using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Security.AccessControl;
using System.Security.Principal;
using Vanara.Extensions;
using Vanara.Security;
using static Vanara.PInvoke.NetApi32;

namespace Vanara
{
	/// <summary>Offline settings for a shared folder.</summary>
	public enum ShareOfflineSettings
	{
		/// <summary>Only the files and programs that users specify are available offline.</summary>
		OnlySpecified = SHI1005_FLAGS.CSC_CACHE_MANUAL_REINT,

		/// <summary>All files and programs that users open from the shared folder are automatically available offline.</summary>
		All = SHI1005_FLAGS.CSC_CACHE_AUTO_REINT,

		/// <summary>
		/// All files and programs that users open from the shared folder are automatically available offline and are cached for performance.
		/// </summary>
		AllOptimized = SHI1005_FLAGS.CSC_CACHE_VDO,

		/// <summary>No files or programs from the shared folder are available offline.</summary>
		None = SHI1005_FLAGS.CSC_CACHE_NONE,
	}

	/// <summary>Represents an open file associated with a share.</summary>
	public class OpenFile
	{
		private FILE_INFO_3 fi;

		internal OpenFile(in FILE_INFO_3 i) => fi = i;

		/// <summary>Gets the number of file locks on the file, device, or pipe.</summary>
		/// <value>Returns a <see cref="int"/> value.</value>
		public int FileLockCount => (int)fi.fi3_num_locks;

		/// <summary>Gets the path of the opened resource.</summary>
		/// <value>Returns a <see cref="string"/> value.</value>
		public string FullPath => fi.fi3_pathname;

		/// <summary>Gets the identification number assigned to the resource when it is opened.</summary>
		/// <value>Returns a <see cref="int"/> value.</value>
		public int Id => (int)fi.fi3_id;

		/// <summary>
		/// Gets the string that specifies which user (on servers that have user-level security) or which computer (on servers that have
		/// share-level security) opened the resource. Note that Windows does not support share-level security.
		/// </summary>
		/// <value>The name of the user.</value>
		public string UserName => fi.fi3_username;
	}

	/// <summary>Represents a connection to a shared device.</summary>
	public class ShareConnection
	{
		private CONNECTION_INFO_1 ci;
		private SharedDevice share;

		internal ShareConnection(in CONNECTION_INFO_1 ci, SharedDevice dev)
		{
			this.ci = ci; share = dev;
		}

		/// <summary>
		/// If the server sharing the resource is running with user-level security, this value describes which user made the connection. If
		/// the server is running with share-level security, this value describes which computer (computername) made the connection. Note
		/// that Windows does not support share-level security.
		/// </summary>
		/// <value>Returns a <see cref="string"/> value.</value>
		public string ConnectedUser => ci.coni1_username;

		/// <summary>Gets the number of users on the connection.</summary>
		/// <value>Returns a <see cref="int"/> value.</value>
		public int ConnectedUserCount => (int)ci.coni1_num_users;

		/// <summary>Gets the duration that the connection has been established.</summary>
		/// <value>The duration of the connection.</value>
		public TimeSpan ConnectionDuration => TimeSpan.FromSeconds(ci.coni1_time);

		/// <summary>Gets the connection identification number.</summary>
		/// <value>Returns a <see cref="int"/> value.</value>
		public int Id => (int)ci.coni1_id;

		/// <summary>Gets the number of files currently open as a result of the connection.</summary>
		/// <value>Returns a <see cref="int"/> value.</value>
		public int OpenFileCount => (int)ci.coni1_num_opens;

		/// <summary>Gets the open files associated with this share.</summary>
		/// <value>Returns a <see cref="IEnumerable{OpenFile}"/> value.</value>
		public IEnumerable<OpenFile> OpenFiles => share.Id.Run(() => NetFileEnum<FILE_INFO_3>(share.Target, share.Path).Where(i => share.Path?.Length > 0 || i.fi3_pathname.StartsWith("\\")).Select(i => new OpenFile(i)));
	}

