Vanara/Windows.Shell.Common/ShellObjects/ShellLink.cs

using System;
using System.IO;
using System.Runtime.InteropServices.ComTypes;
using System.Security.AccessControl;
using System.Security.Permissions;
using Vanara.Extensions;
using Vanara.InteropServices;
using Vanara.PInvoke;
using static Vanara.PInvoke.Kernel32;
using static Vanara.PInvoke.Macros;
using static Vanara.PInvoke.Ole32;
using static Vanara.PInvoke.Shell32;
using static Vanara.PInvoke.User32;

namespace Vanara.Windows.Shell
{
	/// <summary>Flags determining how the links with missing targets are resolved.</summary>
	[Flags]
	public enum LinkResolution : uint
	{
		/// <summary>No flags set.</summary>
		None = 0,

		/// <summary>
		/// Do not display a dialog box if the link cannot be resolved. When NoUI is set, a time-out value that specifies the maximum amount
		/// of time to be spent resolving the link can be specified in milliseconds. The function returns if the link cannot be resolved
		/// within the time-out duration. If the timeout is not set, the time-out duration will be set to the default value of 3,000
		/// milliseconds (3 seconds).
		/// </summary>
		NoUI = 0x1,

		/// <summary>Allow any match during resolution. Has no effect on ME/2000 or above, use the other flags instead.</summary>
		AnyMatch = 0x2,

		/// <summary>
		/// If the link object has changed, update its path and list of identifiers. If UPDATE is set, you do not need to call
		/// IPersistFile::IsDirty to determine whether or not the link object has changed.
		/// </summary>
		Update = 0x4,

		/// <summary>Do not update the link information.</summary>
		NoUpdate = 0x8,

		/// <summary>Do not execute the search heuristics.</summary>
		NoSearch = 0x10,

		/// <summary>Do not use distributed link tracking.</summary>
		NoTrack = 0x20,

		/// <summary>
		/// Disable distributed link tracking. By default, distributed link tracking tracks removable media across multiple devices based on
		/// the volume name. It also uses the UNC path to track remote file systems whose drive letter has changed. Setting NoLinkInfo
		/// disables both types of tracking.
		/// </summary>
		NoLinkInfo = 0x40,

		/// <summary>Call the Microsoft Windows Installer.</summary>
		InvokeMSI = 0x80,

		/// <summary>Windows XP and later. Assume same as NoUI but intended for applications without a hWnd.</summary>
		NoUIWithMsgPump = 0x101,

		/// <summary>
		/// Windows 7 and later. Offer the option to delete the shortcut when this method is unable to resolve it, even if the shortcut is
		/// not a shortcut to a file.
		/// </summary>
		OfferDeleteWithoutFile = 0x200,

		/// <summary>
		/// Windows 7 and later. Report as dirty if the target is a known folder and the known folder was redirected. This only works if the
		/// original target path was a file system path or ID list and not an aliased known folder ID list.
		/// </summary>
		KnownFolder = 0x400,

		/// <summary>
		/// Windows 7 and later. Resolve the computer name in UNC targets that point to a local computer. This value is used with SLDFKEEPLOCALIDLISTFORUNCTARGET.
		/// </summary>
		MachineInLocalTarget = 0x800,

		/// <summary>Windows 7 and later. Update the computer GUID and user SID if necessary.</summary>
		UpdateMachineAndSid = 0x1000,

		/// <summary>?? Assuming this does not update the Object ID</summary>
		NoObjectID = 0x2000
	}

	/// <summary>Represents a Shell Shortcut (.lnk) file.</summary>
	public sealed class ShellLink : ShellItem, IEquatable<IShellLinkW>, IEquatable<ShellLink>
	{
		internal IShellLinkW link;

