/* vim: set expandtab sw=4 ts=4 sts=4: */
/**
 * @fileoverview    Implements the shiftkey + click remove column 
 *                  from order by clause funcationality
 * @name            columndelete
 *
 * @requires    jQuery
 */
 
function captureURL(url)
{
    var URL = {};
    url = '' + url;
    // Exclude the url part till HTTP
    url = url.substr(url.search("sql.php"), url.length);
    // The url part between ORDER BY and &session_max_rows needs to be replaced.
    URL['head'] = url.substr(0, url.indexOf('ORDER+BY') + 9);
    URL['tail'] = url.substr(url.indexOf("&session_max_rows"), url.length); 
    return URL;       
} 

/**
 * This function is for navigating to the generated URL
 *
 * @param object   target HTMLAnchor element 
 * @param object   parent HTMLDom Object
 */

function redirect(target, parent)
{     
    var URL = captureURL(target);
    var begin = target.indexOf('ORDER+BY') + 8;
    var end = target.indexOf('&session_max_rows');
    // get the names of the columns involved
    var between_part = target.substr(begin, end-begin);
    var columns = between_part.split('%2C+'); 
    // If the given column is not part of the order clause exit from this function
    var index = parent.find('small').length ? parent.find('small').text() : ''; 
    if (index == ''){
        return;
    }
    // Remove the current clicked column
    columns.splice(index-1, 1); 
    // If all the columns have been removed dont submit a query with nothing
    // After order by clause.
    if (columns.length == 0){ 
        var head = URL['head'];
        head = head.slice(0,head.indexOf('ORDER+BY')); 
        URL['head'] = head;
        // removing the last sort order should have priority over what 
        // is remembered via the RememberSorting directive
        URL['tail'] += '&discard_remembered_sort=1';
    }
    var middle_part = columns.join('%2C+');  
    url = URL['head'] + middle_part + URL['tail'];  
    window.location.replace(url);
}


AJAX.registerOnload('keyhandler.js', function () { 
    $("th.draggable.column_heading.pointer.marker  a").live('click', function (event) { 
        if (event.shiftKey) {
            event.preventDefault();
            redirect($(this).attr("href"), $(this).parent()); 
        }
    });  
});

AJAX.registerTeardown('keyhandler.js', function () {
    $("th.draggable.column_heading.pointer.marker a").die('click');
});