meeting-assistant/MeetingAssistant.Tests/AzureSpeechSpeakerIdentityMatcherTests.cs

using MeetingAssistant;
using MeetingAssistant.Speakers;
using MeetingAssistant.Transcription;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using NAudio.Wave;

namespace MeetingAssistant.Tests;

public sealed class AzureSpeechSpeakerIdentityMatcherTests
{
    [Fact]
    public void IdentityDiarizationLanguageUsesFirstAutoDetectLanguageWhenConfiguredLanguageIsAuto()
    {
        Assert.Equal(
            "de-DE",
            AzureSpeechSpeakerIdentityDiarizationClient.ResolveRecognitionLanguage(new AzureSpeechOptions
            {
                Language = "auto",
                AutoDetectLanguages = ["de-DE", "en-US"]
            }));
    }

    [Fact]
    public void IdentityDiarizationLanguageUsesConfiguredConcreteLanguage()
    {
        Assert.Equal(
            "en-US",
            AzureSpeechSpeakerIdentityDiarizationClient.ResolveRecognitionLanguage(new AzureSpeechOptions
            {
                Language = "en-US",
                AutoDetectLanguages = ["de-DE"]
            }));
    }

    [Fact]
    public async Task MatcherReturnsIdentityWhenAzureDiarizationAssignsUnknownSnippetToKnownSpeaker()
    {
        var diarizationClient = new FakeSpeakerIdentityDiarizationClient(
        [
            new TranscriptionSegment(TimeSpan.Zero, TimeSpan.FromSeconds(1), "Guest-1", "known"),
            new TranscriptionSegment(TimeSpan.FromSeconds(2), TimeSpan.FromSeconds(3), "Guest-1", "unknown")
        ]);
        var matcher = CreateMatcher(diarizationClient);
        var snippet = CreateWavSnippet();

        var match = await matcher.MatchAsync(
            new SpeakerIdentityMatchRequest(
                "Guest03",
                snippet,
                [new SpeakerIdentityMatchCandidate(42, "Chris", 5, [snippet])]),
            CancellationToken.None);

        Assert.NotNull(match);
        Assert.Equal(42, match.IdentityId);
        Assert.NotNull(diarizationClient.WavPath);
        Assert.False(File.Exists(diarizationClient.WavPath));
    }

    [Fact]
    public async Task MatcherRequiresTwoMatchingKnownSnippetsWhenIdentityHasMultipleSnippets()
    {
        var diarizationClient = new FakeSpeakerIdentityDiarizationClient(
        [
            new TranscriptionSegment(TimeSpan.Zero, TimeSpan.FromSeconds(1), "Guest-1", "known one"),
            new TranscriptionSegment(TimeSpan.FromSeconds(2), TimeSpan.FromSeconds(3), "Guest-2", "known two"),
            new TranscriptionSegment(TimeSpan.FromSeconds(4), TimeSpan.FromSeconds(5), "Guest-1", "unknown")
        ]);
        var matcher = CreateMatcher(diarizationClient);
        var snippet = CreateWavSnippet();

        var match = await matcher.MatchAsync(
            new SpeakerIdentityMatchRequest(
                "Guest03",
                snippet,
                [new SpeakerIdentityMatchCandidate(42, "Chris", 5, [snippet, snippet])]),
            CancellationToken.None);

        Assert.Null(match);
    }

    [Fact]
    public async Task MatcherReturnsNullWhenAzureDiarizationAssignsDifferentSpeakers()
    {
        var diarizationClient = new FakeSpeakerIdentityDiarizationClient(
        [
            new TranscriptionSegment(TimeSpan.Zero, TimeSpan.FromSeconds(1), "Guest-1", "known"),
            new TranscriptionSegment(TimeSpan.FromSeconds(2), TimeSpan.FromSeconds(3), "Guest-2", "unknown")
        ]);
        var matcher = CreateMatcher(diarizationClient);
        var snippet = CreateWavSnippet();

        var match = await matcher.MatchAsync(
            new SpeakerIdentityMatchRequest(
                "Guest03",
                snippet,
                [new SpeakerIdentityMatchCandidate(42, "Chris", 5, [snippet])]),
            CancellationToken.None);

