var DIF_dragging = false;
var DIF_iframeBeingDragged = "";
var DIF_iframeObjects = {};
var DIF_iframeWindows = {};
var DIF_iframeMouseDownLeft = {};
var DIF_iframeMouseDownTop = {};
var DIF_pageMouseDownLeft = {};
var DIF_pageMouseDownTop = {};
var DIF_handles = {};
var DIF_highestZIndex = 99;
var DIF_raiseSelectedIframe = false;
var DIF_allowDragOffScreen = false;

// Set to true to always raise the dragged iframe to top zIndex
function bringSelectedIframeToTop(val)
{
    DIF_raiseSelectedIframe = val;
}

// Set to try to allow iframes to be dragged off the top/left of the document
function allowDragOffScreen(val)
{
    DIF_allowDragOffScreen = val;
}

// Method to be used by iframe content document to specify what object can be draggable in the window
function addHandle(o, win)
{
    if (arguments.length == 2 && win == window)
    {
        // JS is included in the iframe who has a handle, search up the chain to find a parent window that this one is dragged in
        var p = win;
        while (p = p.parent)
        {
            if (p.addHandle)
            {
                p.addHandle(o, win, true);
                return ;
            }
            if (p == win.top)
            {
                return ;
            } // Already reached the top, stop looking
        }
        return ;
        // If it reaches here, there is no parent with the addHandle function defined, so this frame can't be dragged!
    }
    var topRef = win;
    var topRefStr = "window";
    while (topRef.parent && topRef.parent != window)
    {
        topRef = topRef.parent;
        topRefStr = topRefStr + ".parent";
    }
    // Add handlers to child window
    if (typeof(win.DIF_mainHandlersAdded) == "undefined" || !win.DIF_mainHandlersAdded)
    {
        // This is done in a funky way to make Netscape happy
        with(win)
        {
            eval("function OnMouseDownHandler(evt) { if(typeof(evt)=='undefined'){evt=event;}" + topRefStr + ".parent.DIF_begindrag(evt, " + topRefStr + ") }");
            eval("document.onmousedown = OnMouseDownHandler;");
            eval("function OnMouseUpHandler(evt) { if(typeof(evt)=='undefined'){evt=event;}" + topRefStr + ".parent.DIF_enddrag(evt, " + topRefStr + ") }");
            eval("document.onmouseup = OnMouseUpHandler;");
            eval("function OnMouseMoveHandler(evt) { if(typeof(evt)=='undefined'){evt=event;}" + topRefStr + ".parent.DIF_iframemove(evt, " + topRefStr + ") }");
            eval("document.onmousemove = OnMouseMoveHandler;");
            win.DIF_handlersAdded = true;
            win.DIF_mainHandlersAdded = true;
        }
    }
    // Add handler to this window
    if (typeof(window.DIF_handlersAdded) != "undefined" || !window.DIF_handlersAdded)
    {
        eval("function OnMouseMoveHandler(evt) { if(typeof(evt)=='undefined'){evt=event;}DIF_mouseMove(evt, window) }");
        eval("document.onmousemove = OnMouseMoveHandler;");
        window.DIF_handlersAdded = true;
    }
    o.style.cursor = "";
    var name = DIF_getIframeId(topRef);
    if (DIF_handles[name] == null)
    {
        // Initialize relative positions for mouse down events
        DIF_handles[name] = new Array();
        DIF_iframeMouseDownLeft[name] = 0;
        DIF_iframeMouseDownTop[name] = 0;
        DIF_pageMouseDownLeft[name] = 0;
        DIF_pageMouseDownTop[name] = 0;
    }
    DIF_handles[name][DIF_handles[name].length] = o;
}

// Generalized function to get position of an event (like mousedown, mousemove, etc)
function DIF_getEventPosition(evt)
{
    var pos = {};
    pos.x = 0;
    pos.y = 0;
    if (!evt)
    {
        evt = window.event;
    }
    if (typeof(evt.pageX) == 'number')
    {
        pos.x = evt.pageX;
        pos.y = evt.pageY;
    }
    else
    {
        pos.x = evt.clientX;
        pos.y = evt.clientY;
        if (!top.opera)
        {
            if ((!window.document.compatMode) || (window.document.compatMode == 'BackCompat'))
            {
                pos.x += window.document.body.scrollLeft;
                pos.y += window.document.body.scrollTop;
            }
            else
            {
                pos.x += window.document.documentElement.scrollLeft;
                pos.y += window.document.documentElement.scrollTop;
            }
        }
    }
    return pos;
}

