// Copyright (c) Microsoft Corporation
// The Microsoft Corporation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;
using Common.UI;
using Microsoft.Win32;
using Wox.Plugin.Common.VirtualDesktop.Interop;
using Wox.Plugin.Common.Win32;
using Wox.Plugin.Logger;
using Wox.Plugin.Properties;

namespace Wox.Plugin.Common.VirtualDesktop.Helper
{
    /// <summary>
    /// Helper class to work with Virtual Desktops.
    /// This helper uses only public available and documented COM-Interfaces or information from registry.
    /// </summary>
    /// <remarks>
    /// To use this helper you have to create an instance of it and access the method via the helper instance.
    /// We are only allowed to use public documented com interfaces.
    /// </remarks>
    /// <SeeAlso href="https://learn.microsoft.com/windows/win32/api/shobjidl_core/nn-shobjidl_core-ivirtualdesktopmanager">Documentation of IVirtualDesktopManager interface</SeeAlso>
    /// <SeeAlso href="https://learn.microsoft.com/archive/blogs/winsdk/virtual-desktop-switching-in-windows-10">CSharp example code for IVirtualDesktopManager</SeeAlso>
    public class VirtualDesktopHelper
    {
        /// <summary>
        /// Are we running on Windows 11
        /// </summary>
        private readonly bool _isWindowsEleven;

        /// <summary>
        /// Instance of "Virtual Desktop Manager"
        /// </summary>
        private readonly IVirtualDesktopManager _virtualDesktopManager;

        /// <summary>
        /// Internal settings to enable automatic update of desktop list.
        /// This will be off by default to avoid to many registry queries.
        /// </summary>
        private readonly bool _desktopListAutoUpdate;

        /// <summary>
        /// List of all available Virtual Desktop in their real order
        /// The order and list in the registry is always up to date
        /// </summary>
        private List<Guid> _availableDesktops = new List<Guid>();

        /// <summary>
        /// Id of the current visible Desktop.
        /// </summary>
        private Guid _currentDesktop;

        private static readonly CompositeFormat VirtualDesktopHelperDesktop = System.Text.CompositeFormat.Parse(Properties.Resources.VirtualDesktopHelper_Desktop);

        /// <summary>
        /// Initializes a new instance of the <see cref="VirtualDesktopHelper"/> class.
        /// </summary>
        /// <param name="desktopListUpdate">Setting to configure if the list of available desktops should update automatically or only when calling <see cref="UpdateDesktopList"/>. Per default this is set to manual update (false) to have less registry queries.</param>
        public VirtualDesktopHelper(bool desktopListUpdate = false)
        {
            try
            {
                _virtualDesktopManager = (IVirtualDesktopManager)new CVirtualDesktopManager();
            }
            catch (COMException ex)
            {
                Log.Exception("Initialization of <VirtualDesktopHelper> failed: An exception was thrown when creating the instance of COM interface <IVirtualDesktopManager>.", ex, typeof(VirtualDesktopHelper));
                return;
            }

            _isWindowsEleven = OSVersionHelper.IsWindows11();
            _desktopListAutoUpdate = desktopListUpdate;
            UpdateDesktopList();
        }

        /// <summary>
        /// Gets a value indicating whether the Virtual Desktop Manager is initialized successfully
        /// </summary>
        public bool VirtualDesktopManagerInitialized
        {
            get { return _virtualDesktopManager != null; }
        }

        /// <summary>
        /// Method to update the list of Virtual Desktops from Registry
        /// The data in the registry are always up to date
        /// </summary>
        /// <remarks>If we can not read from registry, we set the list/guid to empty values.</remarks>
        public void UpdateDesktopList()
        {
            int userSessionId = Process.GetCurrentProcess().SessionId;
            string registrySessionVirtualDesktops = $"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer\\SessionInfo\\{userSessionId}\\VirtualDesktops"; // Windows 10
            string registryExplorerVirtualDesktops = "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer\\VirtualDesktops"; // Windows 11

