// Copyright 2020-2025 The NATS Authors
// Licensed under the Apache License, Version 2.0

namespace ZB.MOM.NatsNet.Server.IntegrationTests.Helpers;

/// <summary>
/// Provides polling-based check utilities for integration tests,
/// mirroring the Go <c>checkFor</c> pattern.
/// </summary>
public static class CheckHelper
{
    /// <summary>
    /// Polls <paramref name="check"/> every <paramref name="interval"/> until it returns
    /// <c>null</c> (success) or <paramref name="timeout"/> elapses. Throws on timeout.
    /// </summary>
    public static void CheckFor(TimeSpan timeout, TimeSpan interval, Func<string?> check)
    {
        var deadline = DateTime.UtcNow + timeout;
        string? lastError = null;
        while (DateTime.UtcNow < deadline)
        {
            lastError = check();
            if (lastError is null)
                return;
            Thread.Sleep(interval);
        }
        throw new TimeoutException($"CheckFor timed out after {timeout}: {lastError}");
    }

    /// <summary>
    /// Async variant of <see cref="CheckFor"/>.
    /// </summary>
    public static async Task CheckForAsync(TimeSpan timeout, TimeSpan interval, Func<Task<string?>> check)
    {
        var deadline = DateTime.UtcNow + timeout;
        string? lastError = null;
        while (DateTime.UtcNow < deadline)
        {
            lastError = await check();
            if (lastError is null)
                return;
            await Task.Delay(interval);
        }
        throw new TimeoutException($"CheckFor timed out after {timeout}: {lastError}");
    }
}