using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.Json.Serialization;

namespace Terminal.Gui;

/// <summary>
/// The <see cref="Dialog"/> <see cref="View"/> is a <see cref="Window"/> that by default is centered and contains one 
/// or more <see cref="Button"/>s. It defaults to the <see cref="Colors.Dialog"/> color scheme and has a 1 cell padding around the edges.
/// </summary>
/// <remarks>
///  To run the <see cref="Dialog"/> modally, create the <see cref="Dialog"/>, and pass it to <see cref="Application.Run(Func{Exception, bool})"/>. 
///  This will execute the dialog until it terminates via the [ESC] or [CTRL-Q] key, or when one of the views
///  or buttons added to the dialog calls <see cref="Application.RequestStop"/>.
/// </remarks>
public class Dialog : Window {
	/// <summary>
	/// The default <see cref="ButtonAlignments"/> for <see cref="Dialog"/>. 
	/// </summary>
	/// <remarks>
	/// This property can be set in a Theme.
	/// </remarks>
	[SerializableConfigurationProperty (Scope = typeof (ThemeScope))] [JsonConverter (typeof (JsonStringEnumConverter))]
	public static ButtonAlignments DefaultButtonAlignment { get; set; } = ButtonAlignments.Center;

	// TODO: Reenable once border/borderframe design is settled
	/// <summary>
	/// Defines the default border styling for <see cref="Dialog"/>. Can be configured via <see cref="ConfigurationManager"/>.
	/// </summary>
	//[SerializableConfigurationProperty (Scope = typeof (ThemeScope))]
	//public static Border DefaultBorder { get; set; } = new Border () {
	//	LineStyle = LineStyle.Single,
	//};
	internal List<Button> buttons = new ();

	/// <summary>
	/// Initializes a new instance of the <see cref="Dialog"/> class using <see cref="LayoutStyle.Computed"/> positioning 
	/// with no <see cref="Button"/>s.
	/// </summary>
	/// <remarks>
	/// By default, <see cref="View.X"/> and <see cref="View.Y"/> are set to <c>Pos.Center ()</c> and <see cref="View.Width"/> and <see cref="View.Height"/> are set 
	/// to <c>Width = Dim.Percent (85)</c>, centering the Dialog vertically and horizontally. 
	/// </remarks>
	public Dialog () : this (null) { }

	/// <summary>
	/// Initializes a new instance of the <see cref="Dialog"/> class using <see cref="LayoutStyle.Computed"/> positioning 
	/// and an optional set of <see cref="Button"/>s to display
	/// </summary>
	/// <param name="buttons">Optional buttons to lay out at the bottom of the dialog.</param>
	/// <remarks>
	/// By default, <see cref="View.X"/> and <see cref="View.Y"/> are set to <c>Pos.Center ()</c> and <see cref="View.Width"/> and <see cref="View.Height"/> are set 
	/// to <c>Width = Dim.Percent (85)</c>, centering the Dialog vertically and horizontally. 
	/// </remarks>
	public Dialog (params Button [] buttons) : base () => SetInitialProperties (buttons);

	void SetInitialProperties (Button [] buttons)
	{
		X = Pos.Center ();
		Y = Pos.Center ();
		ValidatePosDim = true;

		Width = Dim.Percent (85);
		Height = Dim.Percent (85);

		ColorScheme = Colors.Dialog;

		Modal = true;
		ButtonAlignment = DefaultButtonAlignment;

		if (buttons != null) {
			foreach (var b in buttons) {
				AddButton (b);
			}
		}

		LayoutComplete += (s, args) => {
			LayoutButtons ();
		};

	}

	/// <summary>
	/// Adds a <see cref="Button"/> to the <see cref="Dialog"/>, its layout will be controlled by the <see cref="Dialog"/>
	/// </summary>
	/// <param name="button">Button to add.</param>
	public void AddButton (Button button)
	{
		if (button == null) {
			return;
		}

		//button.AutoSize = false; // BUGBUG: v2 - Hack to get around autosize not accounting for Margin?
		buttons.Add (button);
		Add (button);
		SetNeedsDisplay ();
		if (IsInitialized) {
			LayoutSubviews ();
		}
	}

