<?php
/* For licensing terms, see /license.txt */

require_once api_get_path(LIBRARY_PATH).'online.inc.php';
require_once api_get_path(LIBRARY_PATH).'fileUpload.lib.php';
require_once api_get_path(LIBRARY_PATH).'fileDisplay.lib.php';
require_once api_get_path(LIBRARY_PATH).'group_portal_manager.lib.php';

define('MESSAGE_STATUS_NEW', '0');
define('MESSAGE_STATUS_UNREAD', '1');
//2 ??
define('MESSAGE_STATUS_DELETED', '3');
define('MESSAGE_STATUS_OUTBOX', '4');
define('MESSAGE_STATUS_INVITATION_PENDING', '5');
define('MESSAGE_STATUS_INVITATION_ACCEPTED', '6');
define('MESSAGE_STATUS_INVITATION_DENIED', '7');
define('MESSAGE_STATUS_WALL', '8');
define('MESSAGE_STATUS_WALL_DELETE', '9');
define('MESSAGE_STATUS_WALL_POST', '10');
// Images
define('IMAGE_WALL_SMALL_SIZE', 200);
define('IMAGE_WALL_MEDIUM_SIZE', 500);
define('IMAGE_WALL_BIG_SIZE', 2000);
define('IMAGE_WALL_SMALL', 'small');
define('IMAGE_WALL_MEDIUM', 'medium');
define('IMAGE_WALL_BIG', 'big');

/**
 * Class MessageManager
 *
 * This class provides methods for messages management.
 * Include/require it in your code to use its features.
 *
 * @package chamilo.library
 */
class MessageManager
{
    /**
     * @param int $current_user_id
     * @return array
     */
    public static function get_online_user_list($current_user_id)
    {
        //@todo this is a bad idea to parse all users online
        $count = who_is_online_count();
        $userlist = who_is_online(0, $count, null, null, 30, true);
        $online_user_list = array();
        foreach ($userlist as $user_id) {
            $online_user_list[$user_id] = GetFullUserName($user_id).($current_user_id == $user_id ? ("&nbsp;(".get_lang('Myself').")") : (""));
        }
        return $online_user_list;
    }

    /**
     * Displays info stating that the message is sent successfully.
     * @deprecated
     */
    public static function display_success_message($uid)
    {
        if (isset($_SESSION['social_exist']) &&
            $_SESSION['social_exist'] === true
        ) {
            if (api_get_setting('allow_social_tool') == 'true' && api_get_setting('allow_message_tool') == 'true') {
                $success = get_lang('MessageSentTo').
                    "&nbsp;<b>".
                    GetFullUserName($uid).
                    "</b>";
            } else {
                $success = get_lang('MessageSentTo').
                    "&nbsp;<b>".
                    GetFullUserName($uid).
                    "</b>";
            }
        } else {
            $success = get_lang('MessageSentTo').
                "&nbsp;<b>".
                GetFullUserName($uid).
                "</b>";
        }
        return Display::return_message(api_xml_http_response_encode($success), 'confirmation', false);
    }

    /**
     * Displays the wysiwyg html editor.
     * @deprecated
     */
    public static function display_html_editor_area($name, $resp)
    {
        api_disp_html_area($name, get_lang('TypeYourMessage'), '', '', null, array('ToolbarSet' => 'Messages', 'Width' => '95%', 'Height' => '250'));
    }

    /**
     * Get the new messages for the current user from the database.
     */
    public static function get_new_messages()
    {
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        if (!api_get_user_id()) {
            return false;
        }
        $sql = "SELECT * FROM $table_message
                WHERE user_receiver_id=".api_get_user_id()." AND msg_status=".MESSAGE_STATUS_UNREAD;
        $result = Database::query($sql);
        $i = Database::num_rows($result);
        return $i;
    }

    /**
     * Get the list of user_ids of users who are online.
     */
    public static function users_connected_by_id()
    {
        $count = who_is_online_count();
        $user_connect = who_is_online(0, $count, null, null, 30, true);
        $user_id_list = array();
        for ($i = 0; $i < count($user_connect); $i++) {
            $user_id_list[$i] = $user_connect[$i][0];
        }
        return $user_id_list;
    }

    /**
     * Gets the total number of messages, used for the inbox sortable table
     */
    public static function get_number_of_messages($unread = false)
    {
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        if ($unread) {
            $condition_msg_status = ' msg_status = '.MESSAGE_STATUS_UNREAD.' ';
        } else {
            $condition_msg_status = ' msg_status IN('.MESSAGE_STATUS_NEW.','.MESSAGE_STATUS_UNREAD.') ';
        }

        $sql = "SELECT COUNT(*) as number_messages FROM $table_message
                WHERE $condition_msg_status AND user_receiver_id=".api_get_user_id();
        $sql_result = Database::query($sql);
        $result = Database::fetch_array($sql_result);
        return $result['number_messages'];
    }

    /**
     * Gets information about some messages, used for the inbox sortable table
     * @param int $from
     * @param int $number_of_items
     * @param string $direction
     */
    public static function get_message_data($from, $number_of_items, $column, $direction)
    {
        $from = intval($from);
        $number_of_items = intval($number_of_items);

        //forcing this order
        if (!isset($direction)) {
            $column = 3;
            $direction = 'DESC';
        } else {
            $column = intval($column);
            if (!in_array($direction, array('ASC', 'DESC')))
                $direction = 'ASC';
        }
        $table_message = Database::get_main_table(TABLE_MESSAGE);

        $sql = "SELECT id as col0, user_sender_id as col1, title as col2, send_date as col3, msg_status as col4
                FROM $table_message
                WHERE user_receiver_id=".api_get_user_id()." AND msg_status IN (0,1)
                ORDER BY col$column $direction
                LIMIT $from,$number_of_items";

        $sql_result = Database::query($sql);
        $i = 0;
        $message_list = array();

        while ($result = Database::fetch_row($sql_result)) {
            $message[0] = $result[0];
            $result[2] = Security::remove_XSS($result[2], STUDENT, true);
            $result[2] = cut($result[2], 80, true);

            if ($result[4] == 1) {
                $class = 'class = "unread"';
            } else {
                $class = 'class = "read"';
            }
            $link = '';
            if (isset($_GET['f']) && $_GET['f'] == 'social') {
                $link = '&f=social';
            }
            $message[1] = '<a '.$class.' href="view_message.php?id='.$result[0].$link.'">'.$result[2].'</a><br />'.GetFullUserName(($result[1]));
            $message[3] = '<a href="new_message.php?re_id='.$result[0].$link.'">'.Display::return_icon('message_reply.png', get_lang('ReplyToMessage')).'</a>'.
                '&nbsp;&nbsp;<a onclick="javascript:if(!confirm('."'".addslashes(api_htmlentities(get_lang('ConfirmDeleteMessage')))."'".')) return false;" href="inbox.php?action=deleteone&id='.$result[0].$link.'">'.Display::return_icon('delete.png', get_lang('DeleteMessage')).'</a>';

            $message[2] = api_convert_and_format_date($result[3], DATE_TIME_FORMAT_LONG); //date stays the same
            foreach ($message as $key => $value) {
                $message[$key] = api_xml_http_response_encode($value);
            }
            $message_list[] = $message;
            $i++;
        }

        return $message_list;
    }

    /**
     * Sends a message to a user/group
     *
     * @param int 	   $receiver_user_id
     * @param string  $subject
     * @param string  $content
     * @param array   $file_attachments files array($_FILES) (optional)
     * @param array   $file_comments about attachment files (optional)
     * @param int     $group_id (optional)
     * @param int     $parent_id (optional)
     * @param int 	   $edit_message_id id for updating the message (optional)
     * @param int     $topic_id (optional) the default value is the current user_id
     * @param int     $sender_id
     * @return bool
     */
    public static function send_message(
        $receiver_user_id,
        $subject,
        $content,
        $file_attachments = array(),
        $file_comments = array(),
        $group_id = 0,
        $parent_id = 0,
        $edit_message_id = 0,
        $topic_id = 0,
        $sender_id = null
    ) {
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $group_id = intval($group_id);
        $receiver_user_id = intval($receiver_user_id);
        $parent_id = intval($parent_id);
        $edit_message_id = intval($edit_message_id);
        $topic_id = intval($topic_id);

        if (!empty($receiver_user_id)) {
            $receiverUserInfo = api_get_user_info($receiver_user_id);