            // List of all desktops
            using RegistryKey virtualDesktopKey = Registry.CurrentUser.OpenSubKey(registryExplorerVirtualDesktops, false);
            if (virtualDesktopKey != null)
            {
                byte[] allDeskValue = (byte[])virtualDesktopKey.GetValue("VirtualDesktopIDs", null);
                if (allDeskValue != null)
                {
                    // We clear only, if we can read from registry. Otherwise we keep the existing values.
                    _availableDesktops.Clear();

                    // Each guid has a length of 16 elements
                    int numberOfDesktops = allDeskValue.Length / 16;
                    for (int i = 0; i < numberOfDesktops; i++)
                    {
                        byte[] guidArray = new byte[16];
                        Array.ConstrainedCopy(allDeskValue, i * 16, guidArray, 0, 16);
                        _availableDesktops.Add(new Guid(guidArray));
                    }
                }
                else
                {
                    Log.Debug("VirtualDesktopHelper.UpdateDesktopList() failed to read the list of existing desktops form registry.", typeof(VirtualDesktopHelper));
                }
            }

            // Guid for current desktop
            var virtualDesktopsKeyName = _isWindowsEleven ? registryExplorerVirtualDesktops : registrySessionVirtualDesktops;
            using RegistryKey virtualDesktopsKey = Registry.CurrentUser.OpenSubKey(virtualDesktopsKeyName, false);
            if (virtualDesktopsKey != null)
            {
                var currentVirtualDesktopValue = virtualDesktopsKey.GetValue("CurrentVirtualDesktop", null);
                if (currentVirtualDesktopValue != null)
                {
                    _currentDesktop = new Guid((byte[])currentVirtualDesktopValue);
                }
                else
                {
                    // The registry value is missing when the user hasn't switched the desktop at least one time before reading the registry. In this case we can set it to desktop one.
                    // We can only set it to desktop one, if we have at least one desktop in the desktops list. Otherwise we keep the existing value.
                    Log.Debug("VirtualDesktopHelper.UpdateDesktopList() failed to read the id for the current desktop form registry.", typeof(VirtualDesktopHelper));
                    _currentDesktop = _availableDesktops.Count >= 1 ? _availableDesktops[0] : _currentDesktop;
                }
            }
        }

        /// <summary>
        /// Returns an ordered list with the ids of all existing desktops. The list is ordered in the same way as the existing desktops.
        /// </summary>
        /// <returns>List of desktop ids or an empty list on failure.</returns>
        public List<Guid> GetDesktopIdList()
        {
            if (_desktopListAutoUpdate)
            {
                UpdateDesktopList();
            }

            return _availableDesktops;
        }

        /// <summary>
        /// Returns an ordered list with of all existing desktops and their properties. The list is ordered in the same way as the existing desktops.
        /// </summary>
        /// <returns>List of desktops or an empty list on failure.</returns>
        public List<VDesktop> GetDesktopList()
        {
            if (_desktopListAutoUpdate)
            {
                UpdateDesktopList();
            }

            List<VDesktop> list = new List<VDesktop>();
            foreach (Guid d in _availableDesktops)
            {
                list.Add(CreateVDesktopInstance(d));
            }

            return list;
        }

        /// <summary>
        /// Returns the count of existing desktops
        /// </summary>
        /// <returns>Number of existing desktops or zero on failure.</returns>
        public int GetDesktopCount()
        {
            if (_desktopListAutoUpdate)
            {
                UpdateDesktopList();
            }

            return _availableDesktops.Count;
        }

        /// <summary>
        /// Returns the id of the desktop that is currently visible to the user.
        /// </summary>
        /// <returns>The <see cref="Guid"/> of the current desktop. Or <see cref="Guid.Empty"/> on failure and if we don't know the current desktop.</returns>
        public Guid GetCurrentDesktopId()
        {
            if (_desktopListAutoUpdate)
            {
                UpdateDesktopList();
            }

            return _currentDesktop;
        }

        /// <summary>
        /// Returns an instance of <see cref="VDesktop"/> for the desktop that is currently visible to the user.
        /// </summary>
        /// <returns>An instance of <see cref="VDesktop"/> for the current desktop, or an empty instance of <see cref="VDesktop"/> on failure.</returns>
        public VDesktop GetCurrentDesktop()
        {
            if (_desktopListAutoUpdate)
            {
                UpdateDesktopList();
            }

