using NStack;
using System;
namespace Terminal.Gui {
	/// <summary>
	/// Specifies the style that a <see cref="ProgressBar"/> uses to indicate the progress of an operation.
	/// </summary>
	public enum ProgressBarStyle {
		/// <summary>
		/// Indicates progress by increasing the number of segmented blocks in a <see cref="ProgressBar"/>.
		/// </summary>
		Blocks,
		/// <summary>
		/// Indicates progress by increasing the size of a smooth, continuous bar in a <see cref="ProgressBar"/>.
		/// </summary>
		Continuous,
		/// <summary>
		/// Indicates progress by continuously scrolling a block across a <see cref="ProgressBar"/> in a marquee fashion.
		/// </summary>
		MarqueeBlocks,
		/// <summary>
		/// Indicates progress by continuously scrolling a block across a <see cref="ProgressBar"/> in a marquee fashion.
		/// </summary>
		MarqueeContinuous

	}

	/// <summary>
	///Specifies the format that a <see cref="ProgressBar"/> uses to indicate the visual presentation.
	/// </summary>
	public enum ProgressBarFormat {
		/// <summary>
		/// A simple visual presentation showing only the progress bar.
		/// </summary>
		Simple,
		/// <summary>
		/// A simple visual presentation showing the progress bar and the percentage.
		/// </summary>
		SimplePlusPercentage,
		/// <summary>
		/// A framed visual presentation showing only the progress bar.
		/// </summary>
		Framed,
		/// <summary>
		/// A framed visual presentation showing the progress bar and the percentage.
		/// </summary>
		FramedPlusPercentage,
		/// <summary>
		/// A framed visual presentation showing all with the progress bar padded.
		/// </summary>
		FramedProgressPadded
	}

	/// <summary>
	/// A Progress Bar view that can indicate progress of an activity visually.
	/// </summary>
	/// <remarks>
	///   <para>
	///     <see cref="ProgressBar"/> can operate in two modes, percentage mode, or
	///     activity mode.  The progress bar starts in percentage mode and
	///     setting the Fraction property will reflect on the UI the progress 
	///     made so far.   Activity mode is used when the application has no 
	///     way of knowing how much time is left, and is started when the <see cref="Pulse"/> method is called.  
	///     Call <see cref="Pulse"/> repeatedly as progress is made.
	///   </para>
	/// </remarks>
	public class ProgressBar : View {
		bool isActivity;
		int [] activityPos;
		int delta, padding;

		/// <summary>
		/// Initializes a new instance of the <see cref="ProgressBar"/> class, starts in percentage mode with an absolute position and size.
		/// </summary>
		/// <param name="rect">Rect.</param>
		public ProgressBar (Rect rect) : base (rect)
		{
			Initialize (rect);
		}

		/// <summary>
		/// Initializes a new instance of the <see cref="ProgressBar"/> class, starts in percentage mode and uses relative layout.
		/// </summary>
		public ProgressBar () : base ()
		{
			Initialize (Rect.Empty);
		}

		void Initialize (Rect rect)
		{
			CanFocus = false;
			fraction = 0;
			ColorScheme = new ColorScheme () {
				Normal = Application.Driver.MakeAttribute (Color.BrightGreen, Color.Gray),
				HotNormal = Colors.Base.Normal
			};
			if (rect.IsEmpty) {
				Height = 1;
			}
		}

		float fraction;

		/// <summary>
		/// Gets or sets the <see cref="ProgressBar"/> fraction to display, must be a value between 0 and 1.
		/// </summary>
		/// <value>The fraction representing the progress.</value>
		public float Fraction {
			get => fraction;
			set {
				fraction = Math.Min (value, 1);
				isActivity = false;
				SetNeedsDisplay ();
			}
		}

		ProgressBarStyle progressBarStyle;