            // Disabling messages for inactive users.
            if ($receiverUserInfo['active'] == 0) {
                return false;
            }
        }

        if (empty($sender_id)) {
            $user_sender_id = api_get_user_id();
        } else {
            $user_sender_id = intval($sender_id);
        }

        $total_filesize = 0;
        if (is_array($file_attachments)) {
            foreach ($file_attachments as $file_attach) {
                $total_filesize += $file_attach['size'];
            }
        }

        // Validating fields
        if (empty($subject) && empty($group_id)) {
            return get_lang('YouShouldWriteASubject');
        } else if ($total_filesize > intval(api_get_setting('message_max_upload_filesize'))) {
            return sprintf(
                get_lang("FilesSizeExceedsX"),
                format_file_size(api_get_setting('message_max_upload_filesize'))
            );
        }

        $inbox_last_id = null;

        //Just in case we replace the and \n and \n\r while saving in the DB
        $content = str_replace(array("\n", "\n\r"), '<br />', $content);

        $now = api_get_utc_datetime();
        if (!empty($receiver_user_id) || !empty($group_id)) {

            // message for user friend
            $clean_subject = Database::escape_string($subject);
            $clean_content = Database::escape_string($content);

            //message in inbox for user friend
            //@todo it's possible to edit a message? yes, only for groups
            if ($edit_message_id) {
                $query = " UPDATE $table_message SET
                                update_date = '".$now."',
                                content = '$clean_content'
                           WHERE id = '$edit_message_id' ";
                Database::query($query);
                $inbox_last_id = $edit_message_id;
            } else {
                $query = "INSERT INTO $table_message (user_sender_id, user_receiver_id, msg_status, send_date, title, content, group_id, parent_id, update_date ) ".
                         "VALUES ('$user_sender_id', '$receiver_user_id', '1', '".$now."','$clean_subject','$clean_content','$group_id','$parent_id', '".$now."')";
                Database::query($query);
                $inbox_last_id = Database::insert_id();
            }

            // Save attachment file for inbox messages
            if (is_array($file_attachments)) {
                $i = 0;
                foreach ($file_attachments as $file_attach) {
                    if ($file_attach['error'] == 0) {
                        self::save_message_attachment_file(
                            $file_attach,
                            $file_comments[$i],
                            $inbox_last_id,
                            null,
                            $receiver_user_id,
                            $group_id
                        );
                    }
                    $i++;
                }
            }

            if (empty($group_id)) {
                //message in outbox for user friend or group
                $sql = "INSERT INTO $table_message (user_sender_id, user_receiver_id, msg_status, send_date, title, content, group_id, parent_id, update_date ) ".
                    " VALUES ('$user_sender_id', '$receiver_user_id', '4', '".$now."','$clean_subject','$clean_content', '$group_id', '$parent_id', '".$now."')";
                Database::query($sql);
                $outbox_last_id = Database::insert_id();

                // save attachment file for outbox messages
                if (is_array($file_attachments)) {
                    $o = 0;
                    foreach ($file_attachments as $file_attach) {
                        if ($file_attach['error'] == 0) {
                            self::save_message_attachment_file(
                                $file_attach,
                                $file_comments[$o],
                                $outbox_last_id,
                                $user_sender_id
                            );
                        }
                        $o++;
                    }
                }
            }

            // Load user settings.
            $notification = new Notification();
            $sender_info = api_get_user_info($user_sender_id);

            if (empty($group_id)) {
                $notification->save_notification(
                    Notification::NOTIFICATION_TYPE_MESSAGE,
                    array($receiver_user_id),
                    $subject,
                    $content,
                    $sender_info
                );
            } else {
                $group_info = GroupPortalManager::get_group_data($group_id);
                $group_info['topic_id'] = $topic_id;
                $group_info['msg_id'] = $inbox_last_id;

                $user_list = GroupPortalManager::get_users_by_group($group_id, false, array(), 0, 1000);

                // Adding more sense to the message group
                $subject = sprintf(get_lang('ThereIsANewMessageInTheGroupX'), $group_info['name']);

                $new_user_list = array();
                foreach ($user_list as $user_data) {
                    $new_user_list[] = $user_data['user_id'];
                }
                $group_info = array('group_info' => $group_info, 'user_info' => $sender_info);
                $notification->save_notification(
                    Notification::NOTIFICATION_TYPE_GROUP,
                    $new_user_list,
                    $subject,
                    $content,
                    $group_info
                );
            }
            return $inbox_last_id;
        }
        return false;
    }

    /**
     * A handy way to send message
     */
    public static function send_message_simple(
        $receiver_user_id,
        $subject,
        $message,
        $sender_id = null
    ) {
        return MessageManager::send_message(
            $receiver_user_id,
            $subject,
            $message,
            null,
            null,
            null,
            null,
            null,
            null,
            $sender_id
        );
    }

    /**
     * Update parent ids for other receiver user from current message in groups
     * @author Christian Fasanando Flores
     * @param  int	$parent_id
     * @param  int	$receiver_user_id
     * @param  int	$message_id
     * @return void
     */
    public static function update_parent_ids_from_reply($parent_id, $receiver_user_id, $message_id)
    {
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $parent_id = intval($parent_id);
        $receiver_user_id = intval($receiver_user_id);
        $message_id = intval($message_id);
        // first get data from message id (parent)
        $sql_message = "SELECT * FROM $table_message WHERE id = '$parent_id'";
        $rs_message = Database::query($sql_message);
        $row_message = Database::fetch_array($rs_message);

        // get message id from data found early for other receiver user
        $sql = "SELECT id FROM $table_message
                WHERE
                  user_sender_id ='{$row_message['user_sender_id']}' AND
                  title='{$row_message['title']}' AND
                  content='{$row_message['content']}' AND
                  group_id='{$row_message['group_id']}' AND
                  user_receiver_id='$receiver_user_id'";
        $rs_msg_id = Database::query($sql);
        $row = Database::fetch_array($rs_msg_id);

        // update parent_id for other user receiver
        $sql = "UPDATE $table_message SET parent_id = '{$row[id]}'
                WHERE id = '$message_id'";
        Database::query($sql);
    }

    /**
     * @param int $user_receiver_id
     * @param int $id
     * @return bool|resource
     */
    public static function delete_message_by_user_receiver($user_receiver_id, $id)
    {
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        if ($id != strval(intval($id)))
            return false;
        $user_receiver_id = intval($user_receiver_id);
        $id = intval($id);
        $sql = "SELECT * FROM $table_message WHERE id=".$id." AND msg_status<>4;";
        $rs = Database::query($sql);

        if (Database::num_rows($rs) > 0) {
            // delete attachment file
            self::delete_message_attachment_file($id, $user_receiver_id);
            // delete message
            $query = "UPDATE $table_message SET msg_status=3
                      WHERE user_receiver_id=".$user_receiver_id." AND id=".$id;
            $result = Database::query($query);
            return $result;
        } else {
            return false;
        }
    }

    /**
     * Set status deleted
     * @author Isaac FLores Paz <isaac.flores@dokeos.com>
     * @param  integer
     * @param  integer
     * @return array
     */
    public static function delete_message_by_user_sender($user_sender_id, $id)
    {
        if ($id != strval(intval($id))) {
            return false;
        }

        $table_message = Database::get_main_table(TABLE_MESSAGE);

        $id = intval($id);
        $user_sender_id = intval($user_sender_id);

