using System;
using System.Linq;
using System.Collections.Generic;
using UnityEngine;

namespace UnityEditor.Graphs.Material
{
	public class MaterialSubGraph : BaseMaterialGraph, IGeneratesVertexToFragmentBlock, IGeneratesFunction, IGeneratesVertexShaderBlock, IGenerateProperties
	{
		[SerializeField]
		private SubGraphInputsNode m_InputsNode;

		public SubGraphNode processingOwner { get; set; }

		[SerializeField]
		private SubGraphOutputsNode m_OutputsNode;

		public SubGraphInputsNode inputsNode { get { return m_InputsNode; } }

		public SubGraphOutputsNode outputsNode { get { return m_OutputsNode; } }

		public override BaseMaterialNode masterNode { get { return outputsNode; } }


		public new void OnEnable()
		{
			base.OnEnable ();
			if (m_InputsNode == null)
			{
				m_InputsNode = CreateInstance<SubGraphInputsNode> ();
				m_InputsNode.hideFlags = HideFlags.HideInHierarchy;
				m_InputsNode.Init ();				
				AddMasterNodeNoAddToAsset (m_InputsNode);
			}

			if (m_OutputsNode == null)
			{
				m_OutputsNode = CreateInstance<SubGraphOutputsNode> ();
				m_OutputsNode.hideFlags = HideFlags.HideInHierarchy;
				m_OutputsNode.Init ();
				AddMasterNodeNoAddToAsset (m_OutputsNode);
			}
		}

		public void CreateSubAssets()
		{
			AssetDatabase.AddObjectToAsset(m_InputsNode, this);
			AssetDatabase.AddObjectToAsset(m_OutputsNode, this);
		}

		// Return if the given input slot is wired all the way to an output slot
		// and if that output slot is connected on the SubGraphNode
		public bool InputInternallyWired(string slotName, SubGraphNode subGraphNode)
		{
			var outputSlot = inputsNode.slots.FirstOrDefault (x => x.name == slotName);

			if (outputSlot == null || outputSlot.edges.Count == 0)
				return false;

			var usedInputSlots = new List<Slot> ();
			foreach (var edge in outputSlot.edges)
			{
				if (edge.toSlot.node == outputsNode)
					usedInputSlots.Add (edge.toSlot);

				FindValidInputsToNodeFromNode (outputsNode, edge.toSlot.node, usedInputSlots);
			}

			//var inputWiredToSlots = new List<Slot> ();
			foreach (var foundUsedInputSlot in usedInputSlots)
			{
				Slot slot = foundUsedInputSlot;
				var onExternalNodeSlot = subGraphNode.outputSlots.FirstOrDefault (x => x.name == slot.name);

				if (onExternalNodeSlot != null && onExternalNodeSlot.edges.Count > 0)
					return true;
					//inputWiredToSlots.Add (onExternalNodeSlot);
			}
			return false;

			//return inputWiredToSlots;
		}

		private static void FindValidInputsToNodeFromNode(Node toNode, Node currentNode, ICollection<Slot> foundUsedInputSlots)
		{
			if (currentNode == null || toNode == null)
			{
				Debug.LogError ("Recursing to find valid inputs on NULL node");
				return;
			}

			foreach (var outputSlot in currentNode.outputSlots)
			{
				foreach (var edge in outputSlot.edges)
				{
					if (edge.toSlot.node == toNode && !foundUsedInputSlots.Contains(edge.toSlot))
					{
						var validInputSlotsAtTarget = (edge.toSlot.node as BaseMaterialNode).GetValidInputSlots ();
						if (validInputSlotsAtTarget.Contains (edge.toSlot))
							foundUsedInputSlots.Add (edge.toSlot);
					}
					else
						FindValidInputsToNodeFromNode(toNode, edge.toSlot.node, foundUsedInputSlots);
				}
			}
		}

		public string GetInputVariableNameForSlotByName(string slotName, BaseMaterialNode usageNode, GenerationMode generationMode)
		{
			var outputSlot = inputsNode.slots.FirstOrDefault (x => x.name == slotName);
			if (outputSlot == null)
				return "Could Not Find Slot";
			return inputsNode.GetOutputVariableNameForSlot(outputSlot, generationMode);
		}

