using System;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms;
using System.Windows.Forms.VisualStyles;
using Vanara.Drawing;
using Vanara.Extensions;
using static Vanara.PInvoke.ComCtl32;
using static Vanara.PInvoke.UxTheme;
using static Vanara.PInvoke.Macros;
using static Vanara.PInvoke.User32;
using ComboBoxStyle = System.Windows.Forms.ComboBoxStyle;

namespace Vanara.Windows.Forms
{
	/// <summary>Interface that exposes an <c>Enabled</c> property for an item supplied to <see cref="DisabledItemComboBox"/>.</summary>
	public interface IEnableable
	{
		/// <summary>Gets a value indicating whether an item is enabled.</summary>
		/// <value><c>true</c> if enabled; otherwise, <c>false</c>.</value>
		bool Enabled { get; }
	}

	/// <summary>A version of <see cref="ComboBox"/> that allows for disabled items.</summary>
	[ToolboxBitmap(typeof(DisabledItemComboBox), "Control")]
	public class DisabledItemComboBox : ComboBox
	{
		private const TextFormatFlags tff = TextFormatFlags.Default | TextFormatFlags.VerticalCenter | TextFormatFlags.SingleLine | TextFormatFlags.NoPadding;

		private bool animationsNeedCleanup;
		private ComboBoxState currentState = ComboBoxState.Normal, newState = ComboBoxState.Normal;
		private ListBoxNativeWindow dropDownWindow;
		private readonly VisualStyleRenderer vsr;

		/// <summary>Initializes a new instance of the <see cref="DisabledItemComboBox"/> class.</summary>
		public DisabledItemComboBox()
		{
			SetStyle(/*ControlStyles.Opaque |*/ ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint, true);
			DrawMode = DrawMode.OwnerDrawFixed;
			DropDownStyle = ComboBoxStyle.DropDownList;
			if (Environment.OSVersion.Version.Major >= 6 && VisualStyleRenderer.IsSupported && Application.RenderWithVisualStyles)
				vsr = new VisualStyleRenderer("COMBOBOX", 5, 0);
		}

		/// <summary>
		/// Gets or sets a value indicating whether your code or the operating system will handle drawing of elements in the list.
		/// </summary>
		/// <returns>One of the <see cref="T:System.Windows.Forms.DrawMode"/> enumeration values. The default is <see cref="F:System.Windows.Forms.DrawMode.Normal"/>.</returns>
		/// <PermissionSet><IPermission class="System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/><IPermission class="System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/><IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode, ControlEvidence"/><IPermission class="System.Diagnostics.PerformanceCounterPermission, System, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/></PermissionSet>
		[DefaultValue(DrawMode.OwnerDrawFixed), Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
		public new DrawMode DrawMode
		{
			get => base.DrawMode;
			set => base.DrawMode = value;
		}

		/// <summary>Gets or sets a value specifying the style of the combo box.</summary>
		/// <returns>One of the <see cref="T:System.Windows.Forms.ComboBoxStyle"/> values. The default is DropDown.</returns>
		/// <PermissionSet><IPermission class="System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/><IPermission class="System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/><IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode, ControlEvidence"/><IPermission class="System.Diagnostics.PerformanceCounterPermission, System, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/></PermissionSet>
		[DefaultValue(ComboBoxStyle.DropDownList), Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
		public new ComboBoxStyle DropDownStyle
		{
			get => base.DropDownStyle;
			set => base.DropDownStyle = value;
		}

		/// <summary>Gets or sets the state of the combobox.</summary>
		/// <value>The state.</value>
		private ComboBoxState State
		{
			get => currentState;
			set
			{
				var diff = !Equals(currentState, value);
				newState = value;
				if (diff)
				{
					if (animationsNeedCleanup && IsHandleCreated && !IsDisposed)
						BufferedPaintStopAllAnimations(Handle);
					Invalidate();
				}
			}
		}

		/// <summary>Determines whether an item is enabled.</summary>
		/// <param name="idx">The index of the item.</param>
		/// <returns><c>true</c> if enabled; otherwise, <c>false</c>.</returns>
		public bool IsItemEnabled(int idx) => !(idx > -1 && idx < Items.Count && Items[idx] is IEnableable && !((IEnableable)Items[idx]).Enabled);