        $sql = "SELECT * FROM $table_message WHERE id='$id'";
        $rs = Database::query($sql);

        if (Database::num_rows($rs) > 0) {
            // delete attachment file
            self::delete_message_attachment_file($id, $user_sender_id);
            // delete message
            $query = "UPDATE $table_message SET msg_status=3
                    WHERE user_sender_id='$user_sender_id' AND id='$id'";
            $result = Database::query($query);
            return $result;
        }
        return false;
    }

    /**
     * Saves a message attachment files
     * @param  array 	$_FILES['name']
     * @param  string  	a comment about the uploaded file
     * @param  int		message id
     * @param  int		receiver user id (optional)
     * @param  int		sender user id (optional)
     * @param  int		group id (optional)
     * @return void
     */
    public static function save_message_attachment_file(
        $file_attach,
        $file_comment,
        $message_id,
        $receiver_user_id = 0,
        $sender_user_id = 0,
        $group_id = 0
    ) {
        $tbl_message_attach = Database::get_main_table(TABLE_MESSAGE_ATTACHMENT);

        // Try to add an extension to the file if it hasn't one
        $new_file_name = add_ext_on_mime(stripslashes($file_attach['name']), $file_attach['type']);

        // user's file name
        $file_name = $file_attach['name'];
        if (!filter_extension($new_file_name)) {
            Display :: display_error_message(get_lang('UplUnableToSaveFileFilteredExtension'));
        } else {
            $new_file_name = uniqid('');
            if (!empty($receiver_user_id)) {
                $message_user_id = $receiver_user_id;
            } else {
                $message_user_id = $sender_user_id;
            }

            // User-reserved directory where photos have to be placed.

            if (!empty($group_id)) {
                $path_user_info = GroupPortalManager::get_group_picture_path_by_id($group_id, 'system', true);
            } else {
                $path_user_info = UserManager::get_user_picture_path_by_id($message_user_id, 'system', true);
            }

            $path_message_attach = $path_user_info['dir'].'message_attachments/';

            // If this directory does not exist - we create it.
            if (!file_exists($path_message_attach)) {
                @mkdir($path_message_attach, api_get_permissions_for_new_directories(), true);
            }
            $new_path = $path_message_attach.$new_file_name;
            if (is_uploaded_file($file_attach['tmp_name'])) {
                @copy($file_attach['tmp_name'], $new_path);
            }
            $safe_file_comment = Database::escape_string($file_comment);
            $safe_file_name = Database::escape_string($file_name);
            $safe_new_file_name = Database::escape_string($new_file_name);
            // Storing the attachments if any
            $sql = "INSERT INTO $tbl_message_attach(filename,comment, path,message_id,size)
				    VALUES ('$safe_file_name', '$safe_file_comment', '$safe_new_file_name' , '$message_id', '".$file_attach['size']."' )";
            Database::query($sql);
        }
    }

    /**
     * Delete message attachment files (logically updating the row with a suffix _DELETE_id)
     * @param  int	message id
     * @param  int	message user id (receiver user id or sender user id)
     * @param  int	group id (optional)
     * @return void
     */
    public static function delete_message_attachment_file($message_id, $message_uid, $group_id = 0)
    {
        $message_id = intval($message_id);
        $message_uid = intval($message_uid);
        $table_message_attach = Database::get_main_table(TABLE_MESSAGE_ATTACHMENT);

        $sql = "SELECT * FROM $table_message_attach WHERE message_id = '$message_id'";
        $rs = Database::query($sql);
        while ($row = Database::fetch_array($rs)) {
            $path = $row['path'];
            $attach_id = $row['id'];
            $new_path = $path.'_DELETED_'.$attach_id;

            if (!empty($group_id)) {
                $path_user_info = GroupPortalManager::get_group_picture_path_by_id($group_id, 'system', true);
            } else {
                $path_user_info = UserManager::get_user_picture_path_by_id($message_uid, 'system', true);
            }

            $path_message_attach = $path_user_info['dir'].'message_attachments/';
            if (is_file($path_message_attach.$path)) {
                if (rename($path_message_attach.$path, $path_message_attach.$new_path)) {
                    $sql_upd = "UPDATE $table_message_attach set path='$new_path' WHERE id ='$attach_id'";
                    Database::query($sql_upd);
                }
            }
        }
    }

    /**
     * update messages by user id and message id
     * @param  int		user id
     * @param  int		message id
     * @return resource
     */
    public static function update_message($user_id, $message_id)
    {
        if ($message_id != strval(intval($message_id)) || $user_id != strval(intval($user_id)))
            return false;

        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $sql = "UPDATE $table_message SET msg_status = '0'
                WHERE
                    msg_status<>4 AND
                    user_receiver_id=".intval($user_id)." AND
                    id='".intval($message_id)."'";
        Database::query($sql);
    }

    /**
     * @param int $user_id
     * @param int $message_id
     * @param string $type
     * @return bool
     */
    public static function update_message_status($user_id, $message_id,$type)
    {
        $type = intval($type);
        if ($message_id != strval(intval($message_id)) || $user_id != strval(intval($user_id))) {
            return false;
        }
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $sql = "UPDATE $table_message SET msg_status = '$type'
                WHERE user_receiver_id=".intval($user_id)." AND id='".intval($message_id)."'";
        Database::query($sql);
    }

    /**
     * get messages by user id and message id
     * @param  int		user id
     * @param  int		message id
     * @return array
     */
    public static function get_message_by_user($user_id, $message_id)
    {
        if ($message_id != strval(intval($message_id)) || $user_id != strval(intval($user_id)))
            return false;
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $query = "SELECT * FROM $table_message
                  WHERE user_receiver_id=".intval($user_id)." AND id='".intval($message_id)."'";
        $result = Database::query($query);
        return $row = Database::fetch_array($result);
    }

    /**
     * get messages by group id
     * @param  int		group id
     * @return array
     */
    public static function get_messages_by_group($group_id)
    {
        if ($group_id != strval(intval($group_id)))
            return false;

        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $group_id = intval($group_id);
        $query = "SELECT * FROM $table_message
                  WHERE
                    group_id= $group_id AND
                    msg_status NOT IN ('".MESSAGE_STATUS_OUTBOX."', '".MESSAGE_STATUS_DELETED."')
                  ORDER BY id";
        $rs = Database::query($query);
        $data = array();
        if (Database::num_rows($rs) > 0) {
            while ($row = Database::fetch_array($rs, 'ASSOC')) {
                $data[] = $row;
            }
        }
        return $data;
    }

    /**
     * get messages by group id
     * @param  int $group_id
     * @param int $message_id
     * @return array
     */
    public static function get_messages_by_group_by_message($group_id, $message_id)
    {
        if ($group_id != strval(intval($group_id)))
            return false;
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $group_id = intval($group_id);
        $query = "SELECT * FROM $table_message
                  WHERE
                    group_id = $group_id AND
                    msg_status NOT IN ('".MESSAGE_STATUS_OUTBOX."', '".MESSAGE_STATUS_DELETED."')
                  ORDER BY id ";

        $rs = Database::query($query);
        $data = array();
        $parents = array();
        if (Database::num_rows($rs) > 0) {
            while ($row = Database::fetch_array($rs, 'ASSOC')) {
                if ($message_id == $row['parent_id'] || in_array($row['parent_id'], $parents)) {
                    $parents[] = $row['id'];
                    $data[] = $row;
                }
            }
        }
        return $data;
    }

    /**
     * get messages by parent id optionally with limit
     * @param  int		parent id
     * @param  int		group id (optional)
     * @param  int		offset (optional)
     * @param  int		limit (optional)
     * @return array
     */
    public static function get_messages_by_parent($parent_id, $group_id = '', $offset = 0, $limit = 0)
    {
        if ($parent_id != strval(intval($parent_id))) {
            return false;
        }
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $parent_id = intval($parent_id);

        $condition_group_id = "";
        if ($group_id !== '') {
            $group_id = intval($group_id);
            $condition_group_id = " AND group_id = '$group_id' ";
        }

