using OpenTK;
using OpenTK.Graphics;
using Newtonsoft.Json;
using RecrownedAthenaeum.Data;
using RecrownedAthenaeum.Types;
using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;

namespace RecrownedAthenaeum.Graphics.UI.SkinSystem
{
    /// <summary>
    /// Called when the skin manager has completed a async action.
    /// </summary>
    /// <param name="actionCompleted">The completed action.</param>
    public delegate void AsyncComplete(SkinManager.Action actionCompleted);

    /// <summary>
    /// Manages reference to default and loading of custom skins.
    /// </summary>
    public class SkinManager
    {
        private const string EXTENSION = ".rbskin";
        private readonly MergedSkin mergedSkin = new MergedSkin();
        private Thread thread;
        private Action action;
        private GraphicsDevice graphicsDevice;
        private string selectedSkinPath;
        private SkinData skinDataToUse;

        /// <summary>
        /// Whether or not the skin manager is set up with a <see cref="BaseSkin"/> and <see cref="loadedSkin"/>.
        /// </summary>
        public bool MergingSkins { get { return (loadedSkin != null && SkinUseable); } }

        /// <summary>
        /// Whether or not this manager has been set up with at least a base skin.
        /// </summary>
        public bool SkinUseable { get { return BaseSkin == null; } }

        /// <summary>
        /// The list of paths for all found skins by <see cref="SearchSkinDirectory"/>. May be null.
        /// </summary>
        public volatile List<string> skinPaths;

        /// <summary>
        /// The event that is called when a state changes.
        /// </summary>
        public event AsyncComplete AsyncCompleteEvent;

        /// <summary>
        /// The various possible states a skin manager could be in.
        /// </summary>
        public enum Action
        {
            /// <summary>
            /// After a search has completed.
            /// </summary>
            SEARCH,
            /// <summary>
            /// Having the skin generated to be in a useable state.
            /// </summary>
            LOAD
        }

        /// <summary>
        /// the skin that favors the selected skin, but still has a fallback to the default skin in case anything is missing.
        /// </summary>
        public ISkin Skin { get { return mergedSkin; } }

        /// <summary>
        /// The user loaded skin resulted from asynchronous <see cref="LoadSkin(string, GraphicsDevice)"/>.
        /// </summary>
        public ISkin loadedSkin { get { return mergedSkin.mainSkin; } private set { mergedSkin.mainSkin = value; } }

        /// <summary>
        /// The default skin in case the selected skin doesn't cover a specific definition or color.
        /// </summary>
        public ISkin BaseSkin { get { return mergedSkin.alternateSkin; } set { mergedSkin.alternateSkin = value; } }

        /// <summary>
        /// The directory that contains the skins.
        /// </summary>
        public string skinsDirectory;

        /// <summary>
        /// Performs a recursive asynchronous search of the directory given in a path set by <see cref="skinsDirectory"/>.
        /// </summary>
        public void SearchSkinDirectory()
        {
            action = Action.SEARCH;
            AttemptAsync();
        }

        /// <summary>
        /// Reads skin data if extension is valid.
        /// </summary>
        /// <param name="path">the path to load from.</param>
        /// <returns>A <see cref="SkinData"/> that holds all the information and some metadata for the loaded skin.</returns>
        public SkinData ReadSkinData(string path)
        {
            if (path.ToLower().EndsWith(EXTENSION))
            {
                return JsonConvert.DeserializeObject<SkinData>(File.ReadAllText(path));
            }
            throw new ArgumentException("The path given does not point to a file with the required extension \"" + EXTENSION + "\" rather, has \"" + Path.GetExtension(path) + "\".");
        }

        /// <summary>
        /// loads a skin asynchronously to the <see cref="loadedSkin"/>.
        /// </summary>
        /// <param name="path">The path pointing to the file with the extension "<see cref="EXTENSION"/>".</param>
        /// <param name="graphicsDevice">Graphics device to use for texture creation.</param>
        public void LoadSkin(string path, GraphicsDevice graphicsDevice)
        {
            action = Action.LOAD;
            this.graphicsDevice = graphicsDevice ?? throw new ArgumentNullException("Requires graphics device to create textures.");
            selectedSkinPath = path ?? throw new ArgumentNullException("Requires path to find textures.");
            skinDataToUse = ReadSkinData(path);

