using Microsoft.Extensions.Options;
using PLib.Application.Metadata;

namespace PLib.Tests.Library;

/// <summary>
/// A fixed <see cref="IOptionsMonitor{T}"/> over metadata sources.
/// </summary>
/// <remarks>
/// The service reads <c>CurrentValue</c> on every lookup, because the user can add a source
/// without restarting. A substitute would answer null and blow up in the one place that
/// matters, so the tests hand it a real value instead.
/// </remarks>
internal sealed class MetadataMonitor(MetadataOptions value) : IOptionsMonitor<MetadataOptions>
{
    public static MetadataMonitor Empty { get; } = new(new MetadataOptions());

    public static MetadataMonitor With(params MetadataSourceOptions[] sources) =>
        new(new MetadataOptions { Sources = [.. sources] });

    public static MetadataMonitor With(IReadOnlyList<MetadataSourceOptions> sources, int delayMilliseconds) =>
        new(new MetadataOptions { Sources = [.. sources], RequestDelayMilliseconds = delayMilliseconds });

    public MetadataOptions CurrentValue { get; } = value;

    public MetadataOptions Get(string? name) => CurrentValue;

    public IDisposable? OnChange(Action<MetadataOptions, string?> listener) => null;
}