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

/**
* This file contains additional dropbox functions. Initially there were some
* functions in the init files also but I have moved them over
* to one file -- Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @author Julio Montoya adding c_id support
*/
use ChamiloSession as Session;

$this_section = SECTION_COURSES;

$htmlHeadXtra[] = '<script>
function setFocus(){
    $("#category_title").focus();
}
$(document).ready(function () {
    setFocus();
});
</script>';

/**
* This function is a wrapper function for the multiple actions feature.
* @return   Mixed   If there is a problem, return a string message, otherwise nothing
* @author   Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version  march 2006
*/
function handle_multiple_actions()
{
    $_user = api_get_user_info();
    $is_courseAdmin = api_is_course_admin();
    $is_courseTutor = api_is_course_tutor();

    // STEP 1: are we performing the actions on the received or on the sent files?
    if ($_POST['action'] == 'delete_received' || $_POST['action'] == 'download_received') {
        $part = 'received';
    } elseif ($_POST['action'] == 'delete_sent' || $_POST['action'] == 'download_sent') {
        $part = 'sent';
    }

    // STEP 2: at least one file has to be selected. If not we return an error message
    $ids = isset($_GET['id']) ? $_GET['id'] : array();
    if (count($ids)>0) {
        $checked_file_ids = $_POST['id'];
    } else {
        foreach ($_POST as $key => $value) {
            if (strstr($value, $part.'_') AND $key != 'view_received_category' AND $key != 'view_sent_category') {
                $checked_files = true;
                $checked_file_ids[] = intval(substr($value, strrpos($value, '_')));
            }
        }
    }
    $checked_file_ids = $_POST['id'];

    if (!is_array($checked_file_ids) || count($checked_file_ids) == 0) {
        return get_lang('CheckAtLeastOneFile');
    }

    // STEP 3A: deleting
    if ($_POST['action'] == 'delete_received' || $_POST['action'] == 'delete_sent') {
        $dropboxfile = new Dropbox_Person($_user['user_id'], $is_courseAdmin, $is_courseTutor);
        foreach ($checked_file_ids as $key => $value) {
            if ($_GET['view'] == 'received') {
                $dropboxfile->deleteReceivedWork($value);
                $message = get_lang('ReceivedFileDeleted');
            }
            if ($_GET['view'] == 'sent' OR empty($_GET['view'])) {
                $dropboxfile->deleteSentWork($value);
                $message = get_lang('SentFileDeleted');
            }
        }
        return $message;
    }

    // STEP 3B: giving comment
    if ($_POST['actions'] == 'comment') {
        // This has not been implemented.
        // The idea was that it would be possible to write the same feedback for the selected documents.
    }

    // STEP 3C: moving
    if (strstr($_POST['action'], 'move_')) {
        // check move_received_n or move_sent_n command
        if (strstr($_POST['action'], 'received')) {
              $part = 'received';
              $to_cat_id = str_replace('move_received_', '', $_POST['action']);
        } else {
              $part = 'sent';
              $to_cat_id = str_replace('move_sent_', '', $_POST['action']);
        }

        foreach ($checked_file_ids as $value) {
            store_move($value, $to_cat_id, $part);
        }

        return get_lang('FilesMoved');
    }

    // STEP 3D: downloading
    if ($_POST['action'] == 'download_sent' || $_POST['action'] == 'download_received') {
        zip_download($checked_file_ids);
    }
}

/**
 * Get conf settings
 * @return array
 */
function getDropboxConf()
{
    return Session::read('dropbox_conf');
}

/**
* This function deletes a dropbox category
*
* @todo give the user the possibility what needs to be done with the files in this category: move them to the root, download them as a zip, delete them
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function delete_category($action, $id, $user_id = null)
{
    $course_id = api_get_course_int_id();
    $is_courseAdmin = api_is_course_admin();
    $is_courseTutor = api_is_course_tutor();
    $dropbox_cnf = getDropboxConf();

    if (empty($user_id)) {
        $user_id = api_get_user_id();
    }

    $cat = get_dropbox_category($id);
    if (count($cat)==0) {
        return false;
    }

    if ($cat['user_id'] != $user_id && !api_is_platform_admin($user_id)) {
        return false;
    }

    // an additional check that might not be necessary
    if ($action == 'deletereceivedcategory') {
        $sentreceived = 'received';
        $entries_table = $dropbox_cnf['tbl_post'];
        $id_field = 'file_id';
        $return_message = get_lang('ReceivedCatgoryDeleted');
    } elseif ($action == 'deletesentcategory') {
        $sentreceived = 'sent';
        $entries_table = $dropbox_cnf['tbl_file'];
        $id_field = 'id';
        $return_message = get_lang('SentCatgoryDeleted');
    } else {
        return get_lang('Error');
    }

    // step 1: delete the category
    $sql = "DELETE FROM ".$dropbox_cnf['tbl_category']." WHERE c_id = $course_id AND cat_id='".intval($id)."' AND $sentreceived='1'";
    Database::query($sql);

    // step 2: delete all the documents in this category
    $sql = "SELECT * FROM ".$entries_table." WHERE c_id = $course_id AND cat_id='".intval($id)."'";
    $result = Database::query($sql);

    while($row = Database::fetch_array($result)) {
        $dropboxfile = new Dropbox_Person($user_id, $is_courseAdmin, $is_courseTutor);
        if ($action == 'deletereceivedcategory') {
            $dropboxfile->deleteReceivedWork($row[$id_field]);
        }
        if ($action == 'deletesentcategory') {
            $dropboxfile->deleteSentWork($row[$id_field]);
        }
    }
    return $return_message;
}

