using UnityEngine;
using UnityEditor;
using RelationsInspector.Extensions;

namespace RelationsInspector.Backend
{
	public static class DrawUtil
	{
		public static float sqrt2 = Mathf.Sqrt(2f);
		public static Vector2 boxIconSize = new Vector2(16, 16);
		static Vector2 shadowOffset = new Vector2( 2, 2);

		// draw the content in a rect or circle widget, depending on context
		public static Rect DrawContent(GUIContent content, EntityDrawContext context)
		{
			switch (context.widgetType)
			{
				case EntityWidgetType.Circle:
					return DrawCircleWidget(content, context);

				case EntityWidgetType.Rect:
				default:
					return DrawRectWidget(content, context);
			}
		}

		// draw content box background, outline and selection/unexplored aura
		public static void DrawBoxAndBackground(Rect contentRect, EntityDrawContext context )
		{
			Rect outlineRect = contentRect.AddBorder( 1 );

			// selected items get highlighted
			if ( context.isSelected )
			{
				var auraRect = outlineRect.AddBorder( context.style.highlightStrength );
				EditorGUI.DrawRect( auraRect, context.style.highlightColor );
			}
			else if ( context.isUnexlored )
			{
				var auraRect = outlineRect.AddBorder( context.style.highlightStrength );
				EditorGUI.DrawRect( auraRect, context.style.unexploredColor );
			}
			else
			{
				// draw shadow
				EditorGUI.DrawRect( outlineRect.Move( shadowOffset ), context.style.shadowColor );
			}

			// draw outline rect
			EditorGUI.DrawRect( outlineRect, Color.black );

			// draw content rect
			EditorGUI.DrawRect( contentRect, context.isTarget ? context.style.targetBackgroundColor : context.style.backgroundColor );
		}

		// draw content in rect widget
		public static Rect DrawRectWidget(GUIContent content, EntityDrawContext context)
		{
			// determine the space required for drawing the content
			EditorGUIUtility.SetIconSize(boxIconSize);
			Vector2 contentExtents = context.style.contentStyle.CalcSize(content);
			Rect labelRect = Util.CenterRect(context.position, contentExtents);

			DrawBoxAndBackground( labelRect, context );

			// draw label
			content.tooltip = string.Empty; // RI dll handles tooltip drawing
			GUI.Label( labelRect, content, context.style.contentStyle );

			return labelRect;
		}

		static void DrawSquareTexture( Vector2 center, float width, Color color, Texture2D texture )
		{
			var rect = Util.CenterRect( center, new Vector2( width, width ) );
			GUI.color = color;
			GUI.DrawTexture( rect, texture );
			GUI.color = Color.white;
		}

		public static void DrawCircleAndOutline( float radius, EntityDrawContext context )
		{
			float outlineRadius = radius + 1;

			// selected items get highlighted
			if ( context.isSelected )
			{
				// draw selection aura
				DrawSquareTexture(
					context.position,
					2 * ( outlineRadius + context.style.highlightStrength),
					context.style.highlightColor,
					context.style.discImage
					);
			}
			else if ( context.isUnexlored )
			{
				// draw unexplored aura
				DrawSquareTexture(
					context.position,
					2 * ( outlineRadius + context.style.highlightStrength),
					context.style.unexploredColor,
					context.style.discImage
					);
			}

			// draw outline disc
			DrawSquareTexture( context.position, 2 * outlineRadius, Color.black, context.style.discImage );

			// draw entity disc
			Color entityColor = context.isTarget ? context.style.targetBackgroundColor : context.style.backgroundColor;
			DrawSquareTexture( context.position, 2* radius, entityColor, context.style.discImage);
		}

		// draw content in circle widget
		public static Rect DrawCircleWidget(GUIContent content, EntityDrawContext context)
		{
			float contentSize = 2 * context.style.widgetRadius;
			float radius = context.style.widgetRadius * sqrt2;

			DrawCircleAndOutline( radius, context );

			// draw content icon, if any
			if (content.image != null)
			{
				//2*radius/sqrt2
				Rect contentRect = Util.CenterRect(context.position, new Vector2(contentSize, contentSize));
				GUI.DrawTexture(contentRect, content.image, ScaleMode.ScaleToFit);
			}

			return Util.CenterRect(context.position, new Vector2(radius * 2, radius * 2));
		}

		// draw sprite. we can't draw it directly, instead we have to draw the correct region of its texture
		public static void DrawTextureGUI( Vector2 origin, Sprite sprite, Vector2 size )
		{
			Rect spriteRect = new Rect
				(
				sprite.rect.x / sprite.texture.width,
				sprite.rect.y / sprite.texture.height,
				sprite.rect.width / sprite.texture.width,
				sprite.rect.height / sprite.texture.height
				);

			Vector2 actualSize = size;

			actualSize.y *= ( sprite.rect.height / sprite.rect.width );

			var pos = new Rect
				(
				origin.x,
				origin.y + ( size.y - actualSize.y ) / 2,
				actualSize.x,
				actualSize.y
				);

			GUI.DrawTextureWithTexCoords( pos, sprite.texture, spriteRect );
		}

		// draw the node widget (the icon sprite makes this complicated)
		public static Rect DrawSpriteContent( string label, Sprite icon, EntityDrawContext drawContext )
		{
			var labelContent = new GUIContent( label );

			// fall back to the default widget where there's no icon or the user wants cirles
			if ( icon == null || drawContext.widgetType == EntityWidgetType.Circle )
				return DrawUtil.DrawContent( labelContent, drawContext );

			// calculate layout for icon and label, then draw them
			var iconExtents = new Vector2( 25, 25 );
			var padding = new Vector2( 4, 4 );
			var contentExtents = drawContext.style.contentStyle.CalcSize( labelContent );
			var widgetExtents = new Vector2( 3 * padding.x + iconExtents.x + contentExtents.x, 2 * padding.y + iconExtents.y );

			var widgetRect = Util.CenterRect( drawContext.position, widgetExtents );
			// draw the widget outer box
			DrawUtil.DrawBoxAndBackground( widgetRect, drawContext );

			// draw the icon
			var iconOrigin = widgetRect.GetOrigin() + padding;
			DrawTextureGUI( iconOrigin, icon, iconExtents );

			// draw the label
			var contentRectOrigin = new Vector2
				(
				widgetRect.xMin + 2 * padding.x + iconExtents.x,
				widgetRect.yMin + ( widgetExtents.y - contentExtents.y ) / 2 );

			var contentRect = new Rect( contentRectOrigin.x, contentRectOrigin.y, contentExtents.x, contentExtents.y );
			GUI.Label( contentRect, labelContent, drawContext.style.contentStyle );

			return widgetRect;
		}
	}
}