/*
* Copyright 2012 ZXing.Net authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

using System.Windows;
#if NETFX_CORE
using Windows.UI.Xaml.Media.Imaging;
#else
using System.Windows.Media;
using System.Windows.Media.Imaging;
#endif

namespace ZXing
{
    /// <summary>
    /// class which represents the luminance source values for bitmap source objects
    /// </summary>
    public partial class BitmapSourceLuminanceSource : BaseLuminanceSource
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="BitmapSourceLuminanceSource"/> class.
        /// </summary>
        /// <param name="width">The width.</param>
        /// <param name="height">The height.</param>
        protected BitmapSourceLuminanceSource(int width, int height)
           : base(width, height)
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="BitmapSourceLuminanceSource"/> class.
        /// </summary>
        /// <param name="bitmap">The bitmap.</param>
        public BitmapSourceLuminanceSource(BitmapSource bitmap)
           : base(bitmap.PixelWidth, bitmap.PixelHeight)
        {
            switch (bitmap.Format.ToString())
            {
                case "Bgr24":
                case "Bgr32":
                    CalculateLuminanceBGR(bitmap);
                    break;
                case "Bgra32":
                    CalculateLuminanceBGRA(bitmap);
                    break;
                case "Rgb24":
                    CalculateLuminanceRGB(bitmap);
                    break;
                case "Bgr565":
                    CalculateLuminanceBGR565(bitmap);
                    break;
                default:
                    // there is no special conversion routine to luminance values
                    // we have to convert the image to a supported format
                    bitmap = new FormatConvertedBitmap(bitmap, PixelFormats.Bgra32, null, 0);
                    CalculateLuminanceBGR(bitmap);
                    break;
            }
        }

        private void CalculateLuminanceRGB(BitmapSource bitmap)
        {
            var width = bitmap.PixelWidth;
            var height = bitmap.PixelHeight;
            var stepX = (bitmap.Format.BitsPerPixel + 7) / 8;
            var bufferSize = width * stepX;
            var buffer = new byte[bufferSize];
            var rect = new Int32Rect(0, 0, width, 1);
            var luminanceIndex = 0;

            for (var curY = 0; curY < height; curY++)
            {
                bitmap.CopyPixels(rect, buffer, bufferSize, 0);
                for (var curX = 0; curX < bufferSize; curX += stepX)
                {
                    var r = buffer[curX];
                    var g = buffer[curX + 1];
                    var b = buffer[curX + 2];
                    luminances[luminanceIndex] = (byte)((RChannelWeight * r + GChannelWeight * g + BChannelWeight * b) >> ChannelWeight);
                    luminanceIndex++;
                }
                rect.Y++;
            }
        }

        private void CalculateLuminanceBGR(BitmapSource bitmap)
        {
            var width = bitmap.PixelWidth;
            var height = bitmap.PixelHeight;
            var stepX = (bitmap.Format.BitsPerPixel + 7) / 8;
            var bufferSize = width * stepX;
            var buffer = new byte[bufferSize];
            var rect = new Int32Rect(0, 0, width, 1);
            var luminanceIndex = 0;

            for (var curY = 0; curY < height; curY++)
            {
                bitmap.CopyPixels(rect, buffer, bufferSize, 0);
                for (var curX = 0; curX < bufferSize; curX += stepX)
                {
                    var b = buffer[curX];
                    var g = buffer[curX + 1];
                    var r = buffer[curX + 2];
                    luminances[luminanceIndex] = (byte)((RChannelWeight * r + GChannelWeight * g + BChannelWeight * b) >> ChannelWeight);
                    luminanceIndex++;
                }
                rect.Y++;
            }
        }

        private void CalculateLuminanceBGRA(BitmapSource bitmap)
        {
            var width = bitmap.PixelWidth;
            var height = bitmap.PixelHeight;
            var stepX = (bitmap.Format.BitsPerPixel + 7) / 8;
            var bufferSize = width * stepX;
            var buffer = new byte[bufferSize];
            var rect = new Int32Rect(0, 0, width, 1);
            var luminanceIndex = 0;

            for (var curY = 0; curY < height; curY++)
            {
                bitmap.CopyPixels(rect, buffer, bufferSize, 0);
                for (var curX = 0; curX < bufferSize; curX += stepX)
                {
                    var b = buffer[curX];
                    var g = buffer[curX + 1];
                    var r = buffer[curX + 2];
                    var luminance = (byte)((RChannelWeight * r + GChannelWeight * g + BChannelWeight * b) >> ChannelWeight);
                    var alpha = buffer[curX + 3];
                    luminance = (byte)(((luminance * alpha) >> 8) + (255 * (255 - alpha) >> 8));
                    luminances[luminanceIndex] = luminance;
                    luminanceIndex++;
                }
                rect.Y++;
            }
        }

        private void CalculateLuminanceBGR565(BitmapSource bitmap)
        {
            var width = bitmap.PixelWidth;
            var height = bitmap.PixelHeight;
            var stepX = (bitmap.Format.BitsPerPixel + 7) / 8;
            var bufferSize = width * stepX;
            var buffer = new byte[bufferSize];
            var rect = new Int32Rect(0, 0, width, 1);
            var luminanceIndex = 0;

            for (var curY = 0; curY < height; curY++)
            {
                bitmap.CopyPixels(rect, buffer, bufferSize, 0);
                for (var curX = 0; curX < bufferSize; curX += stepX)
                {
                    var byte1 = buffer[curX];
                    var byte2 = buffer[curX + 1];

                    var b5 = byte1 & 0x1F;
                    var g5 = (((byte1 & 0xE0) >> 5) | ((byte2 & 0x03) << 3)) & 0x1F;
                    var r5 = (byte2 >> 2) & 0x1F;
                    var r8 = (r5 * 527 + 23) >> 6;
                    var g8 = (g5 * 527 + 23) >> 6;
                    var b8 = (b5 * 527 + 23) >> 6;

                    // cheap, not fully accurate conversion
                    //var pixel = (byte2 << 8) | byte1;
                    //b8 = (((pixel) & 0x001F) << 3);
                    //g8 = (((pixel) & 0x07E0) >> 2) & 0xFF;
                    //r8 = (((pixel) & 0xF800) >> 8);

                    luminances[luminanceIndex] = (byte)((RChannelWeight * r8 + GChannelWeight * g8 + BChannelWeight * b8) >> ChannelWeight);
                    luminanceIndex++;
                }
                rect.Y++;
            }
        }

        /// <summary>
        /// Should create a new luminance source with the right class type.
        /// The method is used in methods crop and rotate.
        /// </summary>
        /// <param name="newLuminances">The new luminances.</param>
        /// <param name="width">The width.</param>
        /// <param name="height">The height.</param>
        /// <returns></returns>
        protected override LuminanceSource CreateLuminanceSource(byte[] newLuminances, int width, int height)
        {
            return new BitmapSourceLuminanceSource(width, height) { luminances = newLuminances };
        }
    }
}