	/// <summary>Represents a shared device on a computer.</summary>
	/// <seealso cref="Vanara.INamedEntity"/>
	public class SharedDevice : INamedEntity
	{
		private STYPE type = (STYPE)uint.MaxValue;

		internal SharedDevice(string target, string netname, WindowsIdentity accessIdentity)
		{
			Id = accessIdentity;
			Target = target;
			Name = netname;
		}

		private delegate void Setter<T>(ref T value);

		/// <summary>
		/// Lists all connections made to this shared resource on the target server. If there is more than one user using this connection,
		/// then it is possible to get more than one structure for the same connection, but with a different user name.
		/// </summary>
		/// <value>Returns a <see cref="IEnumerable{ShareConnection}"/> value.</value>
		public IEnumerable<ShareConnection> Connections => Id.Run(() => NetConnectionEnum<CONNECTION_INFO_1>(Target, Name).Select(ci => new ShareConnection(ci, this)));

		/// <summary>Gets or sets an optional comment about the shared resource.</summary>
		/// <value>The resource description.</value>
		public string Description
		{
			get => GetInfo<SHARE_INFO_1>().shi1_remark;
			set => SetInfo((ref SHARE_INFO_1004 i) => i.shi1004_remark = value, false);
		}

		/// <summary>Gets a value indicating whether this instance is communication device.</summary>
		/// <value><see langword="true"/> if this instance is communication device; otherwise, <see langword="false"/>.</value>
		public bool IsCommDevice => (Type & STYPE.STYPE_MASK) == STYPE.STYPE_DEVICE;

		/// <summary>Gets a value indicating whether this instance is disk drive.</summary>
		/// <value><see langword="true"/> if this instance is disk drive; otherwise, <see langword="false"/>.</value>
		public bool IsDiskVolume => (Type & STYPE.STYPE_MASK) == STYPE.STYPE_DISKTREE;

		/// <summary>Gets a value indicating whether this instance is Interprocess Communication.</summary>
		/// <value><see langword="true"/> if this instance is Interprocess Communication; otherwise, <see langword="false"/>.</value>
		public bool IsIPC => (Type & STYPE.STYPE_MASK) == STYPE.STYPE_IPC;

		/// <summary>Gets a value indicating whether this instance is a print queue.</summary>
		/// <value><see langword="true"/> if this instance is a print queue; otherwise, <see langword="false"/>.</value>
		public bool IsPrintQueue => (Type & STYPE.STYPE_MASK) == STYPE.STYPE_PRINTQ;

		/// <summary>
		/// Gets a value indicating a special share reserved for interprocess communication (IPC$) or remote administration of the server
		/// (ADMIN$). Can also refer to administrative shares such as C$, D$, E$, and so forth.
		/// </summary>
		/// <value><see langword="true"/> if this instance is special; otherwise, <see langword="false"/>.</value>
		public bool IsSpecial => Type.IsFlagSet(STYPE.STYPE_SPECIAL);

		/// <summary>Gets a value indicating whether this instance is temporary.</summary>
		/// <value><see langword="true"/> if this instance is temporary; otherwise, <see langword="false"/>.</value>
		public bool IsTemporary => Type.IsFlagSet(STYPE.STYPE_TEMPORARY);

		/// <summary>Gets the share name of a resource.</summary>
		/// <value>Returns a <see cref="string"/> value.</value>
		public string Name { get; }

		/// <summary>Gets or sets the offline settings associated with a disk volume share.</summary>
		/// <value>The offline settings.</value>
		public ShareOfflineSettings OfflineSettings
		{
			get => (ShareOfflineSettings)(GetInfo<SHARE_INFO_1005>().shi1005_flags & SHI1005_FLAGS.CSC_MASK_EXT);
			set => SetInfo((ref SHARE_INFO_1005 i) => i.shi1005_flags = i.shi1005_flags & ~SHI1005_FLAGS.CSC_MASK | (SHI1005_FLAGS)value);
		}

		/// <summary>
		/// Gets or sets the local path for the shared resource. For disks, this is the path being shared. For print queues, this is the name
		/// of the print queue being shared.
		/// </summary>
		/// <value>
		/// Returns a <see cref="string"/> value. If the caller does not have rights to get this information, this property returns <see cref="string.Empty"/>.
		/// </value>
		public string Path
		{
			get { try { return GetInfo<SHARE_INFO_2>().shi2_path; } catch { return string.Empty; } }
			set => SetInfo((ref SHARE_INFO_2 i) => i.shi2_path = value);
		}

