonce_age == 2) {
        $supplemental['replace-autosavenonce'] = wp_create_nonce('autosave');
        $supplemental['replace-getpermalinknonce'] = wp_create_nonce('getpermalink');
        $supplemental['replace-samplepermalinknonce'] = wp_create_nonce('samplepermalink');
        $supplemental['replace-closedpostboxesnonce'] = wp_create_nonce('closedpostboxes');
        $supplemental['replace-_ajax_linking_nonce'] = wp_create_nonce('internal-linking');
        if ($id) {
            if ($_POST['post_type'] == 'post') {
                $supplemental['replace-_wpnonce'] = wp_create_nonce('update-post_' . $id);
            } elseif ($_POST['post_type'] == 'page') {
                $supplemental['replace-_wpnonce'] = wp_create_nonce('update-page_' . $id);
            }
        }
    }
    if (!empty($alert)) {
        $supplemental['alert'] = $alert;
    }
    $x = new WP_Ajax_Response(array('what' => 'autosave', 'id' => $id, 'data' => $id ? $data : '', 'supplemental' => $supplemental));
    $x->send();
}

function wp_ajax_autosave()
{
    define('DOING_AUTOSAVE', true);
    check_ajax_referer('autosave', 'autosavenonce');
    if (!empty($_POST['catslist'])) {
        $_POST['post_category'] = explode(',', $_POST['catslist']);
    }
    if ($_POST['post_type'] == 'page' || empty($_POST['post_category'])) {
        unset($_POST['post_category']);
    }
    $data = '';
    $supplemental = array();
    $id = $revision_id = 0;
    $post_id = (int) $_POST['post_id'];
    $_POST['ID'] = $_POST['post_ID'] = $post_id;
    $post = get_post($post_id);
    if (empty($post->ID) || !current_user_can('edit_post', $post->ID)) {
        wp_die(__('You are not allowed to edit this post.'));
    }
    if ('page' == $post->post_type && !current_user_can('edit_page', $post->ID)) {
        wp_die(__('You are not allowed to edit this page.'));
    }
    if ('auto-draft' == $post->post_status) {
        $_POST['post_status'] = 'draft';
    }
    if (!empty($_POST['autosave'])) {
        if (!wp_check_post_lock($post->ID) && get_current_user_id() == $post->post_author && ('auto-draft' == $post->post_status || 'draft' == $post->post_status)) {
            // Drafts and auto-drafts are just overwritten by autosave for the same user if the post is not locked
            $id = edit_post();
        } else {
            // Non drafts or other users drafts are not overwritten. The autosave is stored in a special post revision for each user.
            $revision_id = wp_create_post_autosave($post->ID);
            if (is_wp_error($revision_id)) {
                $id = $revision_id;
            } else {
                $id = $post->ID;
            }
        }
        if (!is_wp_error($id)) {
            /* translators: draft saved date format, see http://php.net/date */
            $draft_saved_date_format = __('g:i:s a');
            /* translators: %s: date and time */
            $data = sprintf(__('Draft saved at %s.'), date_i18n($draft_saved_date_format));
        }
    } else {
        if (!empty($_POST['auto_draft'])) {
            $id = 0;
        } else {
            $id = $post->ID;
        }
    }
    // @todo Consider exposing any errors, rather than having 'Saving draft...'
    $x = new WP_Ajax_Response(array('what' => 'autosave', 'id' => $id, 'data' => $data, 'supplemental' => $supplemental));
    $x->send();
}

/**
 * Save a post submitted with XHR
 *
 * Intended for use with heartbeat and autosave.js
 *
 * @since 3.9.0
 *
 * @param array $post_data Associative array of the submitted post data.
 * @return mixed The value 0 or WP_Error on failure. The saved post ID on success.
 *               The ID can be the draft post_id or the autosave revision post_id.
 */
function wp_autosave($post_data)
{
    // Back-compat
    if (!defined('DOING_AUTOSAVE')) {
        define('DOING_AUTOSAVE', true);
    }
    $post_id = (int) $post_data['post_id'];
    $post_data['ID'] = $post_data['post_ID'] = $post_id;
    if (false === wp_verify_nonce($post_data['_wpnonce'], 'update-post_' . $post_id)) {
        return new WP_Error('invalid_nonce', __('Error while saving.'));
    }
    $post = get_post($post_id);
    if (!current_user_can('edit_post', $post->ID)) {
        return new WP_Error('edit_posts', __('Sorry, you are not allowed to edit this item.'));
    }
    if ('auto-draft' == $post->post_status) {
        $post_data['post_status'] = 'draft';
    }
    if ($post_data['post_type'] != 'page' && !empty($post_data['catslist'])) {
        $post_data['post_category'] = explode(',', $post_data['catslist']);
    }
    if (!wp_check_post_lock($post->ID) && get_current_user_id() == $post->post_author && ('auto-draft' == $post->post_status || 'draft' == $post->post_status)) {
        // Drafts and auto-drafts are just overwritten by autosave for the same user if the post is not locked
        return edit_post(wp_slash($post_data));
    } else {
        // Non drafts or other users drafts are not overwritten. The autosave is stored in a special post revision for each user.
        return wp_create_post_autosave(wp_slash($post_data));
    }
}

