using System.Collections.Generic;
using System.Formats.Tar;
using System.IO;
using FluentAssertions;
using StellaOps.Replay.Core;
using ZstdSharp;
using Xunit;

namespace StellaOps.Replay.Core.Tests;

public sealed class ReplayBundleWriterTests
{
    [Fact]
    public async Task WriteTarZstAsync_IsDeterministicAndSorted()
    {
        var entries = new[]
        {
            new ReplayBundleEntry("b.txt", "beta"u8.ToArray()),
            new ReplayBundleEntry("a.txt", "alpha"u8.ToArray())
        };

        await using var buffer = new MemoryStream();
        var first = await ReplayBundleWriter.WriteTarZstAsync(entries, buffer, compressionLevel: 3);

        var firstBytes = buffer.ToArray();

        await using var buffer2 = new MemoryStream();
        var second = await ReplayBundleWriter.WriteTarZstAsync(entries.Reverse(), buffer2, compressionLevel: 3);

        first.ZstSha256.Should().Be(second.ZstSha256);
        first.TarSha256.Should().Be(second.TarSha256);
        firstBytes.Should().Equal(buffer2.ToArray());

        // Decompress and verify ordering/content
        buffer.Position = 0;
        await using var decompressed = new MemoryStream();
        await using (var decompress = new DecompressionStream(buffer, 16 * 1024, leaveOpen: true, enableMultiThreaded: false))
        {
            await decompress.CopyToAsync(decompressed);
        }

        decompressed.Position = 0;
        var reader = new TarReader(decompressed, leaveOpen: true);
        var names = new List<string>();
        TarEntry? entry;
        while ((entry = reader.GetNextEntry()) != null)
        {
            names.Add(entry.Name);
            using var ms = new MemoryStream();
            entry.DataStream!.CopyTo(ms);
            var text = System.Text.Encoding.UTF8.GetString(ms.ToArray());
            text.Should().Be(entry.Name.StartsWith("a") ? "alpha" : "beta");
        }

        names.Should().BeEquivalentTo(new[] { "a.txt", "b.txt" }, opts => opts.WithStrictOrdering());
    }

    [Fact]
    public void BuildCasUri_UsesPrefixAndShard()
    {
        ReplayBundleWriter.BuildCasUri("abcdef", null).Should().Be("cas://replay/ab/abcdef.tar.zst");
        ReplayBundleWriter.BuildCasUri("1234", "custom").Should().Be("cas://custom/12/1234.tar.zst");
    }
}