            return CreateVDesktopInstance(_currentDesktop);
        }

        /// <summary>
        /// Checks if a desktop is currently visible to the user.
        /// </summary>
        /// <param name="desktop">The guid of the desktop to check.</param>
        /// <returns><see langword="True"/> if the guid belongs to the currently visible desktop. <see langword="False"/> if not or if we don't know the visible desktop.</returns>
        public bool IsDesktopVisible(Guid desktop)
        {
            if (_desktopListAutoUpdate)
            {
                UpdateDesktopList();
            }

            return _currentDesktop == desktop;
        }

        /// <summary>
        /// Returns the number (position) of a desktop.
        /// </summary>
        /// <param name="desktop">The guid of the desktop.</param>
        /// <returns>Number of the desktop, if found. Otherwise a value of zero.</returns>
        public int GetDesktopNumber(Guid desktop)
        {
            if (_desktopListAutoUpdate)
            {
                UpdateDesktopList();
            }

            // Adding +1 because index starts with zero and humans start counting with one.
            return _availableDesktops.IndexOf(desktop) + 1;
        }

        /// <summary>
        /// Returns the name of a desktop
        /// </summary>
        /// <param name="desktop">Guid of the desktop</param>
        /// <returns>Returns the name of the desktop or <see cref="string.Empty"/> on failure.</returns>
        public string GetDesktopName(Guid desktop)
        {
            if (desktop == Guid.Empty || !GetDesktopIdList().Contains(desktop))
            {
                Log.Debug($"VirtualDesktopHelper.GetDesktopName() failed. Parameter contains an invalid desktop guid ({desktop}) that doesn't belongs to an available desktop. Maybe the guid belongs to the generic 'AllDesktops' view.", typeof(VirtualDesktopHelper));
                return string.Empty;
            }

            // If the desktop name was not changed by the user, it isn't saved to the registry. Then we need the default name for the desktop.
            var defaultName = string.Format(System.Globalization.CultureInfo.InvariantCulture, VirtualDesktopHelperDesktop, GetDesktopNumber(desktop));

            string registryPath = "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Explorer\\VirtualDesktops\\Desktops\\{" + desktop.ToString().ToUpper(System.Globalization.CultureInfo.InvariantCulture) + "}";
            using RegistryKey deskSubKey = Registry.CurrentUser.OpenSubKey(registryPath, false);
            var desktopName = deskSubKey?.GetValue("Name");

            return (desktopName != null) ? (string)desktopName : defaultName;
        }

        /// <summary>
        /// Returns the position type for a desktop.
        /// </summary>
        /// <param name="desktop">Guid of the desktop.</param>
        /// <returns>Type of <see cref="VirtualDesktopPosition"/>. On failure we return <see cref="VirtualDesktopPosition.Unknown"/>.</returns>
        public VirtualDesktopPosition GetDesktopPositionType(Guid desktop)
        {
            int desktopNumber = GetDesktopNumber(desktop);
            int desktopCount = GetDesktopCount();

            if (desktopCount == 0 || desktop == Guid.Empty)
            {
                // On failure or empty guid
                return VirtualDesktopPosition.NotApplicable;
            }
            else if (desktopNumber == 1)
            {
                return VirtualDesktopPosition.FirstDesktop;
            }
            else if (desktopNumber == desktopCount)
            {
                return VirtualDesktopPosition.LastDesktop;
            }
            else if (desktopNumber > 1 & desktopNumber < desktopCount)
            {
                return VirtualDesktopPosition.BetweenOtherDesktops;
            }
            else
            {
                // All desktops view or a guid that doesn't belong to an existing desktop
                return VirtualDesktopPosition.NotApplicable;
            }
        }

        /// <summary>
        /// Returns the desktop id for a window.
        /// </summary>
        /// <param name="hWindow">Handle of the window.</param>
        /// <param name="desktopId">The guid of the desktop, where the window is shown.</param>
        /// <returns>HResult of the called method as integer.</returns>
        public int GetWindowDesktopId(IntPtr hWindow, out Guid desktopId)
        {
            if (_virtualDesktopManager == null)
            {
                Log.Error("VirtualDesktopHelper.GetWindowDesktopId() failed: The instance of <IVirtualDesktopHelper> isn't available.", typeof(VirtualDesktopHelper));
                desktopId = Guid.Empty;
                return unchecked((int)HRESULT.E_UNEXPECTED);
            }

            return _virtualDesktopManager.GetWindowDesktopId(hWindow, out desktopId);
        }