// Gets the ID of a frame given a reference to a window object.
// Also stores a reference to the IFRAME object and it's window object
function DIF_getIframeId(win)
{
    // Loop through the window's IFRAME objects looking for a matching window object
    var iframes = document.getElementsByTagName("IFRAME");
    for (var i = 0; i < iframes.length; i++)
    {
        var o = iframes.item(i);
        var w = null;
        if (o.contentWindow)
        {
            // For IE5.5 and IE6
            w = o.contentWindow;
        }
        else if (window.frames && window.frames[o.id].window)
        {
            w = window.frames[o.id];
        }
        if (w == win)
        {
            DIF_iframeWindows[o.id] = win;
            DIF_iframeObjects[o.id] = o;
            return o.id;
        }
    }
    return null;
}

// Gets the page x, y coordinates of the iframe (or any object)
function DIF_getObjectXY(o)
{
    var res = {};
    res.x = 0;
    res.y = 0;
    if (o != null)
    {
        res.x = o.style.left.substring(0, o.style.left.indexOf("px"));
        res.y = o.style.top.substring(0, o.style.top.indexOf("px"));
    }
    return res;
}

// Function to get the src element clicked for non-IE browsers
function getSrcElement(e)
{
    var tgt = e.target;
    while (tgt.nodeType != 1)
    {
        tgt = tgt.parentNode;
    }
    return tgt;
}

// Check if object clicked is a 'handle' - walk up the node tree if required
function isHandleClicked(handle, objectClicked)
{
    if (handle == objectClicked)
    {
        return true;
    }
    while (objectClicked.parentNode != null)
    {
        if (objectClicked == handle)
        {
            return true;
        }
        objectClicked = objectClicked.parentNode;
    }
    return false;
}

// Called when user clicks an iframe that has a handle in it to begin dragging
function DIF_begindrag(e, win)
{
    // Get the IFRAME ID that was clicked on
    var iframename = DIF_getIframeId(win);
    if (iframename == null)
    {
        return ;
    }
    // Make sure that this IFRAME has a handle and that the handle was clicked
    if (DIF_handles[iframename] == null || DIF_handles[iframename].length < 1)
    {
        return ;
    }
    var isHandle = false;
    var t = e.srcElement || getSrcElement(e);
    for (var i = 0; i < DIF_handles[iframename].length; i++)
    {
        if (isHandleClicked(DIF_handles[iframename][i], t))
        {
            isHandle = true;
            break;
        }
    }
    if (!isHandle)
    {
        return false;
    }
    DIF_iframeBeingDragged = iframename;
    if (DIF_raiseSelectedIframe)
    {
        DIF_iframeObjects[DIF_iframeBeingDragged].style.zIndex = DIF_highestZIndex++;
    }
    DIF_dragging = true;
    var pos = DIF_getEventPosition(e);
    DIF_iframeMouseDownLeft[DIF_iframeBeingDragged] = pos.x;
    DIF_iframeMouseDownTop[DIF_iframeBeingDragged] = pos.y;
    var o = DIF_getObjectXY(DIF_iframeObjects[DIF_iframeBeingDragged]);
    DIF_pageMouseDownLeft[DIF_iframeBeingDragged] = o.x - 0+pos.x;
    DIF_pageMouseDownTop[DIF_iframeBeingDragged] = o.y - 0+pos.y;
}

// Called when mouse button is released after dragging an iframe
function DIF_enddrag(e)
{
    DIF_dragging = false;
    DIF_iframeBeingDragged = "";
}

// Called when mouse moves in the main window
function DIF_mouseMove(e)
{
    if (DIF_dragging)
    {
        var pos = DIF_getEventPosition(e);
        DIF_drag(pos.x - DIF_pageMouseDownLeft[DIF_iframeBeingDragged], pos.y - DIF_pageMouseDownTop[DIF_iframeBeingDragged]);
    }
}

// Called when mouse moves in the IFRAME window
function DIF_iframemove(e)
{
    if (DIF_dragging)
    {
        var pos = DIF_getEventPosition(e);
        DIF_drag(pos.x - DIF_iframeMouseDownLeft[DIF_iframeBeingDragged], pos.y - DIF_iframeMouseDownTop[DIF_iframeBeingDragged]);
    }
}

// Function which actually moves of the iframe object on the screen
function DIF_drag(x, y)
{
    var o = DIF_getObjectXY(DIF_iframeObjects[DIF_iframeBeingDragged]);
    // Don't drag it off the top or left of the screen?
    var newPositionX = o.x - 0+x;
    var newPositionY = o.y - 0+y;
    if (!DIF_allowDragOffScreen)
    {
        if (newPositionX < 0)
        {
            newPositionX = 0;
        }
        if (newPositionY < 0)
        {
            newPositionY = 0;
        }
    }
    DIF_iframeObjects[DIF_iframeBeingDragged].style.left = newPositionX + "px";
    DIF_iframeObjects[DIF_iframeBeingDragged].style.top = newPositionY + "px";
    DIF_pageMouseDownLeft[DIF_iframeBeingDragged] += x;
    DIF_pageMouseDownTop[DIF_iframeBeingDragged] += y;
}