	// Get the width of all buttons, not including any Margin.
	internal int GetButtonsWidth ()
	{
		if (buttons.Count == 0) {
			return 0;
		}
		//var widths = buttons.Select (b => b.TextFormatter.GetFormattedSize ().Width + b.BorderFrame.Thickness.Horizontal + b.Padding.Thickness.Horizontal);
		var widths = buttons.Select (b => b.Frame.Width);
		return widths.Sum ();
	}

	/// <summary>
	/// Determines the horizontal alignment of the Dialog buttons.
	/// </summary>
	public enum ButtonAlignments {
		/// <summary>
		/// Center-aligns the buttons (the default).
		/// </summary>
		Center = 0,

		/// <summary>
		/// Justifies the buttons
		/// </summary>
		Justify,

		/// <summary>
		/// Left-aligns the buttons
		/// </summary>
		Left,

		/// <summary>
		/// Right-aligns the buttons
		/// </summary>
		Right
	}

	/// <summary>
	/// Determines how the <see cref="Dialog"/> <see cref="Button"/>s are aligned along the 
	/// bottom of the dialog. 
	/// </summary>
	public ButtonAlignments ButtonAlignment { get; set; }

	void LayoutButtons ()
	{
		if (buttons.Count == 0 || !IsInitialized) {
			return;
		}

		int shiftLeft = 0;

		int buttonsWidth = GetButtonsWidth ();
		switch (ButtonAlignment) {
		case ButtonAlignments.Center:
			// Center Buttons
			shiftLeft = (Bounds.Width - buttonsWidth - buttons.Count - 1) / 2 + 1;
			for (int i = buttons.Count - 1; i >= 0; i--) {
				var button = buttons [i];
				shiftLeft += button.Frame.Width + (i == buttons.Count - 1 ? 0 : 1);
				if (shiftLeft > -1) {
					button.X = Pos.AnchorEnd (shiftLeft);
				} else {
					button.X = Bounds.Width - shiftLeft;
				}
				button.Y = Pos.AnchorEnd (1);
			}
			break;

		case ButtonAlignments.Justify:
			// Justify Buttons
			// leftmost and rightmost buttons are hard against edges. The rest are evenly spaced.

			int spacing = (int)Math.Ceiling ((double)(Bounds.Width - buttonsWidth) / (buttons.Count - 1));
			for (int i = buttons.Count - 1; i >= 0; i--) {
				var button = buttons [i];
				if (i == buttons.Count - 1) {
					shiftLeft += button.Frame.Width;
					button.X = Pos.AnchorEnd (shiftLeft);
				} else {
					if (i == 0) {
						// first (leftmost) button 
						int left = Bounds.Width;
						button.X = Pos.AnchorEnd (left);
					} else {
						shiftLeft += button.Frame.Width + spacing;
						button.X = Pos.AnchorEnd (shiftLeft);
					}
				}
				button.Y = Pos.AnchorEnd (1);
			}
			break;

		case ButtonAlignments.Left:
			// Left Align Buttons
			var prevButton = buttons [0];
			prevButton.X = 0;
			prevButton.Y = Pos.AnchorEnd (1);
			for (int i = 1; i < buttons.Count; i++) {
				var button = buttons [i];
				button.X = Pos.Right (prevButton) + 1;
				button.Y = Pos.AnchorEnd (1);
				prevButton = button;
			}
			break;

		case ButtonAlignments.Right:
			// Right align buttons
			shiftLeft = buttons [buttons.Count - 1].Frame.Width;
			buttons [buttons.Count - 1].X = Pos.AnchorEnd (shiftLeft);
			buttons [buttons.Count - 1].Y = Pos.AnchorEnd (1);
			for (int i = buttons.Count - 2; i >= 0; i--) {
				var button = buttons [i];
				shiftLeft += button.Frame.Width + 1;
				button.X = Pos.AnchorEnd (shiftLeft);
				button.Y = Pos.AnchorEnd (1);
			}
			break;
		}
	}

	// BUGBUG: Why is this not handled by a key binding???
	///<inheritdoc/>
	public override bool OnProcessKeyDown (Key a)
	{
		switch (a.KeyCode) {
		case KeyCode.Esc:
			Application.RequestStop (this);
			return true;
		}
		return false;
	}
}