// Copyright (c) Six Labors.
// Licensed under the Apache License, Version 2.0.

using System.IO;

using SixLabors.ImageSharp.Formats;
using SixLabors.ImageSharp.Formats.Tiff;
using SixLabors.ImageSharp.Formats.Tiff.Constants;
using SixLabors.ImageSharp.Metadata.Profiles.Exif;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
using SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs;

using Xunit;

namespace SixLabors.ImageSharp.Tests.Formats.Tiff
{
    [Trait("Format", "Tiff")]
    public abstract class TiffEncoderBaseTester
    {
        protected static readonly IImageDecoder ReferenceDecoder = new MagickReferenceDecoder();

        protected static void TestStripLength<TPixel>(
            TestImageProvider<TPixel> provider,
            TiffPhotometricInterpretation photometricInterpretation,
            TiffCompression compression,
            bool useExactComparer = true,
            float compareTolerance = 0.01f)
            where TPixel : unmanaged, IPixel<TPixel>
        {
            // arrange
            var tiffEncoder = new TiffEncoder() { PhotometricInterpretation = photometricInterpretation, Compression = compression };
            using Image<TPixel> input = provider.GetImage();
            using var memStream = new MemoryStream();
            TiffFrameMetadata inputMeta = input.Frames.RootFrame.Metadata.GetTiffMetadata();
            TiffCompression inputCompression = inputMeta.Compression ?? TiffCompression.None;

            // act
            input.Save(memStream, tiffEncoder);

            // assert
            memStream.Position = 0;
            using var output = Image.Load<Rgba32>(memStream);
            ExifProfile exifProfileOutput = output.Frames.RootFrame.Metadata.ExifProfile;
            TiffFrameMetadata outputMeta = output.Frames.RootFrame.Metadata.GetTiffMetadata();
            ImageFrame<Rgba32> rootFrame = output.Frames.RootFrame;

            Number rowsPerStrip = exifProfileOutput.GetValue(ExifTag.RowsPerStrip) != null ? exifProfileOutput.GetValue(ExifTag.RowsPerStrip).Value : TiffConstants.RowsPerStripInfinity;
            Assert.True(output.Height > (int)rowsPerStrip);
            Assert.True(exifProfileOutput.GetValue(ExifTag.StripOffsets)?.Value.Length > 1);
            Number[] stripByteCounts = exifProfileOutput.GetValue(ExifTag.StripByteCounts)?.Value;
            Assert.NotNull(stripByteCounts);
            Assert.True(stripByteCounts.Length > 1);
            Assert.NotNull(outputMeta.BitsPerPixel);

            foreach (Number sz in stripByteCounts)
            {
                Assert.True((uint)sz <= TiffConstants.DefaultStripSize);
            }

            // For uncompressed more accurate test.
            if (compression == TiffCompression.None)
            {
                for (int i = 0; i < stripByteCounts.Length - 1; i++)
                {
                    // The difference must be less than one row.
                    int stripBytes = (int)stripByteCounts[i];
                    int widthBytes = ((int)outputMeta.BitsPerPixel + 7) / 8 * rootFrame.Width;

                    Assert.True((TiffConstants.DefaultStripSize - stripBytes) < widthBytes);
                }
            }

            // Compare with reference.
            TestTiffEncoderCore(
               provider,
               inputMeta.BitsPerPixel,
               photometricInterpretation,
               inputCompression,
               useExactComparer: useExactComparer,
               compareTolerance: compareTolerance);
        }

        protected static void TestTiffEncoderCore<TPixel>(
            TestImageProvider<TPixel> provider,
            TiffBitsPerPixel? bitsPerPixel,
            TiffPhotometricInterpretation photometricInterpretation,
            TiffCompression compression = TiffCompression.None,
            TiffPredictor predictor = TiffPredictor.None,
            bool useExactComparer = true,
            float compareTolerance = 0.001f,
            IImageDecoder imageDecoder = null)
            where TPixel : unmanaged, IPixel<TPixel>
        {
            using Image<TPixel> image = provider.GetImage();
            var encoder = new TiffEncoder
            {
                PhotometricInterpretation = photometricInterpretation,
                BitsPerPixel = bitsPerPixel,
                Compression = compression,
                HorizontalPredictor = predictor
            };

            // Does DebugSave & load reference CompareToReferenceInput():
            image.VerifyEncoder(
                provider,
                "tiff",
                bitsPerPixel,
                encoder,
                useExactComparer ? ImageComparer.Exact : ImageComparer.Tolerant(compareTolerance),
                referenceDecoder: imageDecoder ?? ReferenceDecoder);
        }
    }
}