using UnityEngine;
using UnityEngine.UI;

namespace ImageCropperNamespace
{
	[RequireComponent( typeof( CanvasRenderer ) )]
	public class CircleGraphic : MaskableGraphic
	{
		public enum Mode { FillInside = 0, FillOutside = 1, Edge = 2 };

		[SerializeField]
		private Sprite renderSprite;

		[SerializeField]
		private int detail = 64;

		[SerializeField]
		private Mode mode;

		[SerializeField]
		private float edgeThickness = 1;

		private Vector2 uv;
		private Color32 color32;

		private float width, height;
		private float deltaWidth, deltaHeight;
		private float deltaRadians;

		public override Texture mainTexture { get { return renderSprite != null ? renderSprite.texture : s_WhiteTexture; } }

		protected override void Awake()
		{
			base.Awake();

			if( renderSprite != null )
			{
				Vector4 packedUv = UnityEngine.Sprites.DataUtility.GetOuterUV( renderSprite );
				uv = new Vector2( packedUv.x + packedUv.z, packedUv.y + packedUv.w ) * 0.5f; // uv center point
			}
		}

		protected override void OnPopulateMesh( VertexHelper vh )
		{
			Rect r = GetPixelAdjustedRect();

			color32 = color;
			width = r.width * 0.5f;
			height = r.height * 0.5f;

			vh.Clear();

			Vector2 pivot = rectTransform.pivot;
			deltaWidth = r.width * ( 0.5f - pivot.x );
			deltaHeight = r.height * ( 0.5f - pivot.y );

			if( mode == Mode.FillInside )
			{
				deltaRadians = 360f / detail * Mathf.Deg2Rad;
				FillInside( vh );
			}
			else if( mode == Mode.FillOutside )
			{
				int quarterDetail = ( detail + 3 ) / 4;
				deltaRadians = 360f / ( quarterDetail * 4 ) * Mathf.Deg2Rad;

				vh.AddVert( new Vector3( width + deltaWidth, height + deltaHeight, 0f ), color32, uv );
				vh.AddVert( new Vector3( -width + deltaWidth, height + deltaHeight, 0f ), color32, uv );
				vh.AddVert( new Vector3( -width + deltaWidth, -height + deltaHeight, 0f ), color32, uv );
				vh.AddVert( new Vector3( width + deltaWidth, -height + deltaHeight, 0f ), color32, uv );

				int triangleIndex = 4;
				FillOutside( vh, new Vector3( width + deltaWidth, deltaHeight, 0f ), 0, quarterDetail, ref triangleIndex );
				FillOutside( vh, new Vector3( deltaWidth, height + deltaHeight, 0f ), 1, quarterDetail, ref triangleIndex );
				FillOutside( vh, new Vector3( -width + deltaWidth, deltaHeight, 0f ), 2, quarterDetail, ref triangleIndex );
				FillOutside( vh, new Vector3( deltaWidth, -height + deltaHeight, 0f ), 3, quarterDetail, ref triangleIndex );
			}
			else
			{
				deltaRadians = 360f / detail * Mathf.Deg2Rad;
				GenerateEdges( vh );
			}
		}

		public override void Cull( Rect clipRect, bool validRect )
		{
			canvasRenderer.cull = false;
		}

		private void FillInside( VertexHelper vh )
		{
			vh.AddVert( new Vector3( deltaWidth, deltaHeight, 0f ), color32, uv );
			vh.AddVert( new Vector3( width + deltaWidth, deltaHeight, 0f ), color32, uv );

			int triangleIndex = 2;
			for( int i = 1; i < detail; i++, triangleIndex++ )
			{
				float radians = i * deltaRadians;

				vh.AddVert( new Vector3( Mathf.Cos( radians ) * width + deltaWidth, Mathf.Sin( radians ) * height + deltaHeight, 0f ), color32, uv );
				vh.AddTriangle( triangleIndex, triangleIndex - 1, 0 );
			}

			vh.AddTriangle( 1, triangleIndex - 1, 0 );
		}

		private void FillOutside( VertexHelper vh, Vector3 initialPoint, int quarterIndex, int detail, ref int triangleIndex )
		{
			int startIndex = quarterIndex * detail;
			int endIndex = ( quarterIndex + 1 ) * detail;

			vh.AddVert( initialPoint, color32, uv );
			triangleIndex++;

			for( int i = startIndex + 1; i <= endIndex; i++, triangleIndex++ )
			{
				float radians = i * deltaRadians;

				vh.AddVert( new Vector3( Mathf.Cos( radians ) * width + deltaWidth, Mathf.Sin( radians ) * height + deltaHeight, 0f ), color32, uv );
				vh.AddTriangle( quarterIndex, triangleIndex - 1, triangleIndex );
			}
		}

		private void GenerateEdges( VertexHelper vh )
		{
			float innerWidth = width - edgeThickness;
			float innerHeight = height - edgeThickness;

			vh.AddVert( new Vector3( width + deltaWidth, deltaHeight, 0f ), color32, uv );
			vh.AddVert( new Vector3( innerWidth + deltaWidth, deltaHeight, 0f ), color32, uv );

			int triangleIndex = 2;
			for( int i = 1; i < detail; i++, triangleIndex += 2 )
			{
				float radians = i * deltaRadians;
				float cos = Mathf.Cos( radians );
				float sin = Mathf.Sin( radians );

				vh.AddVert( new Vector3( cos * width + deltaWidth, sin * height + deltaHeight, 0f ), color32, uv );
				vh.AddVert( new Vector3( cos * innerWidth + deltaWidth, sin * innerHeight + deltaHeight, 0f ), color32, uv );

				vh.AddTriangle( triangleIndex, triangleIndex - 2, triangleIndex - 1 );
				vh.AddTriangle( triangleIndex, triangleIndex - 1, triangleIndex + 1 );
			}

			vh.AddTriangle( 0, triangleIndex - 2, triangleIndex - 1 );
			vh.AddTriangle( 0, triangleIndex - 1, 1 );
		}
	}
}