using AvParser.Core.Collecting;
using AvParser.Core.Collecting.Sources;

namespace AvParser.Core.Tests.Collecting;

public class MediaSourceCatalogTests
{
    private sealed class FakeStore(IEnumerable<PatternSourceConfig>? seed = null) : IUserSourceStore
    {
        private readonly List<PatternSourceConfig> _configs = seed?.ToList() ?? [];

        public event EventHandler? Changed;

        public IReadOnlyList<PatternSourceConfig> List() => [.. _configs];

        public Task<PatternSourceConfig> AddAsync(
            PatternSourceConfig config,
            CancellationToken cancellationToken = default
        )
        {
            _configs.Add(config);
            Changed?.Invoke(this, EventArgs.Empty);
            return Task.FromResult(config);
        }

        public Task<bool> UpdateAsync(PatternSourceConfig config, CancellationToken cancellationToken = default)
        {
            var index = _configs.FindIndex(c => c.Id == config.Id);
            if (index < 0)
            {
                return Task.FromResult(false);
            }

            _configs[index] = config;
            Changed?.Invoke(this, EventArgs.Empty);
            return Task.FromResult(true);
        }

        public Task<bool> RemoveAsync(string id, CancellationToken cancellationToken = default)
        {
            var removed = _configs.RemoveAll(c => c.Id == id) > 0;
            if (removed)
            {
                Changed?.Invoke(this, EventArgs.Empty);
            }

            return Task.FromResult(removed);
        }
    }

    private static PatternSourceConfig Config(string id, string name)
    {
        PatternSourceConfig.TryCreate(
            name,
            "https://h/x/",
            6,
            8,
            IdAlphabet.Digits,
            null,
            null,
            allowDirectConnection: false,
            out var config,
            id
        );
        return config!;
    }

    [Fact]
    public void An_empty_store_is_a_valid_empty_catalog()
    {
        using var catalog = new MediaSourceCatalog(new FakeStore());

        catalog.Sources.ShouldBeEmpty();
        catalog.Find("anything").ShouldBeNull();
    }

    [Fact]
    public void Sources_are_materialised_from_the_stored_configs()
    {
        using var catalog = new MediaSourceCatalog(new FakeStore([Config("s1", "Beta"), Config("s2", "Alpha")]));

        // Ordered by display name.
        catalog.Sources.Select(s => s.Id).ShouldBe(["s2", "s1"]);
        catalog.Find("s1").ShouldNotBeNull().DisplayName.ShouldBe("Beta");
    }

    [Fact]
    public async Task Adding_through_the_catalog_rebuilds_and_signals()
    {
        var store = new FakeStore();
        using var catalog = new MediaSourceCatalog(store);
        var changed = 0;
        catalog.Changed += (_, _) => changed++;

        await catalog.AddAsync(Config("s1", "One"), TestContext.Current.CancellationToken);

        changed.ShouldBe(1);
        catalog.Sources.ShouldHaveSingleItem().Id.ShouldBe("s1");
    }

    [Fact]
    public async Task Removing_through_the_catalog_drops_the_source()
    {
        using var catalog = new MediaSourceCatalog(new FakeStore([Config("s1", "One")]));

        await catalog.RemoveAsync("s1", TestContext.Current.CancellationToken);

        catalog.Sources.ShouldBeEmpty();
    }
}