using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using UnityEditor.Experimental.UIElements;
using UnityEditor.Graphing.Util;
using UnityEngine;
using UnityEditor.Graphing;
using Object = UnityEngine.Object;
using Edge = UnityEditor.Experimental.UIElements.GraphView.Edge;
#if UNITY_2018_1
using GeometryChangedEvent = UnityEngine.Experimental.UIElements.PostLayoutEvent;
#else
using UnityEditor.Experimental.UIElements.GraphView;
using GeometryChangedEvent = UnityEngine.Experimental.UIElements.GeometryChangedEvent;
#endif

namespace UnityEditor.ShaderGraph.Drawing
{
    public class MaterialGraphEditWindow : EditorWindow
    {
        [SerializeField]
        string m_Selected;

        [SerializeField]
        GraphObject m_GraphObject;

        [NonSerialized]
        bool m_HasError;

        [NonSerialized]
        public bool forceRedrawPreviews = false;

        ColorSpace m_ColorSpace;

        GraphEditorView m_GraphEditorView;

        GraphEditorView graphEditorView
        {
            get { return m_GraphEditorView; }
            set
            {
                if (m_GraphEditorView != null)
                {
                    m_GraphEditorView.RemoveFromHierarchy();
                    m_GraphEditorView.Dispose();
                }

                m_GraphEditorView = value;
                if (m_GraphEditorView != null)
                {
                    m_GraphEditorView.saveRequested += UpdateAsset;
                    m_GraphEditorView.convertToSubgraphRequested += ToSubGraph;
                    m_GraphEditorView.showInProjectRequested += PingAsset;
                    this.GetRootVisualContainer().Add(graphEditorView);
                }
            }
        }

        GraphObject graphObject
        {
            get { return m_GraphObject; }
            set
            {
                if (m_GraphObject != null)
                    DestroyImmediate(m_GraphObject);
                m_GraphObject = value;
            }
        }

        public string selectedGuid
        {
            get { return m_Selected; }
            private set { m_Selected = value; }
        }

        void Update()
        {
            if (m_HasError)
                return;

            if (PlayerSettings.colorSpace != m_ColorSpace)
            {
                graphEditorView = null;
                m_ColorSpace = PlayerSettings.colorSpace;
            }

            try
            {
                if (graphObject == null && selectedGuid != null)
                {
                    var guid = selectedGuid;
                    selectedGuid = null;
                    Initialize(guid);
                }

                if (graphObject == null)
                {
                    Close();
                    return;
                }

                var materialGraph = graphObject.graph as AbstractMaterialGraph;
                if (materialGraph == null)
                    return;
                if (graphEditorView == null)
                {
                    var asset = AssetDatabase.LoadAssetAtPath<Object>(AssetDatabase.GUIDToAssetPath(selectedGuid));
                    graphEditorView = new GraphEditorView(this, materialGraph, asset.name) { persistenceKey = selectedGuid };
                    m_ColorSpace = PlayerSettings.colorSpace;
                }

                if (forceRedrawPreviews)
                {
                    // Redraw all previews
                    foreach (INode node in m_GraphObject.graph.GetNodes<INode>())
                        node.Dirty(ModificationScope.Node);
                    forceRedrawPreviews = false;
                }

                graphEditorView.HandleGraphChanges();
                graphObject.graph.ClearChanges();
            }
            catch (Exception e)
            {
                m_HasError = true;
                m_GraphEditorView = null;
                graphObject = null;
                Debug.LogException(e);
                throw;
            }
        }

        void OnDisable()
        {
            graphEditorView = null;
        }

        void OnDestroy()
        {
            if (graphObject != null)
            {
                if (graphObject.isDirty && EditorUtility.DisplayDialog("Shader Graph Has Been Modified", "Do you want to save the changes you made in the shader graph?\n\nYour changes will be lost if you don't save them.", "Save", "Don't Save"))
                    UpdateAsset();
                Undo.ClearUndo(graphObject);
                DestroyImmediate(graphObject);
            }

            graphEditorView = null;
        }

        void UpdateDependantGraphs()
        {
            string[] lookFor = new string[] {"Assets"};
            var guids = AssetDatabase.FindAssets("t:shader", lookFor);
            foreach (string guid in guids)
            {
                if (AssetDatabase.GUIDToAssetPath(guid).ToLower().EndsWith(ShaderGraphImporter.ShaderGraphExtension))
                {
                    var path = AssetDatabase.GUIDToAssetPath(guid);

                    var textGraph = File.ReadAllText(path, Encoding.UTF8);
                    var graph = JsonUtility.FromJson<MaterialGraph>(textGraph);
                    graph.LoadedFromDisk();

