using System;
using System.IO;
using System.Linq;
using Xunit;
using ytLive.Services;

namespace ytLive.Tests;

/// <summary>
/// TASK 65 slice 3 — clips on disk, with retention and nothing else.
///
/// <para>The rule: write one file, delete the oldest past the count. No gallery, no prompt. The tests pin
/// the two ways that could go wrong — a zero-byte clip from an empty ring, and pruning taking something
/// that isn't ours.</para>
/// </summary>
public sealed class ClipLibraryTests : IDisposable
{
    private readonly string _root = Path.Combine(Path.GetTempPath(), $"ytLlive-clips-{Guid.NewGuid():N}");

    public ClipLibraryTests() => Directory.CreateDirectory(_root);

    public void Dispose()
    {
        try { Directory.Delete(_root, recursive: true); } catch { /* best effort */ }
    }

    private ClipLibrary Library() => new(() => _root);

    [Fact]
    public void SaveWritesIntoClipsBesideTheRecordings()
    {
        var path = Library().Save(new byte[] { 1, 2, 3 }, DateTime.Now, keep: 3);

        Assert.NotNull(path);
        Assert.EndsWith(".mp4", path);
        Assert.Equal(Path.Combine(_root, "clips"), Path.GetDirectoryName(path));
        Assert.True(File.Exists(path));
    }

    [Fact]
    public void AnEmptySnapshotNeverBecomesAZeroByteFile()
    {
        Assert.Null(Library().Save(Array.Empty<byte>(), DateTime.Now, keep: 3));
        Assert.False(Directory.Exists(Path.Combine(_root, "clips"))
                     && Directory.EnumerateFiles(Path.Combine(_root, "clips")).Any());
    }

    [Fact]
    public void RetentionKeepsTheNewestAndDeletesTheRest()
    {
        var library = Library();
        var folder = library.EnsureFolder();
        for (var i = 0; i < 6; i++)
            File.WriteAllText(Path.Combine(folder, $"clip-20261110-12000{i}.mp4"), "x");
        File.WriteAllText(Path.Combine(folder, "someone-elses-file.mp4"), "keep me");

        var removed = library.Prune(keep: 3);

        Assert.Equal(3, removed);
        var remaining = library.Recent();
        Assert.Equal(3, remaining.Count);
        Assert.Contains("120005", remaining[0]);        // newest first
        Assert.True(File.Exists(Path.Combine(folder, "someone-elses-file.mp4")));
    }

    [Fact]
    public void RingBytesFollowLengthAndBitrate_WithHeadroom()
    {
        var tenAt8 = ClipLibrary.RingBytesFor(10, 8000);
        var fifteenAt8 = ClipLibrary.RingBytesFor(15, 8000);

        Assert.True(tenAt8 > 10L * 8000 * 1000 / 8);          // more than the exact wire size
        Assert.True(fifteenAt8 > tenAt8);
        Assert.True(tenAt8 < 15L * 1024 * 1024);               // and still modest
    }
}