		/// <summary>Gets or sets the permissions of the shared resource.</summary>
		/// <value>
		/// The access permissions for the share. If the caller does not have rights to get this information, this property returns <see langword="null"/>.
		/// </value>
		public RawSecurityDescriptor Permissions
		{
			get { try { return GetInfo<SHARE_INFO_502>().shi502_security_descriptor.ToManaged(); } catch { return null; } }
			set => SetInfo((ref SHARE_INFO_502 i) => i.shi502_security_descriptor = value.ToNative());
		}

		/// <summary>
		/// Gets or sets the maximum number of concurrent connections that the shared resource can accommodate. The number of connections is
		/// unlimited if the value specified in this member is –1.
		/// </summary>
		/// <value>The maximum number of concurrent connections.</value>
		public int UserLimit
		{
			get { try { return unchecked((int)GetInfo<SHARE_INFO_2>().shi2_max_uses); } catch { return -1; } }
			set => SetInfo((ref SHARE_INFO_2 i) => i.shi2_max_uses = unchecked((uint)value));
		}

		internal WindowsIdentity Id { get; private set; }
		internal string Target { get; private set; }

		/// <summary>Gets the shared resource's permissions for servers running with share-level security.</summary>
		/// <value>Returns a <see cref="ShareLevelAccess"/> value.</value>
		private ShareLevelAccess Access => GetInfo<SHARE_INFO_2>().shi2_permissions;

		private STYPE Type => (uint)type == uint.MaxValue ? type = GetInfo<SHARE_INFO_1>().shi1_type : type;

		/// <summary>Creates the disk volume share.</summary>
		/// <param name="target">
		/// A string that specifies the DNS or NetBIOS name of the remote server on which the function is to execute. If this parameter is
		/// <see langword="null"/>, the local computer is used.
		/// </param>
		/// <param name="name">The share name of a resource.</param>
		/// <param name="comment">An optional comment about the shared resource.</param>
		/// <param name="path">
		/// The local path for the shared resource. For disks, this is the path being shared. For print queues, this is the name of the print
		/// queue being shared.
		/// </param>
		/// <returns>On success, a new instance of <see cref="SharedDevice"/> represented a newly created shared disk.</returns>
		public static SharedDevice CreateDiskVolumeShare(string target, string name, string comment, string path) =>
			Create(target, name, comment, path, STYPE.STYPE_DISKTREE, null);

		/// <summary>Creates the specified target.</summary>
		/// <param name="target">
		/// A string that specifies the DNS or NetBIOS name of the remote server on which the function is to execute. If this parameter is
		/// <see langword="null"/>, the local computer is used.
		/// </param>
		/// <param name="name">The share name of a resource.</param>
		/// <param name="comment">An optional comment about the shared resource.</param>
		/// <param name="path">
		/// The local path for the shared resource. For disks, this is the path being shared. For print queues, this is the name of the
		/// print queue being shared.
		/// </param>
		/// <param name="type">A combination of values that specify the type of the shared resource. The default is for disk drives.</param>
		/// <param name="identity">
		/// The identity of the user used to create the device. If this value is <see langword="null"/>, the current user's credentials are used.
		/// </param>
		/// <returns>On success, a new instance of <see cref="SharedDevice"/> represented a newly created shared resource.</returns>
		internal static SharedDevice Create([Optional] string target, string name, [Optional] string comment, string path, STYPE type = STYPE.STYPE_DISKTREE, WindowsIdentity identity = null)
		{
			identity.Run(() => NetShareAdd(target, new SHARE_INFO_2 { shi2_netname = name, shi2_remark = comment, shi2_path = path, shi2_max_uses = unchecked((uint)-1), shi2_type = type }));
			return new SharedDevice(target, name, identity);
		}

		private T GetInfo<T>() where T : struct => Id.Run(() => NetShareGetInfo<T>(Target, Name));

		private void SetInfo<T>(Setter<T> f, bool getFirst = true) where T : struct
		{
			Id.Run(() =>
			{
				var value = getFirst ? GetInfo<T>() : default;
				f(ref value);
				NetShareSetInfo(Target, Name, value);
			});
		}
	}