/**
* Displays the form to move one individual file to a category
*@ return html code of the form that appears in a message box.
* @author Julio Montoya - function rewritten
*/
function display_move_form($part, $id, $target = array(), $extra_params = array(), $viewReceivedCategory, $viewSentCategory, $view)
{
    $form = new FormValidator(
        'form1',
        'post',
        api_get_self().'?view_received_category='.$viewReceivedCategory.'&view_sent_category='.$viewSentCategory.'&view='.$view.'&'.$extra_params
    );
    $form->addElement('header', get_lang('MoveFileTo'));
    $form->addElement('hidden', 'id', intval($id));
    $form->addElement('hidden', 'part', Security::remove_XSS($part));

    $options = array('0' => get_lang('Root'));
    foreach ($target as $category) {
        $options[$category['cat_id']] = $category['cat_name'];
    }
    $form->addElement('select', 'move_target', get_lang('MoveFileTo'), $options);
    $form->addElement('button', 'do_move', get_lang('MoveFile'));
    $form->display();
}

/**
* This function moves a file to a different category
*
* @param $id the id of the file we are moving
* @param $target the id of the folder we are moving to
* @param $part are we moving a received file or a sent file?
*
* @return language string
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function store_move($id, $target, $part)
{
    $_user = api_get_user_info();
    $dropbox_cnf = getDropboxConf();
    $course_id = api_get_course_int_id();

    if ((isset($id) AND $id != '') AND (isset($target) AND $target != '') AND (isset($part) AND $part != '')) {

        if ($part == 'received') {
            $sql = "UPDATE ".$dropbox_cnf["tbl_post"]." SET cat_id = ".intval($target)."
                        WHERE c_id = $course_id AND dest_user_id = ".intval($_user['user_id'])."
                        AND file_id = ".intval($id)."";
            Database::query($sql);
            $return_message = get_lang('ReceivedFileMoved');
        }
        if ($part == 'sent') {
            $sql = "UPDATE ".$dropbox_cnf["tbl_file"]." SET cat_id = ".intval($target)."
                        WHERE c_id = $course_id AND uploader_id = ".intval($_user['user_id'])."
                        AND id = ".intval($id)."";
            Database::query($sql);
            $return_message = get_lang('SentFileMoved');
        }
    } else {
        $return_message = get_lang('NotMovedError');
    }
    return $return_message;
}

/**
* This functions displays all teh possible actions that can be performed on multiple files. This is the dropdown list that
* appears below the sortable table of the sent / or received files.
*
* @return html value for the dropdown list
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function display_action_options($part, $categories, $current_category = 0)
{
    echo '<select name="actions">';
    echo '<option value="download">'.get_lang('Download').'</option>';
    echo '<option value="delete">'.get_lang('Delete').'</option>';
    if (is_array($categories)) {
        echo '<optgroup label="'.get_lang('MoveTo').'">';
        if ($current_category != 0) {
            echo '<option value="move_0">'.get_lang('Root').'</a>';
        }
        foreach ($categories as $value) {
            if ($current_category != $value['cat_id']) {
                echo '<option value="move_'.$value['cat_id'].'">'.$value['cat_name'].'</option>';
            }
        }
        echo '</optgroup>';
    }
    echo '</select>';
    echo '<input type="submit" name="do_actions_'.Security::remove_XSS($part).'" value="'.get_lang('Ok').'" />';
}

/**
* this function returns the html code that displays the checkboxes next to the files so that
* multiple actions on one file are possible.
*
* @param $id the unique id of the file
* @param $part are we dealing with a sent or with a received file?
*
* @return html code
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function display_file_checkbox($id, $part) {
    if (isset($_GET['selectall'])) {
        $checked = 'checked';
    }
    $return_value = '<input type="checkbox" name="'.Security::remove_XSS($part).'_'.Security::remove_XSS($id).'" value="'.Security::remove_XSS($id).'" '.$checked.' />';
    return $return_value;
}

/**
* This function retrieves all dropbox categories and returns them as an array
*
* @param $filter default '', when we need only the categories of the sent or the received part.
*
* @return array
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function get_dropbox_categories($filter = '')
{
    $course_id = api_get_course_int_id();
    $_user = api_get_user_info();
    $dropbox_cnf = getDropboxConf();
    $return_array = array();

    $session_id = api_get_session_id();
    $condition_session = api_get_session_condition($session_id);

    $sql = "SELECT * FROM ".$dropbox_cnf['tbl_category']." WHERE c_id = $course_id AND user_id='".$_user['user_id']."' $condition_session";

    $result = Database::query($sql);
    while ($row = Database::fetch_array($result)) {
        if (($filter == 'sent' AND $row['sent'] == 1) OR ($filter == 'received' AND $row['received'] == 1) OR $filter == '') {
            $return_array[$row['cat_id']] = $row;
        }
    }

    return $return_array;
}

/**
 * Get a dropbox category details
 * @param int The category ID
 * @return array The details of this category
 */
function get_dropbox_category($id)
{
    $dropbox_cnf = getDropboxConf();
    $course_id = api_get_course_int_id();
    if (empty($id) or $id != intval($id)) { return array(); }
    $sql = "SELECT * FROM ".$dropbox_cnf['tbl_category']." WHERE c_id = $course_id AND cat_id='".$id."'";
    $res = Database::query($sql);
    if ($res === false) {
        return array();
    }
    $row = Database::fetch_assoc($res);
    return $row;
}

/**
* This functions stores a new dropboxcategory
*
* @var  it might not seem very elegant if you create a category in sent and in received with the same name that you get two entries in the
*       dropbox_category table but it is the easiest solution. You get
*       cat_name | received | sent | user_id
*       test     |    1     |   0  |    237
*       test     |    0     |   1  |    237
*       more elegant would be
*       test     |    1     |   1  |    237
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function store_addcategory()
{
    $course_id = api_get_course_int_id();
    $_user = api_get_user_info();
    $dropbox_cnf = getDropboxConf();

