using Microsoft.Win32;
using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Vanara.Windows.Shell.Registration;
using static Vanara.PInvoke.ShlwApi;

namespace Vanara.Windows.Shell
{
	/// <summary>Represents a programmatic identifier in the registry for an application.</summary>
	/// <example>
	/// <code title="Register a ProgId with a verb and associated extension.">
	///using (var progId = ProgId.Register("Company.Product.1", "My first product", systemWide))
	///{
	///   progId.Verbs.Add("open", "Open", Application.ExecutablePath);
	///   progId.FileTypeAssociations.Add(".txt");
	///}
	/// </code>
	/// </example>
	/// <seealso cref="System.IDisposable"/>
	public class ProgId : RegBasedSettings
	{
		private const string OpenWithProgIds = "OpenWithProgIds";

		internal ProgId(string progId, RegistryKey pkey, bool readOnly) : base(pkey, readOnly)
		{
			ID = progId;
			FileTypeAssociations = new FileTypeCollection(progId, readOnly, IsSystemWide);
			Verbs = new CommandVerbDictionary(this, readOnly);
		}

		/// <summary>
		/// Gets a value indicating whether to signal that Windows should ignore this ProgID when determining a default handler for a public
		/// file type. Regardless of whether this value is set, the ProgID continues to appear in the OpenWith shortcut menu and dialog.
		/// </summary>
		public bool AllowSilentDefaultTakeOver
		{
			get => key.HasSubKey("AllowSilentDefaultTakeOver");
			set => ToggleKeyValue("AllowSilentDefaultTakeOver", value);
		}

		/// <summary>Overrides one of the folder options that hides the extension of known file types.</summary>
		public bool AlwaysShowExt
		{
			get => key.HasValue("AlwaysShowExt");
			set => ToggleValue("AlwaysShowExt", value);
		}

		/// <summary>
		/// Gets the application's explicit Application User Model ID (AppUserModelID) if the application uses an explicit AppUserModelID
		/// and uses either the system's automatically generated Recent or Frequent Jump Lists or provides a custom Jump List. If an
		/// application uses an explicit AppUserModelID and does not set this value, items will not appear in that application's Jump Lists.
		/// </summary>
		public string AppUserModelID
		{
			get => key.GetValue("AppUserModelID")?.ToString();
			set => UpdateValue("AppUserModelID", value);
		}

		/// <summary>Gets or sets the CLSID of the COM server associated with this ProgId.</summary>
		public Guid? CLSID
		{
			get { var s = key.GetSubKeyDefaultValue("CLSID")?.ToString(); return s == null ? (Guid?)null : new Guid(s); }
			set => UpdateKeyValue("CLSID", value?.ToRegString());
		}

		/// <summary>Gets or sets the versioned ProgId for this instance.</summary>
		public string CurVer
		{
			get => key.GetSubKeyDefaultValue("CurVer")?.ToString();
			set => UpdateKeyValue("CurVer", value);
		}

		/// <summary>Gets the default icon to display for file types associated with this ProgID.</summary>
		public IconLocation DefaultIcon
		{
			get => IconLocation.TryParse(key.GetSubKeyDefaultValue("DefaultIcon")?.ToString(), out var loc) ? loc : null;
			set => UpdateKeyValue("DefaultIcon", value?.ToString());
		}

		/// <summary>
		/// Gets flags that control some aspects of the Shell's handling of the file types linked to this ProgID. EditFlags may also limit
		/// how much the user can modify certain aspects of these file types using a file's property sheet.
		/// </summary>
		public FILETYPEATTRIBUTEFLAGS EditFlags
		{
			get
			{
				var val = key.GetValue("EditFlags", 0);
				if (val is byte[] b) val = BitConverter.ToInt32(b, 0);
				if (val is int i) return (FILETYPEATTRIBUTEFLAGS)i;
				throw new InvalidOperationException("Unable to retrieve EditFlags value.");
			}
			set => UpdateValue("EditFlags", (uint)value, RegistryValueKind.DWord, (uint)FILETYPEATTRIBUTEFLAGS.FTA_None);
		}

