const MAX_HISTORY_MENU_ITEMS = 15;

function FillHistoryMenu( aParent, aMenu )
  {
    var shistory;
    // Get the content area docshell
    var docShell = null;
    var result = appCore.getContentDocShell(docShell);            
    if (docShell)
      {
        //Get the session history component from docshell
        docShell = docShell.QueryInterface(Components.interfaces.nsIWebNavigation);
        if (docShell)
          {
            shistory = docShell.sessionHistory;
            if (shistory)
              {
                //Remove old entries if any
                deleteHistoryItems( aParent );
                var count = shistory.count;
                var index = shistory.index;
                switch (aMenu)
                  {
                    case "back":
                      var end = (index > MAX_HISTORY_MENU_ITEMS) ? index - MAX_HISTORY_MENU_ITEMS : 0;
                      for ( var j = index - 1; j >= end; j--) 
                        {
                          var entry = shistory.getEntryAtIndex(j, false);
                          if (entry) 
                            createMenuItem( aParent, j, entry.getTitle() );
                        }
                      break;
                    case "forward":
                      var end  = ((count-index) > MAX_HISTORY_MENU_ITEMS) ? index + MAX_HISTORY_MENU_ITEMS : count;
                      for ( var j = index + 1; j < end; j++)
                        {
                          var entry = shistory.getEntryAtIndex(j, false);
                          if (entry)
                            createMenuItem( aParent, j, entry.getTitle() );
                        }
                      break;
                    case "go":
                      var end = count > MAX_HISTORY_MENU_ITEMS 
                                  ? count - MAX_HISTORY_MENU_ITEMS 
                                  : 0;
                      for( var j = count - 1; j >= end; j-- )
                        {
                          var entry = shistory.getEntryAtIndex(j, false);
                          if (entry)
                            createMenuItem( aParent, j, entry.getTitle() );
                        }
                      break;
                  }
              }
          }
      }
  }
 
function executeUrlBarHistoryCommand( aEvent ) 
  {
    var index = aEvent.target.getAttribute("index");
    var value = aEvent.target.value;
    if (index && value) 
      {
        gURLBar.value = value;
        BrowserLoadURL();
      }
  } 
 
function createUBHistoryMenu( aEvent )
  {
    var ubHistory = appCore.urlbarHistory;
    if (ubHistory)
      {
        var len = ubHistory.count;
        var end = (len > MAX_HISTORY_MENU_ITEMS) ? (len - MAX_HISTORY_MENU_ITEMS) : 0;
        if (len > 0)
          deleteHistoryItems( aEvent ); // Delete old History Menus
        for (var i = len - 1; i >= end; i--)
          createMenuItem( aEvent.target, i, ubHistory.getEntryAtIndex(i));
      }
  }

function addToUrlbarHistory()
  {
    var ubHistory = appCore.urlbarHistory;
    if (ubHistory) 
      {
        ubHistory.addEntry( gURLBar.value );
        ubHistory.printHistory()
      }
  }
  
function createMenuItem( aParent, aIndex, aValue)
  {
    var menuitem = document.createElement( "menuitem" );
    menuitem.setAttribute( "value", aValue );
    menuitem.setAttribute( "index", aIndex );
    aParent.appendChild( menuitem );
  }

function deleteHistoryItems( aEvent )
  {
    var children = aEvent.target.childNodes;
    for (var i = 0; i < children.length; i++ )
      {
        var index = children[i].getAttribute( "index" );
        if (index)
          aEvent.target.removeChild( children[i] );
      }
  }

function updateGoMenu(event)
  {
    appCore.updateGoMenu(event.target);
  }