    // check if the target is valid
    if ($_POST['target'] == 'sent') {
        $sent = 1;
        $received = 0;
    } elseif ($_POST['target'] == 'received') {
        $sent = 0;
        $received = 1;
    } else {
        return get_lang('Error');
    }

    // check if the category name is valid
    if ($_POST['category_name'] == '') {
        return array('type' => 'error', 'message' => get_lang('ErrorPleaseGiveCategoryName'));
    }

    if (!$_POST['edit_id']) {
        $session_id = api_get_session_id();
        // step 3a, we check if the category doesn't already exist
        $sql = "SELECT * FROM ".$dropbox_cnf['tbl_category']." WHERE c_id = $course_id AND user_id='".$_user['user_id']."' AND cat_name='".Database::escape_string($_POST['category_name'])."' AND received='".$received."' AND sent='$sent' AND session_id='$session_id'";
        $result = Database::query($sql);

        // step 3b, we add the category if it does not exist yet.
        if (Database::num_rows($result) == 0) {
            $sql = "INSERT INTO ".$dropbox_cnf['tbl_category']." (c_id, cat_name, received, sent, user_id, session_id)
                    VALUES ($course_id, '".Database::escape_string($_POST['category_name'])."', '".Database::escape_string($received)."', '".Database::escape_string($sent)."', ".intval($_user['user_id']).", $session_id)";
            Database::query($sql);
            return array('type' => 'confirmation', 'message' => get_lang('CategoryStored'));
        } else {
            return array('type' => 'error', 'message' => get_lang('CategoryAlreadyExistsEditIt'));
        }
    } else {
        $sql = "UPDATE ".$dropbox_cnf['tbl_category']." SET cat_name='".Database::escape_string($_POST['category_name'])."', received='".Database::escape_string($received)."' , sent='".Database::escape_string($sent)."'
                WHERE c_id = $course_id AND user_id = ".intval($_user['user_id'])."
                AND cat_id = ".intval($_POST['edit_id'])."";
        Database::query($sql);
        return array('type' => 'confirmation', 'message' => get_lang('CategoryModified'));
    }
}

/**
* This function displays the form to add a new category.
*
* @param $category_name this parameter is the name of the category (used when no section is selected)
* @param $id this is the id of the category we are editing.
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
  @author Julio Montoya UI changes
 *
* @version march 2006
*/
function display_addcategory_form($category_name = '', $id = '', $action)
{
    $dropbox_cnf = getDropboxConf();
    $course_id = api_get_course_int_id();
    $title = get_lang('AddNewCategory');

    if (isset($id) AND $id != '') {
        // retrieve the category we are editing
        $sql = "SELECT * FROM ".$dropbox_cnf['tbl_category']." WHERE c_id = $course_id AND cat_id = ".intval($id)."";
        $result = Database::query($sql);
        $row = Database::fetch_array($result);

        if (empty($category_name)) { // after an edit with an error we do not want to return to the original name but the name we already modified. (happens when createinrecievedfiles AND createinsentfiles are not checked)
            $category_name = $row['cat_name'];
        }
        if ($row['received'] == '1') {
            $target = 'received';
        }
        if ($row['sent'] == '1') {
            $target = 'sent';
        }
        $title = get_lang('EditCategory');
    }

    if ($action == 'addreceivedcategory') {
        $target = 'received';
    }
    if ($action == 'addsentcategory') {
        $target = 'sent';
    }

    if ($action == 'editcategory') {
        $text = get_lang('ModifyCategory');
        $class = 'save';
    } elseif ($action == 'addreceivedcategory' or $action == 'addsentcategory') {
        $text = get_lang('CreateCategory');
        $class = 'add';
    }

    $form = new FormValidator('add_new_category', 'post', api_get_self().'?view='.Security::remove_XSS($_GET['view']));
    $form->addElement('header', $title);

    if (isset($id) AND $id != '') {
        $form->addElement('hidden', 'edit_id', intval($id));
    }
    $form->addElement('hidden', 'action', Security::remove_XSS($action));
    $form->addElement('hidden', 'target', Security::remove_XSS($target));

    $form->addElement('text', 'category_name', get_lang('CategoryName'));
    $form->addRule('category_name', get_lang('ThisFieldIsRequired'), 'required');
    $form->addElement('button', 'StoreCategory', $text);

    $defaults = array();
    $defaults['category_name'] = $category_name;
    $form->setDefaults($defaults);
    $form->display();
}

/**
* this function displays the form to upload a new item to the dropbox.
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function display_add_form($dropbox_unid, $viewReceivedCategory, $viewSentCategory, $view)
{
    $course_info = api_get_course_info();
    $_user = api_get_user_info();
    $is_courseAdmin = api_is_course_admin();
    $is_courseTutor = api_is_course_tutor();
    $origin = isset($_GET['origin']) ? $_GET['origin'] : null;

    $token = Security::get_token();
    $dropbox_person = new Dropbox_Person(api_get_user_id(), $is_courseAdmin, $is_courseTutor);

    $form = new FormValidator(
        'sent_form',
        'post',
        api_get_self().'?view_received_category='.$viewReceivedCategory.'&view_sent_category='.$viewSentCategory.'&view='.$view.'&'.api_get_cidreq(),
        null,
        array('enctype' => 'multipart/form-data', 'onsubmit' => 'javascript: return checkForm(this);')
    );

    $form->addElement('header', get_lang('UploadNewFile'));
    $form->addElement('hidden', 'MAX_FILE_SIZE', dropbox_cnf('maxFilesize'));
    $form->addElement('hidden', 'dropbox_unid', $dropbox_unid);
    $form->addElement('hidden', 'sec_token', $token);
    $form->addElement('hidden', 'origin', $origin);
    $form->addElement('file', 'file', get_lang('UploadFile'), array('onChange' => 'javascript: checkfile(this.value);'));

    if (dropbox_cnf('allowOverwrite')) {
        $form->addElement('checkbox', 'cb_overwrite',  null, get_lang('OverwriteFile'), array('id' => 'cb_overwrite'));
    }

