using System.IO;
using System.Windows.Media.Imaging;
using IvfTl.ControlHost.Debug;
using Xunit;

namespace IvfTl.ControlHost.Tests
{
    public class MjpegStreamWriterTests
    {
        // 造一张 4x4 纯色 24bpp BGR 像素(每像素 3 字节)。
        private static byte[] SolidBgr(int w, int h, byte b, byte g, byte r)
        {
            var buf = new byte[w * h * 3];
            for (int i = 0; i < w * h; i++) { buf[i * 3] = b; buf[i * 3 + 1] = g; buf[i * 3 + 2] = r; }
            return buf;
        }

        [Fact]
        public void EncodeJpeg_ProducesDecodableJpeg_WithRightSize()
        {
            var rgb = SolidBgr(4, 4, 10, 20, 30);
            byte[] jpeg = MjpegStreamWriter.EncodeJpeg(rgb, 4, 4);

            Assert.NotNull(jpeg);
            Assert.True(jpeg.Length > 2);
            // JPEG 魔数 FF D8 开头
            Assert.Equal(0xFF, jpeg[0]);
            Assert.Equal(0xD8, jpeg[1]);
            // 能被解码器读回、尺寸对
            var dec = new JpegBitmapDecoder(new MemoryStream(jpeg),
                BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
            Assert.Equal(4, dec.Frames[0].PixelWidth);
            Assert.Equal(4, dec.Frames[0].PixelHeight);
        }

        [Fact]
        public void FrameBytes_WrapsJpegInMultipartBoundary()
        {
            var jpeg = new byte[] { 0xFF, 0xD8, 1, 2, 0xFF, 0xD9 };
            byte[] frame = MjpegStreamWriter.FrameBytes(jpeg);

            string head = System.Text.Encoding.ASCII.GetString(frame, 0, 60);
            Assert.Contains("--frame", head);
            Assert.Contains("Content-Type: image/jpeg", head);
            Assert.Contains("Content-Length: 6", head);
            // 帧体起点 = header 长度;尾部是 \r\n
            string headerStr = "--frame\r\nContent-Type: image/jpeg\r\nContent-Length: 6\r\n\r\n";
            int bodyStart = System.Text.Encoding.ASCII.GetByteCount(headerStr);
            var body = new byte[jpeg.Length];
            System.Array.Copy(frame, bodyStart, body, 0, jpeg.Length);
            Assert.Equal(jpeg, body);   // 帧体整段 == 原 jpeg
            Assert.Equal((byte)'\r', frame[frame.Length - 2]);
            Assert.Equal((byte)'\n', frame[frame.Length - 1]);
        }
    }
}