		/// <summary>
		/// Gets/Sets the progress bar style based on the <see cref="Terminal.Gui.ProgressBarStyle"/>
		/// </summary>
		public ProgressBarStyle ProgressBarStyle {
			get => progressBarStyle;
			set {
				progressBarStyle = value;
				switch (value) {
				case ProgressBarStyle.Blocks:
					SegmentCharacter = Driver.BlocksMeterSegment;
					break;
				case ProgressBarStyle.Continuous:
					SegmentCharacter = Driver.ContinuousMeterSegment;
					break;
				case ProgressBarStyle.MarqueeBlocks:
					SegmentCharacter = Driver.BlocksMeterSegment;
					break;
				case ProgressBarStyle.MarqueeContinuous:
					SegmentCharacter = Driver.ContinuousMeterSegment;
					break;
				}
				SetNeedsDisplay ();
			}
		}

		private ProgressBarFormat progressBarFormat;

		/// <summary>
		/// Specifies the format that a <see cref="ProgressBar"/> uses to indicate the visual presentation.
		/// </summary>
		public ProgressBarFormat ProgressBarFormat {
			get => progressBarFormat;
			set {
				progressBarFormat = value;
				switch (progressBarFormat) {
				case ProgressBarFormat.Simple:
					Height = 1;
					break;
				case ProgressBarFormat.SimplePlusPercentage:
					Height = 2;
					break;
				case ProgressBarFormat.Framed:
					Height = 3;
					break;
				case ProgressBarFormat.FramedPlusPercentage:
					Height = 4;
					break;
				case ProgressBarFormat.FramedProgressPadded:
					Height = 6;
					break;
				}
				SetNeedsDisplay ();
			}
		}

		private Rune segmentCharacter = Driver.BlocksMeterSegment;

		/// <summary>
		/// Segment indicator for meter views.
		/// </summary>
		public Rune SegmentCharacter {
			get => segmentCharacter;
			set {
				segmentCharacter = value;
				SetNeedsDisplay ();
			}
		}

		///<inheritdoc/>
		public override ustring Text {
			get => GetPercentageText ();
			set {
				base.Text = SetPercentageText (value);
			}
		}

		private bool bidirectionalMarquee = true;

		/// <summary>
		/// Specifies if the <see cref="ProgressBarStyle.MarqueeBlocks"/> or the
		///  <see cref="ProgressBarStyle.MarqueeContinuous"/> styles is unidirectional
		///  or bidirectional.
		/// </summary>
		public bool BidirectionalMarquee {
			get => bidirectionalMarquee;
			set {
				bidirectionalMarquee = value;
				SetNeedsDisplay ();
			}
		}

		ustring GetPercentageText ()
		{
			switch (progressBarStyle) {
			case ProgressBarStyle.Blocks:
			case ProgressBarStyle.Continuous:
				return $"{fraction * 100:F0}%";
			case ProgressBarStyle.MarqueeBlocks:
			case ProgressBarStyle.MarqueeContinuous:
				break;
			}

			return base.Text;
		}

		ustring SetPercentageText (ustring value)
		{
			switch (progressBarStyle) {
			case ProgressBarStyle.Blocks:
			case ProgressBarStyle.Continuous:
				return $"{fraction * 100:F0}%";
			case ProgressBarStyle.MarqueeBlocks:
			case ProgressBarStyle.MarqueeContinuous:
				break;
			}

			return value;
		}

		/// <summary>
		/// Notifies the <see cref="ProgressBar"/> that some progress has taken place.
		/// </summary>
		/// <remarks>
		/// If the <see cref="ProgressBar"/> is percentage mode, it switches to activity
		/// mode. If is in activity mode, the marker is moved.
		/// </remarks>
		public void Pulse ()
		{
			if (activityPos == null) {
				PopulateActivityPos ();
			}
			if (!isActivity) {
				isActivity = true;
				delta = 1;
			} else {
				for (int i = 0; i < activityPos.Length; i++) {
					activityPos [i] += delta;
				}
				int fWidth = GetFrameWidth ();
				if (activityPos [activityPos.Length - 1] < 0) {
					for (int i = 0; i < activityPos.Length; i++) {
						activityPos [i] = i - activityPos.Length + 2;
					}
					delta = 1;
				} else if (activityPos [0] >= fWidth) {
					if (bidirectionalMarquee) {
						for (int i = 0; i < activityPos.Length; i++) {
							activityPos [i] = fWidth + i - 2;
						}
						delta = -1;
					} else {
						PopulateActivityPos ();
					}
				}
			}