    // List of all users in this course and all virtual courses combined with it
    if (api_get_session_id()) {
        $complete_user_list_for_dropbox = array();
        if (api_get_setting('dropbox_allow_student_to_student') == 'true' || $_user['status'] != STUDENT) {
            $complete_user_list_for_dropbox = CourseManager:: get_user_list_from_course_code(
                $course_info['code'],
                api_get_session_id(),
                null,
                null,
                0
            );
        }

        $hideCoach = api_get_setting('dropbox_hide_course_coach');

        if ($hideCoach !== 'true') {
            $complete_user_list2 = CourseManager::get_coach_list_from_course_code(
                $course_info['code'],
                api_get_session_id()
            );
            $complete_user_list_for_dropbox = array_merge(
                $complete_user_list_for_dropbox,
                $complete_user_list2
            );
        }
    } else {
        if (api_get_setting('dropbox_allow_student_to_student') == 'true' || $_user['status'] != STUDENT) {
            $complete_user_list_for_dropbox = CourseManager :: get_user_list_from_course_code($course_info['code'], api_get_session_id());
        } else {
            $complete_user_list_for_dropbox = CourseManager :: get_teacher_list_from_course_code($course_info['code'], false);
        }
    }

    if (!empty($complete_user_list_for_dropbox)) {
        foreach ($complete_user_list_for_dropbox as $k => $e) {
            $complete_user_list_for_dropbox[$k] = $e + array('lastcommafirst' => api_get_person_name($e['firstname'], $e['lastname']));
        }
        $complete_user_list_for_dropbox = TableSort::sort_table($complete_user_list_for_dropbox, 'lastcommafirst');
    }

    /*
        Create the options inside the select box:
        List all selected users their user id as value and a name string as display
    */

    $current_user_id = '';
    $options = array();
    foreach ($complete_user_list_for_dropbox as $current_user) {
        if (($dropbox_person -> isCourseTutor
                || $dropbox_person -> isCourseAdmin
                || dropbox_cnf('allowStudentToStudent')
                || $current_user['status'] != 5                         // Always allow teachers.
                || $current_user['is_tutor'] == 1                       // Always allow tutors.
                ) && $current_user['user_id'] != $_user['user_id']) {   // Don't include yourself.
            if ($current_user['user_id'] == $current_user_id) {
                continue;
            }
            $full_name = $current_user['lastcommafirst'];
            $current_user_id = $current_user['user_id'];
            $options['user_' . $current_user_id] = $full_name;
            //echo '<option value="user_' . $current_user_id . '">' . $full_name . '</option>';
        }
    }


    /*
    * Show groups
    */
    if (($dropbox_person -> isCourseTutor || $dropbox_person -> isCourseAdmin)
        && dropbox_cnf('allowGroup') || dropbox_cnf('allowStudentToStudent')) {
        $complete_group_list_for_dropbox = GroupManager::get_group_list(null, dropbox_cnf('courseId'));

        if (count($complete_group_list_for_dropbox) > 0) {
            foreach ($complete_group_list_for_dropbox as $current_group) {
                if ($current_group['number_of_members'] > 0) {
                    //echo '<option value="group_'.$current_group['id'].'">G: '.$current_group['name'].' - '.$current_group['number_of_members'].' '.get_lang('Users').'</option>';
                    $options['group_'.$current_group['id']] = 'G: '.$current_group['name'].' - '.$current_group['number_of_members'].' '.get_lang('Users');
                }
            }
        }
    }

    if (dropbox_cnf('allowJustUpload')) {
        //echo '<option value="upload">'.get_lang('JustUploadInSelect').'</option>';
        //echo '<option value="user_'.$_user['user_id'].'">'.get_lang('JustUploadInSelect').'</option>';
        $options['user_'.$_user['user_id']] = get_lang('JustUploadInSelect');
    }

    $form->addElement('select', 'recipients', get_lang('SendTo'), $options, array('multiple' => 'multiple', 'size' => '10', 'class' => 'span4'));
    $form->addElement('button', 'submitWork', get_lang('Upload'),'paper-plane','btn btn-success');
    $form->display();
}

/**
* returns username or false if user isn't registered anymore
* @todo check if this function is still necessary. There might be a library function for this.
*/
function getUserNameFromId($id)
{
    $dropbox_cnf = getDropboxConf();

    $mailingId = $id - dropbox_cnf('mailingIdBase');
    if ($mailingId > 0) {
        return get_lang('MailingAsUsername', '') . $mailingId;
    }
    $id = intval($id);
    $sql = "SELECT ".(api_is_western_name_order() ? "CONCAT(firstname,' ', lastname)" : "CONCAT(lastname,' ', firstname)")." AS name
            FROM " . $dropbox_cnf['tbl_user'] . "
            WHERE user_id='$id'";
    $result = Database::query($sql);
    $res = Database::fetch_array($result);

    if (!$res) return false;
    return stripslashes($res['name']);
}

/**
* returns loginname or false if user isn't registered anymore
* @todo check if this function is still necessary. There might be a library function for this.
*/
function getLoginFromId($id)
{
    $id = intval($id);
    $sql = "SELECT username
            FROM " . dropbox_cnf('tbl_user') . "
            WHERE user_id='$id'";
    $result = Database::query($sql);
    $res = Database::fetch_array($result);
    if (!$res) return false;
    return stripslashes($res['username']);
}