		public bool OutputInternallyWired (string slotName) 
		{
			var inputSlot = outputsNode.slots.FirstOrDefault(x => x.name == slotName);

			if (inputSlot == null)
				return false;

			return inputSlot.edges.Count > 0;
		}

		public string GetOutputVariableNameForSlotByName(string slotName, BaseMaterialNode usageNode, GenerationMode generationMode)
		{
			var inputSlot = outputsNode.slots.FirstOrDefault (x => x.name == slotName);
			if (inputSlot == null || inputSlot.edges.Count == 0)
				return "Slot Error";

			var bmn = inputSlot.edges[0].fromSlot.node as BaseMaterialNode;
			return bmn == null ? "Slot Error" : bmn.GetOutputVariableNameForSlot (inputSlot.edges[0].fromSlot, generationMode);
		}


		private IEnumerable<BaseMaterialNode> GetCollectedNodes()
		{
			return outputsNode.CollectChildNodesByExecutionOrder ();
		}

		public void GenerateNodeCode (ShaderGenerator visitor, SubGraphNode generatingFor)
		{
			// First find which outputs are connected externally
			var externallyConnected = new List<Slot> ();
			foreach (var slot in outputsNode.inputSlots)
			{
				var externalSlot = generatingFor.outputSlots.FirstOrDefault (x => x.name == slot.name);
				if (externalSlot == null)
					continue;

				if (externalSlot.edges.Count > 0)
					externallyConnected.Add (slot);
			}

			// then collect the valid nodes
			var collectedNodes = new List<BaseMaterialNode>();
			foreach (var s in externallyConnected)
				outputsNode.CollectChildNodesByExecutionOrder (collectedNodes, s, false);

			// then generate code for the connected nodes
			foreach (var n in collectedNodes.OfType<IGeneratesBodyCode>())
				n.GenerateNodeCode(visitor, GenerationMode.SurfaceShader);
		}

		public void GenerateVertexToFragmentBlock (ShaderGenerator visitor, GenerationMode generationMode)
		{
			foreach (var n in GetCollectedNodes ().OfType<IGeneratesVertexToFragmentBlock> ())
				n.GenerateVertexToFragmentBlock(visitor, generationMode);
		}

		public void GenerateNodeFunction (ShaderGenerator visitor, GenerationMode generationMode)
		{
			foreach (var n in GetCollectedNodes ().OfType<IGeneratesFunction> ())
				n.GenerateNodeFunction(visitor, generationMode);
		}

		public void GenerateVertexShaderBlock(ShaderGenerator visitor, GenerationMode generationMode)
		{
			foreach (var n in GetCollectedNodes ().OfType<IGeneratesVertexShaderBlock> ())
				n.GenerateVertexShaderBlock (visitor, generationMode);
		}

		public void GeneratePropertyBlock(PropertyGenerator visitor, GenerationMode generationMode)
		{
			foreach (var n in GetCollectedNodes().OfType<IGenerateProperties>())
				n.GeneratePropertyBlock (visitor, generationMode);
		}

		public void GeneratePropertyUsages(ShaderGenerator visitor, GenerationMode generationMode)
		{
			foreach (var n in GetCollectedNodes ().OfType<IGenerateProperties> ())
				n.GeneratePropertyUsages (visitor, generationMode);
		}

		// Returns a list of preview properties that need to be set
		public IEnumerable<PreviewProperty> GetPreviewProperties ()
		{
			var properties = new List<PreviewProperty> ();
			foreach (var tnode in nodes.Where (x => x is TextureNode).Cast<TextureNode> ())
			{
				properties.Add (tnode.GetPreviewProperty ());	
			}

			foreach (var subNode in nodes.Where (x=>x is SubGraphNode).Cast<SubGraphNode> ())
			{
				if (subNode.subGraphAsset != null)
					properties.AddRange (subNode.subGraphAsset.GetPreviewProperties ());
			}
			return properties.Distinct();
		}
	}
}