			SetNeedsDisplay ();
		}

		///<inheritdoc/>
		public override void Redraw (Rect region)
		{
			DrawFrame ();

			Driver.SetAttribute (GetNormalColor ());

			int fWidth = GetFrameWidth ();
			if (isActivity) {
				Move (padding, padding);
				for (int i = 0; i < fWidth; i++)
					if (Array.IndexOf (activityPos, i) != -1)
						Driver.AddRune (SegmentCharacter);
					else
						Driver.AddRune (' ');
			} else {
				Move (padding, padding);
				int mid = (int)(fraction * fWidth);
				int i;
				for (i = 0; i < mid & i < fWidth; i++)
					Driver.AddRune (SegmentCharacter);
				for (; i < fWidth; i++)
					Driver.AddRune (' ');
			}

			DrawText (fWidth);
		}

		int GetFrameWidth ()
		{
			switch (progressBarFormat) {
			case ProgressBarFormat.Simple:
			case ProgressBarFormat.SimplePlusPercentage:
				break;
			case ProgressBarFormat.Framed:
			case ProgressBarFormat.FramedPlusPercentage:
				return Frame.Width - 2;
			case ProgressBarFormat.FramedProgressPadded:
				return Frame.Width - 2 - padding;
			}

			return Frame.Width;
		}

		void DrawText (int fWidth)
		{
			switch (progressBarFormat) {
			case ProgressBarFormat.Simple:
			case ProgressBarFormat.Framed:
				break;
			case ProgressBarFormat.SimplePlusPercentage:
			case ProgressBarFormat.FramedPlusPercentage:
			case ProgressBarFormat.FramedProgressPadded:
				var tf = new TextFormatter () {
					Alignment = TextAlignment.Centered,
					Text = Text
				};
				var row = padding + (progressBarFormat == ProgressBarFormat.FramedProgressPadded
					? 2 : 1);
				Move (padding, row);
				var rect = new Rect (padding, row, fWidth, Frame.Height);
				tf?.Draw (ViewToScreen (rect), ColorScheme.HotNormal, ColorScheme.HotNormal,
					SuperView == null ? default : SuperView.ViewToScreen (SuperView.Bounds));
				break;
			}
		}

		void DrawFrame ()
		{
			switch (progressBarFormat) {
			case ProgressBarFormat.Simple:
			case ProgressBarFormat.SimplePlusPercentage:
				padding = 0;
				break;
			case ProgressBarFormat.Framed:
			case ProgressBarFormat.FramedPlusPercentage:
				padding = 1;
				Application.Driver.DrawWindowFrame (ViewToScreen (Bounds), padding, padding, padding, padding, true);
				break;
			case ProgressBarFormat.FramedProgressPadded:
				padding = 2;
				Application.Driver.DrawWindowFrame (ViewToScreen (Bounds), padding, padding, padding, padding + 1, true);
				Application.Driver.DrawWindowFrame (ViewToScreen (Bounds), padding - 1, padding - 1, padding - 1, padding - 1, true);
				break;
			}
		}

		void PopulateActivityPos ()
		{
			activityPos = new int [Math.Min (Frame.Width / 3, 5)];
			for (int i = 0; i < activityPos.Length; i++) {
				activityPos [i] = i - activityPos.Length + 1;
			}
		}

		///<inheritdoc/>
		public override bool OnEnter (View view)
		{
			Application.Driver.SetCursorVisibility (CursorVisibility.Invisible);

			return base.OnEnter (view);
		}
	}
}