/**
* @return boolean indicating if user with user_id=$user_id is a course member
* @todo check if this function is still necessary. There might be a library function for this.
*/
function isCourseMember($user_id)
{
    $_course = api_get_course_info();
    $course_code = $_course['code'];
    $is_course_member = CourseManager::is_user_subscribed_in_course($user_id, $course_code, true);
    return $is_course_member;
}

/**
* Checks if there are files in the dropbox_file table that aren't used anymore in dropbox_person table.
* If there are, all entries concerning the file are deleted from the db + the file is deleted from the server
*/
function removeUnusedFiles()
{
    $course_id = api_get_course_int_id();

    // select all files that aren't referenced anymore
    $sql = "SELECT DISTINCT f.id, f.filename
            FROM " . dropbox_cnf('tbl_file') . " f
            LEFT JOIN " . dropbox_cnf('tbl_person') . " p
            ON (f.id = p.file_id)
            WHERE p.user_id IS NULL AND
                  f.c_id = $course_id
            ";
    $result = Database::query($sql);
    while ($res = Database::fetch_array($result)) {
        //delete the selected files from the post and file tables
        $sql = "DELETE FROM " . dropbox_cnf('tbl_post') . " WHERE c_id = $course_id AND file_id = '" . $res['id'] . "'";
        Database::query($sql);
        $sql = "DELETE FROM " . dropbox_cnf('tbl_file') . " WHERE c_id = $course_id AND id ='" . $res['id'] . "'";
        Database::query($sql);
        //delete file from server
        @unlink( dropbox_cnf('sysPath') . '/' . $res['filename']);
    }
}

/**
*
* Mailing zip-file is posted to (dest_user_id = ) mailing pseudo_id
* and is only visible to its uploader (user_id).
*
* Mailing content files have uploader_id == mailing pseudo_id, a normal recipient,
* and are visible initially to recipient and pseudo_id.
*
* @author René Haentjens, Ghent University
*
* @todo check if this function is still necessary.
*/
function getUserOwningThisMailing($mailingPseudoId, $owner = 0, $or_die = '')
{
    $course_id = api_get_course_int_id();
    $dropbox_cnf = getDropboxConf();

    $mailingPseudoId = intval($mailingPseudoId);
    $sql = "SELECT f.uploader_id
            FROM " . $dropbox_cnf['tbl_file'] . " f
            LEFT JOIN " . $dropbox_cnf['tbl_post'] . " p ON (f.id = p.file_id AND f.c_id = $course_id AND p.c_id = $course_id)
            WHERE
                p.dest_user_id = '" . $mailingPseudoId . "' AND
                p.c_id = $course_id
            ";
    $result = Database::query($sql);

    if (!($res = Database::fetch_array($result)))
        die(get_lang('GeneralError').' (code 901)');
    if ($owner == 0) return $res['uploader_id'];
    if ($res['uploader_id'] == $owner) return true;
    die(get_lang('GeneralError').' (code '.$or_die.')');
}

/**
* @author René Haentjens, Ghent University
* @todo check if this function is still necessary.
*/
function removeMoreIfMailing($file_id)
{
    $course_id = api_get_course_int_id();
    $dropbox_cnf = getDropboxConf();
    // when deleting a mailing zip-file (posted to mailingPseudoId):
    // 1. the detail window is no longer reachable, so
    //    for all content files, delete mailingPseudoId from person-table
    // 2. finding the owner (getUserOwningThisMailing) is no longer possible, so
    //    for all content files, replace mailingPseudoId by owner as uploader
    $file_id = intval($file_id);
    $sql = "SELECT p.dest_user_id
            FROM " . $dropbox_cnf['tbl_post'] . " p
            WHERE c_id = $course_id AND p.file_id = '" . $file_id . "'";
    $result = Database::query($sql);

    if ($res = Database::fetch_array($result)) {
        $mailingPseudoId = $res['dest_user_id'];
        if ($mailingPseudoId > dropbox_cnf('mailingIdBase')) {
            $sql = "DELETE FROM " . dropbox_cnf('tbl_person') . " WHERE c_id = $course_id AND user_id='" . $mailingPseudoId . "'";
            Database::query($sql);

            $sql = "UPDATE " . dropbox_cnf('tbl_file') .
                " SET uploader_id='" . api_get_user_id() . "' WHERE c_id = $course_id AND uploader_id='" . $mailingPseudoId . "'";
            Database::query($sql);
        }
    }
}


/**
* Function that finds a given config setting
*
* @author René Haentjens, Ghent University
*/
function dropbox_cnf($variable)
{
    $dropbox_cnf = getDropboxConf();
    return $dropbox_cnf[$variable];
}

/**
 * @return array|null|string
 */
function store_add_dropbox()
{
    $_course = api_get_course_info();
    $_user = api_get_user_info();
    $dropbox_cnf = getDropboxConf();

    // Validating the form data

    // there are no recipients selected
    if (!isset($_POST['recipients']) || count( $_POST['recipients']) <= 0) {
        return get_lang('YouMustSelectAtLeastOneDestinee');
    } else {
        // Check if all the recipients are valid
        $thisIsAMailing = false;
        $thisIsJustUpload = false;
        foreach ($_POST['recipients'] as $rec) {
            if ($rec == 'mailing') {
                $thisIsAMailing = true;
            } elseif ($rec == 'upload') {
                $thisIsJustUpload = true;
            } elseif (strpos($rec, 'user_') === 0 && !isCourseMember(substr($rec, strlen('user_')))) {
                return get_lang('InvalideUserDetected');
            } elseif (strpos($rec, 'group_') !== 0 && strpos($rec, 'user_') !== 0) {
                return get_lang('InvalideGroupDetected');
            }
        }
    }

    // we are doing a mailing but an additional recipient is selected
    if ($thisIsAMailing && (count($_POST['recipients']) != 1)) {
        return get_lang('MailingSelectNoOther');
    }