		/// <summary>Initializes a new instance of the <see cref="ShellLink"/> class, which acts as a wrapper for a .lnk file.</summary>
		/// <param name="linkFile">The shortcut file (.lnk) to load.</param>
		/// <param name="window">
		/// The window that the Shell will use as the parent for a dialog box. The Shell displays the dialog box if it needs to prompt the
		/// user for more information while resolving a Shell link.
		/// </param>
		/// <param name="resolveFlags">The resolve flags.</param>
		/// <param name="timeOut">The time out.</param>
		/// <exception cref="System.ArgumentNullException">linkFile</exception>
		public ShellLink(string linkFile, LinkResolution resolveFlags = LinkResolution.NoUI, HWND window = default, TimeSpan timeOut = default) : base(linkFile) =>
			LoadAndResolve(linkFile, (SLR_FLAGS)resolveFlags, window, (ushort)timeOut.TotalMilliseconds);

		/// <summary>
		/// Initializes a new instance of the <see cref="ShellLink"/> class and sets many properties. This link is not saved as a file.
		/// </summary>
		/// <param name="targetFilename">The full path to the target file.</param>
		/// <param name="arguments">The arguments for the target's execution.</param>
		/// <param name="workingDirectory">The working directory for the execution of the target.</param>
		/// <param name="description">The description of the link.</param>
		public ShellLink(string targetFilename, string arguments, string workingDirectory = null, string description = null) : this()
		{
			TargetPath = targetFilename;
			Description = description;
			WorkingDirectory = workingDirectory;
			Arguments = arguments;
			// TODO: Determine if IShellItem is required. => Init(null);
		}

		internal ShellLink(IShellItem iItem) => LoadAndResolve(iItem.GetDisplayName(SIGDN.SIGDN_FILESYSPATH), SLR_FLAGS.SLR_NO_UI);

		private ShellLink() => link = new IShellLinkW();

		/// <summary>Gets/sets any command line arguments associated with the link</summary>
		public string Arguments
		{
			get => GetStringValue(link.GetArguments, MAX_PATH);
			set { link.SetArguments(value); Save(); }
		}

		/// <summary>Gets the current option settings.</summary>
		/// <value>One or more of the SHELL_LINK_DATA_FLAGS that indicate the current option settings.</value>
		public SHELL_LINK_DATA_FLAGS DataFlags
		{
			get => ((IShellLinkDataList)link).GetFlags();
			set { ((IShellLinkDataList)link).SetFlags(value); Save(); }
		}

		/// <summary>Gets/sets the description of the link</summary>
		public string Description
		{
			get => GetStringValue(link.GetDescription, ComCtl32.INFOTIPSIZE);
			set { link.SetDescription(value); Save(); }
		}

		/// <summary>Gets/sets the HotKey to start the shortcut (if any).</summary>
		/// <value>
		/// <para>
		/// The keyboard shortcut. The virtual key code is in the low-order byte, and the modifier flags are in the high-order byte. The
		/// modifier flags can be a combination of the following values.
		/// </para>
		/// <list type="table">
		/// <listheader>
		/// <term>Value</term>
		/// <term>Meaning</term>
		/// </listheader>
		/// <item>
		/// <term><c>HOTKEYF_ALT</c> 0x04</term>
		/// <term>ALT key</term>
		/// </item>
		/// <item>
		/// <term><c>HOTKEYF_CONTROL</c> 0x02</term>
		/// <term>CTRL key</term>
		/// </item>
		/// <item>
		/// <term><c>HOTKEYF_EXT</c> 0x08</term>
		/// <term>Extended key</term>
		/// </item>
		/// <item>
		/// <term><c>HOTKEYF_SHIFT</c> 0x01</term>
		/// <term>SHIFT key</term>
		/// </item>
		/// </list>
		/// </value>
		public ushort HotKey
		{
			get => link.GetHotKey();
			set { link.SetHotKey(value); Save(); }
		}

		/// <summary>Gets the index of this icon within the icon path's resources.</summary>
		public IconLocation IconLocation
		{
			get
			{
				var iconIndex = 0;
				try { return new IconLocation(GetStringValue((sb, l) => link.GetIconLocation(sb, l, out iconIndex)), iconIndex); }
				catch { return null; }
			}

			set { link.SetIconLocation(value.ModuleFileName, value.ResourceId); Save(); }
		}

