namespace ZB.MOM.WW.MxGateway.Tests.TestSupport;

/// <summary>
/// <see cref="TimeProvider"/> with a manually advanced clock for deterministic
/// timestamp / heartbeat / lease tests. Tests inject one of these instead of
/// <see cref="TimeProvider.System"/> so timing assertions don't depend on the
/// wall clock. Constructed without arguments (or with <c>default</c>) it seeds
/// from <see cref="DateTimeOffset.UtcNow"/>; for fully deterministic tests pass
/// an explicit start instant.
/// </summary>
/// <param name="start">Initial clock value. When <c>default</c>, the clock seeds from <see cref="DateTimeOffset.UtcNow"/>.</param>
public sealed class ManualTimeProvider(DateTimeOffset start = default) : TimeProvider
{
    private DateTimeOffset _now = start == default ? DateTimeOffset.UtcNow : start;

    /// <inheritdoc />
    public override DateTimeOffset GetUtcNow() => _now;

    /// <summary>Advances the manual clock by the given amount.</summary>
    /// <param name="delta">Amount of time to add to the current clock value.</param>
    public void Advance(TimeSpan delta) => _now += delta;
}