		/// <summary>
		/// Releases the unmanaged resources used by the <see cref="T:System.Windows.Forms.ComboBox"/> and optionally releases the managed resources.
		/// </summary>
		/// <param name="disposing">true to release both managed and unmanaged resources; false to release only unmanaged resources.</param>
		protected override void Dispose(bool disposing)
		{
			if (animationsNeedCleanup && !IsDisposed)
			{
				BufferedPaintUnInit();
				animationsNeedCleanup = false;
			}
			base.Dispose(disposing);
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.ComboBox.DrawItem"/> event.</summary>
		/// <param name="e">A <see cref="T:System.Windows.Forms.DrawItemEventArgs"/> that contains the event data.</param>
		protected override void OnDrawItem(DrawItemEventArgs e)
		{
			var itemString = e.Index >= 0 ? GetItemText(Items[e.Index]) : string.Empty;

			if ((e.State & DrawItemState.ComboBoxEdit) != DrawItemState.ComboBoxEdit)
			{
				if (e.Index >= 0)
				{
					var iEnabled = IsItemEnabled(e.Index);
					if (iEnabled)
					{
						e.DrawBackground();
						e.DrawFocusRectangle();
					}
					else
					{
						using (var bb = new SolidBrush(e.BackColor))
							e.Graphics.FillRectangle(bb, e.Bounds);
					}
					TextRenderer.DrawText(e.Graphics, itemString, e.Font, Rectangle.Inflate(e.Bounds, -2, 0), iEnabled ? e.ForeColor : SystemColors.GrayText, tff);
				}
			}
			base.OnDrawItem(e);
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.ComboBox.DropDown"/> event.</summary>
		/// <param name="e">An <see cref="T:System.EventArgs"/> that contains the event data.</param>
		protected override void OnDropDown(EventArgs e)
		{
			base.OnDropDown(e);
			State = ComboBoxState.Pressed;
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.ComboBox.DropDownClosed"/> event.</summary>
		/// <param name="e">An <see cref="T:System.EventArgs"/> that contains the event data.</param>
		protected override void OnDropDownClosed(EventArgs e)
		{
			base.OnDropDownClosed(e);
			State = ComboBoxState.Normal;
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.Control.HandleCreated"/> event.</summary>
		/// <param name="e">An <see cref="T:System.EventArgs"/> that contains the event data.</param>
		protected override void OnHandleCreated(EventArgs e)
		{
			base.OnHandleCreated(e);
			if (vsr != null)
			{
				BufferedPaintInit();
				animationsNeedCleanup = true;
			}
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.Control.HandleDestroyed"/> event.</summary>
		/// <param name="e">An <see cref="T:System.EventArgs"/> that contains the event data.</param>
		protected override void OnHandleDestroyed(EventArgs e)
		{
			dropDownWindow?.ReleaseHandle();
			dropDownWindow = null;
			base.OnHandleDestroyed(e);
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.Control.KeyPress"/> event.</summary>
		/// <param name="e">A <see cref="T:System.Windows.Forms.KeyPressEventArgs"/> that contains the event data.</param>
		protected override void OnKeyPress(KeyPressEventArgs e)
		{
			var idx = FindEnabledString(e.KeyChar.ToString(), SelectedIndex);
			if (idx == -1 || idx == SelectedIndex)
				e.Handled = true;
			base.OnKeyPress(e);
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.Control.LostFocus"/> event.</summary>
		/// <param name="e">An <see cref="T:System.EventArgs"/> that contains the event data.</param>
		protected override void OnLostFocus(EventArgs e)
		{
			base.OnLostFocus(e);
			Invalidate();
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.Control.MouseDown"/> event.</summary>
		/// <param name="e">A <see cref="T:System.Windows.Forms.MouseEventArgs"/> that contains the event data.</param>
		protected override void OnMouseDown(MouseEventArgs e)
		{
			base.OnMouseDown(e);
			State = ComboBoxState.Pressed;
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.Control.MouseEnter"/> event.</summary>
		/// <param name="e">An <see cref="T:System.EventArgs"/> that contains the event data.</param>
		protected override void OnMouseEnter(EventArgs e)
		{
			base.OnMouseEnter(e);
			State = ComboBoxState.Hot;
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.Control.MouseLeave"/> event.</summary>
		/// <param name="e">An <see cref="T:System.EventArgs"/> that contains the event data.</param>
		protected override void OnMouseLeave(EventArgs e)
		{
			base.OnMouseLeave(e);
			if (State != ComboBoxState.Pressed)
				State = ComboBoxState.Normal;
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.Control.MouseMove"/> event.</summary>
		/// <param name="e">A <see cref="T:System.Windows.Forms.MouseEventArgs"/> that contains the event data.</param>
		protected override void OnMouseMove(MouseEventArgs e)
		{
			base.OnMouseMove(e);
			if (State != ComboBoxState.Pressed)
				State = ComboBoxState.Hot;
		}