    // we are doing a just upload but an additional recipient is selected.
    // note: why can't this be valid? It is like sending a document to yourself AND to a different person (I do this quite often with my e-mails)
    if ($thisIsJustUpload && (count($_POST['recipients']) != 1)) {
        return get_lang('MailingJustUploadSelectNoOther');
    }

    if (empty($_FILES['file']['name'])) {
        $error = true;
        return get_lang('NoFileSpecified');
    }

    // are we overwriting a previous file or sending a new one

    $dropbox_overwrite = false;
    if (isset($_POST['cb_overwrite']) && $_POST['cb_overwrite']) {
        $dropbox_overwrite = true;
    }

    // doing the upload

    $dropbox_filename = $_FILES['file']['name'];
    $dropbox_filesize = $_FILES['file']['size'];
    $dropbox_filetype = $_FILES['file']['type'];
    $dropbox_filetmpname = $_FILES['file']['tmp_name'];

    // check if the filesize does not exceed the allowed size.
    if ($dropbox_filesize <= 0 || $dropbox_filesize > $dropbox_cnf['maxFilesize']) {
        return get_lang('DropboxFileTooBig'); // TODO: The "too big" message does not fit in the case of uploading zero-sized file.
    }

    // check if the file is actually uploaded
    if (!is_uploaded_file($dropbox_filetmpname)) { // check user fraud : no clean error msg.
        return get_lang('TheFileIsNotUploaded');
    }

    $upload_ok = process_uploaded_file($_FILES['file'], true);

    if (!$upload_ok) {
        return null;
    }

    // Try to add an extension to the file if it hasn't got one
    $dropbox_filename = add_ext_on_mime($dropbox_filename, $dropbox_filetype);
    // Replace dangerous characters
    $dropbox_filename = api_replace_dangerous_char($dropbox_filename);
    // Transform any .php file in .phps fo security
    $dropbox_filename = php2phps($dropbox_filename);

    //filter extension
    if (!filter_extension($dropbox_filename)) {
        return get_lang('UplUnableToSaveFileFilteredExtension');
    }

    // set title
    $dropbox_title = $dropbox_filename;
    // set author
    if (!isset($_POST['authors'])) {
        $_POST['authors'] = getUserNameFromId($_user['user_id']);
    }

    // note: I think we could better migrate everything from here on to separate functions: store_new_dropbox, store_new_mailing, store_just_upload

    if ($dropbox_overwrite) {
        $dropbox_person = new Dropbox_Person($_user['user_id'], api_is_course_admin(), api_is_course_tutor());

        foreach ($dropbox_person->sentWork as $w) {
            if ($w->title == $dropbox_filename) {
                if (($w->recipients[0]['id'] > dropbox_cnf('mailingIdBase')) xor $thisIsAMailing) {
                    return get_lang('MailingNonMailingError');
                }
                if (($w->recipients[0]['id'] == $_user['user_id']) xor $thisIsJustUpload) {
                    return get_lang('MailingJustUploadSelectNoOther');
                }
                $dropbox_filename = $w->filename;
                $found = true; // note: do we still need this?
                break;
            }
        }
    } else {  // rename file to login_filename_uniqueId format
        $dropbox_filename = getLoginFromId($_user['user_id']) . "_" . $dropbox_filename . "_".uniqid('');
    }

    // creating the array that contains all the users who will receive the file
    $new_work_recipients = array();
    foreach ($_POST['recipients'] as $rec) {
        if (strpos($rec, 'user_') === 0) {
            $new_work_recipients[] = substr($rec, strlen('user_') );
        } elseif (strpos($rec, 'group_') === 0) {
            $userList = GroupManager::get_subscribed_users(substr($rec, strlen('group_')));
            foreach ($userList as $usr) {
                if (!in_array($usr['user_id'], $new_work_recipients) && $usr['user_id'] != $_user['user_id']) {
                    $new_work_recipients[] = $usr['user_id'];
                }
            }
        }
    }

    @move_uploaded_file($dropbox_filetmpname, dropbox_cnf('sysPath') . '/' . $dropbox_filename);

    $b_send_mail = api_get_course_setting('email_alert_on_new_doc_dropbox');

    if ($b_send_mail) {
        foreach ($new_work_recipients as $recipient_id) {
            $recipent_temp = api_get_user_info($recipient_id);
            $additionalParameters = array(
                'smsType' => SmsPlugin::NEW_FILE_SHARED_COURSE_BY,
                'userId' => $recipient_id,
                'courseTitle' => $_course['title'],
                'userUsername' => $recipent_temp['username']
            );
            api_mail_html(
                api_get_person_name(
                    $recipent_temp['firstname'].' '.$recipent_temp['lastname'],
                    null,
                    PERSON_NAME_EMAIL_ADDRESS
                ),
                $recipent_temp['email'],
                get_lang('NewDropboxFileUploaded'),
                get_lang('NewDropboxFileUploadedContent').' '.api_get_path(WEB_CODE_PATH).
                'dropbox/index.php?cidReq='.$_course['sysCode']."\n\n".
                api_get_person_name(
                    $_user['firstName'],
                    $_user['lastName'],
                    null,
                    PERSON_NAME_EMAIL_ADDRESS
                )."\n".  get_lang('Email') ." : ".$_user['mail'],
                api_get_person_name(
                    $_user['firstName'],
                    $_user['lastName'],
                    null,
                    PERSON_NAME_EMAIL_ADDRESS
                ),
                $_user['mail'],
                null,
                null,
                null,
                $additionalParameters
            );
        }
    }

    new Dropbox_SentWork($_user['user_id'], $dropbox_title, $_POST['description'], strip_tags($_POST['authors']), $dropbox_filename, $dropbox_filesize, $new_work_recipients);