		/// <summary>Gets or sets the list of properties to show in the listview on extended tiles.</summary>
		public PropertyDescriptionList ExtendedTileInfo
		{
			get => GetPDL(key, "ExtendedTileInfo");
			set => UpdateValue("ExtendedTileInfo", value?.ToString());
		}

		/// <summary>A collection of extensions with which this ProgId is associated.</summary>
		public ICollection<string> FileTypeAssociations { get; }

		/// <summary>
		/// Gets a friendly name for that ProgID, suitable to display to the user. The use of this entry to hold the friendly name is
		/// deprecated by the FriendlyTypeName entry on systems running Windows 2000 or later. However, it may be set for backward compatibility.
		/// </summary>
		public string FriendlyName
		{
			get => key.GetValue(null)?.ToString();
			set => UpdateValue(null, value ?? "");
		}

		/// <summary>Gets the friendly name for the ProgID, suitable to display to the user.</summary>
		public IndirectString FriendlyTypeName
		{
			get => IndirectString.TryParse(key.GetValue("FriendlyTypeName")?.ToString(), out var loc) ? loc : null;
			set => UpdateValue("FriendlyTypeName", value?.ToString());
		}

		/// <summary>Gets or sets the list of all the properties to show in the details page.</summary>
		public PropertyDescriptionList FullDetails
		{
			get => GetPDL(key, "FullDetails");
			set => UpdateValue("FullDetails", value?.ToString());
		}

		/// <summary>Gets the programmatic identifier.</summary>
		public string ID { get; }

		/// <summary>
		/// Gets the brief help message that the Shell displays for this ProgID. This may be a string, a IndirectString, or a PropertyDescriptionList.
		/// </summary>
		public object InfoTip
		{
			get
			{
				var val = key.GetValue("InfoTip")?.ToString();
				if (val == null) return null;
				if (val.StartsWith("@")) return IndirectString.TryParse(val, out var loc) ? loc : null;
				if (val.StartsWith("prop:")) return new PropertyDescriptionList(val);
				return val;
			}
			set => UpdateValue("InfoTip", value?.ToString());
		}

		/// <summary>
		/// Allows an application to register a file name extension as a shortcut file type. If a file has a file name extension that has
		/// been registered as a shortcut file type, the system automatically adds the system-defined link overlay icon (a small arrow) to
		/// the file's icon.
		/// </summary>
		public bool IsShortcut
		{
			get => key.HasValue("IsShortcut");
			set => ToggleValue("IsShortcut", value);
		}

		/// <summary>Gets or sets a value indicating that the extension is never to be shown regardless of folder options.</summary>
		public bool NeverShowExt
		{
			get => key.HasValue("NeverShowExt");
			set => ToggleValue("NeverShowExt", value);
		}

		/// <summary>
		/// Specifies that the associated ProgId should not be opened by users. The value is presented as a warning to users. Use <see
		/// cref="string.Empty"/> to use the system prompt.
		/// </summary>
		public string NoOpen
		{
			get => key.GetValue("NoOpen")?.ToString();
			set => UpdateValue("NoOpen", value);
		}

		/// <summary>Gets or sets the list of properties to display in the preview pane.</summary>
		public PropertyDescriptionList PreviewDetails
		{
			get => GetPDL(key, "PreviewDetails");
			set => UpdateValue("PreviewDetails", value?.ToString());
		}

		/// <summary>Gets or sets the one or two properties to display in the preview pane title section.</summary>
		public PropertyDescriptionList PreviewTitle
		{
			get => GetPDL(key, "PreviewTitle");
			set => UpdateValue("PreviewTitle", value?.ToString());
		}

		/// <summary>Gets or sets the list of properties to show in the listview on tiles.</summary>
		public PropertyDescriptionList TileInfo
		{
			get => GetPDL(key, "TileInfo");
			set => UpdateValue("TileInfo", value?.ToString());
		}

		/// <summary>Gets the command verbs associated with this ProgID.</summary>
		public CommandVerbDictionary Verbs { get; }

