using System;
using System.Linq;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Security;
using System.Text;

namespace Vanara.PInvoke
{
	public static partial class Shell32
	{
		/// <remarks>Methods in this class will only work on Vista and above.</remarks>
		public static class ShellUtil
		{
			/// <summary>Gets the KNOWNFOLDERID enum from a KNOWNFOLDERID Guid.</summary>
			/// <param name="knownFolder">The KNOWNFOLDERID Guid.</param>
			/// <returns>The KNOWNFOLDERID enum.</returns>
			public static KNOWNFOLDERID GetKnownFolderFromGuid(Guid knownFolder) =>
				Enum.GetValues(typeof(KNOWNFOLDERID)).Cast<KNOWNFOLDERID>().Single(k => k.Guid() == knownFolder);

			/// <summary>Gets the KNOWNFOLDERID enum from a path.</summary>
			/// <param name="path">The folder path.</param>
			/// <returns>The KNOWNFOLDERID enum.</returns>
			public static KNOWNFOLDERID GetKnownFolderFromPath(string path)
			{
				if (Environment.OSVersion.Version.Major < 6)
					return Enum.GetValues(typeof(KNOWNFOLDERID)).Cast<KNOWNFOLDERID>().Single(k => string.Equals(k.FullPath(), path, StringComparison.InvariantCultureIgnoreCase));
				var ikfm = new IKnownFolderManager();
				return GetKnownFolderFromGuid(ikfm.FindFolderFromPath(path, FFFP_MODE.FFFP_EXACTMATCH).GetId());
			}

			/// <summary>Gets the path for a KNOWNFOLDERID Guid.</summary>
			/// <param name="knownFolder">The KNOWNFOLDERID Guid.</param>
			/// <returns>The file system path.</returns>
			[SecurityCritical]
			public static string GetPathForKnownFolder(Guid knownFolder)
			{
				if (knownFolder == default)
					return null;

				var pathBuilder = new StringBuilder(260);
				if (SHGetFolderPathEx(knownFolder, 0, HTOKEN.NULL, pathBuilder, (uint)pathBuilder.Capacity).Failed)
					return null;
				return pathBuilder.ToString();
			}

			/// <summary>Gets the path from shell item.</summary>
			/// <param name="item">The shell item.</param>
			/// <returns>The file system path.</returns>
			[SecurityCritical]
			public static string GetPathFromShellItem(IShellItem item) => item.GetDisplayName(SIGDN.SIGDN_DESKTOPABSOLUTEEDITING);

			/// <summary>Gets the shell item for a file system path.</summary>
			/// <returns>The file system path.</returns>
			/// <returns>The corresponding IShellItem.</returns>
			[SecurityCritical]
			public static IShellItem GetShellItemForPath(string path)
			{
				if (string.IsNullOrEmpty(path))
					return null;

				var hr = SHCreateItemFromParsingName(path, null, typeof(IShellItem).GUID, out var unk);
				if (hr == 0x80070002)
				{
					Ole32.CreateBindCtx(0, out var ibc).ThrowIfFailed();
					using (var _ibc = new InteropServices.ComReleaser<IBindCtx>(ibc))
					{
						var bd = new IntFileSysBindData();
						ibc.RegisterObjectParam(STR_FILE_SYS_BIND_DATA, bd);
						hr = SHCreateItemFromParsingName(path, ibc, typeof(IShellItem).GUID, out unk);
					}
				}
				hr.ThrowIfFailed();
				return (IShellItem)unk;
			}

			[ComVisible(true)]
			private class IntFileSysBindData : IFileSystemBindData2
			{
				private static readonly Guid CLSID_UnknownJunction = new Guid("{fc0a77e6-9d70-4258-9783-6dab1d0fe31e}");
				private Guid clsidJunction;
				private WIN32_FIND_DATA fd;
				private long fileId;

				public IntFileSysBindData()
				{
				}

				public long GetFileID() => fileId;

				public void GetFindData(out WIN32_FIND_DATA pfd) => pfd = fd;

				[return: MarshalAs(UnmanagedType.LPStruct)]
				public Guid GetJunctionCLSID() => clsidJunction != CLSID_UnknownJunction ? clsidJunction : throw new COMException("Unable to handle junctions", unchecked((int)HRESULT.E_FAIL));

				public void SetFileID(long liFileID) => fileId = liFileID;

				public void SetFindData(in WIN32_FIND_DATA pfd) => fd = pfd;

				public void SetJunctionCLSID(in Guid clsid) => clsidJunction = clsid;
			}
		}
	}
}