                    foreach (SubGraphNode graphNode in graph.GetNodes<SubGraphNode>())
                    {
                        var subpath = AssetDatabase.GetAssetPath(graphNode.subGraphAsset);
                        var subguid = AssetDatabase.AssetPathToGUID(subpath);
                        if (subguid == selectedGuid)
                        {
                            UpdateShaderGraphOnDisk(path, graph);
                        }
                    }
                }
            }
        }

        public void PingAsset()
        {
            if (selectedGuid != null)
            {
                var path = AssetDatabase.GUIDToAssetPath(selectedGuid);
                var asset = AssetDatabase.LoadAssetAtPath<Object>(path);
                EditorGUIUtility.PingObject(asset);
            }
        }

        public void UpdateAsset()
        {
            if (selectedGuid != null && graphObject != null)
            {
                var path = AssetDatabase.GUIDToAssetPath(selectedGuid);
                if (string.IsNullOrEmpty(path) || graphObject == null)
                    return;

                if (m_GraphObject.graph.GetType() == typeof(MaterialGraph))
                    UpdateShaderGraphOnDisk(path);

                if (m_GraphObject.graph.GetType() == typeof(SubGraph))
                    UpdateAbstractSubgraphOnDisk<SubGraph>(path);

                graphObject.isDirty = false;
                var windows = Resources.FindObjectsOfTypeAll<MaterialGraphEditWindow>();
                foreach (var materialGraphEditWindow in windows)
                {
                    materialGraphEditWindow.Rebuild();
                }
            }
        }

        public void ToSubGraph()
        {
            var path = EditorUtility.SaveFilePanelInProject("Save subgraph", "New SubGraph", "ShaderSubGraph", "");
            path = path.Replace(Application.dataPath, "Assets");
            if (path.Length == 0)
                return;

            graphObject.RegisterCompleteObjectUndo("Convert To Subgraph");
            var graphView = graphEditorView.graphView;

            var nodes = graphView.selection.OfType<MaterialNodeView>().Where(x => !(x.node is PropertyNode)).Select(x => x.node as INode).ToArray();
            var bounds = Rect.MinMaxRect(float.PositiveInfinity, float.PositiveInfinity, float.NegativeInfinity, float.NegativeInfinity);
            foreach (var node in nodes)
            {
                var center = node.drawState.position.center;
                bounds = Rect.MinMaxRect(
                        Mathf.Min(bounds.xMin, center.x),
                        Mathf.Min(bounds.yMin, center.y),
                        Mathf.Max(bounds.xMax, center.x),
                        Mathf.Max(bounds.yMax, center.y));
            }
            var middle = bounds.center;
            bounds.center = Vector2.zero;

            // Collect the property nodes and get the corresponding properties
            var propertyNodeGuids = graphView.selection.OfType<MaterialNodeView>().Where(x => (x.node is PropertyNode)).Select(x => ((PropertyNode)x.node).propertyGuid);
            var metaProperties = graphView.graph.properties.Where(x => propertyNodeGuids.Contains(x.guid));

            var copyPasteGraph = new CopyPasteGraph(
                    graphView.graph.guid,
                    graphView.selection.OfType<MaterialNodeView>().Where(x => !(x.node is PropertyNode)).Select(x => x.node as INode),
                    graphView.selection.OfType<Edge>().Select(x => x.userData as IEdge),
                    graphView.selection.OfType<BlackboardField>().Select(x => x.userData as IShaderProperty),
                    metaProperties);

            var deserialized = CopyPasteGraph.FromJson(JsonUtility.ToJson(copyPasteGraph, false));
            if (deserialized == null)
                return;

            var subGraph = new SubGraph();
            var subGraphOutputNode = new SubGraphOutputNode();
            {
                var drawState = subGraphOutputNode.drawState;
                drawState.position = new Rect(new Vector2(bounds.xMax + 200f, 0f), drawState.position.size);
                subGraphOutputNode.drawState = drawState;
            }
            subGraph.AddNode(subGraphOutputNode);

            var nodeGuidMap = new Dictionary<Guid, Guid>();
            foreach (var node in deserialized.GetNodes<INode>())
            {
                var oldGuid = node.guid;
                var newGuid = node.RewriteGuid();
                nodeGuidMap[oldGuid] = newGuid;
                var drawState = node.drawState;
                drawState.position = new Rect(drawState.position.position - middle, drawState.position.size);
                node.drawState = drawState;
                subGraph.AddNode(node);
            }

            // figure out what needs remapping
            var externalOutputSlots = new List<IEdge>();
            var externalInputSlots = new List<IEdge>();
            foreach (var edge in deserialized.edges)
            {
                var outputSlot = edge.outputSlot;
                var inputSlot = edge.inputSlot;