        /// <summary>
        /// Returns an instance of <see cref="VDesktop"/> for the desktop where the window is assigned to.
        /// </summary>
        /// <param name="hWindow">Handle of the window.</param>
        /// <returns>An instance of <see cref="VDesktop"/> for the desktop where the window is assigned to, or an empty instance of <see cref="VDesktop"/> on failure.</returns>
        public VDesktop GetWindowDesktop(IntPtr hWindow)
        {
            if (_virtualDesktopManager == null)
            {
                Log.Error("VirtualDesktopHelper.GetWindowDesktop() failed: The instance of <IVirtualDesktopHelper> isn't available.", typeof(VirtualDesktopHelper));
                return CreateVDesktopInstance(Guid.Empty);
            }

            int hr = _virtualDesktopManager.GetWindowDesktopId(hWindow, out Guid desktopId);
            return (hr != (int)HRESULT.S_OK || desktopId == Guid.Empty) ? VDesktop.Empty : CreateVDesktopInstance(desktopId, hWindow);
        }

        /// <summary>
        /// Returns the desktop assignment type for a window.
        /// </summary>
        /// <param name="hWindow">Handle of the window.</param>
        /// <param name="desktop">Optional the desktop id if known</param>
        /// <returns>Type of <see cref="VirtualDesktopAssignmentType"/>.</returns>
        public VirtualDesktopAssignmentType GetWindowDesktopAssignmentType(IntPtr hWindow, Guid? desktop = null)
        {
            if (_virtualDesktopManager == null)
            {
                Log.Error("VirtualDesktopHelper.GetWindowDesktopAssignmentType() failed: The instance of <IVirtualDesktopHelper> isn't available.", typeof(VirtualDesktopHelper));
                return VirtualDesktopAssignmentType.Unknown;
            }

            _ = _virtualDesktopManager.IsWindowOnCurrentVirtualDesktop(hWindow, out int isOnCurrentDesktop);
            Guid windowDesktopId = desktop ?? Guid.Empty; // Prepare variable in case we have no input parameter for desktop
            int hResult = desktop is null ? GetWindowDesktopId(hWindow, out windowDesktopId) : 0;

            if (hResult != (int)HRESULT.S_OK)
            {
                return VirtualDesktopAssignmentType.Unknown;
            }
            else if (windowDesktopId == Guid.Empty)
            {
                return VirtualDesktopAssignmentType.NotAssigned;
            }
            else if (isOnCurrentDesktop == 1 && !GetDesktopIdList().Contains(windowDesktopId))
            {
                // These windows are marked as visible on the current desktop, but the desktop id doesn't belongs to an existing desktop.
                // In this case the desktop id belongs to the generic view 'AllDesktops'.
                return VirtualDesktopAssignmentType.AllDesktops;
            }
            else if (isOnCurrentDesktop == 1)
            {
                return VirtualDesktopAssignmentType.CurrentDesktop;
            }
            else
            {
                return VirtualDesktopAssignmentType.OtherDesktop;
            }
        }

        /// <summary>
        /// Returns a value indicating if the window is assigned to a currently visible desktop.
        /// </summary>
        /// <param name="hWindow">Handle to the top level window.</param>
        /// <param name="desktop">Optional the desktop id if known</param>
        /// <returns><see langword="True"/> if the desktop with the window is visible or if the window is assigned to all desktops. <see langword="False"/> if the desktop is not visible and on failure,</returns>
        public bool IsWindowOnVisibleDesktop(IntPtr hWindow, Guid? desktop = null)
        {
            return GetWindowDesktopAssignmentType(hWindow, desktop) == VirtualDesktopAssignmentType.CurrentDesktop || GetWindowDesktopAssignmentType(hWindow, desktop) == VirtualDesktopAssignmentType.AllDesktops;
        }