	/// <summary>Represents all the shared devices on a computers.</summary>
	public class SharedDevices : Collections.VirtualDictionary<string, SharedDevice>
	{
		private readonly WindowsIdentity identity;
		private readonly string target = null;

		/// <summary>Initializes a new instance of the <see cref="SharedDevices"/> class.</summary>
		/// <param name="serverName">Name of the computer from which to retrieve and manage the shared devices.</param>
		/// <param name="accessIdentity">
		/// The Windows identity used to access the shared device information. If this value <see langword="null"/>, the current identity is used.
		/// </param>
		public SharedDevices(string serverName = null, WindowsIdentity accessIdentity = null) : base(false)
		{
			target = serverName;
			identity = accessIdentity ?? WindowsIdentity.GetCurrent();
		}

		internal SharedDevices(Computer computer) : this(computer.Target, computer.Identity)
		{
		}

		/// <summary>Gets the number of elements contained in the <see cref="T:System.Collections.Generic.IDictionary`2"/>.</summary>
		/// <value>The number of elements contained in the <see cref="T:System.Collections.Generic.IDictionary`2"/>.</value>
		public override int Count
		{
			get
			{
				var h = 0U;
				var cnt = 0U;
				identity.Run(() => NetShareEnum(target, 0, out var _, MAX_PREFERRED_LENGTH, out cnt, out _, ref h).ThrowIfFailed());
				return (int)cnt;
			}
		}

		/// <summary>Gets an <see cref="T:System.Collections.Generic.ICollection`1"/> containing the keys of the <see cref="T:System.Collections.Generic.IDictionary`2"/>.</summary>
		/// <value>An <see cref="T:System.Collections.Generic.ICollection`1"/> containing the keys of the object that implements <see cref="T:System.Collections.Generic.IDictionary`2"/>.</value>
		public override ICollection<string> Keys => identity.Run(() => NetShareEnum<SHARE_INFO_0>(target).Select(i => i.shi0_netname).ToArray());

		/// <summary>Creates the specified target.</summary>
		/// <param name="name">The share name of a resource.</param>
		/// <param name="comment">An optional comment about the shared resource.</param>
		/// <param name="path">
		/// The local path for the shared resource. For disks, this is the path being shared. For print queues, this is the name of the print
		/// queue being shared.
		/// </param>
		/// <param name="type">A combination of values that specify the type of the shared resource.</param>
		/// <returns>On success, a new instance of <see cref="SharedDevice"/> represented a newly created shared resource.</returns>
		public SharedDevice Add(string name, string comment, string path, STYPE type = STYPE.STYPE_DISKTREE) => SharedDevice.Create(target, name, comment, path, type, identity);

		/// <summary>Removes the element with the specified key from the <see cref="T:System.Collections.Generic.IDictionary`2"/>.</summary>
		/// <param name="key">The key of the element to remove.</param>
		/// <returns>
		/// <see langword="true"/> if the element is successfully removed; otherwise, <see langword="false"/>. This method also returns false
		/// if key was not found in the original <see cref="T:System.Collections.Generic.IDictionary`2"/>.
		/// </returns>
		public override bool Remove(string key) => identity.Run(() => NetShareDel(target, key).Succeeded);

		/// <summary>Gets the value associated with the specified key.</summary>
		/// <param name="key">The key whose value to get.</param>
		/// <param name="value">
		/// When this method returns, the value associated with the specified key, if the key is found; otherwise, the default value for the
		/// type of the <paramref name="value"/> parameter. This parameter is passed uninitialized.
		/// </param>
		/// <returns>
		/// <see langword="true"/> if the <see cref="T:System.Collections.Generic.IDictionary`2"/> contains an element with the key;
		/// otherwise, <see langword="false"/>.
		/// </returns>
		public override bool TryGetValue(string key, out SharedDevice value)
		{
			value = ContainsKey(key) ? new SharedDevice(target, key, identity) : null;
			return !(value is null);
		}
	}
}