using System;
using UnityEngine;
using UnityEngine.Experimental.Rendering;
using System.Linq;
using System.Reflection;
using System.IO;
using Object = UnityEngine.Object;

#if UNITY_EDITOR
using UnityEditor;
using UnityEditor.Callbacks;
#endif

namespace X.Rendering.Assets
{
    public interface IGradientTextureForEditor
    {
        void CreateTexture();

        Texture2D GetTexture();

        void LoadExisitingTexture();
    }

    /// <summary>
    /// Main Asset, holds settings, create, hold and change Texture2D's pixels, name
    /// </summary>
    [CreateAssetMenu(fileName = "NewGradientName", menuName = "Texture/Gradient")]
    public class GradientTexture : ScriptableObject, IEquatable<Texture2D>, ISerializationCallbackReceiver,
        IGradientTextureForEditor
    {
        [SerializeField] Vector2Int _resolution = new Vector2Int(256, 256);
        [SerializeField] bool _sRGB = true;
        [SerializeField] AnimationCurve _verticalLerp = AnimationCurve.Linear(0, 0, 1, 1);
        [SerializeField, GradientUsage(true)] Gradient _horizontalTop = GetDefaultGradient();
        [SerializeField, GradientUsage(true)] Gradient _horizontalBottom = GetDefaultGradient();
        [SerializeField, HideInInspector] Texture2D _texture = default;

        public Texture2D GetTexture() => _texture;

        public bool GetSRGB() => _sRGB;

        public void SetSRGB(bool value)
        {
            _sRGB = value;
            OnValidate();
        }

        int _width => _resolution.x;
        int _height => _resolution.y;

        public static implicit operator Texture2D(GradientTexture asset) => asset.GetTexture();

        static Gradient GetDefaultGradient() => new Gradient
        {
            alphaKeys = new[] { new GradientAlphaKey(1, 1) },
            colorKeys = new[]
            {
                new GradientColorKey(Color.black, 0),
                new GradientColorKey(Color.white, 1)
            }
        };

        public void FillColors(bool useRGB)
        {
            bool isLinear = QualitySettings.activeColorSpace == ColorSpace.Linear;

            float tVertical = 0;

            for (int y = 0; y < _height; y++)
            {
                tVertical = _verticalLerp.Evaluate((float)y / _height);

                for (int x = 0; x < _width; x++)
                {
                    float tHorizontal = (float)x / _width;

                    Color color = Color.Lerp(_horizontalBottom.Evaluate(tHorizontal),
                        _horizontalTop.Evaluate(tHorizontal),
                        tVertical);

                    color = useRGB && isLinear ? color.linear : color;
                    _texture.SetPixel(x, y, color);
                }
            }

            _texture.Apply();
        }

        public bool Equals(Texture2D other)
        {
            return _texture.Equals(other);
        }

        void OnValidate() => ValidateTextureValues();

        void IGradientTextureForEditor.LoadExisitingTexture()
        {
#if UNITY_EDITOR
            if (!_texture)
            {
                string assetPath = AssetDatabase.GetAssetPath(this);
                _texture = AssetDatabase.LoadAssetAtPath<Texture2D>(assetPath);
            }
#endif
        }

        void IGradientTextureForEditor.CreateTexture()
        {
#if UNITY_EDITOR
            //if (EditorApplication.isUpdating) return;

            string assetPath = AssetDatabase.GetAssetPath(this);
            if (string.IsNullOrEmpty(assetPath)) return;

            if (!_texture && this != null && !EditorApplication.isUpdating)
            {
                AssetDatabase.ImportAsset(assetPath);
                _texture = AssetDatabase.LoadAssetAtPath<Texture2D>(assetPath);
            }

            if (!_texture)
            {
#if UNITY_2018
                _texture = new Texture2D(_resolution.x, _resolution.y);
#else
                _texture = new Texture2D(_resolution.x, _resolution.y, DefaultFormat.LDR, TextureCreationFlags.None);
#endif
                if (_texture.name != name) _texture.name = name;
            }

            if (!_texture) return;

            ValidateTextureValues();

            if (!EditorUtility.IsPersistent(this)) return;
            if (AssetDatabase.IsSubAsset(_texture)) return;
            if (AssetDatabase.LoadAssetAtPath<Texture2D>(assetPath)) return;

