using MeetingAssistant;
using MeetingAssistant.Speakers;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;

namespace MeetingAssistant.Tests;

public sealed class SpeakerIdentityMergeServiceTests
{
    [Fact]
    public async Task MergeRecentIdentitiesConfirmsMatchTwiceAndMergesAliasesAndSamples()
    {
        await using var fixture = await SpeakerIdentityMergeFixture.CreateAsync();
        var older = await fixture.AddIdentityAsync(
            canonicalName: "Manuel",
            aliases: ["M. Schweigert"],
            snippets: [[1], [2], [3]],
            createdAt: DateTimeOffset.UtcNow.AddMonths(-2),
            transcriptionCount: 5);
        var recent = await fixture.AddIdentityAsync(
            canonicalName: "Guest Manuel",
            aliases: [],
            snippets: [[4], [5]],
            createdAt: DateTimeOffset.UtcNow.AddDays(-1),
            transcriptionCount: 2);
        fixture.Matcher.MatchIdentityIds.Enqueue(older.Id);
        fixture.Matcher.MatchIdentityIds.Enqueue(older.Id);
        var service = fixture.CreateService();

        var result = await service.MergeRecentIdentitiesAsync(TimeSpan.FromDays(14), CancellationToken.None);

        Assert.Equal(1, result.MergedPairs);
        Assert.Equal(2, fixture.Matcher.Requests.Count);
        Assert.Equal([4], fixture.Matcher.Requests[0].UnknownSnippet);
        Assert.Equal([5], fixture.Matcher.Requests[1].UnknownSnippet);
        var savedOlder = await fixture.LoadIdentityAsync(older.Id);
        Assert.Equal("Manuel", savedOlder.CanonicalName);
        Assert.Equal(7, savedOlder.TranscriptionCount);
        Assert.True(savedOlder.UpdatedAt > older.UpdatedAt);
        Assert.Equal(["Guest Manuel", "M. Schweigert"], savedOlder.Aliases.Select(alias => alias.Name).Order());
        Assert.Equal(3, savedOlder.Snippets.Count);
        Assert.False(await fixture.Context.SpeakerIdentities.AnyAsync(identity => identity.Id == recent.Id));
    }

    [Fact]
    public async Task MergeRecentIdentitiesDoesNotMergeWithoutSecondValidation()
    {
        await using var fixture = await SpeakerIdentityMergeFixture.CreateAsync();
        var older = await fixture.AddIdentityAsync("Manuel", [], [[1]], DateTimeOffset.UtcNow.AddMonths(-2), 5);
        var recent = await fixture.AddIdentityAsync("Guest Manuel", [], [[4], [5]], DateTimeOffset.UtcNow.AddDays(-1), 2);
        fixture.Matcher.MatchIdentityIds.Enqueue(older.Id);
        var service = fixture.CreateService();

        var result = await service.MergeRecentIdentitiesAsync(TimeSpan.FromDays(14), CancellationToken.None);

        Assert.Equal(0, result.MergedPairs);
        Assert.True(await fixture.Context.SpeakerIdentities.AnyAsync(identity => identity.Id == recent.Id));
    }

    [Fact]
    public async Task MergeRecentIdentitiesIgnoresOldSourceIdentities()
    {
        await using var fixture = await SpeakerIdentityMergeFixture.CreateAsync();
        await fixture.AddIdentityAsync("Older A", [], [[1], [2]], DateTimeOffset.UtcNow.AddMonths(-2), 5);
        await fixture.AddIdentityAsync("Older B", [], [[4], [5]], DateTimeOffset.UtcNow.AddMonths(-1), 2);
        var service = fixture.CreateService();

        var result = await service.MergeRecentIdentitiesAsync(TimeSpan.FromDays(14), CancellationToken.None);

