using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System;
using System.Collections.Generic;
using System.Linq;

namespace OpenVIII
{
    public abstract class Texture_Base
    {
        #region Fields

        private const ushort blue_mask = 0x7C00;

        private const ushort green_mask = 0x3E0;

        /// <summary>
        /// all bits except the STP bit.
        /// </summary>
        private const ushort NotSTP_mask = 0x7FFF;

        private const ushort red_mask = 0x1F;

        /// <summary>
        /// Special Transparency Processing bit.
        /// </summary>
        /// <remarks>
        /// The STP (special transparency processing) bit has varying special meanings. Depending on
        /// the current transparency processing mode, it denotes if pixels of this color should be
        /// treated as transparent or not. If transparency processing is enabled, pixels of this
        /// color will be rendered transparent if the STP bit is set. A special case is black pixels
        /// (RGB 0,0,0), which by default are treated as transparent by the PlayStation unless the
        /// STP bit is set.
        /// </remarks>
        /// <see cref="http://www.psxdev.net/forum/viewtopic.php?t=109"/>
        /// <seealso cref="http://www.raphnet.net/electronique/psx_adaptor/Playstation.txt"/>
        private const ushort STP_mask = 0x8000;

        #endregion Fields

        //#region Enums

        //public enum TextureType : byte
        //{
        //    TEX,
        //    TIM,
        //    Texture2D,
        //    PNG
        //}

        //#endregion Enums

        #region Properties

        public abstract byte GetBytesPerPixel { get; }
        public abstract int GetClutCount { get; }
        public abstract int GetClutSize { get; }
        public abstract int GetColorsCountPerPalette { get; }
        public abstract int GetHeight { get; }
        public abstract int GetOrigX { get; }
        public abstract int GetOrigY { get; }
        public abstract int GetWidth { get; }

        #endregion Properties

        #region Methods

        /// <summary>
        /// Convert ABGR1555 color to RGBA 32bit color
        /// </summary>
        /// <remarks>
        /// FromPsColor from TEX does the same thing I think. Unsure which is better. I like the masks
        /// </remarks>
        public static Color ABGR1555toRGBA32bit(ushort pixel, bool ignoreAlpha = false)
        {
            // alert to let me know if we might need to check something.
            if (pixel == 0 && !ignoreAlpha) return Color.TransparentBlack;
            //https://docs.microsoft.com/en-us/windows/win32/directshow/working-with-16-bit-rgb
            // had the masks. though they were doing rgb but we are doing bgr so i switched red and blue.
            var ret = new Color
            {
                R = (byte)MathHelper.Clamp((pixel & red_mask) << 3, 0, 255),
                G = (byte)MathHelper.Clamp(((pixel & green_mask) >> 5) << 3, 0, 255),
                B = (byte)MathHelper.Clamp(((pixel & blue_mask) >> 10) << 3, 0, 255),
                A = 255
            };
            //if (GetSTP(pixel))
            //{
            //    //ret.A = Transparency.GetAlpha;
            //    Debug.WriteLine($"Special Transparency Processing bit set 16 bit color: {pixel & 0x7FFF}, 32 bit color: {ret}");
            //    //Debug.Assert(false);
            //}
            //TDW has STP
            return ret;
        }

        /// <summary>
        /// Custom Convert 16BIT color to RGBA 32bit color
        /// </summary>
        /// <remarks>
        /// TEX file actually has it's own masks and shift varibles. if these are honor'ed could have
        /// the 16 bit color in any order. Though I think they are all the same. Unsure if these
        /// values also work for 32 bit. or 24 bit. (Needs testing and Tex needs to be adjusted
        /// to read those values, they are in the header)
        /// </remarks>
        public static Color Custom_16BITtoRGBA32bit(ushort pixel, ushort c_red_mask, ushort c_red_shift, ushort c_green_mask, ushort c_green_shift, ushort c_blue_mask, ushort c_blue_shift, bool ignoreAlpha = false)
        {
            // alert to let me know if we might need to check something.
            if (pixel == 0 && !ignoreAlpha) return Color.TransparentBlack;
            //https://docs.microsoft.com/en-us/windows/win32/directshow/working-with-16-bit-rgb
            // had the masks. though they were doing rgb but we are doing bgr so i switched red and blue.
            var ret = new Color
            {
                R = (byte)MathHelper.Clamp(((pixel & c_red_mask) >> c_red_shift) << 3, 0, 255),
                G = (byte)MathHelper.Clamp(((pixel & c_green_mask) >> c_green_shift) << 3, 0, 255),
                B = (byte)MathHelper.Clamp(((pixel & c_blue_mask) >> c_blue_shift) << 3, 0, 255),
                A = 255
            };
            return ret;
        }