		/// <summary>Raises the <see cref="E:System.Windows.Forms.Control.Paint"/> event.</summary>
		/// <param name="e">A <see cref="T:System.Windows.Forms.PaintEventArgs"/> that contains the event data.</param>
		protected override void OnPaint(PaintEventArgs e)
		{
			base.OnPaint(e);

			if (IsDisposed)
				return;

			BufferedPaint.PaintAnimation(e.Graphics, this, ClientRectangle, PaintControl, currentState, Enabled ? newState : ComboBoxState.Disabled, (a, b) => (int)vsr.GetTransitionDuration((int)a, (int)b));
		}

		/// <summary>Paints the background of the control.</summary>
		/// <param name="pevent">A <see cref="T:System.Windows.Forms.PaintEventArgs"/> that contains information about the control to paint.</param>
		protected override void OnPaintBackground(PaintEventArgs pevent)
		{
			// don't paint the control's background
		}

		/// <summary>Paints the control.</summary>
		/// <param name="dc">The dc.</param>
		/// <param name="bounds">The bounds.</param>
		/// <param name="state">State of the current.</param>
		/// <param name="data">The data.</param>
		protected virtual void PaintControl(Graphics dc, Rectangle bounds, ComboBoxState state, int data)
		{
			var cbi = COMBOBOXINFO.FromHandle(Handle);

			var itemText = SelectedIndex >= 0 ? GetItemText(SelectedItem) : string.Empty;
			Rectangle tr = cbi.rcItem;
			/*Rectangle tr = bounds;
			tr.Width -= (SystemInformation.VerticalScrollBarWidth + 2);
			tr.Inflate(0, -2);
			tr.Offset(1, 0);*/
			Rectangle br = cbi.rcButton;
			var vsSuccess = false;
			if (vsr != null)
			{
				/*Rectangle r = Rectangle.Inflate(bounds, 1, 1);
				if (this.DropDownStyle != ComboBoxStyle.DropDownList)
				{
					dc.Clear(this.BackColor);
					ComboBoxRenderer.DrawTextBox(dc, r, itemText, this.Font, tr, tff, state);
					ComboBoxRenderer.DrawDropDownButton(dc, br, state);
				}
				else*/
				{
					try
					{
						vsr.DrawParentBackground(dc, bounds, this);
						vsr.DrawBackground(dc, bounds);
						if (DropDownStyle != ComboBoxStyle.DropDownList) br.Inflate(1, 1);
						var cr = DropDownStyle == ComboBoxStyle.DropDownList ? Rectangle.Inflate(br, -1, -1) : br;
						vsr.SetState((int)(br.Contains(PointToClient(Cursor.Position)) ? state : ComboBoxState.Normal));
						vsr.DrawBackground(dc, br, cr);
						if (Focused && State != ComboBoxState.Pressed)
						{
							var sz = TextRenderer.MeasureText(dc, "Wg", Font, tr.Size, TextFormatFlags.Default);
							var fr = Rectangle.Inflate(tr, 0, (sz.Height - tr.Height) / 2 + 1);
							ControlPaint.DrawFocusRectangle(dc, fr);
						}
						TextRenderer.DrawText(dc, itemText, Font, tr, ForeColor, tff);
						vsSuccess = true;
					}
					catch { }
				}
			}

			if (!vsSuccess)
			{
				System.Diagnostics.Debug.WriteLine($"CR:{bounds};Foc:{Focused};St:{state};Tx:{itemText}");
				var bgc = Enabled ? BackColor : SystemColors.Control;
				dc.Clear(bgc);
				ControlPaint.DrawBorder3D(dc, bounds, Border3DStyle.Sunken);
				ControlPaint.DrawComboButton(dc, br, Enabled ? (state == ComboBoxState.Pressed ? ButtonState.Pushed : ButtonState.Normal) : ButtonState.Inactive);
				//using (var bb = new SolidBrush(this.BackColor))
				//	dc.FillRectangle(bb, tr);
				if (Focused)
				{
					var sz = TextRenderer.MeasureText(dc, "Wg", Font, tr.Size, TextFormatFlags.Default);
					var fr = Rectangle.Inflate(tr, 0, (sz.Height - tr.Height) / 2 + 1);
					dc.FillRectangle(SystemBrushes.Highlight, fr);
					ControlPaint.DrawFocusRectangle(dc, fr); //, this.ForeColor, SystemColors.Highlight);
				}
				TextRenderer.DrawText(dc, itemText, Font, tr, Focused ? SystemColors.HighlightText : (Enabled ? ForeColor : SystemColors.GrayText), bgc, tff);
			}
		}