		/// <summary>Get or sets the list of item identifiers for a Shell link.</summary>
		public PIDL IDList
		{
			get => link.GetIDList();
			set { link.SetIDList(value); Save(); }
		}

		/// <summary>Gets a value indicating whether this instance is link.</summary>
		/// <value><c>true</c> if this instance is link; otherwise, <c>false</c>.</value>
		public override bool IsLink => true;

		/// <summary>Gets/sets the relative path to the link's target</summary>
		public string RelativeTargetPath
		{
			get => GetPath(SLGP.SLGP_RELATIVEPRIORITY);
			set { link.SetRelativePath(value); Save(); }
		}

		/// <summary>Gets or sets a value indicating whether the target is run with Administrator rights.</summary>
		/// <value><c>true</c> if run as Administrator; otherwise, <c>false</c>.</value>
		public bool RunAsAdministrator
		{
			get => DataFlags.IsFlagSet(SHELL_LINK_DATA_FLAGS.SLDF_RUNAS_USER);
			set
			{
				var pdl = (IShellLinkDataList)link;
				pdl.SetFlags(pdl.GetFlags().SetFlags(SHELL_LINK_DATA_FLAGS.SLDF_RUNAS_USER, value));
				Save();
			}
		}

		/// <summary>Gets/sets the short (8.3 format) path to the link's target</summary>
		public string ShortTargetPath => GetPath(SLGP.SLGP_SHORTPATH);

		/// <summary>Gets or sets the show command for a Shell link object.</summary>
		/// <value>The show command for a Shell link object.</value>
		public ShowWindowCommand ShowState
		{
			get => link.GetShowCmd();
			set { link.SetShowCmd(value); Save(); }
		}

		/// <summary>Gets or sets the target with a <see cref="ShellItem"/> instance.</summary>
		public ShellItem Target
		{
			get => TargetPath is null ? null : new ShellItem(TargetPath);
			set { link.SetIDList(value.PIDL); Save(); }
		}

		/// <summary>Gets/sets the fully qualified path to the link's target</summary>
		public string TargetPath
		{
			get => GetPath(SLGP.SLGP_RAWPATH);
			set { link.SetPath(value); Save(); }
		}

		/// <summary>Gets/sets the display name of the link through the PKEY_Title property.</summary>
		public string Title
		{
			get => (string)Properties[PROPERTYKEY.System.Title];
			set { Properties[PROPERTYKEY.System.Title] = value; Properties.Commit(); Save(); }
		}

		/// <summary>Gets/sets the Working Directory for the Link</summary>
		public string WorkingDirectory
		{
			get => GetStringValue(link.GetWorkingDirectory, MAX_PATH);
			set { link.SetWorkingDirectory(value); Save(); }
		}

		/// <summary>Creates or overwrites a new link file.</summary>
		/// <param name="linkFilename">The link filename.</param>
		/// <param name="targetFilename">The full path to the target file.</param>
		/// <param name="description">The description of the link.</param>
		/// <param name="workingDirectory">The working directory for the execution of the target.</param>
		/// <param name="arguments">The arguments for the target's execution.</param>
		/// <returns>An instance of a <see cref="ShellLink"/> representing the values supplied.</returns>
		public static ShellLink Create(string linkFilename, string targetFilename, string description = null, string workingDirectory = null, string arguments = null)
		{
			if (File.Exists(linkFilename)) throw new InvalidOperationException("File already exists.");
			var lnk = new ShellLink(targetFilename, arguments, workingDirectory, description);
			lnk.SaveAs(linkFilename);
			return lnk;
		}

		/// <summary>Creates or overwrites a new link file.</summary>
		/// <param name="linkFilename">The link filename.</param>
		/// <param name="target">The ShellItem for the target.</param>
		/// <param name="description">The description of the link.</param>
		/// <param name="workingDirectory">The working directory for the execution of the target.</param>
		/// <param name="arguments">The arguments for the target's execution.</param>
		/// <returns>An instance of a <see cref="ShellLink"/> representing the values supplied.</returns>
		public static ShellLink Create(string linkFilename, ShellItem target, string description = null, string workingDirectory = null, string arguments = null)
		{
			if (File.Exists(linkFilename)) throw new InvalidOperationException("File already exists.");
			var lnk = new ShellLink
			{
				link = new IShellLinkW(),
				Target = target,
				Description = description,
				WorkingDirectory = workingDirectory,
				Arguments = arguments
			};
			lnk.SaveAs(linkFilename);
			lnk.Init(SHCreateItemFromParsingName<IShellItem>(Path.GetFullPath(linkFilename)));
			return lnk;
		}