		/// <summary>Initializes a new instance of the <see cref="ProgId"/> class.</summary>
		/// <param name="progId">The programmatic identifier string.</param>
		/// <param name="readOnly">
		/// If <see langword="true"/>, provides read-only access to the registration; If <see langword="false"/>, the properties can be set
		/// to update the registration values.
		/// </param>
		/// <param name="autoLoadVersioned">
		/// if set to <c>true</c> automatically load a referenced versioned ProgId instead of the specified ProgId.
		/// </param>
		/// <param name="systemWide">
		/// If <see langword="true"/>, open the ProgId for system-wide use. If <see langword="false"/>, open the ProgId for the current user only.
		/// </param>
		/// <returns>The requested <see cref="ProgId"/> instance.</returns>
		public static ProgId Open(string progId, bool readOnly = true, bool autoLoadVersioned = true, bool systemWide = false)
		{
			var key = ShellRegistrar.GetRoot(systemWide, !readOnly, progId ?? throw new ArgumentNullException(nameof(progId)));
			if (autoLoadVersioned)
			{
				var cv = key?.GetSubKeyDefaultValue("CurVer")?.ToString();
				if (cv != null && cv != progId)
				{
					key.Close();
					key = ShellRegistrar.GetRoot(systemWide, !readOnly, cv);
				}
			}
			if (key is null) throw new ArgumentException("Unable to load specified ProgId", nameof(progId));
			return new ProgId(progId, key, readOnly);
		}

		/// <summary>Registers the programmatic identifier (ProgId).</summary>
		/// <param name="progId">
		/// The key name for the ProgId. The proper format of a ProgID key name is [Vendor or Application].[Component].[Version], separated
		/// by periods and with no spaces, as in Word.Document.6. The Version portion is optional but strongly recommended.
		/// </param>
		/// <param name="friendlyName">
		/// The friendly name for this ProgID, suitable to display to the user. The use of this entry to hold the friendly name is
		/// overridden by the FriendlyTypeName entry on systems running Windows 2000 or later.
		/// </param>
		/// <param name="systemWide">
		/// If <see langword="true"/>, register the ProgId system-wide. If <see langword="false"/>, register the ProgId for the current user only.
		/// </param>
		/// <returns>A <see cref="ProgId"/> instance to continue definition of ProgId settings.</returns>
		public static ProgId Register(string progId, string friendlyName, bool systemWide = false)
		{
			if (progId == null) throw new ArgumentNullException(nameof(progId));
			if (progId.Length > 39 || !System.Text.RegularExpressions.Regex.IsMatch(progId, @"^[a-zA-Z][\w\.]+$", System.Text.RegularExpressions.RegexOptions.Singleline))
				throw new ArgumentException("A ProgID may not have more then 39 characters, must start with a letter, and may only contain letters, numbers and periods.");
			using var root = ShellRegistrar.GetRoot(systemWide, true);
			return new ProgId(progId, root.CreateSubKey(progId, friendlyName), false);
		}

		/// <summary>Unregisters the ProgID.</summary>
		/// <param name="progId">The key for the ProgID. The function will succeed even if this value does not exists.</param>
		/// <param name="withFileExt">If set to <see langword="true"/>, also remove all associated registered file extensions.</param>
		/// <param name="systemWide">
		/// If <see langword="true"/>, register the ProgId system-wide. If <see langword="false"/>, register the ProgId for the current user only.
		/// </param>
		public static void Unregister(string progId, bool withFileExt = true, bool systemWide = false)
		{
			if (progId is null) return;
			using var reg = ShellRegistrar.GetRoot(systemWide, true);

			if (withFileExt)
			{
				foreach (var ext in GetAssociatedFileExtensions(progId, systemWide))
				{
					using var ftype = FileTypeAssociation.Open(ext, systemWide, false);
					if (ftype.DefaultProgId == progId)
						ftype.DefaultProgId = null;
					ftype.OpenWithProgIds.Remove(progId);
				}
			}

			try { reg.DeleteSubKeyTree(progId); }
			catch { reg.DeleteSubKey(progId, false); }