        $condition_limit = "";
        if ($offset && $limit) {
            $offset = ($offset - 1) * $limit;
            $condition_limit = " LIMIT $offset,$limit ";
        }

        $query = "SELECT * FROM $table_message
                 WHERE parent_id='$parent_id' AND msg_status <> ".MESSAGE_STATUS_OUTBOX." $condition_group_id
                 ORDER BY send_date DESC $condition_limit ";
        $rs = Database::query($query);
        $data = array();
        if (Database::num_rows($rs) > 0) {
            while ($row = Database::fetch_array($rs)) {
                $data[$row['id']] = $row;
            }
        }
        return $data;
    }

    /**
     * Gets information about if exist messages
     * @author Isaac FLores Paz <isaac.flores@dokeos.com>
     * @param  integer
     * @param  integer
     * @return boolean
     */
    public static function exist_message($user_id, $id)
    {
        if ($id != strval(intval($id)) || $user_id != strval(intval($user_id)))
            return false;
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $query = "SELECT id FROM $table_message
                  WHERE
                    user_receiver_id = ".intval($user_id)." AND
                    id = '".intval($id)."'";
        $result = Database::query($query);
        $num = Database::num_rows($result);
        if ($num > 0) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Gets information about messages sent
     * @param  integer
     * @param  integer
     * @param  string
     * @return array
     */
    public static function get_message_data_sent($from, $number_of_items, $column, $direction)
    {
        $from = intval($from);
        $number_of_items = intval($number_of_items);
        if (!isset($direction)) {
            $column = 3;
            $direction = 'DESC';
        } else {
            $column = intval($column);
            if (!in_array($direction, array('ASC', 'DESC')))
                $direction = 'ASC';
        }
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $request = api_is_xml_http_request();
        $sql = "SELECT
                    id as col0, user_sender_id as col1, title as col2, send_date as col3, user_receiver_id as col4, msg_status as col5
                FROM $table_message
                WHERE
                    user_sender_id=".api_get_user_id()." AND
                    msg_status=".MESSAGE_STATUS_OUTBOX."
                ORDER BY col$column $direction
                LIMIT $from, $number_of_items";
        $sql_result = Database::query($sql);
        $i = 0;
        $message_list = array();
        while ($result = Database::fetch_row($sql_result)) {
            if ($request === true) {
                $message[0] = '<input type="checkbox" value='.$result[0].' name="out[]">';
            } else {
                $message[0] = ($result[0]);
            }
            $class = 'class = "read"';
            $result[2] = Security::remove_XSS($result[2]);

            if ($request === true) {
                $message[1] = '<a onclick="show_sent_message('.$result[0].')" href="javascript:void(0)">'.GetFullUserName($result[4]).'</a>';
                $message[2] = '<a onclick="show_sent_message('.$result[0].')" href="javascript:void(0)">'.str_replace("\\", "", $result[2]).'</a>';
                $message[3] = api_convert_and_format_date($result[3], DATE_TIME_FORMAT_LONG); //date stays the same

                $message[4] = '&nbsp;&nbsp;<a onclick="delete_one_message_outbox('.$result[0].')" href="javascript:void(0)"  >'.Display::return_icon('delete.png', get_lang('DeleteMessage')).'</a>';
            } else {
                $link = '';
                if ($_GET['f'] == 'social') {
                    $link = '&f=social';
                }
                $message[1] = '<a '.$class.' onclick="show_sent_message ('.$result[0].')" href="../messages/view_message.php?id_send='.$result[0].$link.'">'.$result[2].'</a><br />'.GetFullUserName($result[4]);
                //$message[2] = '<a '.$class.' onclick="show_sent_message ('.$result[0].')" href="../messages/view_message.php?id_send='.$result[0].$link.'">'.$result[2].'</a>';
                $message[2] = api_convert_and_format_date($result[3], DATE_TIME_FORMAT_LONG); //date stays the same
                $message[3] = '<a href="outbox.php?action=deleteone&id='.$result[0].'&f='.Security::remove_XSS($_GET['f']).'"  onclick="javascript:if(!confirm('."'".addslashes(api_htmlentities(get_lang('ConfirmDeleteMessage')))."'".')) return false;" >'.Display::return_icon('delete.png', get_lang('DeleteMessage')).'</a>';
            }

            foreach ($message as $key => $value) {
                $message[$key] = $value;
            }
            $message_list[] = $message;
            $i++;
        }

        return $message_list;
    }

    /**
     * Gets information about number messages sent
     * @author Isaac FLores Paz <isaac.flores@dokeos.com>
     * @param void
     * @return integer
     */
    public static function get_number_of_messages_sent()
    {
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $sql = "SELECT COUNT(*) as number_messages FROM $table_message
                WHERE msg_status=".MESSAGE_STATUS_OUTBOX." AND user_sender_id=".api_get_user_id();
        $sql_result = Database::query($sql);
        $result = Database::fetch_array($sql_result);
        return $result['number_messages'];
    }

    /**
     * display message box in the inbox
     * @param int the message id
     * @param string inbox or outbox strings are available
     * @todo replace numbers with letters in the $row array pff...
     * @return string html with the message content
     */
    public static function show_message_box($message_id, $source = 'inbox')
    {
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $message_id = intval($message_id);

        if ($source == 'outbox') {
            if (isset($message_id) && is_numeric($message_id)) {
                $query = "SELECT * FROM $table_message
                          WHERE user_sender_id=".api_get_user_id()." AND id=".$message_id." AND msg_status=4;";
                $result = Database::query($query);
                $path = 'outbox.php';
            }
        } else {
            if (is_numeric($message_id) && !empty($message_id)) {
                $query = "UPDATE $table_message SET msg_status = '".MESSAGE_STATUS_NEW."'
                          WHERE user_receiver_id=".api_get_user_id()." AND id='".$message_id."';";
                Database::query($query);

                $query = "SELECT * FROM $table_message
                          WHERE msg_status<>4 AND user_receiver_id=".api_get_user_id()." AND id='".$message_id."';";
                $result = Database::query($query);
            }
            $path = 'inbox.php';
        }
        $row = Database::fetch_array($result, 'ASSOC');
        $user_sender_id = $row['user_sender_id'];

        // get file attachments by message id
        $files_attachments = self::get_links_message_attachment_files($message_id, $source);

        $user_con = self::users_connected_by_id();
        $band = 0;
        for ($i = 0; $i < count($user_con); $i++) {
            if ($user_sender_id == $user_con[$i]) {
                $band = 1;
            }
        }

        $title = Security::remove_XSS($row['title'], STUDENT, true);
        $content = Security::remove_XSS($row['content'], STUDENT, true);

        $from_user = UserManager::get_user_info_by_id($user_sender_id);
        $name = api_get_person_name($from_user['firstname'], $from_user['lastname']);
        $user_image = UserManager::get_picture_user($row['user_sender_id'], $from_user['picture_uri'], 80);
        $user_image = Display::img($user_image['file'], $name, array('title' => $name));

        $message_content = Display::page_subheader(str_replace("\\", "", $title));

        if (api_get_setting('allow_social_tool') == 'true') {
            $message_content .= $user_image.' ';
        }