                Guid remappedOutputNodeGuid;
                Guid remappedInputNodeGuid;
                var outputSlotExistsInSubgraph = nodeGuidMap.TryGetValue(outputSlot.nodeGuid, out remappedOutputNodeGuid);
                var inputSlotExistsInSubgraph = nodeGuidMap.TryGetValue(inputSlot.nodeGuid, out remappedInputNodeGuid);

                // pasting nice internal links!
                if (outputSlotExistsInSubgraph && inputSlotExistsInSubgraph)
                {
                    var outputSlotRef = new SlotReference(remappedOutputNodeGuid, outputSlot.slotId);
                    var inputSlotRef = new SlotReference(remappedInputNodeGuid, inputSlot.slotId);
                    subGraph.Connect(outputSlotRef, inputSlotRef);
                }

                // one edge needs to go to outside world
                else if (outputSlotExistsInSubgraph)
                {
                    externalInputSlots.Add(edge);
                }
                else if (inputSlotExistsInSubgraph)
                {
                    externalOutputSlots.Add(edge);
                }
            }

            // Find the unique edges coming INTO the graph
            var uniqueIncomingEdges = externalOutputSlots.GroupBy(
                    edge => edge.outputSlot,
                    edge => edge,
                    (key, edges) => new { slotRef = key, edges = edges.ToList() });

            var externalInputNeedingConnection = new List<KeyValuePair<IEdge, IShaderProperty>>();
            foreach (var group in uniqueIncomingEdges)
            {
                var sr = group.slotRef;
                var fromNode = graphObject.graph.GetNodeFromGuid(sr.nodeGuid);
                var fromSlot = fromNode.FindOutputSlot<MaterialSlot>(sr.slotId);

                IShaderProperty prop;
                switch (fromSlot.concreteValueType)
                {
                    case ConcreteSlotValueType.Texture2D:
                        prop = new TextureShaderProperty();
                        break;
                    case ConcreteSlotValueType.Cubemap:
                        prop = new CubemapShaderProperty();
                        break;
                    case ConcreteSlotValueType.Vector4:
                        prop = new Vector4ShaderProperty();
                        break;
                    case ConcreteSlotValueType.Vector3:
                        prop = new Vector3ShaderProperty();
                        break;
                    case ConcreteSlotValueType.Vector2:
                        prop = new Vector2ShaderProperty();
                        break;
                    case ConcreteSlotValueType.Vector1:
                        prop = new Vector1ShaderProperty();
                        break;
                    case ConcreteSlotValueType.Boolean:
                        prop = new BooleanShaderProperty();
                        break;
                    default:
                        throw new ArgumentOutOfRangeException();
                }

                if (prop != null)
                {
                    var materialGraph = (AbstractMaterialGraph)graphObject.graph;
                    var fromPropertyNode = fromNode as PropertyNode;
                    var fromProperty = fromPropertyNode != null ? materialGraph.properties.FirstOrDefault(p => p.guid == fromPropertyNode.propertyGuid) : null;
                    prop.displayName = fromProperty != null ? fromProperty.displayName : fromNode.name;
                    subGraph.AddShaderProperty(prop);
                    var propNode = new PropertyNode();
                    {
                        var drawState = propNode.drawState;
                        drawState.position = new Rect(new Vector2(bounds.xMin - 300f, 0f), drawState.position.size);
                        propNode.drawState = drawState;
                    }
                    subGraph.AddNode(propNode);
                    propNode.propertyGuid = prop.guid;

                    foreach (var edge in group.edges)
                    {
                        subGraph.Connect(
                            new SlotReference(propNode.guid, PropertyNode.OutputSlotId),
                            new SlotReference(nodeGuidMap[edge.inputSlot.nodeGuid], edge.inputSlot.slotId));
                        externalInputNeedingConnection.Add(new KeyValuePair<IEdge, IShaderProperty>(edge, prop));
                    }
                }
            }

            var uniqueOutgoingEdges = externalInputSlots.GroupBy(
                    edge => edge.inputSlot,
                    edge => edge,
                    (key, edges) => new { slot = key, edges = edges.ToList() });

            var externalOutputsNeedingConnection = new List<KeyValuePair<IEdge, IEdge>>();
            foreach (var group in uniqueOutgoingEdges)
            {
                var outputNode = subGraph.outputNode;
                var slotId = outputNode.AddSlot();

                var inputSlotRef = new SlotReference(outputNode.guid, slotId);

                foreach (var edge in group.edges)
                {
                    var newEdge = subGraph.Connect(new SlotReference(nodeGuidMap[edge.outputSlot.nodeGuid], edge.outputSlot.slotId), inputSlotRef);
                    externalOutputsNeedingConnection.Add(new KeyValuePair<IEdge, IEdge>(edge, newEdge));
                }
            }

