xenadmin/XenAdmin/Core/History.cs

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using System.Drawing;
using System.Windows.Forms;
using XenAdmin.XenSearch;
using XenAPI;
using XenCenterLib;

namespace XenAdmin.Core
{
    class History
    {
        private static readonly LimitedStack<HistoryItem> backwardHistory = new LimitedStack<HistoryItem>(15);
        private static readonly LimitedStack<HistoryItem> forwardHistory = new LimitedStack<HistoryItem>(15);
        private static HistoryItem currentHistoryItem;
        private static bool InHistoryNavigation;

        /// <summary>
        /// Use this when modifying a search
        /// </summary>
        public static void ReplaceHistoryItem(HistoryItem historyItem)
        {
            if (InHistoryNavigation)
                return;

            currentHistoryItem = historyItem;

            EnableHistoryButtons();
        }

        public static void NewHistoryItem(HistoryItem historyItem)
        {
            if (InHistoryNavigation)
                return;

            if (historyItem.Equals(currentHistoryItem))
                return;

            if (currentHistoryItem != null)
                backwardHistory.Push(currentHistoryItem);

            forwardHistory.Clear();

            currentHistoryItem = historyItem;

            EnableHistoryButtons();
        }

        public static void Back(int i)
        {
            while (i > 0)
            {
                forwardHistory.Push(currentHistoryItem);
                currentHistoryItem = backwardHistory.Pop();
                i--;
            }

            DoHistoryItem(currentHistoryItem);
        }

        public static void Forward(int i)
        {
            while (i > 0)
            {
                backwardHistory.Push(currentHistoryItem);
                currentHistoryItem = forwardHistory.Pop();
                i--;
            }
            
            DoHistoryItem(currentHistoryItem);
        }

        private static void DoHistoryItem(HistoryItem item)
        {
            InHistoryNavigation = true;

            try
            {
                item.Go();
            }
            finally
            {
                InHistoryNavigation = false;

                EnableHistoryButtons();
            }
        }

        public static void EnableHistoryButtons()
        {
            Program.MainWindow.forwardButton.Enabled = forwardHistory.Peek() != null;
            Program.MainWindow.backButton.Enabled = backwardHistory.Peek() != null;
        }

        private delegate void HistoryNavigationDelegate(int i);

        public static void PopulateForwardDropDown(ToolStripSplitButton button)
        {
            PopulateMenuWith(button, forwardHistory, Forward);
        }

        public static void PopulateBackDropDown(ToolStripSplitButton button)
        {
            PopulateMenuWith(button, backwardHistory, Back);
        }

        private static void PopulateMenuWith(ToolStripSplitButton button, LimitedStack<HistoryItem> history, 
            HistoryNavigationDelegate historyNavigationDelegate)
        {
            button.DropDownItems.Clear();

            int i = 0;
            foreach (HistoryItem item in history)
            {
                int j = ++i;
                var menuItem = new ToolStripMenuItem
                {
                    Text = item.Name.EscapeAmpersands(),
                    Image = item.Image,
                    ImageScaling = ToolStripItemImageScaling.None
                };
                menuItem.Click += (sender, e) => historyNavigationDelegate(j);

                button.DropDownItems.Add(menuItem);
            }
        }
    }

    internal abstract class HistoryItem
    {
        public abstract void Go();
        public abstract string Name { get; }
        public abstract Image Image { get; }
    }

    internal class XenModelObjectHistoryItem : HistoryItem
    {
        private readonly IXenObject o;
        private readonly TabPage tab;

        public XenModelObjectHistoryItem(IXenObject o, TabPage tab)
        {
            this.o = o;
            this.tab = tab;
        }

        public override void Go()
        {
            if (Program.MainWindow.SelectObjectInTree(o))
                Program.MainWindow.TheTabControl.SelectedTab = tab;
        }

        public override bool Equals(object obj)
        {
            XenModelObjectHistoryItem other = obj as XenModelObjectHistoryItem;
            if (other == null)
                return false;

            if (other.tab != tab)
                return false;

            if (other.o == null && o == null)
                return true;

            if (other.o == null || o == null)
                return false;

            return other.o.opaque_ref == o.opaque_ref;
        }

        public override int GetHashCode()
        {
            return o.opaque_ref.GetHashCode();
        }

        public override string Name => string.Format("{0}, ({1})",
            o == null ? BrandManager.BrandConsole : Helpers.GetName(o), tab.Text);

        public override Image Image => o == null ? Images.GetImage16For(Icons.XenCenter) : Images.GetImage16For(o);
    }

    internal class SearchHistoryItem : HistoryItem
    {
        private readonly Search search;

        public SearchHistoryItem(Search search)
        {
            this.search = search;
        }

        public override void Go()
        {
            Program.MainWindow.DoSearch(search);
        }

        public override bool Equals(object obj)
        {
            SearchHistoryItem other = obj as SearchHistoryItem;
            if (other == null)
                return false;

            return other.search.Equals(search);
        }

        public override int GetHashCode()
        {
            return search.GetHashCode();
        }

        public override string Name => search.Name;

        public override Image Image => Images.GetImage16For(search);
    }

    internal class ModifiedSearchHistoryItem : HistoryItem
    {
        private readonly IXenObject o;
        private readonly Search search;

        public ModifiedSearchHistoryItem(IXenObject o, Search search)
        {
            this.o = o;
            this.search = search;
        }

        public override void Go()
        {
            if (Program.MainWindow.SelectObjectInTree(o))
            {
                Program.MainWindow.TheTabControl.SelectedTab = Program.MainWindow.TabPageSearch;
                Program.MainWindow.SearchPage.Search = search;
            }
        }

        public override bool Equals(object obj)
        {
            ModifiedSearchHistoryItem other = obj as ModifiedSearchHistoryItem;
            if (other == null)
                return false;

            if (!other.search.Equals(search))
                return false;

            if (other.o == null && o == null)
                return true;

            if (other.o == null || o == null)
                return false;

            return other.o.opaque_ref == o.opaque_ref;
        }

        public override int GetHashCode()
        {
            return o.opaque_ref.GetHashCode();
        }

        public override string Name => string.Format("{0}, ({1})",
            o == null ? BrandManager.BrandConsole : Helpers.GetName(o), Program.MainWindow.TabPageSearch.Text);

        public override Image Image => o == null ? Images.GetImage16For(Icons.XenCenter) : Images.GetImage16For(o);
    }
}