        /// <summary>
        /// Returns a value indicating if the window is cloaked by VirtualDesktopManager.
        /// (A cloaked window is not visible to the user. But the window is still composed by DWM.)
        /// </summary>
        /// <param name="hWindow">Handle of the window.</param>
        /// <param name="desktop">Optional the desktop id if known</param>
        /// <returns>A value indicating if the window is cloaked by Virtual Desktop Manager, because it is moved to another desktop.</returns>
        public bool IsWindowCloakedByVirtualDesktopManager(IntPtr hWindow, Guid? desktop = null)
        {
            // If a window is hidden because it is moved to another desktop, then DWM returns type "CloakedShell". If DWM returns another type the window is not cloaked by shell or VirtualDesktopManager.
            _ = NativeMethods.DwmGetWindowAttribute(hWindow, (int)DwmWindowAttributes.Cloaked, out int dwmCloakedState, sizeof(uint));
            return GetWindowDesktopAssignmentType(hWindow, desktop) == VirtualDesktopAssignmentType.OtherDesktop && dwmCloakedState == (int)DwmWindowCloakStates.CloakedShell;
        }

        /// <summary>
        /// Moves the window to a specific desktop.
        /// </summary>
        /// <param name="hWindow">Handle of the top level window.</param>
        /// <param name="desktopId">Guid of the target desktop.</param>
        /// <returns><see langword="True"/> on success and <see langword="false"/> on failure.</returns>
        public bool MoveWindowToDesktop(IntPtr hWindow, in Guid desktopId)
        {
            if (_virtualDesktopManager == null)
            {
                Log.Error("VirtualDesktopHelper.MoveWindowToDesktop() failed: The instance of <IVirtualDesktopHelper> isn't available.", typeof(VirtualDesktopHelper));
                return false;
            }

            int hr = _virtualDesktopManager.MoveWindowToDesktop(hWindow, desktopId);
            if (hr != (int)HRESULT.S_OK)
            {
                Log.Exception($"VirtualDesktopHelper.MoveWindowToDesktop() failed: An exception was thrown when moving the window ({hWindow}) to another desktop ({desktopId}).", Marshal.GetExceptionForHR(hr), typeof(VirtualDesktopHelper));
                return false;
            }

            return true;
        }

        /// <summary>
        /// Move a window one desktop left.
        /// </summary>
        /// <param name="hWindow">Handle of the top level window.</param>
        /// <returns><see langword="True"/> on success and <see langword="false"/> on failure.</returns>
        public bool MoveWindowOneDesktopLeft(IntPtr hWindow)
        {
            int hr = GetWindowDesktopId(hWindow, out Guid windowDesktop);
            if (hr != (int)HRESULT.S_OK)
            {
                Log.Error($"VirtualDesktopHelper.MoveWindowOneDesktopLeft() failed when moving the window ({hWindow}) one desktop left: Can't get current desktop of the window.", typeof(VirtualDesktopHelper));
                return false;
            }

            if (GetDesktopIdList().Count == 0 || GetWindowDesktopAssignmentType(hWindow, windowDesktop) == VirtualDesktopAssignmentType.Unknown || GetWindowDesktopAssignmentType(hWindow, windowDesktop) == VirtualDesktopAssignmentType.NotAssigned)
            {
                Log.Error($"VirtualDesktopHelper.MoveWindowOneDesktopLeft() failed when moving the window ({hWindow}) one desktop left: We can't find the target desktop. This can happen if the desktop list is empty or if the window isn't assigned to a specific desktop.", typeof(VirtualDesktopHelper));
                return false;
            }

            int windowDesktopNumber = GetDesktopIdList().IndexOf(windowDesktop);
            if (windowDesktopNumber == 1)
            {
                Log.Error($"VirtualDesktopHelper.MoveWindowOneDesktopLeft() failed when moving the window ({hWindow}) one desktop left: The window is on the first desktop.", typeof(VirtualDesktopHelper));
                return false;
            }

            Guid newDesktop = _availableDesktops[windowDesktopNumber - 1];
            return MoveWindowToDesktop(hWindow, newDesktop);
        }

