using System;
using System.Linq;
using UnityEngine;

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

		private const string kPointInputName = "Point";
		private const string kConstantInputName = "Constant";
		private const string kOutputSlotName = "Output";

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

		public override void Init()
		{
			name = "MandelbrotNode";
			base.Init();
			AddSlot(new Slot(SlotType.InputSlot, kPointInputName));
			AddSlot(new Slot(SlotType.InputSlot, kConstantInputName));
			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_mandelbrot_" + precision + " (" + precision + "2 p, " + precision + "2 c, float limit, float scale, int iterations)", false);
				outputString.AddShaderChunk("{", false);
				outputString.Indent();
				outputString.AddShaderChunk(precision + " zr = p.x * 4 - 2, zi = p.y * 4 - 2, dzr = 1, dzi = 0, r = 0, len2;", false);
				outputString.AddShaderChunk("for (int n = 0; n < iterations; n++)", false);
				outputString.AddShaderChunk("{", false);
				outputString.Indent();
				outputString.AddShaderChunk(precision + " tmp1 = 2 * zr * zi + c.y; zr = zr * zr - zi * zi + c.x; zi = tmp1;", false);
				outputString.AddShaderChunk(precision + " tmp2 = 2 * (dzr * zi + dzi * zr); dzr = 2 * (dzr * zr - dzi * zi) + 1; dzi = tmp2;", false);
				outputString.AddShaderChunk("len2 = zr * zr + zi * zi;", false);
				outputString.AddShaderChunk("if (len2 > 1000000 * limit) { r = n; break; }", false);
				outputString.Deindent();
				outputString.AddShaderChunk("}", false);
				outputString.AddShaderChunk("return scale * sqrt(len2 / (dzr * dzr + dzi * dzi)) * log(len2);", false);
				outputString.Deindent();
				outputString.AddShaderChunk("}", false);
			}

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

		public void GenerateNodeCode(ShaderGenerator visitor, GenerationMode generationMode)
		{
			var outputSlot = outputSlots.FirstOrDefault(x => x.name == kOutputSlotName);
			var pointInput = GetValidInputSlots().FirstOrDefault(x => x.name == kPointInputName);
			var constantInput = GetValidInputSlots().FirstOrDefault(x => x.name == kConstantInputName);
			if (outputSlot == null || pointInput == null || constantInput == null)
			{
				Debug.LogError("Invalid slot configuration on node: " + name);
				return;
			}

			//TODO: This will break if there is NO input connected, use default in that case
			var pointProvider = pointInput.edges[0].fromSlot.node as BaseMaterialNode;
			var pointName = pointProvider.GetOutputVariableNameForSlot(pointInput.edges[0].fromSlot, generationMode);

			var constantProvider = constantInput.edges[0].fromSlot.node as BaseMaterialNode;
			var constantName = constantProvider.GetOutputVariableNameForSlot(constantInput.edges[0].fromSlot, generationMode);

			string outName = GetOutputVariableNameForSlot(outputSlot, generationMode);
			visitor.AddShaderChunk(precision + "4 " + outName + " = unity_mandelbrot_" + precision + "(" + pointName + ".xy, " + constantName + ".xy, " + constantName + ".z, " + constantName + ".w, " + 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();
		}
	}
}