using System;
using System.Linq;
using UnityEngine;

namespace UnityEditor.Graphs.Material
{
	[Title("Fractal/Kaleidoscope Node")]
	class KaleidoscopeNode : BaseMaterialNode, IGeneratesFunction, IGeneratesBodyCode
	{
		[SerializeField]
		private int m_Iterations = 6;

		private const string kPointInputName = "Point";
		private const string kConstant1InputName = "Constant1";
		private const string kConstant2InputName = "Constant2";
		private const string kOutputSlotName = "Output";

		public override bool hasPreview { get { return true; } }

		public override void Init()
		{
			name = "KaleidoscopeNode";
			base.Init();
			AddSlot(new Slot(SlotType.InputSlot, kPointInputName));
			AddSlot(new Slot(SlotType.InputSlot, kConstant1InputName));
			AddSlot(new Slot(SlotType.InputSlot, kConstant2InputName));
			AddSlot(new Slot(SlotType.OutputSlot, kOutputSlotName));
		}

		public void GenerateNodeFunction(ShaderGenerator visitor, GenerationMode generationMode)
		{
			var outputString = new ShaderGenerator();
			foreach (var precision in m_PrecisionNames)
			{
				outputString.AddShaderChunk("inline " + precision + "4 unity_kaleidoscope_" + precision + " (" + precision + "2 p, " + precision + "4 c1, " + precision + "4 c2, int iterations)", false);
				outputString.AddShaderChunk("{", false);
				outputString.Indent();
				outputString.AddShaderChunk("c1 = c1 * 2 - 1;", false);
				outputString.AddShaderChunk("c2 = c2 * 2 - 1;", false);
				outputString.AddShaderChunk("for (int n = 0; n < iterations; n++)", false);
				outputString.AddShaderChunk("{", false);
				outputString.Indent();
				outputString.AddShaderChunk("p = c1.xy + p * c1.zw + " + precision + "2(dot(p, c2.xy), dot(p, c2.zw));", false);
				outputString.AddShaderChunk("if(p.x < p.y) p.xy = -p.yx;", false);
				outputString.Deindent();
				outputString.AddShaderChunk("}", false);
				outputString.AddShaderChunk("return " + precision + "4(p, 1, 1);", false);
				outputString.Deindent();
				outputString.AddShaderChunk("}", false);
			}

			visitor.AddShaderChunk(outputString.GetShaderString(0), true);
		}

		public void GenerateNodeCode(ShaderGenerator visitor, GenerationMode generationMode)
		{
			var outputSlot = FindOutputSlot (kOutputSlotName);
			var pointInput = FindInputSlot (kPointInputName);
			var constant1Input = FindInputSlot (kConstant1InputName);
			var constant2Input = FindInputSlot (kConstant2InputName);

			if (outputSlot == null || pointInput == null || constant1Input == null || constant2Input == null)
			{
				Debug.LogError("Invalid slot configuration on node: " + name);
				return;
			}

			string pointInputValue = GetSlotValue (pointInput, generationMode);
			string constant1InputValue = GetSlotValue (constant1Input, generationMode);
			string constant2InputValue = GetSlotValue (constant2Input, generationMode);

			string outName = GetOutputVariableNameForSlot (outputSlot, generationMode);
			visitor.AddShaderChunk (precision + "4 " + outName + " = unity_kaleidoscope_" + precision + "(" + pointInputValue + ".xy, " + constant1InputValue + ", " + constant2InputValue + ", " + m_Iterations + ");", false);
		}

		static float Slider(string title, float value, float from, float to)
		{
			GUILayout.BeginHorizontal();
			GUILayout.Label(title);
			value = GUILayout.HorizontalSlider(value, from, to, GUILayout.Width(64));
			GUILayout.EndHorizontal();
			return value;
		}

		public override void NodeUI(Graphs.GraphGUI host)
		{
			base.NodeUI(host);

			EditorGUI.BeginChangeCheck();
			m_Iterations = (int)Slider("Iterations", (float)m_Iterations, 1, 50);
			if (EditorGUI.EndChangeCheck())
				RegeneratePreviewShaders();
		}
	}
}