using LibHac.Common;
using LibHac.Fs;
using LibHac.Fs.Fsa;
using Xunit;

namespace LibHac.Tests.Fs.IFileSystemTestBase;

public abstract partial class CommittableIFileSystemTests
{
    [Fact]
    public void Commit_AfterSuccessfulCommit_CanReadCommittedData()
    {
        // "Random" test data
        byte[] data1 = [7, 4, 1, 0, 8, 5, 2, 9, 6, 3];
        byte[] data2 = [6, 1, 6, 8, 0, 3, 9, 7, 5, 1];

        IReopenableFileSystemCreator fsCreator = GetFileSystemCreator();
        IFileSystem fs = fsCreator.Create();

        // Make sure to test both directories and files
        fs.CreateDirectory("/dir1").ThrowIfFailure();
        fs.CreateDirectory("/dir2").ThrowIfFailure();

        fs.CreateFile("/dir1/file", data1.Length, CreateFileOptions.None).ThrowIfFailure();
        fs.CreateFile("/dir2/file", data2.Length, CreateFileOptions.None).ThrowIfFailure();

        using var file1 = new UniqueRef<IFile>();
        using var file2 = new UniqueRef<IFile>();

        fs.OpenFile(ref file1.Ref, "/dir1/file", OpenMode.Write).ThrowIfFailure();
        fs.OpenFile(ref file2.Ref, "/dir2/file", OpenMode.Write).ThrowIfFailure();

        file1.Get.Write(0, data1, WriteOption.Flush).ThrowIfFailure();
        file2.Get.Write(0, data2, WriteOption.Flush).ThrowIfFailure();

        file1.Reset();
        file2.Reset();

        fs.Commit().ThrowIfFailure();
        fs.Dispose();

        // Reopen after committing
        fs = fsCreator.Create();

        byte[] readData1 = new byte[data1.Length];
        byte[] readData2 = new byte[data2.Length];

        Assert.Success(fs.OpenFile(ref file1.Ref, "/dir1/file", OpenMode.Read));

        Assert.Success(file1.Get.Read(out long bytesReadFile1, 0, readData1, ReadOption.None));
        file1.Reset();
        Assert.Equal(data1.Length, bytesReadFile1);

        Assert.Equal(data1, readData1);

        Assert.Success(fs.OpenFile(ref file2.Ref, "/dir2/file", OpenMode.Read));

        Assert.Success(file2.Get.Read(out long bytesReadFile2, 0, readData2, ReadOption.None));
        Assert.Equal(data2.Length, bytesReadFile2);

        Assert.Equal(data2, readData2);
    }

    [Fact]
    public void Rollback_CreateFileThenRollback_FileDoesNotExist()
    {
        IFileSystem fs = CreateFileSystem();

        fs.CreateDirectory("/dir").ThrowIfFailure();
        fs.CreateFile("/dir/file", 0, CreateFileOptions.None).ThrowIfFailure();

        // Rollback should succeed
        Assert.Success(fs.Rollback());

        // Make sure the file and directory are gone
        Assert.Result(ResultFs.PathNotFound, fs.GetEntryType(out _, "/dir"));
        Assert.Result(ResultFs.PathNotFound, fs.GetEntryType(out _, "/dir/file"));
    }

    [Fact]
    public void Rollback_CreateFileThenCloseFs_FileDoesNotExist()
    {
        IReopenableFileSystemCreator fsCreator = GetFileSystemCreator();
        IFileSystem fs = fsCreator.Create();

        fs.CreateDirectory("/dir").ThrowIfFailure();
        fs.CreateFile("/dir/file", 0, CreateFileOptions.None).ThrowIfFailure();

        // Close without committing and reopen the file system
        fs.Dispose();
        fs = fsCreator.Create();

        // Make sure the file and directory are gone
        Assert.Result(ResultFs.PathNotFound, fs.GetEntryType(out _, "/dir"));
        Assert.Result(ResultFs.PathNotFound, fs.GetEntryType(out _, "/dir/file"));
    }

    [Fact]
    public void Rollback_AfterChangingExistingFiles_GoesBackToOriginalData()
    {
        // "Random" test data
        byte[] data1 = [7, 4, 1, 0, 8, 5, 2, 9, 6, 3];
        byte[] data2 = [6, 1, 6, 8, 0, 3, 9, 7, 5, 1];

        IReopenableFileSystemCreator fsCreator = GetFileSystemCreator();
        IFileSystem fs = fsCreator.Create();

        fs.CreateDirectory("/dir").ThrowIfFailure();
        fs.CreateFile("/dir/file", data1.Length, CreateFileOptions.None).ThrowIfFailure();

        using var file = new UniqueRef<IFile>();
        fs.OpenFile(ref file.Ref, "/dir/file", OpenMode.Write).ThrowIfFailure();
        file.Get.Write(0, data1, WriteOption.Flush).ThrowIfFailure();
        file.Reset();

        // Commit and reopen the file system
        fs.Commit().ThrowIfFailure();
        fs.Dispose();

        fs = fsCreator.Create();

        // Make changes to the file
        fs.OpenFile(ref file.Ref, "/dir/file", OpenMode.Write).ThrowIfFailure();
        file.Get.Write(0, data2, WriteOption.Flush).ThrowIfFailure();
        file.Reset();

        Assert.Success(fs.Rollback());

        // The file should contain the original data after the rollback
        byte[] readData = new byte[data1.Length];

        Assert.Success(fs.OpenFile(ref file.Ref, "/dir/file", OpenMode.Read));

        Assert.Success(file.Get.Read(out long bytesRead, 0, readData, ReadOption.None));
        Assert.Equal(data1.Length, bytesRead);

        Assert.Equal(data1, readData);
    }
}