        Assert.Null(match);
    }

    [Fact]
    public async Task MatcherReturnsNullWhenDiarizationTimesOut()
    {
        var matcher = CreateMatcher(
            new HangingSpeakerIdentityDiarizationClient(),
            TimeSpan.FromMilliseconds(20));
        var snippet = CreateWavSnippet();

        var match = await matcher.MatchAsync(
            new SpeakerIdentityMatchRequest(
                "Guest03",
                snippet,
                [new SpeakerIdentityMatchCandidate(42, "Chris", 5, [snippet])]),
            CancellationToken.None);

        Assert.Null(match);
    }

    [Fact]
    public async Task MatcherReturnsNullWhenSecondaryValidatorRejectsPrimaryMatch()
    {
        var diarizationClient = new FakeSpeakerIdentityDiarizationClient(
        [
            new TranscriptionSegment(TimeSpan.Zero, TimeSpan.FromSeconds(1), "Guest-1", "known"),
            new TranscriptionSegment(TimeSpan.FromSeconds(2), TimeSpan.FromSeconds(3), "Guest-1", "unknown")
        ]);
        var validator = new RejectingSpeakerIdentityMatchValidator();
        var matcher = CreateMatcher(diarizationClient, validator: validator);
        var snippet = CreateWavSnippet();

        var match = await matcher.MatchAsync(
            new SpeakerIdentityMatchRequest(
                "Guest03",
                snippet,
                [new SpeakerIdentityMatchCandidate(42, "Chris", 5, [snippet])]),
            CancellationToken.None);

        Assert.Null(match);
        Assert.Equal(1, validator.MatchValidationCount);
    }

    private static AzureSpeechSpeakerIdentityMatcher CreateMatcher(
        ISpeakerIdentityDiarizationClient diarizationClient,
        TimeSpan? matchTimeout = null,
        ISpeakerIdentityMatchValidator? validator = null)
    {
        return new AzureSpeechSpeakerIdentityMatcher(
            diarizationClient,
            Options.Create(new MeetingAssistantOptions
            {
                SpeakerIdentification = new SpeakerIdentificationOptions
                {
                    SilenceBetweenSnippetsSeconds = 1,
                    MatchTimeout = matchTimeout ?? TimeSpan.FromMinutes(1)
                }
            }),
            NullLogger<AzureSpeechSpeakerIdentityMatcher>.Instance,
            validator ?? new NoopSpeakerIdentityMatchValidator());
    }

    private static byte[] CreateWavSnippet()
    {
        using var stream = new MemoryStream();
        using (var writer = new WaveFileWriter(stream, new WaveFormat(16000, 16, 1)))
        {
            writer.Write(new byte[16000 * 2], 0, 16000 * 2);
        }

        return stream.ToArray();
    }

    private sealed class FakeSpeakerIdentityDiarizationClient : ISpeakerIdentityDiarizationClient
    {
        private readonly IReadOnlyList<TranscriptionSegment> segments;

        public FakeSpeakerIdentityDiarizationClient(IReadOnlyList<TranscriptionSegment> segments)
        {
            this.segments = segments;
        }

        public string? WavPath { get; private set; }

        public Task<IReadOnlyList<TranscriptionSegment>> DiarizeAsync(
            string wavPath,
            CancellationToken cancellationToken)
        {
            WavPath = wavPath;
            Assert.True(File.Exists(wavPath));
            return Task.FromResult(segments);
        }
    }

    private sealed class HangingSpeakerIdentityDiarizationClient : ISpeakerIdentityDiarizationClient
    {
        public async Task<IReadOnlyList<TranscriptionSegment>> DiarizeAsync(
            string wavPath,
            CancellationToken cancellationToken)
        {
            await Task.Delay(Timeout.InfiniteTimeSpan, cancellationToken);
            return [];
        }
    }

    private sealed class RejectingSpeakerIdentityMatchValidator : ISpeakerIdentityMatchValidator
    {
        public int MatchValidationCount { get; private set; }

        public Task<bool> ValidateSampleAsync(byte[] wavBytes, CancellationToken cancellationToken)
        {
            return Task.FromResult(true);
        }

        public Task<bool> ValidateMatchAsync(
            SpeakerIdentityMatchValidationRequest request,
            CancellationToken cancellationToken)
        {
            MatchValidationCount++;
            return Task.FromResult(false);
        }
    }
}