//! \file       ImageAJP.cs
//! \date       Mon Sep 12 21:25:27 2016
//! \brief      AliceSoft JPEG image.
//
// Copyright (C) 2016 by morkt
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//

using System.ComponentModel.Composition;
using System.IO;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using GameRes.Utility;

namespace GameRes.Formats.AliceSoft
{
    internal class AjpMetaData : ImageMetaData
    {
        public uint ImageOffset;
        public uint ImageSize;
        public uint AlphaOffset;
        public uint AlphaSize;
    }

    [Export(typeof(ImageFormat))]
    public class AjpFormat : ImageFormat
    {
        public override string         Tag { get { return "AJP"; } }
        public override string Description { get { return "AliceSoft JPEG image format"; } }
        public override uint     Signature { get { return 0x504A41; } } // 'AJP'

        internal static byte[] Key = {
            0x5D, 0x91, 0xAE, 0x87, 0x4A, 0x56, 0x41, 0xCD, 0x83, 0xEC, 0x4C, 0x92, 0xB5, 0xCB, 0x16, 0x34
        };

        public override ImageMetaData ReadMetaData (IBinaryStream stream)
        {
            var header = new byte[0x18];
            stream.Position = 0xC;
            if (header.Length != stream.Read (header, 0, header.Length))
                return null;
            return new AjpMetaData
            {
                Width   = LittleEndian.ToUInt32 (header, 0),
                Height  = LittleEndian.ToUInt32 (header, 4),
                BPP     = 32,
                ImageOffset = LittleEndian.ToUInt32 (header, 8),
                ImageSize   = LittleEndian.ToUInt32 (header, 0xC),
                AlphaOffset = LittleEndian.ToUInt32 (header, 0x10),
                AlphaSize   = LittleEndian.ToUInt32 (header, 0x14),
            };
        }

        public override ImageData Read (IBinaryStream stream, ImageMetaData info)
        {
            var meta = (AjpMetaData)info;
            int stride = (int)meta.Width * 4;
            byte[] pixels;
            using (var jpeg = DecryptStream (stream.AsStream, meta.ImageOffset, meta.ImageSize))
            {
                var decoder = new JpegBitmapDecoder (jpeg,
                    BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
                BitmapSource bitmap = decoder.Frames[0];
                if (0 == meta.AlphaOffset || 0 == meta.AlphaSize)
                {
                    bitmap.Freeze();
                    return new ImageData (bitmap, info);
                }
                if (bitmap.Format.BitsPerPixel != 32)
                    bitmap = new FormatConvertedBitmap (bitmap, PixelFormats.Bgr32, null, 0);

                pixels = new byte[stride * (int)meta.Height];
                bitmap.CopyPixels (pixels, stride, 0);
            }
            using (var mask = DecryptStream (stream.AsStream, meta.AlphaOffset, meta.AlphaSize))
            {
                var alpha = ReadMask (mask);
                int src = 0;
                for (int dst = 3; dst < pixels.Length; dst += 4)
                {
                    pixels[dst] = alpha[src++];
                }
                return ImageData.Create (info, PixelFormats.Bgra32, null, pixels, stride);
            }
        }

        Stream DecryptStream (Stream input, uint offset, uint size)
        {
            var header = new byte[Key.Length];
            input.Position = offset;
            input.Read (header, 0, header.Length);
            for (int i = 0; i < header.Length; ++i)
                header[i] ^= Key[i];
            if (size > header.Length)
            {
                var rest = new StreamRegion (input, input.Position, size - header.Length, true);
                return new PrefixStream (header, rest);
            }
            else
                return new MemoryStream (header, 0, (int)size);
        }

        byte[] ReadMask (Stream input)
        {
            var header = new byte[0x40];
            input.Read (header, 0, header.Length);
            int width       = LittleEndian.ToInt32 (header, 0x18);
            int height      = LittleEndian.ToInt32 (header, 0x1C);
            int data_offset = LittleEndian.ToInt32 (header, 0x20);
            int pal_offset  = LittleEndian.ToInt32 (header, 0x24);
            var pixels = new byte[width * height];
            int dst = 0;
            input.Position = data_offset;
            while (dst < pixels.Length)
            {
                int c = input.ReadByte();
                if (-1 == c)
                    break;
                if (c < 0xF8)
                {
                    pixels[dst++] = (byte)c;
                    continue;
                }

                int count = 0;
                switch (c)
                {
                case 0xF8:
                    pixels[dst++] = (byte)input.ReadByte();
                    break;

                case 0xFC:
                    count = input.ReadByte();
                    input.Read (pixels, dst, 2);
                    count = count * 2 + 4;
                    Binary.CopyOverlapped (pixels, dst, dst+2, count);
                    dst += count+2;
                    break;

                case 0xFD:
                    count = input.ReadByte() + 4;
                    byte b = (byte)input.ReadByte();
                    while (count --> 0)
                        pixels[dst++] = b;
                    break;

                case 0xFE:
                    count = input.ReadByte() + 3;
                    Binary.CopyOverlapped (pixels, dst - width*2, dst, count);
                    dst += count;
                    break;

                case 0xFF:
                    count = input.ReadByte() + 3;
                    Binary.CopyOverlapped (pixels, dst - width, dst, count);
                    dst += count;
                    break;

                default:
                    throw new InvalidFormatException();
                }
            }
            input.Position = pal_offset;
            var index = ReadGrayPalette (input);
            for (int i = 0; i < pixels.Length; ++i)
                pixels[i] = index[pixels[i]];
            return pixels;
        }

        byte[] ReadGrayPalette (Stream input)
        {
            var palette = new byte[0x300];
            if (0x300 != input.Read (palette, 0, 0x300))
                throw new EndOfStreamException();
            var gray = new byte[0x100];
            for (int i = 0; i < 0x100; ++i)
            {
                int c = i * 3;
                gray[i] = (byte)((palette[c] + palette[c+1] + palette[c+2]) / 3);
            }
            return gray;
        }

        public override void Write (Stream file, ImageData image)
        {
            throw new System.NotImplementedException ("AjpFormat.Write not implemented");
        }
    }
}