#if UNITY_2020_1_OR_NEWER
            if (AssetDatabase.IsAssetImportWorkerProcess()) return;
#endif
            AssetDatabase.AddObjectToAsset(_texture, this);
            AssetDatabase.SaveAssets();
            AssetDatabase.Refresh();
            AssetDatabase.ImportAsset(assetPath, ImportAssetOptions.ForceUpdate);
#endif
        }

        void ValidateTextureValues()
        {
            if (!_texture) return;
            if (_texture.name != name)
            {
                _texture.name = name;
            }
            else
            {
                if (_texture.width != _resolution.x ||
                    _texture.height != _resolution.y)
                {
#if UNITY_2022_1_OR_NEWER
                    _texture.Reinitialize(_resolution.x, _resolution.y);
#else
                    _texture.Resize(_resolution.x, _resolution.y);
#endif
                }

#if UNITY_EDITOR
                _texture.alphaIsTransparency = true;
#endif
                FillColors(_sRGB);

                SetDirtyTexture();
            }
        }

        #region Editor

        [System.Diagnostics.Conditional("UNITY_EDITOR")]
        void SetDirtyTexture()
        {
#if UNITY_EDITOR
            if (!_texture) return;

            EditorUtility.SetDirty(_texture);
#endif
        }

        #endregion

        public void OnAfterDeserialize()
        {
        }

        public void OnBeforeSerialize()
        {
#if UNITY_EDITOR
            if (!_texture || _texture.name == name) return;

            _texture.name = name;

            //AssetDatabase.SaveAssets();
#endif
        }
    }

#if UNITY_EDITOR
    [CustomEditor(typeof(GradientTexture), true), CanEditMultipleObjects]
    public class GradientTextureEditor : UnityEditor.Editor
    {
        GradientTexture _gradientTexture;
        UnityEditor.Editor _editor;

        public override bool HasPreviewGUI() => true;

        void OnEnable()
        {
            _gradientTexture = target as GradientTexture;
        }

        public override void OnInspectorGUI()
        {
            if (_gradientTexture.GetTexture() == null)
            {
                (_gradientTexture as IGradientTextureForEditor).CreateTexture();
            }

            base.OnInspectorGUI();

            string buttonText = "Encode to PNG" + (targets.Length > 1 ? $" ({targets.Length})" : "");

            if (GUILayout.Button(buttonText))
            {
                foreach (Object target in targets)
                {
                    GradientTexture targetTexture = target as GradientTexture;

                    string path = EditorUtility.SaveFilePanelInProject("Save file",
                        $"{targetTexture.name}_baked",
                        "png",
                        "Choose path to save file");

                    if (string.IsNullOrEmpty(path))
                    {
                        Debug.LogError("[ GradientTextureEditor ] EncodeToPNG() save path is empty! canceled",
                            targetTexture);

                        return;
                    }

                    bool wasSRGB = targetTexture.GetSRGB();
                    if (wasSRGB) targetTexture.SetSRGB(false);
                    byte[] bytes = ImageConversion.EncodeToPNG(targetTexture.GetTexture());
                    targetTexture.SetSRGB(wasSRGB);

                    int length = "Assets".Length;
                    string dataPath = Application.dataPath;
                    dataPath = dataPath.Remove(dataPath.Length - length, length);
                    dataPath += path;
                    File.WriteAllBytes(dataPath, bytes);

                    AssetDatabase.SaveAssets();
                    AssetDatabase.Refresh();
                    AssetDatabase.ImportAsset(path);
                    Texture2D image = AssetDatabase.LoadAssetAtPath<Texture2D>(path);

                    TextureImporter importer = (TextureImporter)AssetImporter.GetAtPath(path);
                    importer.sRGBTexture = targetTexture.GetSRGB();
                    importer.SaveAndReimport();
                    AssetDatabase.SaveAssets();
                    AssetDatabase.Refresh();

                    Debug.Log($"[ GradientTextureEditor ] EncodeToPNG() Success! png-gradient saved at '{path}'",
                        image);