/**
 * Save draft or manually autosave for showing preview.
 *
 * @package WordPress
 * @since 2.7.0
 *
 * @uses get_post_status()
 * @uses edit_post()
 * @uses get_post()
 * @uses current_user_can()
 * @uses wp_die()
 * @uses wp_create_post_autosave()
 * @uses add_query_arg()
 * @uses wp_create_nonce()
 *
 * @return str URL to redirect to show the preview
 */
function post_preview()
{
    $post_ID = (int) $_POST['post_ID'];
    $status = get_post_status($post_ID);
    if ('auto-draft' == $status) {
        wp_die(__('Preview not available. Please save as a draft first.'));
    }
    if (isset($_POST['catslist'])) {
        $_POST['post_category'] = explode(",", $_POST['catslist']);
    }
    if (isset($_POST['tags_input'])) {
        $_POST['tags_input'] = explode(",", $_POST['tags_input']);
    }
    if ($_POST['post_type'] == 'page' || empty($_POST['post_category'])) {
        unset($_POST['post_category']);
    }
    $_POST['ID'] = $post_ID;
    $post = get_post($post_ID);
    if ('page' == $post->post_type) {
        if (!current_user_can('edit_page', $post_ID)) {
            wp_die(__('You are not allowed to edit this page.'));
        }
    } else {
        if (!current_user_can('edit_post', $post_ID)) {
            wp_die(__('You are not allowed to edit this post.'));
        }
    }
    $user_id = get_current_user_id();
    $locked = wp_check_post_lock($post->ID);
    if (!$locked && 'draft' == $post->post_status && $user_id == $post->post_author) {
        $id = edit_post();
    } else {
        // Non drafts are not overwritten. The autosave is stored in a special post revision.
        $id = wp_create_post_autosave($post->ID);
        if (!is_wp_error($id)) {
            $id = $post->ID;
        }
    }
    if (is_wp_error($id)) {
        wp_die($id->get_error_message());
    }
    if (!$locked && $_POST['post_status'] == 'draft' && $user_id == $post->post_author) {
        $url = add_query_arg('preview', 'true', get_permalink($id));
    } else {
        $nonce = wp_create_nonce('post_preview_' . $id);
        $args = array('preview' => 'true', 'preview_id' => $id, 'preview_nonce' => $nonce);
        if (isset($_POST['post_format'])) {
            $args['post_format'] = empty($_POST['post_format']) ? 'standard' : sanitize_key($_POST['post_format']);
        }
        $url = add_query_arg($args, get_permalink($id));
    }
    return apply_filters('preview_post_link', $url);
}

/**
 * Save draft or manually autosave for showing preview.
 *
 * @package WordPress
 * @since 2.7
 *
 * @uses wp_write_post()
 * @uses edit_post()
 * @uses get_post()
 * @uses current_user_can()
 * @uses wp_create_post_autosave()
 *
 * @return str URL to redirect to show the preview
 */
function post_preview()
{
    $post_ID = (int) $_POST['post_ID'];
    if ($post_ID < 1) {
        wp_die(__('Preview not available. Please save as a draft first.'));
    }
    if (isset($_POST['catslist'])) {
        $_POST['post_category'] = explode(",", $_POST['catslist']);
    }
    if (isset($_POST['tags_input'])) {
        $_POST['tags_input'] = explode(",", $_POST['tags_input']);
    }
    if ($_POST['post_type'] == 'page' || empty($_POST['post_category'])) {
        unset($_POST['post_category']);
    }
    $_POST['ID'] = $post_ID;
    $post = get_post($post_ID);
    if ('page' == $post->post_type) {
        if (!current_user_can('edit_page', $post_ID)) {
            wp_die(__('You are not allowed to edit this page.'));
        }
    } else {
        if (!current_user_can('edit_post', $post_ID)) {
            wp_die(__('You are not allowed to edit this post.'));
        }
    }
    if ('draft' == $post->post_status) {
        $id = edit_post();
    } else {
        // Non drafts are not overwritten.  The autosave is stored in a special post revision.
        $id = wp_create_post_autosave($post->ID);
        if (!is_wp_error($id)) {
            $id = $post->ID;
        }
    }
    if (is_wp_error($id)) {
        wp_die($id->get_error_message());
    }
    if ($_POST['post_status'] == 'draft') {
        $url = add_query_arg('preview', 'true', get_permalink($id));
    } else {
        $nonce = wp_create_nonce('post_preview_' . $id);
        $url = add_query_arg(array('preview' => 'true', 'preview_id' => $id, 'preview_nonce' => $nonce), get_permalink($id));
    }
    return $url;
}

     if ('page' == $post->post_type) {
         if (!current_user_can('edit_page', $post_ID)) {
             die(__('You are not allowed to edit this page.'));
         }
     } else {
         if (!current_user_can('edit_post', $post_ID)) {
             die(__('You are not allowed to edit this post.'));
         }
     }
     if ($do_autosave) {
         // Drafts are just overwritten by autosave
         if ('draft' == $post->post_status) {
             $id = edit_post();
         } else {
             // Non drafts are not overwritten.  The autosave is stored in a special post revision.
             $revision_id = wp_create_post_autosave($post->ID);
             if (is_wp_error($revision_id)) {
                 $id = $revision_id;
             } else {
                 $id = $post->ID;
             }
         }
         $data = $message;
     } else {
         $id = $post->ID;
     }
 }
 if ($do_lock && $id && is_numeric($id)) {
     wp_set_post_lock($id);
 }
 if ($nonce_age == 2) {