        Assert.Equal(0, result.MergedPairs);
        Assert.Empty(fixture.Matcher.Requests);
    }

    private sealed class SpeakerIdentityMergeFixture : IAsyncDisposable
    {
        private readonly string dbPath;

        private SpeakerIdentityMergeFixture(string dbPath, SpeakerIdentityDbContext context)
        {
            this.dbPath = dbPath;
            Context = context;
        }

        public SpeakerIdentityDbContext Context { get; }

        public QueueingSpeakerIdentityMatcher Matcher { get; } = new();

        public static async Task<SpeakerIdentityMergeFixture> CreateAsync()
        {
            var dbPath = Path.Combine(Path.GetTempPath(), "meeting-assistant-tests", $"{Guid.NewGuid():N}.db");
            Directory.CreateDirectory(Path.GetDirectoryName(dbPath)!);
            var context = new SpeakerIdentityDbContext(new DbContextOptionsBuilder<SpeakerIdentityDbContext>()
                .UseSqlite($"Data Source={dbPath};Pooling=False")
                .Options);
            await SpeakerIdentitySchema.EnsureCreatedOrUpdatedAsync(context, CancellationToken.None);
            return new SpeakerIdentityMergeFixture(dbPath, context);
        }

        public SpeakerIdentityMergeService CreateService()
        {
            return new SpeakerIdentityMergeService(
                new TestSpeakerIdentityDbContextFactory(dbPath),
                Matcher,
                Options.Create(new MeetingAssistantOptions
                {
                    SpeakerIdentification = new SpeakerIdentificationOptions
                    {
                        MatchBatchSize = 6,
                        MaxSnippetsPerSpeaker = 3
                    }
                }),
                NullLogger<SpeakerIdentityMergeService>.Instance);
        }

        public async Task<SpeakerIdentity> AddIdentityAsync(
            string? canonicalName,
            IReadOnlyList<string> aliases,
            IReadOnlyList<byte[]> snippets,
            DateTimeOffset createdAt,
            int transcriptionCount)
        {
            var identity = new SpeakerIdentity
            {
                CanonicalName = canonicalName,
                CreatedAt = createdAt,
                UpdatedAt = createdAt,
                TranscriptionCount = transcriptionCount,
                Aliases = aliases.Select(alias => new SpeakerAlias { Name = alias }).ToList(),
                Snippets = snippets
                    .Select((snippet, index) => new SpeakerSnippet
                    {
                        WavBytes = snippet,
                        CreatedAt = createdAt.AddMinutes(index)
                    })
                    .ToList()
            };
            Context.SpeakerIdentities.Add(identity);
            await Context.SaveChangesAsync();
            return identity;
        }

        public Task<SpeakerIdentity> LoadIdentityAsync(int id)
        {
            Context.ChangeTracker.Clear();
            return Context.SpeakerIdentities
                .Include(identity => identity.Aliases)
                .Include(identity => identity.Snippets)
                .SingleAsync(identity => identity.Id == id);
        }

        public async ValueTask DisposeAsync()
        {
            await Context.DisposeAsync();
            if (File.Exists(dbPath))
            {
                File.Delete(dbPath);
            }
        }
    }

    private sealed class TestSpeakerIdentityDbContextFactory : IDbContextFactory<SpeakerIdentityDbContext>
    {
        private readonly string dbPath;

        public TestSpeakerIdentityDbContextFactory(string dbPath)
        {
            this.dbPath = dbPath;
        }

        public SpeakerIdentityDbContext CreateDbContext()
        {
            return new SpeakerIdentityDbContext(new DbContextOptionsBuilder<SpeakerIdentityDbContext>()
                .UseSqlite($"Data Source={dbPath};Pooling=False")
                .Options);
        }
    }

    private sealed class QueueingSpeakerIdentityMatcher : ISpeakerIdentityMatcher
    {
        public Queue<int> MatchIdentityIds { get; } = new();

        public List<SpeakerIdentityMatchRequest> Requests { get; } = [];

        public Task<SpeakerIdentityMatch?> MatchAsync(
            SpeakerIdentityMatchRequest request,
            CancellationToken cancellationToken)
        {
            Requests.Add(request);
            if (!MatchIdentityIds.TryDequeue(out var identityId))
            {
                return Task.FromResult<SpeakerIdentityMatch?>(null);
            }

            return Task.FromResult<SpeakerIdentityMatch?>(new SpeakerIdentityMatch(identityId));
        }
    }
}