        $message_content .='<tr>';
        if (api_get_setting('allow_social_tool') == 'true') {
            if ($source == 'outbox') {
                $message_content .= get_lang('From').': <a href="'.api_get_path(WEB_PATH).'main/social/profile.php?u='.$user_sender_id.'">'.$name.'</a> '.api_strtolower(get_lang('To')).'&nbsp;<b>'.GetFullUserName($row[2]).'</b>';
            } else {
                $message_content .= get_lang('From').' <a href="'.api_get_path(WEB_PATH).'main/social/profile.php?u='.$user_sender_id.'">'.$name.'</a> '.api_strtolower(get_lang('To')).'&nbsp;<b>'.get_lang('Me').'</b>';
            }
        } else {
            if ($source == 'outbox') {
                $message_content .= get_lang('From').':&nbsp;'.$name.'</b> '.api_strtolower(get_lang('To')).' <b>'.GetFullUserName($row['user_receiver_id']).'</b>';
            } else {
                $message_content .= get_lang('From').':&nbsp;'.$name.'</b> '.api_strtolower(get_lang('To')).' <b>'.get_lang('Me').'</b>';
            }
        }
        $message_content .=' '.get_lang('Date').':  '.api_get_local_time($row['send_date']).'
		        <br />
		        <hr style="color:#ddd" />
		        <table height="209px" width="100%">
		            <tr>
		              <td valign=top class="view-message-content">'.str_replace("\\", "", $content).'</td>
		            </tr>
		        </table>
		        <div id="message-attach">'.(!empty($files_attachments) ? implode('<br />', $files_attachments) : '').'</div>
		        <div style="padding: 15px 0px 5px 0px">';
        $social_link = '';
        if (isset($_GET['f']) && $_GET['f'] == 'social') {
            $social_link = 'f=social';
        }
        if ($source == 'outbox') {
            $message_content .= '<a href="outbox.php?'.$social_link.'">'.Display::return_icon('back.png', get_lang('ReturnToOutbox')).'</a> &nbsp';
        } else {
            $message_content .= '<a href="inbox.php?'.$social_link.'">'.Display::return_icon('back.png', get_lang('ReturnToInbox')).'</a> &nbsp';
            $message_content .= '<a href="new_message.php?re_id='.$message_id.'&'.$social_link.'">'.Display::return_icon('message_reply.png', get_lang('ReplyToMessage')).'</a> &nbsp';
        }
        $message_content .= '<a href="inbox.php?action=deleteone&id='.$message_id.'&'.$social_link.'" >'.Display::return_icon('delete.png', get_lang('DeleteMessage')).'</a>&nbsp';

        $message_content .='</div></td>
		      <td width=10></td>
		    </tr>
		</table>';
        return $message_content;
    }

    /**
     * display message box sent showing it into outbox
     * @return void
     */
    public static function show_message_box_sent()
    {
        $table_message = Database::get_main_table(TABLE_MESSAGE);
        $tbl_message_attach = Database::get_main_table(TABLE_MESSAGE_ATTACHMENT);

        $message_id = '';
        if (is_numeric($_GET['id_send'])) {
            $query = "SELECT * FROM $table_message
                      WHERE
                            user_sender_id=".api_get_user_id()." AND
                            id=".intval($_GET['id_send'])." AND
                            msg_status = 4;";
            $result = Database::query($query);
            $message_id = intval($_GET['id_send']);
        }
        $path = 'outbox.php';

        // get file attachments by message id
        $files_attachments = self::get_links_message_attachment_files($message_id, 'outbox');

        $row = Database::fetch_array($result);
        $user_con = self::users_connected_by_id();
        $band = 0;
        $reply = '';
        for ($i = 0; $i < count($user_con); $i++)
            if ($row[1] == $user_con[$i])
                $band = 1;
        echo '<div class=actions>';
        echo '<a onclick="close_and_open_outbox()" href="javascript:void(0)">'.Display::return_icon('folder_up.gif', api_xml_http_response_encode(get_lang('BackToOutbox'))).api_xml_http_response_encode(get_lang('BackToOutbox')).'</a>';
        echo '<a onclick="delete_one_message_outbox('.$row[0].')" href="javascript:void(0)"  >'.Display::return_icon('delete.png', api_xml_http_response_encode(get_lang('DeleteMessage'))).api_xml_http_response_encode(get_lang('DeleteMessage')).'</a>';
        echo '</div><br />';
        echo '
		<table class="message_view_table" >
		    <TR>
		      <TD width=10>&nbsp; </TD>
		      <TD vAlign=top width="100%">
		      	<TABLE>
		            <TR>
		              <TD width="100%">
		                    <TR> <h1>'.str_replace("\\", "", api_xml_http_response_encode($row[5])).'</h1></TR>
		              </TD>
		              <TR>
		              	<TD>'.api_xml_http_response_encode(get_lang('From').'&nbsp;<b>'.GetFullUserName($row[1]).'</b> '.api_strtolower(get_lang('To')).'&nbsp;  <b>'.GetFullUserName($row[2])).'</b> </TD>
		              </TR>
		              <TR>
		              <TD >'.api_xml_http_response_encode(get_lang('Date').'&nbsp; '.$row[4]).'</TD>
		              </TR>
		            </TR>
		        </TABLE>
		        <br />
		        <TABLE height="209px" width="100%" bgColor=#ffffff>
		          <TBODY>
		            <TR>
		              <TD vAlign=top>'.str_replace("\\", "", api_xml_http_response_encode($row[6])).'</TD>
		            </TR>
		          </TBODY>
		        </TABLE>
		        <div id="message-attach">'.(!empty($files_attachments) ? implode('<br />', $files_attachments) : '').'</div>
		        <DIV class=HT style="PADDING-BOTTOM: 5px"> </DIV></TD>
		      <TD width=10>&nbsp;</TD>
		    </TR>
		</TABLE>';
    }

    /**
     * get user id by user email
     * @param string $user_email
     * @return int user id
     */
    public static function get_user_id_by_email($user_email)
    {
        $tbl_user = Database::get_main_table(TABLE_MAIN_USER);
        $sql = 'SELECT user_id FROM '.$tbl_user.'
                WHERE email="'.Database::escape_string($user_email).'";';
        $rs = Database::query($sql);
        $row = Database::fetch_array($rs, 'ASSOC');
        if (isset($row['user_id'])) {
            return $row['user_id'];
        } else {
            return null;
        }
    }

    /**
     * Displays messages of a group with nested view
     *
     * @param int $group_id
     */
    public static function display_messages_for_group($group_id)
    {
        global $my_group_role;

        $rows = self::get_messages_by_group($group_id);
        $topics_per_page = 10;
        $html_messages = '';
        $query_vars = array('id' => $group_id, 'topics_page_nr' => 0);

        if (is_array($rows) && count($rows) > 0) {

            // prepare array for topics with its items
            $topics = array();
            $x = 0;
            foreach ($rows as $index => $value) {
                if (empty($value['parent_id'])) {
                    $topics[$value['id']] = $value;
                }
            }

            $new_topics = array();

            foreach ($topics as $id => $value) {
                $rows = null;
                $rows = self::get_messages_by_group_by_message($group_id, $value['id']);
                if (!empty($rows)) {
                    $count = count(self::calculate_children($rows, $value['id']));
                } else {
                    $count = 0;
                }
                $value['count'] = $count;
                $new_topics[$id] = $value;
            }
            //$new_topics = sort_column($new_topics,'count');
            $param_names = array_keys($_GET);
            $array_html = array();

            foreach ($new_topics as $index => $topic) {
                $html = '';
                // topics
                //$indent	= 0;
                $user_sender_info = UserManager::get_user_info_by_id($topic['user_sender_id']);
                //$files_attachments  = self::get_links_message_attachment_files($topic['id']);
                $name = api_get_person_name($user_sender_info['firstname'], $user_sender_info['lastname']);

                $html .= '<div class="row">';

                $items = $topic['count'];
                $reply_label = ($items == 1) ? get_lang('GroupReply') : get_lang('GroupReplies');

                $html .= '<div class="span1">';
                $html .= Display::div(Display::tag('span', $items).$reply_label, array('class' => 'group_discussions_replies'));
                $html .= '</div>';

                $topic['title'] = trim($topic['title']);

                if (empty($topic['title'])) {
                    $topic['title'] = get_lang('Untitled');
                }

                $html .= '<div class="span4">';
                $html .= Display::tag('h4', Display::url(Security::remove_XSS($topic['title'], STUDENT, true), 'group_topics.php?id='.$group_id.'&topic_id='.$topic['id']));

                if ($my_group_role == GROUP_USER_PERMISSION_ADMIN || $my_group_role == GROUP_USER_PERMISSION_MODERATOR) {
                    $actions = '<br />'.Display::url(get_lang('Delete'), api_get_path(WEB_CODE_PATH).'social/group_topics.php?action=delete&id='.$group_id.'&topic_id='.$topic['id'], array('class' => 'btn'));
                }

