using Xunit;

namespace LehrerApp.Data.Tests;

public sealed class LiteAttachmentStorageTests
{
    private static LiteDbContext NewInMemoryContext() => new(new MemoryStream());

    [Fact]
    public void Upload_OpenRead_RoundtripLiefertDenGespeichertenInhalt()
    {
        using var db = NewInMemoryContext();
        var storage = new LiteAttachmentStorage(db);
        var bytes = "Elternbrief-Inhalt äöü"u8.ToArray();

        string id;
        using (var ms = new MemoryStream(bytes))
            id = storage.Upload("Brief.pdf", ms);

        using var result = storage.OpenRead(id);
        Assert.NotNull(result);
        using var reader = new MemoryStream();
        result!.CopyTo(reader);
        Assert.Equal(bytes, reader.ToArray());
    }

    [Fact]
    public void Upload_GroessereDateiAlsDasLimit_WirftException()
    {
        using var db = NewInMemoryContext();
        var storage = new LiteAttachmentStorage(db);
        using var ms = new MemoryStream(new byte[LehrerApp.Core.Interfaces.IAttachmentStorage.MaxSizeBytes + 1]);

        Assert.Throws<InvalidOperationException>(() => storage.Upload("zu-gross.bin", ms));
    }

    [Fact]
    public void OpenRead_UnbekannteId_GibtNullZurueck()
    {
        using var db = NewInMemoryContext();
        var storage = new LiteAttachmentStorage(db);

        Assert.Null(storage.OpenRead("fehlt"));
    }

    [Fact]
    public void Delete_EntferntDenAnhangEndgueltig()
    {
        using var db = NewInMemoryContext();
        var storage = new LiteAttachmentStorage(db);
        string id;
        using (var ms = new MemoryStream([1, 2, 3]))
            id = storage.Upload("a.bin", ms);

        storage.Delete(id);

        Assert.Null(storage.OpenRead(id));
    }
}