    Security::clear_token();
    return get_lang('FileUploadSucces');
}

/**
* this function transforms the array containing all the feedback into something visually attractive.
*
* @param an array containing all the feedback about the given message.
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function feedback($array) {
    $output = null;
    foreach ($array as $value) {
        $output .= format_feedback($value);
    }
    $output .= feedback_form();
    return $output;
}

/**
* This function returns the html code to display the feedback messages on a given dropbox file
* @param $feedback_array an array that contains all the feedback messages about the given document.
* @return html code
* @todo add the form for adding new comment (if the other party has not deleted it yet).
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function format_feedback($feedback)
{
    $userInfo = api_get_user_info($feedback['author_user_id']);
    $output = UserManager::getUserProfileLink($userInfo);
    $output .= '&nbsp;&nbsp;'.api_convert_and_format_date($feedback['feedback_date'], DATE_TIME_FORMAT_LONG).'<br />';
    $output .= '<div style="padding-top:6px">'.nl2br($feedback['feedback']).'</div><hr size="1" noshade/><br />';
    return $output;
}

/**
* this function returns the code for the form for adding a new feedback message to a dropbox file.
* @return html code
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function feedback_form()
{
    $return = get_lang('AddNewFeedback').'<br />';
    $number_users_who_see_file = check_if_file_exist($_GET['id']);
    if ($number_users_who_see_file) {
        $token = Security::get_token();
        $return .= '<textarea name="feedback" style="width: 80%; height: 80px;"></textarea>';
        $return .= '<input type="hidden" name="sec_token" value="'.$token.'"/>';
        $return .= '<br /><button type="submit" class="add" name="store_feedback" value="'.get_lang('Ok').'"
                    onclick="javascript: document.form_dropbox.attributes.action.value = document.location;">'.get_lang('AddComment').'</button>';
    } else {
        $return .= get_lang('AllUsersHaveDeletedTheFileAndWillNotSeeFeedback');
    }
    return $return;
}

function user_can_download_file($id, $user_id) {
    $dropbox_cnf = getDropboxConf();
    $course_id = api_get_course_int_id();
    $id = intval($id);
    $user_id = intval($user_id);

    $sql = "SELECT file_id FROM ".$dropbox_cnf['tbl_person']." WHERE c_id = $course_id AND user_id = $user_id AND file_id = ".$id;
    $result = Database::query($sql);
    $number_users_who_see_file = Database::num_rows($result);

    $sql = "SELECT file_id FROM ".$dropbox_cnf["tbl_post"]."  WHERE c_id = $course_id AND dest_user_id = $user_id AND file_id = ".$id;
    $result = Database::query($sql);
    $count = Database::num_rows($result);
    return $number_users_who_see_file > 0 || $count > 0;
}

// we now check if the other users have not delete this document yet. If this is the case then it is useless to see the
// add feedback since the other users will never get to see the feedback.
function check_if_file_exist($id) {
    $dropbox_cnf = getDropboxConf();
    $id = intval($id);
    $course_id = api_get_course_int_id();
    $sql = "SELECT file_id FROM ".$dropbox_cnf['tbl_person']." WHERE c_id = $course_id AND file_id = ".$id;
    $result = Database::query($sql);
    $number_users_who_see_file = Database::num_rows($result);

    $sql = "SELECT file_id FROM ".$dropbox_cnf["tbl_post"]."  WHERE c_id = $course_id AND file_id = ".$id;
    $result = Database::query($sql);
    $count = Database::num_rows($result);
    return $number_users_who_see_file > 0 || $count > 0;
}



/**
* @return a language string (depending on the success or failure.
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function store_feedback()
{
    $dropbox_cnf = getDropboxConf();
    if (!is_numeric($_GET['id'])) {
        return get_lang('FeedbackError');
    }
    $course_id = api_get_course_int_id();
    if (empty($_POST['feedback'])) {
        return get_lang('PleaseTypeText');
    } else {
        $sql="INSERT INTO ".$dropbox_cnf['tbl_feedback']." (c_id, file_id, author_user_id, feedback, feedback_date) VALUES
              ($course_id, '".intval($_GET['id'])."','".api_get_user_id()."','".Database::escape_string($_POST['feedback'])."', '".api_get_utc_datetime()."')";
        Database::query($sql);
        return get_lang('DropboxFeedbackStored');
    }
}

/**
* This function downloads all the files of the input array into one zip
* @param array $fileList containing all the ids of the files that have to be downloaded.
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @todo consider removing the check if the user has received or sent this file (zip download of a folder already sufficiently checks for this).
* @todo integrate some cleanup function that removes zip files that are older than 2 days
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @author Julio Montoya  Addin c_id support
* @version march 2006
*/
function zip_download($fileList)
{
    $_course = api_get_course_info();
    $dropbox_cnf = getDropboxConf();
    $course_id = api_get_course_int_id();
    $fileList = array_map('intval', $fileList);

    // note: we also have to add the check if the user has received or sent this file.
    $sql = "SELECT DISTINCT file.filename, file.title, file.author, file.description
            FROM ".$dropbox_cnf['tbl_file']." file
            INNER JOIN ".$dropbox_cnf['tbl_person']." person
            ON (person.file_id=file.id AND file.c_id = $course_id AND person.c_id = $course_id)
            INNER JOIN ".$dropbox_cnf['tbl_post']." post
            ON (post.file_id = file.id AND post.c_id = $course_id AND file.c_id = $course_id)
            WHERE
                file.id IN (".implode(', ', $fileList).") AND
                file.id = person.file_id AND
                (
                    person.user_id = '".api_get_user_id()."' OR
                    post.dest_user_id = '".api_get_user_id()."'
                ) ";
    $result = Database::query($sql);