                $date = '';
                if ($topic['send_date'] != $topic['update_date']) {
                    if (!empty($topic['update_date']) && $topic['update_date'] != '0000-00-00 00:00:00') {
                        $date .= '<div class="message-group-date" > <i>'.get_lang('LastUpdate').' '.date_to_str_ago($topic['update_date']).'</i></div>';
                    }
                } else {
                    $date .= '<div class="message-group-date"> <i>'.get_lang('Created').' '.date_to_str_ago($topic['send_date']).'</i></div>';
                }
                $html .= $date.$actions;
                $html .= '</div>';

                $image_path = UserManager::get_user_picture_path_by_id($topic['user_sender_id'], 'web', false, true);
                $image_repository = $image_path['dir'];
                $existing_image = $image_path['file'];

                $user_info = '<td valign="top"><a href="'.api_get_path(WEB_PATH).'main/social/profile.php?u='.$topic['user_sender_id'].'">'.$name.'&nbsp;</a>';
                $user_info .= '<div class="message-group-author"><img src="'.$image_repository.$existing_image.'" alt="'.$name.'"  width="32" height="32" title="'.$name.'" /></div>';
                $user_info .= '</td>';

                $html .= '<div class="span2">';
                $html .= $user_info;
                $html .= '</div>';
                $html .= '</div>';

                $array_html[] = array($html);
            }
            // grids for items and topics  with paginations
            $html_messages .= Display::return_sortable_grid(
                'topics',
                array(),
                $array_html,
                array(
                    'hide_navigation' => false,
                    'per_page' => $topics_per_page
                ),
                $query_vars,
                false,
                array(true, true, true, false),
                false
            );
        }
        return $html_messages;
    }

    /**
     * Displays messages of a group with nested view
     * @param $group_id
     * @param $topic_id
     * @param $is_member
     * @param $message_id
     * @return string
     */
    public static function display_message_for_group($group_id, $topic_id, $is_member, $message_id)
    {
        global $my_group_role;
        $main_message = self::get_message_by_id($topic_id);
        if (empty($main_message)) {
            return false;
        }
        $rows = self::get_messages_by_group_by_message($group_id, $topic_id);
        $rows = self::calculate_children($rows, $topic_id);
        $current_user_id = api_get_user_id();

        $items_per_page = 50;

        $query_vars = array('id' => $group_id, 'topic_id' => $topic_id, 'topics_page_nr' => 0);

        // Main message

        $user_link = '';
        $links = '';
        $main_content = '';

        $items_page_nr = null;

        $html = '';

        $delete_button = '';
        if (api_is_platform_admin()) {
            $delete_button = Display::url(Display::return_icon('delete.png', get_lang('Delete'), array(), ICON_SIZE_SMALL), 'group_topics.php?action=delete&id='.$group_id.'&topic_id='.$topic_id);
        }
        $html .= Display::page_subheader(Security::remove_XSS($main_message['title'].$delete_button, STUDENT, true));

        $user_sender_info = UserManager::get_user_info_by_id($main_message['user_sender_id']);
        $files_attachments = self::get_links_message_attachment_files($main_message['id']);
        $name = api_get_person_name($user_sender_info['firstname'], $user_sender_info['lastname']);

        $topic_page_nr = isset($_GET['topics_page_nr']) ? intval($_GET['topics_page_nr']) : null;
        $links.= '<div id="message-reply-link">';
        if (($my_group_role == GROUP_USER_PERMISSION_ADMIN || $my_group_role == GROUP_USER_PERMISSION_MODERATOR) || $main_message['user_sender_id'] == $current_user_id) {
            $links.= '<a href="'.api_get_path(WEB_CODE_PATH).'social/message_for_group_form.inc.php?view_panel=1&height=390&width=610&&user_friend='.$current_user_id.'&group_id='.$group_id.'&message_id='.$main_message['id'].'&action=edit_message_group&anchor_topic=topic_'.$main_message['id'].'&topics_page_nr='.$topic_page_nr.'&items_page_nr='.$items_page_nr.'&topic_id='.$main_message['id'].'" class="group_message_popup" title="'.get_lang('Edit').'">';
            $links.= Display :: return_icon('edit.png', get_lang('Edit'), array(), ICON_SIZE_SMALL).'</a>';
        }
        $links.= '&nbsp;&nbsp;<a href="'.api_get_path(WEB_CODE_PATH).'social/message_for_group_form.inc.php?view_panel=1&height=390&width=610&&user_friend='.api_get_user_id().'&group_id='.$group_id.'&message_id='.$main_message['id'].'&action=reply_message_group&anchor_topic=topic_'.$main_message['id'].'&topics_page_nr='.$topic_page_nr.'&items_page_nr='.$items_page_nr.'&topic_id='.$main_message['id'].'" class="group_message_popup" title="'.get_lang('Reply').'">';
        $links.= Display :: return_icon('talk.png', get_lang('Reply')).'</a>';
        $links.= '</div>';

        $image_path = UserManager::get_user_picture_path_by_id($main_message['user_sender_id'], 'web', false, true);
        $image_repository = $image_path['dir'];
        $existing_image = $image_path['file'];
        $main_content.= '<div class="message-group-author"><img src="'.$image_repository.$existing_image.'" alt="'.$name.'"  width="32" height="32" title="'.$name.'" /></div>';
        $user_link = '<a href="'.api_get_path(WEB_PATH).'main/social/profile.php?u='.$main_message['user_sender_id'].'">'.$name.'&nbsp;</a>';

        $date = '';
        if ($main_message['send_date'] != $main_message['update_date']) {
            if (!empty($main_message['update_date']) && $main_message['update_date'] != '0000-00-00 00:00:00') {
                $date = '<div class="message-group-date"> '.get_lang('LastUpdate').' '.date_to_str_ago($main_message['update_date']).'</div>';
            }
        } else {
            $date = '<div class="message-group-date"> '.get_lang('Created').' '.date_to_str_ago($main_message['send_date']).'</div>';
        }
        $attachment = '<div class="message-attach">'.(!empty($files_attachments) ? implode('<br />', $files_attachments) : '').'</div>';
        $main_content.= '<div class="message-group-content">'.$links.$user_link.' '.$date.$main_message['content'].$attachment.'</div>';
        $main_content = Security::remove_XSS($main_content, STUDENT, true);

        $html .= Display::div(Display::div(Display::div($main_content, array('class' => 'group_social_sub_item', 'style' => 'background-color:#fff;')), array('class' => 'group_social_item')), array('class' => 'group_social_grid'));

        $topic_id = $main_message['id'];

        if (is_array($rows) && count($rows) > 0) {
            $topics = $rows;
            $array_html_items = array();
            foreach ($topics as $index => $topic) {
                if (empty($topic['id'])) {
                    continue;
                }
                $items_page_nr = isset($_GET['items_'.$topic['id'].'_page_nr']) ? intval($_GET['items_'.$topic['id'].'_page_nr']) : null;

                $user_link = '';
                $links = '';
                $html_items = '';
                $user_sender_info = UserManager::get_user_info_by_id($topic['user_sender_id']);
                $files_attachments = self::get_links_message_attachment_files($topic['id']);
                $name = api_get_person_name($user_sender_info['firstname'], $user_sender_info['lastname']);