			ShellRegistrar.NotifyShell();
		}

		/// <inheritdoc/>
		public override void Dispose()
		{
			base.Dispose();
			ShellRegistrar.NotifyShell();
		}

		internal static IEnumerable<string> GetAssociatedFileExtensions(string progId, bool systemWide = false)
		{
			using var root = ShellRegistrar.GetRoot(systemWide, false);
			foreach (var ext in root.GetSubKeyNames().Where(ext => ext.StartsWith(".")))
			{
				var hasValue = false;
				using (var openWithKey = root.OpenSubKey(Path.Combine(ext, OpenWithProgIds)))
					hasValue = openWithKey?.HasValue(progId) ?? false;
				if (hasValue)
					yield return ext;
			}
		}

		private static PropertyDescriptionList GetPDL(RegistryKey key, string valueName)
		{
			var pdl = key.GetValue(valueName)?.ToString();
			return pdl == null ? null : new PropertyDescriptionList(pdl);
		}
	}

	/// <summary>A virtual collection of file types associated with a ProgId in the Windows Registry.</summary>
	class FileTypeCollection : ICollection<string>
	{
		protected internal string progId;

		protected internal FileTypeCollection(string progId, bool readOnly, bool systemWide)
		{
			this.progId = progId ?? throw new ArgumentNullException(nameof(progId));
			IsReadOnly = readOnly;
			IsSystemWide = systemWide;
		}

		/// <summary>Gets the count.</summary>
		/// <value>The count.</value>
		public int Count => Enum().Count();

		/// <summary>Gets or sets a value indicating whether these settings are read-only.</summary>
		public bool IsReadOnly { get; }

		/// <summary>Gets or sets a value indicating whether these settings are read-only.</summary>
		public bool IsSystemWide { get; }

		/// <summary>Adds the specified item.</summary>
		/// <param name="ext">The extension to associate.</param>
		public void Add(string ext)
		{
			EnsureWritable();
			using var assoc = FileTypeAssociation.Register(ext, IsSystemWide);
			assoc.OpenWithProgIds.Add(progId);
		}

		/// <summary>Clears this instance.</summary>
		public void Clear() => throw new NotSupportedException();

		/// <summary>Determines whether this instance contains the object.</summary>
		/// <param name="item">The item.</param>
		/// <returns><see langword="true"/> if [contains] [the specified item]; otherwise, <see langword="false"/>.</returns>
		public bool Contains(string item) => ShellRegistrar.GetRoot(IsSystemWide, false, Path.Combine(item, "OpenWithProgIds")).HasValue(progId);

		/// <summary>Copies to.</summary>
		/// <param name="array">The array.</param>
		/// <param name="arrayIndex">Index of the array.</param>
		public void CopyTo(string[] array, int arrayIndex) => Array.Copy(Enum().ToArray(), 0, array, arrayIndex, Count);

		/// <summary>Gets the enumerator.</summary>
		/// <returns></returns>
		public IEnumerator<string> GetEnumerator() => Enum().GetEnumerator();

		/// <summary>Removes the specified item.</summary>
		/// <param name="item">The item.</param>
		/// <returns></returns>
		public bool Remove(string item)
		{
			EnsureWritable();
			using var openWithKey = ShellRegistrar.GetRoot(IsSystemWide, true, Path.Combine(item, "OpenWithProgIds"));
			try
			{
				openWithKey.DeleteValue(progId, true);
				return true;
			}
			catch { return false; }
		}

		/// <summary>Gets the enumerator.</summary>
		/// <returns></returns>
		System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() => GetEnumerator();

		/// <summary>Checks the ReadOnly flag and throws an exception if it is true.</summary>
		protected void EnsureWritable() { if (IsReadOnly) throw new NotSupportedException("The collection is read only."); }

		private IEnumerable<string> Enum() => ProgId.GetAssociatedFileExtensions(progId, IsSystemWide);
	}
}