    $files = array();
    while ($row = Database::fetch_array($result)) {
        $files[$row['filename']] = array(
            'filename' => $row['filename'],
            'title' => $row['title'],
            'author' => $row['author'],
            'description' => $row['description']
        );
    }

    // Step 3: create the zip file and add all the files to it
    $temp_zip_file = api_get_path(SYS_ARCHIVE_PATH).api_get_unique_id().".zip";
    Session::write('dropbox_files_to_download', $files);
    $zip = new PclZip($temp_zip_file);
    foreach ($files as $value) {
        $zip->add(
            api_get_path(SYS_COURSE_PATH).$_course['path'].'/dropbox/'.$value['filename'],
            PCLZIP_OPT_REMOVE_ALL_PATH,
            PCLZIP_CB_PRE_ADD,
            'my_pre_add_callback'
        );
    }
    Session::erase('dropbox_files_to_download');
    $name = 'dropbox-'.api_get_utc_datetime().'.zip';
    DocumentManager::file_send_for_download($temp_zip_file, true, $name);
    @unlink($temp_zip_file);
    exit;
}

/**
* This is a callback function to decrypt the files in the zip file to their normal filename (as stored in the database)
* @param array $p_event a variable of PCLZip
* @param array $p_header a variable of PCLZip
*
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function my_pre_add_callback($p_event, &$p_header)
{
    $files = Session::read('dropbox_files_to_download');
    $p_header['stored_filename'] = $files[$p_header['stored_filename']]['title'];
    return 1;
}

/**
 * @desc Generates the contents of a html file that gives an overview of all the files in the zip file.
 *       This is to know the information of the files that are inside the zip file (who send it, the comment, ...)
 * @author Patrick Cool <patrick.cool@UGent.be>, Ghent University, March 2006
 * @author Ivan Tcholakov, 2010, code for html metadata has been added.
 */
function generate_html_overview($files, $dont_show_columns = array(), $make_link = array())
{
    $return = '<!DOCTYPE html'."\n";
    $return .= "\t".'PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"'."\n";
    $return .= "\t".'"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">'."\n";
    $return .= '<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="'.api_get_language_isocode().'" lang="'.api_get_language_isocode().'">'."\n";

    $return .= "<head>\n\t<title>".get_lang('OverviewOfFilesInThisZip')."</title>\n";
    $return .= "\t".'<meta http-equiv="Content-Type" content="text/html; charset='.api_get_system_encoding().'" />'."\n";
    $return .= "</head>\n\n";
    $return .= '<body dir="'.api_get_text_direction().'">'."\n\n";
    $return .= "<table border=\"1px\">\n";

    $counter = 0;
    foreach ($files as $value) {

        // Adding the header.
        if ($counter == 0) {
            $columns_array = array_keys($value);
            $return .= "\n<tr>";
            foreach ($columns_array as $columns_array_key => $columns_array_value) {
                if (!in_array($columns_array_value, $dont_show_columns)) {
                    $return .= "\n\t<th>".$columns_array_value."</th>";
                }
                $column[] = $columns_array_value;
            }
            $return .= "\n</tr>\n";
        }
        $counter++;

        // Adding the content.
        $return .= "\n<tr>";
        foreach ($column as $column_key => $column_value) {
            if (!in_array($column_value,$dont_show_columns)) {
                $return .= "\n\t<td>";
                if (in_array($column_value, $make_link)) {
                    $return .= '<a href="'.$value[$column_value].'">'.$value[$column_value].'</a>';
                } else {
                    $return .= $value[$column_value];
                }
                $return .= "</td>";
            }
        }
        $return .= "\n</tr>\n";
    }
    $return .= "\n</table>\n\n</body>";
    $return .= "\n</html>";

    return $return;
}

/**
* @desc This function retrieves the number of feedback messages on every document. This function might become obsolete when
*       the feedback becomes user individual.
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function get_total_number_feedback($file_id = '') {
    $dropbox_cnf = getDropboxConf();
    $course_id = api_get_course_int_id();
    $sql = "SELECT COUNT(feedback_id) AS total, file_id FROM ".$dropbox_cnf['tbl_feedback']."
            WHERE c_id = $course_id GROUP BY file_id";
    $result = Database::query($sql);
    $return = array();
    while ($row=Database::fetch_array($result)) {
        $return[$row['file_id']] = $row['total'];
    }
    return $return;
}


/**
* @desc this function checks if the key exists. If this is the case it returns the value, if not it returns 0
* @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
* @version march 2006
*/
function check_number_feedback($key, $array) {
    if (is_array($array)) {
        if (array_key_exists($key, $array)) {
            return $array[$key];
        } else {
            return 0;
        }
    } else {
        return 0;
    }
}

/**
 * Get the last access to a given tool of a given user
 * @param $tool string the tool constant
 * @param $courseId the course_id
 * @param $user_id the id of the user
 * @return string last tool access date
 *
 * @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
 * @version march 2006
 *
 * @todo consider moving this function to a more appropriate place.
 */
function get_last_tool_access($tool, $courseId = null, $user_id = null)
{
    // The default values of the parameters
    if (empty($courseId)) {
        $courseId = api_get_course_int_id();
    }
    if (empty($user_id)) {
        $user_id = api_get_user_id();
    }

    // the table where the last tool access is stored (=track_e_lastaccess)
    $table_last_access = Database::get_main_table('track_e_lastaccess');

    $sql = "SELECT access_date FROM $table_last_access
            WHERE
                access_user_id = ".intval($user_id)." AND
                c_id='".intval($courseId)."' AND
                access_tool='".Database::escape_string($tool)."'
                ORDER BY access_date DESC
                LIMIT 1";
    $result = Database::query($sql);
    $row = Database::fetch_array($result);
    return $row['access_date'];
}