                $links.= '<div id="message-reply-link">';
                if (($my_group_role == GROUP_USER_PERMISSION_ADMIN || $my_group_role == GROUP_USER_PERMISSION_MODERATOR) || $topic['user_sender_id'] == $current_user_id) {
                    $links.= '<a href="'.api_get_path(WEB_CODE_PATH).'social/message_for_group_form.inc.php?view_panel=1&height=390&width=610&&user_friend='.$current_user_id.'&group_id='.$group_id.'&message_id='.$topic['id'].'&action=edit_message_group&anchor_topic=topic_'.$topic_id.'&topics_page_nr='.$topic_page_nr.'&items_page_nr='.$items_page_nr.'&topic_id='.$topic_id.'" class="group_message_popup" title="'.get_lang('Edit').'">'.Display :: return_icon('edit.png', get_lang('Edit'), array(), ICON_SIZE_SMALL).'</a>';
                }
                $links.= '&nbsp;&nbsp;<a href="'.api_get_path(WEB_CODE_PATH).'social/message_for_group_form.inc.php?view_panel=1&height=390&width=610&&user_friend='.api_get_user_id().'&group_id='.$group_id.'&message_id='.$topic['id'].'&action=reply_message_group&anchor_topic=topic_'.$topic_id.'&topics_page_nr='.$topic_page_nr.'&items_page_nr='.$items_page_nr.'&topic_id='.$topic_id.'" class="group_message_popup" title="'.get_lang('Reply').'">';
                $links.= Display :: return_icon('talk.png', get_lang('Reply')).'</a>';
                $links.= '</div>';

                $image_path = UserManager::get_user_picture_path_by_id($topic['user_sender_id'], 'web', false, true);
                $image_repository = $image_path['dir'];
                $existing_image = $image_path['file'];
                $html_items.= '<div class="message-group-author"><img src="'.$image_repository.$existing_image.'" alt="'.$name.'"  width="32" height="32" title="'.$name.'" /></div>';
                $user_link = '<a href="'.api_get_path(WEB_PATH).'main/social/profile.php?u='.$topic['user_sender_id'].'">'.$name.'&nbsp;</a>';

                $date = '';
                if ($topic['send_date'] != $topic['update_date']) {
                    if (!empty($topic['update_date']) && $topic['update_date'] != '0000-00-00 00:00:00') {
                        $date = '<div class="message-group-date"> '.get_lang('LastUpdate').' '.date_to_str_ago($topic['update_date']).'</div>';
                    }
                } else {
                    $date = '<div class="message-group-date"> '.get_lang('Created').' '.date_to_str_ago($topic['send_date']).'</div>';
                }
                $attachment = '<div class="message-attach">'.(!empty($files_attachments) ? implode('<br />', $files_attachments) : '').'</div>';
                $html_items.= '<div class="message-group-content">'.$links.$user_link.' '.$date.Security::remove_XSS($topic['content'], STUDENT, true).$attachment.'</div>';

                $base_padding = 20;

                if ($topic['indent_cnt'] == 0) {
                    $indent = $base_padding;
                } else {
                    $indent = intval($topic['indent_cnt']) * $base_padding + $base_padding;
                }
                $class = 'group_social_sub_item';
                if (isset($message_id) && $message_id == $topic['id']) {
                    $class .= ' group_social_sub_item_highlight';
                }

                $html_items = Display::div($html_items, array('class' => $class, 'id' => 'msg_'.$topic['id']));
                $html_items = Display::div($html_items, array('class' => '', 'style' => 'margin-left:'.$indent.'px'));
                $array_html_items[] = array($html_items);
            }
            // grids for items with paginations
            $options = array('hide_navigation' => false, 'per_page' => $items_per_page);
            $visibility = array(true, true, true, false);

            $style_class = array('item' => array('class' => 'group_social_item'), 'main' => array('class' => 'group_social_grid'));
            if (!empty($array_html_items)) {
                $html .= Display::return_sortable_grid('items_'.$topic['id'], array(), $array_html_items, $options, $query_vars, null, $visibility, false, $style_class);
            }
        }
        return $html;
    }

    /**
     * Add children to messages by id is used for nested view messages
     * @param array  rows of messages
     * @return array new list adding the item children
     */
    public static function calculate_children($rows, $first_seed)
    {
        $rows_with_children = array();
        foreach ($rows as $row) {
            $rows_with_children[$row["id"]] = $row;
            $rows_with_children[$row["parent_id"]]["children"][] = $row["id"];
        }
        $rows = $rows_with_children;
        $sorted_rows = array(0 => array());
        self::message_recursive_sort($rows, $sorted_rows, $first_seed);
        unset($sorted_rows[0]);
        return $sorted_rows;
    }

    /**
     * Sort recursively the messages, is used for for nested view messages
     * @param array  original rows of messages
     * @param array  list recursive of messages
     * @param int   seed for calculate the indent
     * @param int   indent for nested view
     * @return void
     */
    public static function message_recursive_sort($rows, &$messages, $seed = 0, $indent = 0)
    {
        if ($seed > 0 && isset($rows[$seed]["id"])) {
            $messages[$rows[$seed]["id"]] = $rows[$seed];
            $messages[$rows[$seed]["id"]]["indent_cnt"] = $indent;
            $indent++;
        }

        if (isset($rows[$seed]["children"])) {
            foreach ($rows[$seed]["children"] as $child) {
                self::message_recursive_sort($rows, $messages, $child, $indent);
            }
        }
    }

    /**
     * Sort date by desc from a multi-dimensional array
     * @param array1  first array to compare
     * @param array2  second array to compare
     * @return bool
     */
    public function order_desc_date($array1, $array2)
    {
        return strcmp($array2['send_date'], $array1['send_date']);
    }

    /**
     * Get array of links (download) for message attachment files
     * @param int  		message id
     * @param string	type message list (inbox/outbox)
     * @return array
     */
    public static function get_links_message_attachment_files($message_id, $type = '')
    {
        $tbl_message_attach = Database::get_main_table(TABLE_MESSAGE_ATTACHMENT);
        $message_id = intval($message_id);

        // get file attachments by message id
        $links_attach_file = array();
        if (!empty($message_id)) {

            $sql = "SELECT * FROM $tbl_message_attach WHERE message_id = '$message_id'";

            $rs_file = Database::query($sql);
            if (Database::num_rows($rs_file) > 0) {
                $attach_icon = Display::return_icon('attachment.gif', '');
                $archiveURL = api_get_path(WEB_CODE_PATH).'messages/download.php?type='.$type.'&file=';
                while ($row_file = Database::fetch_array($rs_file)) {
                    $archiveFile = $row_file['path'];
                    $filename = $row_file['filename'];
                    $filesize = format_file_size($row_file['size']);
                    $filecomment = $row_file['comment'];
                    $links_attach_file[] = $attach_icon.'&nbsp;<a href="'.$archiveURL.$archiveFile.'">'.$filename.'</a>&nbsp;('.$filesize.')'.(!empty($filecomment) ? '&nbsp;-&nbsp;<i>'.$filecomment.'</i>' : '');
                }
            }
        }
        return $links_attach_file;
    }

    /**
     * Get message list by id
     * @param int  message id
     * @return array
     */
    public static function get_message_by_id($message_id)
    {
        $tbl_message = Database::get_main_table(TABLE_MESSAGE);
        $message_id = intval($message_id);
        $sql = "SELECT * FROM $tbl_message WHERE id = '$message_id' AND msg_status <> '".MESSAGE_STATUS_DELETED."' ";
        $res = Database::query($sql);
        $item = array();
        if (Database::num_rows($res) > 0) {
            $item = Database::fetch_array($res, 'ASSOC');
        }
        return $item;
    }

    /**
     * @param $id
     * @param array $params
     * @return string
     */
    public static function generate_message_form($id, $params = array())
    {
        $form = new FormValidator('send_message', null, 'post', null, array('id' => $id.'_form', 'class' => 'form-vertical'));
        $form->addElement('text', 'subject', get_lang('Subject'), array('id' => 'subject_id', 'class' => 'span5'));
        $form->addElement('textarea', 'content', get_lang('Message'), array('id' => 'content_id', 'rows' => '5', 'class' => 'span5'));
        $div = Display::div($form->return_form(), array('id' => $id.'_div', 'style' => 'display:none'));
        return $div;
    }

    public static function generate_invitation_form($id, $params = array())
    {
        $form = new FormValidator('send_invitation', null, 'post', null, array('id' => $id.'_form', 'class' => 'form-vertical'));
        //$form->addElement('text', 'subject', get_lang('Subject'), array('id' => 'subject_id'));
        $form->addElement('textarea', 'content', get_lang('AddPersonalMessage'), array('id' => 'content_invitation_id', 'rows' => '5', 'class' => 'span5'));
        $div = Display::div($form->return_form(), array('id' => $id.'_div', 'style' => 'display:none'));
        return $div;
    }