                    EditorGUIUtility.PingObject(image);
                    Selection.activeObject = image;
                }
            }
        }

        public override void DrawPreview(Rect previewArea)
        {
            Texture2D texture = _gradientTexture.GetTexture();
            bool check = !_editor || _editor.target != texture;

            if (check && texture && (_editor == null || _editor.target != texture))
            {
                try
                {
                    _editor = CreateEditor(targets.Select(t => (t as GradientTexture)?.GetTexture()).ToArray());
                }
                catch
                {
                    _editor = null;
                    //Debug.LogException(e);
                    //throw;
                }
            }

            if (_editor && _editor.target)
            {
                try
                {
                    _editor.DrawPreview(previewArea);
                }
                catch
                {
                    //Debug.LogException(e);
                    //throw;
                }
            }
        }

        public override void OnPreviewSettings()
        {
            if (_editor && _editor.target)
            {
                try
                {
                    _editor.OnPreviewSettings();
                }
                catch
                {
                    //Debug.LogException(e);
                    //throw;
                }
            }
        }

        public override void ReloadPreviewInstances()
        {
            if (_editor && _editor.target)
            {
                try
                {
                    _editor.ReloadPreviewInstances();
                }
                catch
                {
                    //Debug.LogException(e);
                    //throw;
                }
            }
        }

        public override void OnInteractivePreviewGUI(Rect r, GUIStyle background)
        {
            if (_editor && _editor.target)
            {
                try
                {
                    _editor.OnInteractivePreviewGUI(r, background);
                }
                catch
                {
                    //Debug.LogException(e);
                    //throw;
                }
            }
        }

        public override void OnPreviewGUI(Rect r, GUIStyle background)
        {
            if (_editor && _editor.target)
            {
                try
                {
                    _editor.OnPreviewGUI(r, background);
                }
                catch
                {
                    //Debug.LogException(e);
                    //throw;
                }
            }
        }

        public override Texture2D RenderStaticPreview(string assetPath, Object[] subAssets, int width, int height)
        {
            if (_gradientTexture == null) return null;
            if (_gradientTexture.GetTexture() == null) return null;
            Texture2D tex = new Texture2D(width, height);
            EditorUtility.CopySerialized(_gradientTexture.GetTexture(), tex);
            return tex;
        }

        void OnDisable()
        {
            if (_editor)
            {
                _editor.GetType().GetMethod("OnDisable", BindingFlags.NonPublic)?.Invoke(_editor, null);
            }
        }

        void OnDestroy()
        {
            if (_editor)
            {
                DestroyImmediate(_editor);
            }
        }
    }

    public static class DragAndDropUtility
    {
        static DragAndDrop.ProjectBrowserDropHandler _handlerProject;

        [InitializeOnLoadMethod]
        public static void Init()
        {
            _handlerProject = ProjectDropHandler;
            DragAndDrop.RemoveDropHandler(_handlerProject);
            DragAndDrop.AddDropHandler(_handlerProject);
        }

        private static DragAndDropVisualMode ProjectDropHandler(int dragInstanceId, string dropUponPath, bool perform)
        {
            if (!perform)
            {
                var dragged = DragAndDrop.objectReferences;
                bool found = false;
                for (var i = 0; i < dragged.Length; i++)
                {
                    if (dragged[i] is GradientTexture gradient)
                    {
                        dragged[i] = gradient.GetTexture();
                        found = true;
                    }
                }
                if (found)
                {
                    DragAndDrop.objectReferences = dragged;
                    GUI.changed = true;
                    return default;
                }

            }
            return default;
        }
    }

    public class ProjectIconsUtility
    {
        [DidReloadScripts]
        static ProjectIconsUtility()
        {
            EditorApplication.projectWindowItemOnGUI -= ItemOnGUI;
            EditorApplication.projectWindowItemOnGUI += ItemOnGUI;
        }

        static void ItemOnGUI(string guid, Rect rect)
        {
            string assetPath = AssetDatabase.GUIDToAssetPath(guid);
            var asset = AssetDatabase.LoadAssetAtPath<GradientTexture>(assetPath);

            if (asset == null) return;
            if (!asset.GetTexture()) return;


            if (rect.height > 30)
            {
                // rect.position = new Vector2(rect.position.x + rect.height * .1f + rect.width - rect.height, rect.position.y);
                // rect.height *= .87f;
                // rect.width = rect.height - 5;
                // rect.height *= .95f;
            }
            else
            {
                //rect.position = new Vector2(rect.position.x-2 + rect.width - rect.height, rect.position.y);
                rect.width = rect.height *= .9f;
                GUI.DrawTexture(rect, asset.GetTexture());
            }

        }
    }
#endif
}