        /// <summary>
        /// Get Special Transparency Processing bit.
        /// </summary>
        /// <param name="pixel">16 bit color</param>
        /// <returns>true if bit is set and not black, otherwise false.</returns>
        public static bool GetSTP(ushort pixel) =>
            // I set this to always return false for black. As it's transparency is handled in
            // conversion method.
            (pixel & NotSTP_mask) == 0 ? false : (pixel & STP_mask) != 0;

        public static Texture_Base Open(byte[] buffer, uint offset = 0)
        {
            switch (BitConverter.ToUInt32(buffer, (int)(0 + offset)))
            {
                case 0x1:
                case 0x2:
                    return new TEX(buffer);

                case 0x10:
                    return new TIM2(buffer, 0);

                default:
                    return null;
            }
        }

        public abstract void ForceSetClutColors(ushort newNumOfColors);

        public abstract void ForceSetClutCount(ushort newClut);

        public abstract Color[] GetClutColors(ushort clut);

        public Texture2D GetTexture(Dictionary<int, Color> colorOverride, sbyte clut = -1)
        {
            if (colorOverride == null || colorOverride.Count == 0) return null;
            var colors = clut > 0 && clut < GetClutCount ? GetClutColors((ushort)clut) : new Color[GetColorsCountPerPalette];
            if (colors == null) return null;
            colorOverride.Where(x => x.Key < colors.Length).ForEach(x => colors[x.Key] = x.Value);
            return GetTexture((colors));
        }

        public abstract Texture2D GetTexture(Color[] colors);

        public abstract Texture2D GetTexture(ushort clut);

        public virtual Texture2D GetTexture() => GetTexture(GetClutColors(0));

        public abstract void Load(byte[] buffer, uint offset = 0);

        public abstract void Save(string path);

        public abstract void SaveCLUT(string path);

        public virtual void SavePNG(string path, short clut = -1)
        { }

        #endregion Methods

        //public static class Transparency
        //{
        //    /// <summary>
        //    /// <para>PSX Transparency Mode</para>
        //    /// <para>
        //    /// GPU first reads the pixel it wants to write to, and then calculates the color it will
        //    /// write from the 2 pixels according to the semi-transparency mode selected
        //    /// </para>
        //    /// <para>OFF is 100% alpha</para>
        //    /// <para>Mode 1 is 50%</para>
        //    /// <para>Mode 2 is supposed to be existing pixel plus value of new one.</para>
        //    /// <para>Mode 3 is supposed to be existing pixel minus value of new one.</para>
        //    /// <para>Mode 4 is 25%</para>
        //    /// <para>Unsure if the pixel is supposed to be 50% alpha before this</para>
        //    /// </summary>
        //    /// <see cref="http://www.raphnet.net/electronique/psx_adaptor/Playstation.txt"/>
        //    //public static readonly byte[] Modes = { 0xFF 0x7F, 0xFF, 0x7F, 0x3F }; // if 100% before calculation
        //    public static readonly byte[] Modes = { 0xFF, 0x3F, 0x7F, 0x7F, 0x1F }; // if 50% before calculation
        //If color is not black and STP bit on, possible semi-transparency.

        //http://www.raphnet.net/electronique/psx_adaptor/Playstation.txt
        //4 modes psx could use for Semi-Transparency. I donno which one ff8 uses or if it uses only one.
        //If Black is transparent when bit is off. And visible when bit is on.

        ///// <summary>
        ///// Ratio needed to convert 16 bit to 32 bit color
        ///// </summary>
        ///// <seealso cref="https://github.com/myst6re/vincent-tim/blob/master/PsColor.h"/>
        //public const double COEFF_COLOR = (double)255 / 31;

        ///// <summary>
        ///// converts 16 bit color to 32bit with alpha. alpha needs to be set true manually per pixel
        ///// unless you know the color value.
        ///// </summary>
        ///// <param name="color">16 bit color</param>
        ///// <param name="useAlpha">area is Visible or not</param>
        ///// <returns>byte[4] red green blue alpha, i think</returns>
        ///// <see cref="https://github.com/myst6re/vincent-tim/blob/master/PsColor.cpp"/>
        //public static Color FromPsColor(ushort color, bool useAlpha = false) => new Color((byte)Math.Round((color & 31) * COEFF_COLOR), (byte)Math.Round(((color >> 5) & 31) * COEFF_COLOR), (byte)Math.Round(((color >> 10) & 31) * COEFF_COLOR), (byte)(color == 0 && useAlpha ? 0 : 255));
    }
}