		/// <summary>Copies an existing file to a new file, allowing the overwriting of an existing file.</summary>
		/// <param name="destShellLink">The name of the new file to copy to.</param>
		/// <param name="overwrite"><c>true</c> to allow an existing file to be overwritten; otherwise <c>false</c>.</param>
		/// <returns>
		/// A new file, or an overwrite of an existing file if overwrite is true. If the file exists and overwrite is false, an IOException
		/// is thrown.
		/// </returns>
		public ShellLink CopyTo(string destShellLink, bool overwrite = false)
		{
			File.Copy(FileSystemPath, destShellLink, overwrite);
			return new ShellLink(destShellLink);
		}

		/// <summary>Dispose the object, releasing the COM ShellLink object</summary>
		public override void Dispose()
		{
			link = null;
			//Release(link);
			base.Dispose();
		}

		/// <summary>Determines whether the specified <see cref="object"/>, is equal to this instance.</summary>
		/// <param name="obj">The <see cref="object"/> to compare with this instance.</param>
		/// <returns><see langword="true"/> if the specified <see cref="object"/> is equal to this instance; otherwise, <see langword="false"/>.</returns>
		public override bool Equals(object obj) => obj switch
		{
			ShellLink sl => Equals(sl),
			IShellLinkW isl => Equals(isl),
			_ => base.Equals(obj),
		};

		/// <summary>
		/// Gets a FileSecurity object that encapsulates the specified type of access control list (ACL) entries for the file described by
		/// the current FileInfo object.
		/// </summary>
		/// <param name="includeSections">
		/// One of the AccessControlSections values that specifies which group of access control entries to retrieve.
		/// </param>
		/// <returns>A FileSecurity object that encapsulates the access control rules for the current file.</returns>
		public FileSecurity GetAccessControl(AccessControlSections includeSections = AccessControlSections.Access | AccessControlSections.Group | AccessControlSections.Owner) =>
			new(FileSystemPath, includeSections);

		/// <summary>Returns a hash code for this instance.</summary>
		/// <returns>A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.</returns>
		public override int GetHashCode() => ToString().GetHashCode();

		/// <summary>Gets the icon for this link file.</summary>
		/// <param name="large">if set to <c>true</c> retrieve the large icon; other retrieve the small icon.</param>
		/// <returns>The icon.</returns>
		public SafeHICON GetIcon(bool large)
		{
			var loc = IconLocation;
			if (loc.IsValid) return loc.Icon;

			// If there are no details set for the icon, then we must use the shell to get the icon for the target
			var sfi = new ShellFileInfo(TargetPath);
			return large ? sfi.LargeIcon : sfi.SmallIcon;
		}

		/// <summary>
		/// Applies access control list (ACL) entries described by a FileSecurity object to the file described by the current FileInfo object.
		/// </summary>
		/// <param name="fileSecurity">
		/// A FileSecurity object that describes an access control list (ACL) entry to apply to the current file.
		/// </param>
		public void SetAccessControl(FileSecurity fileSecurity) => new FileInfo(FileSystemPath).SetAccessControl(fileSecurity);