            AttemptAsync();
        }

        private void AttemptAsync()
        {
            if (thread != null && thread.IsAlive) throw new InvalidOperationException("Already performing task: " + action);
            thread = new Thread(ThreadStart);
        }

        private void ThreadStart()
        {
            switch (action)
            {
                case Action.SEARCH:
                    SearchForSkins();
                    OnAsyncComplete(action);
                    break;
                case Action.LOAD:
                    loadedSkin = LoadSkinFromData(skinDataToUse, selectedSkinPath, graphicsDevice);
                    OnAsyncComplete(action);
                    break;
            }
        }

        private void SearchForSkins()
        {
            skinPaths.Clear();
            skinPaths = RecursiveSkinSearch(skinsDirectory);
        }

        private Skin LoadSkinFromData(SkinData skinData, string path, GraphicsDevice graphicsDevice)
        {
            TextureAtlasDataReader textureAtlasDataReader = new TextureAtlasDataReader();
            FileInfo[] skinFiles = Directory.GetParent(path).GetFiles();
            Dictionary<string, string> filePath = new Dictionary<string, string>();
            for (int i = 0; i < skinFiles.Length; i++)
            {
                filePath.Add(skinFiles[i].Name, skinFiles[i].FullName);
            }
            TextureAtlasDataReader tatlasDataReader = new TextureAtlasDataReader();
            TextureAtlasData atlasData;
            atlasData = JsonConvert.DeserializeObject<TextureAtlasData>(File.ReadAllText(filePath[skinData.nameOfTextureAtlas]));
            Texture2D atlasTexture;
            using (FileStream stream = new FileStream(filePath[atlasData.textureName], FileMode.Open))
            {
                atlasTexture = Texture2D.FromStream(graphicsDevice, stream);
                Vector4[] data = new Vector4[atlasTexture.Width * atlasTexture.Height];
                atlasTexture.GetData(data);
                for (int i = 0; i < data.Length; i++)
                {
                    Color4Ext.FromNonPremultiplied(ref data[i]);
                }
                atlasTexture.SetData(data);
            }
            TextureAtlas.Region[] regions = textureAtlasDataReader.GenerateAtlasRegionsFromData(atlasData, atlasTexture);
            TextureAtlas textureAtlas = new TextureAtlas(atlasTexture, regions);
            Texture2D cursorTexture;
            if (Path.HasExtension(skinData.cursorTextureName) && filePath.ContainsKey(skinData.cursorTextureName))
            {
                using (FileStream stream = new FileStream(filePath[skinData.cursorTextureName], FileMode.Open))
                {
                    cursorTexture = Texture2D.FromStream(graphicsDevice, stream);
                    Vector4[] data = new Vector4[cursorTexture.Width * cursorTexture.Height];
                    atlasTexture.GetData(data);
                    for (int i = 0; i < data.Length; i++)
                    {
                        Color4Ext.FromNonPremultiplied(ref data[i]);
                    }
                    cursorTexture.SetData(data);
                }
            }
            else
            {
                cursorTexture = textureAtlas[skinData.cursorTextureName].AsTexture2D(graphicsDevice);
            }
            Skin skin = new Skin(new TextureAtlas(atlasTexture, regions), cursorTexture);

            for (int i = 0; i < skinData.colors.Length; i++)
            {
                SkinData.ColorData colorData = skinData.colors[i];
                skin.AddColor(colorData.name, new Color4(colorData.r, colorData.g, colorData.b, colorData.a));
            }

            for (int i = 0; i < skinData.definitions.Length; i++)
            {
                SkinData.DefinitionData definitionData = skinData.definitions[i];
                skin.AddDefinition(definitionData.skin, definitionData.name);
            }

            return skin;
        }

        private List<string> RecursiveSkinSearch(string path)
        {
            string[] files = Directory.GetFiles(path);
            string[] folders = Directory.GetDirectories(path);
            List<string> skins = new List<string>();
            for (int i = 0; i < files.Length; i++)
            {
                if (files[i].ToLower().EndsWith(EXTENSION))
                {
                    skins.Add(files[i]);
                }
            }
            for (int i = 0; i < folders.Length; i++)
            {
                skins.AddRange(RecursiveSkinSearch(folders[i]));
            }

            return skins;
        }

        private void OnAsyncComplete(Action newState)
        {
            AsyncCompleteEvent?.Invoke(newState);
        }
    }
}