using System.Text;
using dy.net.storage;
using dy.net.Tests.TestInfrastructure;

namespace dy.net.Tests;

public class LocalMediaStorageTests
{
    [Fact]
    public async Task WriteAsync_CreatesAndAtomicallyOverwritesFile()
    {
        using var temporaryDirectory = new TemporaryDirectory();
        var storage = new LocalMediaStorage();
        var path = Path.Combine(temporaryDirectory.Path, "nested", "video.mp4");

        await WriteAsync(storage, path, "first");
        await WriteAsync(storage, path, "replacement");

        Assert.Equal("replacement", await File.ReadAllTextAsync(path));
        Assert.Empty(Directory.GetFiles(Path.GetDirectoryName(path), "*.part-*"));
    }

    [Fact]
    public async Task ExistsLengthRangeAndDelete_FollowStorageContract()
    {
        using var temporaryDirectory = new TemporaryDirectory();
        var storage = new LocalMediaStorage();
        var path = Path.Combine(temporaryDirectory.Path, "sample.mp4");
        await WriteAsync(storage, path, "0123456789");

        Assert.True(await storage.ExistsAsync(path));
        Assert.Equal(10, await storage.GetLengthAsync(path));

        await using (var range = await storage.OpenReadAsync(path, 2, 5))
        {
            Assert.Equal(206, range.StatusCode);
            Assert.Equal(4, range.ContentLength);
            Assert.Equal("bytes 2-5/10", range.ContentRange);
            var bytes = new byte[range.ContentLength.Value];
            var read = await range.Stream.ReadAsync(bytes);
            Assert.Equal(bytes.Length, read);
            Assert.Equal("2345", Encoding.UTF8.GetString(bytes));
        }

        await storage.DeleteAsync(path);
        Assert.False(await storage.ExistsAsync(path));
        Assert.Null(await storage.GetLengthAsync(path));
    }

    [Fact]
    public async Task WriteAsync_RejectsEmptyAndLengthMismatchWithoutReplacingExistingFile()
    {
        using var temporaryDirectory = new TemporaryDirectory();
        var storage = new LocalMediaStorage();
        var path = Path.Combine(temporaryDirectory.Path, "video.mp4");
        await WriteAsync(storage, path, "original");

        await using (var empty = new MemoryStream(Array.Empty<byte>(), false))
            await Assert.ThrowsAsync<IOException>(() => storage.WriteAsync(path, empty, 0, "video/mp4"));
        await using (var shortSource = new MemoryStream(Encoding.UTF8.GetBytes("short"), false))
            await Assert.ThrowsAsync<IOException>(() => storage.WriteAsync(path, shortSource, 99, "video/mp4"));

        Assert.Equal("original", await File.ReadAllTextAsync(path));
        Assert.Empty(Directory.GetFiles(temporaryDirectory.Path, "*.part-*"));
    }

    private static async Task WriteAsync(LocalMediaStorage storage, string path, string content)
    {
        var bytes = Encoding.UTF8.GetBytes(content);
        await using var source = new MemoryStream(bytes, false);
        await storage.WriteAsync(path, source, bytes.Length, "video/mp4");
    }
}