        /// <summary>
        /// Move a window one desktop right.
        /// </summary>
        /// <param name="hWindow">Handle of the top level window.</param>
        /// <returns><see langword="True"/> on success and <see langword="false"/> on failure.</returns>
        public bool MoveWindowOneDesktopRight(IntPtr hWindow)
        {
            int hr = GetWindowDesktopId(hWindow, out Guid windowDesktop);
            if (hr != (int)HRESULT.S_OK)
            {
                Log.Error($"VirtualDesktopHelper.MoveWindowOneDesktopRight() failed when moving the window ({hWindow}) one desktop right: Can't get current desktop of the window.", typeof(VirtualDesktopHelper));
                return false;
            }

            if (GetDesktopIdList().Count == 0 || GetWindowDesktopAssignmentType(hWindow, windowDesktop) == VirtualDesktopAssignmentType.Unknown || GetWindowDesktopAssignmentType(hWindow, windowDesktop) == VirtualDesktopAssignmentType.NotAssigned)
            {
                Log.Error($"VirtualDesktopHelper.MoveWindowOneDesktopRight() failed when moving the window ({hWindow}) one desktop right: We can't find the target desktop. This can happen if the desktop list is empty or if the window isn't assigned to a specific desktop.", typeof(VirtualDesktopHelper));
                return false;
            }

            int windowDesktopNumber = GetDesktopIdList().IndexOf(windowDesktop);
            if (windowDesktopNumber == GetDesktopCount())
            {
                Log.Error($"VirtualDesktopHelper.MoveWindowOneDesktopRight() failed when moving the window ({hWindow}) one desktop right: The window is on the last desktop.", typeof(VirtualDesktopHelper));
                return false;
            }

            Guid newDesktop = _availableDesktops[windowDesktopNumber + 1];
            return MoveWindowToDesktop(hWindow, newDesktop);
        }

        /// <summary>
        /// Returns an instance of <see cref="VDesktop"/> for a Guid.
        /// </summary>
        /// <param name="desktop">Guid of the desktop.</param>
        /// <param name="hWindow">Handle of the window shown on the desktop. If this parameter is set we can detect if it is the AllDesktops view.</param>
        /// <returns>A <see cref="VDesktop"/> instance. If the parameter desktop is <see cref="Guid.Empty"/>, we return an empty <see cref="VDesktop"/> instance.</returns>
        private VDesktop CreateVDesktopInstance(Guid desktop, IntPtr hWindow = default)
        {
            if (desktop == Guid.Empty)
            {
                return VDesktop.Empty;
            }

            // Can be only detected if method is invoked with window handle parameter.
            VirtualDesktopAssignmentType desktopType = (hWindow != default) ? GetWindowDesktopAssignmentType(hWindow, desktop) : VirtualDesktopAssignmentType.Unknown;
            bool isAllDesktops = (hWindow != default) && desktopType == VirtualDesktopAssignmentType.AllDesktops;
            bool isDesktopVisible = (hWindow != default) ? (isAllDesktops || desktopType == VirtualDesktopAssignmentType.CurrentDesktop) : IsDesktopVisible(desktop);

            return new VDesktop()
            {
                Id = desktop,
                Name = isAllDesktops ? Resources.VirtualDesktopHelper_AllDesktops : GetDesktopName(desktop),
                Number = GetDesktopNumber(desktop),
                IsVisible = isDesktopVisible || isAllDesktops,
                IsAllDesktopsView = isAllDesktops,
                Position = GetDesktopPositionType(desktop),
            };
        }
    }

    /// <summary>
    /// Enum to show in which way a window is assigned to a desktop
    /// </summary>
    public enum VirtualDesktopAssignmentType
    {
        Unknown = -1,
        NotAssigned = 0,
        AllDesktops = 1,
        CurrentDesktop = 2,
        OtherDesktop = 3,
    }

    /// <summary>
    /// Enum to show the position of a desktop in the list of all desktops
    /// </summary>
    public enum VirtualDesktopPosition
    {
        FirstDesktop,
        BetweenOtherDesktops,
        LastDesktop,
        NotApplicable, // If not applicable or unknown
    }
}
