TableSortHeading

/**
 * Table Sort Heading
 * 
 * @param list $columns - list of maps/str to generate headings
 * @param uri $uri - base uri (default: page.uri)
 * @param map $params - query params to preserve
 * @param str $default - default field to sort by
 * @param bool $enabled - allow sorting (default: true)
 */
var uri = $uri ?? page.uri;
var params = $params ?? {};
var columns = $columns ?? [];
var sortEnabled = $enabled ?? true;
var sortKey = $key ?? "sortby";
var sortField = $current ?? __request.args[sortKey] ?? $default ?? "";

// determine the current sorting information
var sortDesc = string.startswith(sortField, "-");
if (sortDesc) {
    let sortField = string.substr(sortField, 1);
}

// generate column widths
<colgroup>
foreach (var column in columns) {
    <col class=("col-" .. __count .. " " .. column.class) width=(column.width ?? "") />
}
</colgroup>

<thead>
    <tr>
        foreach (var column in columns) {
            var headingClass = column.class;
            // auto-classing
            let headingClass ..= " sortable col-" .. __count;
            let headingClass ..= (sortEnabled ? "" : " ui-state-disabled");
            <th class=(headingClass) title=(column.label)>
                var sortClass = column.sortclass;
                if (sortEnabled && column.field) {

                    // sortable column
                    var text = column.label;
                    var columnSortField = column.field;
                    var columnSortType = string.startswith(columnSortField, "-") ? "-" : "";
                    if (columnSortType == "-") {
                        let columnSortField = substr(columnSortField, 1);
                    }

                    // check if we are sorting by this column
                    if (columnSortField == sortField) {
                        let columnSortType = sortDesc ? "" : "-";
                        let sortClass ..= sortDesc ? " sort-desc" : " sort-asc";
                    }

                    // generate the sort heading
                    var columnParams = params .. {(sortKey): (columnSortType .. columnSortField)};
                    <a class=(sortClass) href=(uri & columnParams)>text;</a>
                } else {
                    if (!column.field) {
                        let sortClass ..= " nosort"; 
                    }
                    <span class=(sortClass)><span>column.label</span></span>;
                }
            </th>
        }
    </tr>
</thead>