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

using System.Text;
using SixLabors.ImageSharp.Formats.Gif;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.Primitives;
using Xunit;
using System.IO;
using SixLabors.ImageSharp.Advanced;

// ReSharper disable InconsistentNaming
namespace SixLabors.ImageSharp.Tests
{
    using System.Collections.Generic;

    using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;

    public class GifDecoderTests
    {
        private const PixelTypes TestPixelTypes = PixelTypes.Rgba32 | PixelTypes.RgbaVector | PixelTypes.Argb32;

        public static readonly string[] MultiFrameTestFiles =
            {
                TestImages.Gif.Giphy, TestImages.Gif.Kumin
            };

        public static readonly string[] BasicVerificationFiles =
            {
                TestImages.Gif.Cheers,
                TestImages.Gif.Rings,

                // previously DecodeBadApplicationExtensionLength:
                TestImages.Gif.Issues.BadAppExtLength,
                TestImages.Gif.Issues.BadAppExtLength_2,

                // previously DecodeBadDescriptorDimensionsLength:
                TestImages.Gif.Issues.BadDescriptorWidth
            };

        private static readonly Dictionary<string, int> BasicVerificationFrameCount =
            new Dictionary<string, int>
                {
                    [TestImages.Gif.Cheers] = 93,
                    [TestImages.Gif.Issues.BadDescriptorWidth] = 36,
            };

        public static readonly string[] BadAppExtFiles = { TestImages.Gif.Issues.BadAppExtLength, TestImages.Gif.Issues.BadAppExtLength_2 };

        [Theory]
        [WithFileCollection(nameof(MultiFrameTestFiles), PixelTypes.Rgba32)]
        public void Decode_VerifyAllFrames<TPixel>(TestImageProvider<TPixel> provider)
            where TPixel : struct, IPixel<TPixel>
        {
            using (Image<TPixel> image = provider.GetImage())
            {
                image.DebugSaveMultiFrame(provider);
                image.CompareToReferenceOutputMultiFrame(provider, ImageComparer.Exact);
            }
        }

        [Theory]
        [WithFile(TestImages.Gif.Trans, TestPixelTypes)]
        public void GifDecoder_IsNotBoundToSinglePixelType<TPixel>(TestImageProvider<TPixel> provider)
            where TPixel : struct, IPixel<TPixel>
        {
            using (Image<TPixel> image = provider.GetImage())
            {
                image.DebugSave(provider);
                image.CompareFirstFrameToReferenceOutput(provider, ImageComparer.Exact);
            }
        }

        [Theory]
        [WithFileCollection(nameof(BasicVerificationFiles), PixelTypes.Rgba32)]
        public void Decode_VerifyRootFrameAndFrameCount<TPixel>(TestImageProvider<TPixel> provider)
            where TPixel : struct, IPixel<TPixel>
        {
            if (!BasicVerificationFrameCount.TryGetValue(provider.SourceFileOrDescription, out int expectedFrameCount))
            {
                expectedFrameCount = 1;
            }

            using (Image<TPixel> image = provider.GetImage())
            {
                Assert.Equal(expectedFrameCount, image.Frames.Count);
                image.DebugSave(provider);
                image.CompareFirstFrameToReferenceOutput(provider, ImageComparer.Exact);
            }
        }
        
        [Fact]
        public void Decode_IgnoreMetadataIsFalse_CommentsAreRead()
        {
            var options = new GifDecoder
            {
                IgnoreMetadata = false
            };

            var testFile = TestFile.Create(TestImages.Gif.Rings);

            using (Image<Rgba32> image = testFile.CreateImage(options))
            {
                Assert.Equal(1, image.MetaData.Properties.Count);
                Assert.Equal("Comments", image.MetaData.Properties[0].Name);
                Assert.Equal("ImageSharp", image.MetaData.Properties[0].Value);
            }
        }

        [Fact]
        public void Decode_IgnoreMetadataIsTrue_CommentsAreIgnored()
        {
            var options = new GifDecoder
            {
                IgnoreMetadata = true
            };

            var testFile = TestFile.Create(TestImages.Gif.Rings);

            using (Image<Rgba32> image = testFile.CreateImage(options))
            {
                Assert.Equal(0, image.MetaData.Properties.Count);
            }
        }

        [Fact]
        public void Decode_TextEncodingSetToUnicode_TextIsReadWithCorrectEncoding()
        {
            var options = new GifDecoder
            {
                TextEncoding = Encoding.Unicode
            };

            var testFile = TestFile.Create(TestImages.Gif.Rings);

            using (Image<Rgba32> image = testFile.CreateImage(options))
            {
                Assert.Equal(1, image.MetaData.Properties.Count);
                Assert.Equal("浉条卥慨灲", image.MetaData.Properties[0].Value);
            }
        }

        [Theory]
        [WithFile(TestImages.Gif.Giphy, PixelTypes.Rgba32)]
        public void CanDecodeJustOneFrame<TPixel>(TestImageProvider<TPixel> provider)
            where TPixel : struct, IPixel<TPixel>
        {
            using (Image<TPixel> image = provider.GetImage(new GifDecoder { DecodingMode = FrameDecodingMode.First }))
            {
                Assert.Equal(1, image.Frames.Count);
            }
        }

        [Theory]
        [WithFile(TestImages.Gif.Giphy, PixelTypes.Rgba32)]
        public void CanDecodeAllFrames<TPixel>(TestImageProvider<TPixel> provider)
            where TPixel : struct, IPixel<TPixel>
        {
            using (Image<TPixel> image = provider.GetImage(new GifDecoder { DecodingMode = FrameDecodingMode.All }))
            {
                Assert.True(image.Frames.Count > 1);
            }
        }

        [Theory]
        [InlineData(TestImages.Gif.Cheers, 8)]
        [InlineData(TestImages.Gif.Giphy, 8)]
        [InlineData(TestImages.Gif.Rings, 8)]
        [InlineData(TestImages.Gif.Trans, 8)]
        public void DetectPixelSize(string imagePath, int expectedPixelSize)
        {
            TestFile testFile = TestFile.Create(imagePath);
            using (var stream = new MemoryStream(testFile.Bytes, false))
            {
                Assert.Equal(expectedPixelSize, Image.Identify(stream)?.PixelType?.BitsPerPixel);
            }
        }

        [Fact]
        public void CanDecodeIntermingledImages()
        {
            using (var kumin1 = Image.Load(TestFile.Create(TestImages.Gif.Kumin).Bytes))
            using (var icon = Image.Load(TestFile.Create(TestImages.Png.Icon).Bytes))
            using (var kumin2 = Image.Load(TestFile.Create(TestImages.Gif.Kumin).Bytes))
            {
                for (int i = 0; i < kumin1.Frames.Count; i++)
                {
                    ImageFrame<Rgba32> first = kumin1.Frames[i];
                    ImageFrame<Rgba32> second = kumin2.Frames[i];
                    first.ComparePixelBufferTo(second.GetPixelSpan());
                }
            }
        }
    }
}