		/// <summary>Processes a command key.</summary>
		/// <param name="msg">
		/// A <see cref="T:System.Windows.Forms.Message"/>, passed by reference, that represents the window message to process.
		/// </param>
		/// <param name="keyData">One of the <see cref="T:System.Windows.Forms.Keys"/> values that represents the key to process.</param>
		/// <returns>true if the character was processed by the control; otherwise, false.</returns>
		protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
		{
			var visItems = DropDownHeight / ItemHeight;
			switch (keyData)
			{
				case Keys.Down:
				case Keys.Right:
					SelectedIndex = GetNextEnabledItemIndex(SelectedIndex, true);
					return true;

				case Keys.Up:
				case Keys.Left:
					SelectedIndex = GetNextEnabledItemIndex(SelectedIndex, false);
					return true;

				case Keys.PageDown:
					if (SelectedIndex + visItems > Items.Count)
						SelectedIndex = GetNextEnabledItemIndex(Items.Count, false);
					else
						SelectedIndex = GetNextEnabledItemIndex(SelectedIndex + visItems, true);
					return true;

				case Keys.PageUp:
					if (SelectedIndex - visItems < 0)
						SelectedIndex = GetNextEnabledItemIndex(-1, true);
					else
						SelectedIndex = GetNextEnabledItemIndex(SelectedIndex - visItems, false);
					return true;

				case Keys.Home:
					SelectedIndex = GetNextEnabledItemIndex(-1, true);
					return true;

				case Keys.End:
					SelectedIndex = GetNextEnabledItemIndex(Items.Count, false);
					return true;

				case Keys.Enter:
					var pt = dropDownWindow?.MapPointToClient(Cursor.Position) ?? default;
					var idx = dropDownWindow?.IndexFromPoint(pt.X, pt.Y) ?? default;
					if (idx >= 0 && IsItemEnabled(idx))
						return false;
					DroppedDown = false;
					return true;

				case Keys.Escape:
					DroppedDown = false;
					return true;
			}
			return base.ProcessCmdKey(ref msg, keyData);
		}

		/// <summary>Processes Windows messages.</summary>
		/// <param name="m">The Windows <see cref="T:System.Windows.Forms.Message"/> to process.</param>
		protected override void WndProc(ref Message m)
		{
			base.WndProc(ref m);
			if ((int)(long)m.WParam == 0x3e80001 && !IsDisposed)
			{
				dropDownWindow = new ListBoxNativeWindow(m.LParam, this);
			}
		}

		private int FindEnabledString(string str, int startIndex)
		{
			if (str != null)
			{
				if (startIndex < -1 || startIndex >= Items.Count)
					return -1;
				var length = str.Length;
				var num2 = 0;
				for (var i = (startIndex + 1) % Items.Count; num2 < Items.Count; i = (i + 1) % Items.Count)
				{
					num2++;
					if (IsItemEnabled(i) && string.Compare(str, 0, GetItemText(Items[i]), 0, length, true, System.Globalization.CultureInfo.CurrentUICulture) == 0)
						return i;
				}
			}
			return -1;
		}

		private int GetNextEnabledItemIndex(int startIndex, bool forward = true)
		{
			if (forward)
			{
				for (var i = startIndex + 1; i < Items.Count; i++)
				{
					if (IsItemEnabled(i))
						return i;
				}
				return startIndex;
			}
			else
			{
				for (var i = startIndex - 1; i >= 0; i--)
				{
					if (IsItemEnabled(i))
						return i;
				}
				return startIndex;
			}
		}

		private class ListBoxNativeWindow : NativeWindow
		{
			private readonly DisabledItemComboBox Parent;

			public ListBoxNativeWindow(IntPtr handle, DisabledItemComboBox parent)
			{
				Parent = parent;
				AssignHandle(handle);
			}

			public int IndexFromPoint(int x, int y)
			{
				var n = SendMessage(Handle, 0x1a9u /* LB_ITEMFROMPOINT */, IntPtr.Zero, MAKELPARAM((ushort)x, (ushort)y));
				if (HIWORD(n) == 0)
					return LOWORD(n);
				return -1;
			}

			protected override void WndProc(ref Message m)
			{
				if (!Parent.IsDisposed && m.Msg == 0x0202 || m.Msg == 0x0201 || m.Msg == 0x0203) /* WM_LBUTTONUP or WM_LBUTTONDOWN or WM_LBUTTONDBLCLK */
				{
					var idx = IndexFromPoint(SignedLOWORD(m.LParam), SignedHIWORD(m.LParam));
					if (idx >= 0 && !Parent.IsItemEnabled(idx))
						return;
				}
				base.WndProc(ref m);
			}
		}
	}
}