// Cross Browser selectionStart/selectionEnd
// Version 0.2
// Copyright (c) 2005-2007 KOSEKI Kengo
// 
// This script is distributed under the MIT licence.
// http://www.opensource.org/licenses/mit-license.php

function Selection(textareaElement) {
    this.element = textareaElement;
}

Selection.prototype.create = function() {
    if (document.selection != null && this.element.selectionStart == null) {
        return this._ieGetSelection();
    } else {
        return this._mozillaGetSelection();
    }
}

Selection.prototype._mozillaGetSelection = function() {
    return { 
        start: this.element.selectionStart, 
        end: this.element.selectionEnd 
    };
}

Selection.prototype._ieGetSelection = function() {
    this.element.focus();

    var range = document.selection.createRange();
    var bookmark = range.getBookmark();

    var contents = this.element.value;
    var originalContents = contents;
    var marker = this._createSelectionMarker();
    while(contents.indexOf(marker) != -1) {
        marker = this._createSelectionMarker();
    }

    var parent = range.parentElement();
    if (parent == null || parent.type != "textarea") {
        return { start: 0, end: 0 };
    }
    range.text = marker + range.text + marker;
    contents = this.element.value;

    var result = {};
    result.start = contents.indexOf(marker);
    contents = contents.replace(marker, "");
    result.end = contents.indexOf(marker);

    this.element.value = originalContents;
    range.moveToBookmark(bookmark);
    range.select();

    return result;
}

Selection.prototype._createSelectionMarker = function() {
    return "##SELECTION_MARKER_" + Math.random() + "##";
}