		/// <summary>Returns a <see cref="System.String"/> that represents this instance.</summary>
		/// <returns>A <see cref="System.String"/> that represents this instance.</returns>
		// Path and title should be case insensitive. Shell treats arguments as case sensitive because apps can handle those differently.
		public override string ToString() =>
			$"{Title?.ToUpperInvariant() ?? ""} {TargetPath.ToUpperInvariant()} {Arguments}";

		private string GetPath(SLGP value) => GetStringValue((sb, l) => link.GetPath(sb, l, out _, value));

		private void InitBaseFromPath(string linkFilename) => Init(SHCreateItemFromParsingName<IShellItem>(Path.GetFullPath(linkFilename)));

		private void LoadAndResolve(string linkFile, SLR_FLAGS resolveFlags, HWND hWin = default, ushort timeOut = 0)
		{
			var fullPath = Path.GetFullPath(linkFile ?? throw new ArgumentNullException(nameof(linkFile)));
			if (!File.Exists(fullPath)) throw new FileNotFoundException("Link file not found.", linkFile);

			link = new IShellLinkW();

			if (resolveFlags.IsFlagSet(SLR_FLAGS.SLR_NO_UI) && timeOut != 0)
				resolveFlags = (SLR_FLAGS)MAKELONG((ushort)resolveFlags, timeOut);
#if !NETSTANDARD
			new FileIOPermission(FileIOPermissionAccess.Read, fullPath).Demand();
#endif
			((IPersistFile)link).Load(fullPath, (int)STGM.STGM_DIRECT);
			link.Resolve(hWin, resolveFlags);

			InitBaseFromPath(linkFile);
		}

		/// <summary>Saves the shortcut to ShortCutFile.</summary>
		private void Save()
		{
			if (string.IsNullOrEmpty(FileSystemPath)) return;
			SaveAs(File.Exists(FileSystemPath) ? null : FileSystemPath);
		}

		/// <summary>Saves the shortcut to the specified file.</summary>
		/// <param name="linkFile">The shortcut file (.lnk).</param>
		public void SaveAs(string linkFile)
		{
			using (var pIPF = ComReleaserFactory.Create((IPersistFile)link))
				pIPF.Item.Save(linkFile, true);
			if (linkFile != null)
				InitBaseFromPath(linkFile);
		}

		/// <summary>Determines if two shell links are equal by looking at the title, path and arguments.</summary>
		/// <param name="left">The left shell link to evaluate.</param>
		/// <param name="right">The right shell link to evaluate.</param>
		/// <returns><see langword="true"/> if the two links are equal; otherwise <see langword="false"/>.</returns>
		internal static bool Equals(IShellLinkW left, IShellLinkW right)
		{
			if (ReferenceEquals(left, right)) return true;
			if (left is null || right is null) return false;
			return string.Equals(GetCompareString(left), GetCompareString(right), StringComparison.Ordinal);
		}

		/// <summary>Gets a string representation of an <see cref="IShellLinkW"/> instance that includes the title, path and arguments for comparison.</summary>
		/// <param name="l">The <see cref="IShellLinkW"/> instance.</param>
		/// <returns>The string representation for comparison.</returns>
		internal static string GetCompareString(IShellLinkW l)
		{
			var ps = (PropSys.IPropertyStore)l;
			var title = ps.GetValue(PROPERTYKEY.System.Title)?.ToString();
			var exe = GetStringValue((sb, z) => l.GetPath(sb, z, out _, SLGP.SLGP_RAWPATH));
			var args = GetStringValue(l.GetArguments, MAX_PATH);
			return exe?.ToUpperInvariant() + title?.ToUpperInvariant() + args;
		}

		/// <summary>Determines whether the specified <see cref="IShellLinkW"/>, is equal to this instance.</summary>
		/// <param name="other">The <see cref="IShellLinkW"/> to compare with this instance.</param>
		/// <returns><see langword="true"/> if the specified <see cref="IShellLinkW"/> is equal to this instance; otherwise, <see langword="false"/>.</returns>
		public bool Equals(IShellLinkW other) => Equals(link, other);

		/// <summary>Determines whether the specified <see cref="ShellLink"/>, is equal to this instance.</summary>
		/// <param name="other">The <see cref="ShellLink"/> to compare with this instance.</param>
		/// <returns><see langword="true"/> if the specified <see cref="ShellLink"/> is equal to this instance; otherwise, <see langword="false"/>.</returns>
		public bool Equals(ShellLink other) => Equals(link, other?.link);
	}
}