#region Copyright & License Information
/*
 * Copyright 2007-2011 The OpenRA Developers (see AUTHORS)
 * This file is part of OpenRA, which is free software. It is made
 * available to you under the terms of the GNU General Public License
 * as published by the Free Software Foundation. For more information,
 * see COPYING.
 */
#endregion

using System;
using System.Drawing;
using OpenRA.Graphics;

namespace OpenRA.Widgets
{
	public class SliderWidget : Widget
	{
		public Func<bool> IsDisabled = () => false;
		public event Action<float> OnChange = _ => {};
		public int Ticks = 0;
		public int TrackHeight = 5;

		public float MinimumValue = 0;
		public float MaximumValue = 1;
		public float Value = 0;

		protected bool isMoving = false;

		public SliderWidget() : base() {}

		public SliderWidget(SliderWidget other)
			: base(other)
		{
			OnChange = other.OnChange;
			Ticks = other.Ticks;
			MinimumValue = other.MinimumValue;
			MaximumValue = other.MaximumValue;
			Value = other.Value;
			TrackHeight = other.TrackHeight;
		}

		void UpdateValue(float newValue)
		{
			Value = newValue.Clamp(MinimumValue, MaximumValue);
			OnChange(Value);
		}

		public override bool HandleMouseInput(MouseInput mi)
		{
			if (mi.Button != MouseButton.Left) return false;
			if (IsDisabled()) return false;
			if (mi.Event == MouseInputEvent.Down && !TakeFocus(mi))	return false;
			if (!Focused) return false;

			switch( mi.Event )
			{
			case MouseInputEvent.Up:
				isMoving = false;
				LoseFocus(mi);
				break;

			case MouseInputEvent.Down:
				isMoving = true;
				/* TODO: handle snapping to ticks properly again */
				/* TODO: handle nudge via clicking outside the thumb */
				UpdateValue(ValueFromPx(mi.Location.X - RenderBounds.Left));
				break;

			case MouseInputEvent.Move:
				if (isMoving)
					UpdateValue(ValueFromPx(mi.Location.X - RenderBounds.Left));
				break;
			}

			return ThumbRect.Contains(mi.Location);
		}

		float ValueFromPx(int x) { return MinimumValue + (MaximumValue - MinimumValue) * (1f * x / RenderBounds.Width); }
		int PxFromValue(float x) { return (int)(RenderBounds.Width * (x - MinimumValue) / (MaximumValue - MinimumValue)); }

		public override Widget Clone() { return new SliderWidget(this); }

		Rectangle ThumbRect
		{
			get
			{
				var thumbPos = PxFromValue(Value);
				var rb = RenderBounds;
				var width = rb.Height;
				var height = rb.Height;
				var origin = (int)(rb.X + thumbPos - width/2f);
				return new Rectangle(origin, rb.Y, width, height);
			}
		}

		public override void Draw()
		{
			if (!IsVisible())
				return;

			var tr = ThumbRect;
			var rb = RenderBounds;
			var trackWidth = rb.Width;
			var trackOrigin = rb.X;
			var trackRect = new Rectangle(trackOrigin - 1, rb.Y + (rb.Height - TrackHeight) / 2, trackWidth + 2, TrackHeight);

			// Tickmarks (hacked until we have real art)
			for (int i = 0; i < Ticks; i++)
			{
				var tickRect = new Rectangle(trackOrigin - 1 + (int)(i * trackWidth * 1f / (Ticks - 1)),
						  rb.Y + rb.Height / 2, 2, rb.Height / 2);
				WidgetUtils.DrawPanel("slider-tick", tickRect);
			}

			// Track
			WidgetUtils.DrawPanel("slider-track", trackRect);

			// Thumb
			var thumbHover = Ui.MouseOverWidget == this && tr.Contains(Viewport.LastMousePos);
			ButtonWidget.DrawBackground("scrollthumb", tr, IsDisabled(), isMoving, thumbHover, false);
		}
	}
}