            File.WriteAllText(path, EditorJsonUtility.ToJson(subGraph));
            AssetDatabase.ImportAsset(path);

            var loadedSubGraph = AssetDatabase.LoadAssetAtPath(path, typeof(MaterialSubGraphAsset)) as MaterialSubGraphAsset;
            if (loadedSubGraph == null)
                return;

            var subGraphNode = new SubGraphNode();
            var ds = subGraphNode.drawState;
            ds.position = new Rect(middle - new Vector2(100f, 150f), Vector2.zero);
            subGraphNode.drawState = ds;
            graphObject.graph.AddNode(subGraphNode);
            subGraphNode.subGraphAsset = loadedSubGraph;

            foreach (var edgeMap in externalInputNeedingConnection)
            {
                graphObject.graph.Connect(edgeMap.Key.outputSlot, new SlotReference(subGraphNode.guid, edgeMap.Value.guid.GetHashCode()));
            }

            foreach (var edgeMap in externalOutputsNeedingConnection)
            {
                graphObject.graph.Connect(new SlotReference(subGraphNode.guid, edgeMap.Value.inputSlot.slotId), edgeMap.Key.inputSlot);
            }

            graphObject.graph.RemoveElements(
                graphView.selection.OfType<MaterialNodeView>().Select(x => x.node as INode),
                Enumerable.Empty<IEdge>());
            graphObject.graph.ValidateGraph();
        }

        void UpdateAbstractSubgraphOnDisk<T>(string path) where T : SubGraph
        {
            var graph = graphObject.graph as T;
            if (graph == null)
                return;

            File.WriteAllText(path, EditorJsonUtility.ToJson(graph, true));
            AssetDatabase.ImportAsset(path);

            UpdateDependantGraphs();
        }

        void UpdateShaderGraphOnDisk(string path)
        {
            var graph = graphObject.graph as IShaderGraph;
            if (graph == null)
                return;

            UpdateShaderGraphOnDisk(path, graph);
        }

        static void UpdateShaderGraphOnDisk(string path, IShaderGraph graph)
        {
            var shaderImporter = AssetImporter.GetAtPath(path) as ShaderGraphImporter;
            if (shaderImporter == null)
                return;

            File.WriteAllText(path, EditorJsonUtility.ToJson(graph, true));
            shaderImporter.SaveAndReimport();
            AssetDatabase.ImportAsset(path);
        }

        private void Rebuild()
        {
            if (graphObject != null && graphObject.graph != null)
            {
                var subNodes = graphObject.graph.GetNodes<SubGraphNode>();
                foreach (var node in subNodes)
                    node.UpdateSlots();
            }
        }

        public void Initialize(string assetGuid)
        {
            try
            {
                m_ColorSpace = PlayerSettings.colorSpace;

                var asset = AssetDatabase.LoadAssetAtPath<Object>(AssetDatabase.GUIDToAssetPath(assetGuid));
                if (asset == null)
                    return;

                if (!EditorUtility.IsPersistent(asset))
                    return;

                if (selectedGuid == assetGuid)
                    return;

                var path = AssetDatabase.GetAssetPath(asset);
                var extension = Path.GetExtension(path);
                Type graphType;
                switch (extension)
                {
                    case ".ShaderGraph":
                        graphType = typeof(MaterialGraph);
                        break;
                    case ".ShaderSubGraph":
                        graphType = typeof(SubGraph);
                        break;
                    default:
                        return;
                }

                selectedGuid = assetGuid;

                var textGraph = File.ReadAllText(path, Encoding.UTF8);
                graphObject = CreateInstance<GraphObject>();
                graphObject.hideFlags = HideFlags.HideAndDontSave;
                graphObject.graph = JsonUtility.FromJson(textGraph, graphType) as IGraph;
                graphObject.graph.OnEnable();
                graphObject.graph.ValidateGraph();

                graphEditorView = new GraphEditorView(this, m_GraphObject.graph as AbstractMaterialGraph, asset.name) { persistenceKey = selectedGuid };
                graphEditorView.RegisterCallback<GeometryChangedEvent>(OnGeometryChanged);

                titleContent = new GUIContent(asset.name);

                Repaint();
            }
            catch (Exception)
            {
                m_HasError = true;
                m_GraphEditorView = null;
                graphObject = null;
                throw;
            }
        }

        void OnGeometryChanged(GeometryChangedEvent evt)
        {
            graphEditorView.UnregisterCallback<GeometryChangedEvent>(OnGeometryChanged);
            graphEditorView.graphView.FrameAll();
        }
    }
}