    //@todo this functions should be in the message class

    public static function inbox_display()
    {
        $success = get_lang('SelectedMessagesDeleted');
        $success_read = get_lang('SelectedMessagesRead');
        $success_unread = get_lang('SelectedMessagesUnRead');
        $html = '';

        if (isset($_REQUEST['action'])) {
            switch ($_REQUEST['action']) {
                 case 'mark_as_unread' :
                    $number_of_selected_messages = count($_POST['id']);
                    if (is_array($_POST['id'])) {
                        foreach ($_POST['id'] as $index => $message_id) {
                            MessageManager::update_message_status(api_get_user_id(), $message_id, MESSAGE_STATUS_UNREAD);
                        }
                    }
                    $html .= Display::return_message(api_xml_http_response_encode($success_unread), 'normal', false);
                    break;
                case 'mark_as_read' :
                    $number_of_selected_messages = count($_POST['id']);
                    if (is_array($_POST['id'])) {
                        foreach ($_POST['id'] as $index => $message_id) {
                            MessageManager::update_message_status(api_get_user_id(), $message_id, MESSAGE_STATUS_NEW);
                        }
                    }
                    $html .= Display::return_message(api_xml_http_response_encode($success_read), 'normal', false);
                    break;
                case 'delete' :
                    $number_of_selected_messages = count($_POST['id']);
                    foreach ($_POST['id'] as $index => $message_id) {
                        MessageManager::delete_message_by_user_receiver(api_get_user_id(), $message_id);
                    }
                    $html .= Display::return_message(api_xml_http_response_encode($success), 'normal', false);
                    break;
                case 'deleteone' :
                    MessageManager::delete_message_by_user_receiver(api_get_user_id(), $_GET['id']);
                    $html .= Display::return_message(api_xml_http_response_encode($success), 'confirmation', false);
                    break;
            }
        }

        // display sortable table with messages of the current user
        $table = new SortableTable('message_inbox', array('MessageManager', 'get_number_of_messages'), array('MessageManager', 'get_message_data'), 3, 20, 'DESC');
        $table->set_header(0, '', false, array('style' => 'width:15px;'));
        $table->set_header(1, get_lang('Messages'), false);
        $table->set_header(2, get_lang('Date'), true, array('style' => 'width:180px;'));
        $table->set_header(3, get_lang('Modify'), false, array('style' => 'width:70px;'));

        if (isset($_REQUEST['f']) && $_REQUEST['f'] == 'social') {
            $parameters['f'] = 'social';
            $table->set_additional_parameters($parameters);
        }
        $table->set_form_actions(array('delete' => get_lang('DeleteSelectedMessages'),'mark_as_unread' => get_lang('MailMarkSelectedAsUnread'),'mark_as_read' => get_lang('MailMarkSelectedAsRead')));
        $html .= $table->return_table();
        return $html;
    }

    /**
     * @return string
     */
    static function outbox_display()
    {
        $social_link = false;
        if (isset($_REQUEST['f']) && $_REQUEST['f'] == 'social') {
            $social_link = 'f=social';
        }
        $success = get_lang('SelectedMessagesDeleted').'&nbsp</b><br /><a href="outbox.php?'.$social_link.'">'.get_lang('BackToOutbox').'</a>';

        $html = null;
        if (isset($_REQUEST['action'])) {
            switch ($_REQUEST['action']) {
                case 'delete' :
                    $number_of_selected_messages = count($_POST['id']);
                    if ($number_of_selected_messages != 0) {
                        foreach ($_POST['id'] as $index => $message_id) {
                            MessageManager::delete_message_by_user_receiver(api_get_user_id(), $message_id);
                        }
                    }
                    $html .= Display::return_message(api_xml_http_response_encode($success), 'normal', false);
                    break;
                case 'deleteone' :
                    MessageManager::delete_message_by_user_receiver(api_get_user_id(), $_GET['id']);
                    $html .=Display::return_message(api_xml_http_response_encode($success), 'normal', false);
                    $html .= '<br/>';
                    break;
            }
        }

        // display sortable table with messages of the current user
        $table = new SortableTable('message_outbox', array('MessageManager', 'get_number_of_messages_sent'), array('MessageManager', 'get_message_data_sent'), 3, 20, 'DESC');

        $parameters['f'] = Security::remove_XSS($_GET['f']);
        $table->set_additional_parameters($parameters);
        $table->set_header(0, '', false, array('style' => 'width:15px;'));

        $table->set_header(1, get_lang('Messages'), false);
        $table->set_header(2, get_lang('Date'), true, array('style' => 'width:160px;'));
        $table->set_header(3, get_lang('Modify'), false, array('style' => 'width:70px;'));

        $table->set_form_actions(array('delete' => get_lang('DeleteSelectedMessages')));
        $html .= $table->return_table();
        return $html;
    }

    /**
     * Get the count of the last received messages for a user
     * @param int $userId The user id
     * @param int $lastId The id of the last received message
     * @return int The count of new messages
     */
    public static function countMessagesFromLastReceivedMessage($userId, $lastId = 0)
    {
        $userId = intval($userId);
        $lastId = intval($lastId);

        if (empty($userId)) {
            return 0;
        }

        $messagesTable = Database::get_main_table(TABLE_MESSAGE);

        $conditions = array(
            'where' => array(
                'user_receiver_id = ?' => $userId,
                'AND msg_status = ?' => MESSAGE_STATUS_UNREAD,
                'AND id > ?' => $lastId
            )
        );

        $result = Database::select('COUNT(1) AS qty', $messagesTable, $conditions);

        if (!empty($result)) {
            $row = current($result);

            return $row['qty'];
        }

        return 0;
    }

    /**
     * Get the data of the last received messages for a user
     * @param int $userId The user id
     * @param int $lastId The id of the last received message
     * @return int The count of new messages
     */
    public static function getMessagesFromLastReceivedMessage($userId, $lastId = 0)
    {
        $userId = intval($userId);
        $lastId = intval($lastId);

        if (empty($userId)) {
            return 0;
        }

        $messagesTable = Database::get_main_table(TABLE_MESSAGE);
        $userTable = Database::get_main_table(TABLE_MAIN_USER);

        $messages = array();

        $sql = "SELECT m.*, u.user_id, u.lastname, u.firstname "
                . "FROM $messagesTable as m "
                . "INNER JOIN $userTable as u "
                . "ON m.user_sender_id = u.user_id "
                . "WHERE m.user_receiver_id = $userId "
                . "AND m.msg_status = " . MESSAGE_STATUS_UNREAD . " "
                . "AND m.id > $lastId "
                . "ORDER BY m.send_date DESC";

        $result = Database::query($sql);

        if ($result !== false) {
            while ($row = Database::fetch_assoc($result)) {
                $messages[] = $row;
            }
        }

        return $messages;
    }

    /**
     * Check whether a message has attachments
     * @param int $messageId The message id
     * @return boolean Whether the message has attachments return true. Otherwise return false
     */
    public static function hasAttachments($messageId)
    {
        $messageId = intval($messageId);

        if (empty($messageId)) {
            return false;
        }

        $messageAttachmentTable = Database::get_main_table(TABLE_MESSAGE_ATTACHMENT);

        $conditions = array(
            'where' => array(
                'message_id = ?' => $messageId
            )
        );

        $result = Database::select('COUNT(1) AS qty', $messageAttachmentTable, $conditions, 'first');

        if (!empty($result)) {
            if ($result['qty'] > 0) {
                return true;
            }
        }

        return false;
    }

}
