using System.Diagnostics;
using System.Net;
using System.Net.Sockets;
using System.Text;
using ZB.MOM.WW.ScadaBridge.CLI;

namespace ZB.MOM.WW.ScadaBridge.CLI.Tests;

/// <summary>
/// Regression tests for CLI-013 — <see cref="ManagementHttpClient.SendCommandAsync"/>
/// (success, error-body parsing, connection-failure, and timeout paths) was untested.
/// Uses a stub <see cref="HttpMessageHandler"/> so no live server is required.
/// </summary>
public class ManagementHttpClientTests
{
    private sealed class StubHandler : HttpMessageHandler
    {
        private readonly Func<HttpRequestMessage, CancellationToken, Task<HttpResponseMessage>> _responder;

        public StubHandler(HttpStatusCode status, string body)
            : this((_, _) => Task.FromResult(new HttpResponseMessage(status)
            {
                Content = new StringContent(body, Encoding.UTF8, "application/json"),
            }))
        {
        }

        public StubHandler(Func<HttpRequestMessage, CancellationToken, Task<HttpResponseMessage>> responder)
        {
            _responder = responder;
        }

        protected override Task<HttpResponseMessage> SendAsync(
            HttpRequestMessage request, CancellationToken cancellationToken)
            => _responder(request, cancellationToken);
    }

    private static ManagementHttpClient ClientWith(StubHandler handler)
        => new(new HttpClient(handler), "http://localhost:9001", "user", "pass");

    [Fact]
    public async Task SendCommandAsync_Success_ReturnsJsonData()
    {
        using var client = ClientWith(new StubHandler(HttpStatusCode.OK, "{\"id\":1}"));

        var response = await client.SendCommandAsync("ListSites", new { }, TimeSpan.FromSeconds(5));

        Assert.Equal(200, response.StatusCode);
        Assert.Equal("{\"id\":1}", response.JsonData);
        Assert.Null(response.Error);
        Assert.Null(response.ErrorCode);
    }

    [Fact]
    public async Task SendCommandAsync_ErrorBody_ParsesErrorAndCode()
    {
        using var client = ClientWith(new StubHandler(
            HttpStatusCode.BadRequest, "{\"error\":\"Bad input\",\"code\":\"INVALID_ARGUMENT\"}"));

        var response = await client.SendCommandAsync("ListSites", new { }, TimeSpan.FromSeconds(5));

        Assert.Equal(400, response.StatusCode);
        Assert.Null(response.JsonData);
        Assert.Equal("Bad input", response.Error);
        Assert.Equal("INVALID_ARGUMENT", response.ErrorCode);
    }

    [Fact]
    public async Task SendCommandAsync_NonJsonErrorBody_FallsBackToRawBody()
    {
        using var client = ClientWith(new StubHandler(
            HttpStatusCode.BadGateway, "<html>Bad Gateway</html>"));

        var response = await client.SendCommandAsync("ListSites", new { }, TimeSpan.FromSeconds(5));

        Assert.Equal(502, response.StatusCode);
        Assert.Equal("<html>Bad Gateway</html>", response.Error);
        Assert.Null(response.ErrorCode);
    }

    [Fact]
    public async Task SendCommandAsync_ConnectionFailure_ReturnsStatusZero()
    {
        using var client = ClientWith(new StubHandler((_, _) =>
            throw new HttpRequestException("connection refused")));

        var response = await client.SendCommandAsync("ListSites", new { }, TimeSpan.FromSeconds(5));

        Assert.Equal(0, response.StatusCode);
        Assert.Equal("CONNECTION_FAILED", response.ErrorCode);
        Assert.Contains("connection refused", response.Error);
    }

    [Fact]
    public async Task SendCommandAsync_Timeout_Returns504()
    {
        using var client = ClientWith(new StubHandler(async (_, ct) =>
        {
            await Task.Delay(Timeout.Infinite, ct);
            return new HttpResponseMessage(HttpStatusCode.OK);
        }));

        var response = await client.SendCommandAsync("ListSites", new { }, TimeSpan.FromMilliseconds(50));

        Assert.Equal(504, response.StatusCode);
        Assert.Equal("TIMEOUT", response.ErrorCode);
    }
}

/// <summary>
/// The public <see cref="ManagementHttpClient"/> constructor must leave
/// <see cref="HttpClient.Timeout"/> INFINITE so the per-call
/// <see cref="CancellationTokenSource"/> is the single overall deadline — a fixed
/// client timeout silently truncated every caller with a longer per-call timeout
/// (<c>deploy site</c>'s 5-minute bulk deploy, the 5-minute <c>bundle</c> calls),
/// which then printed a fake 504 while the server kept working. The connect phase
/// is bounded separately on <see cref="SocketsHttpHandler.ConnectTimeout"/>, honoring
/// the <c>SCADABRIDGE_HTTP_CONNECT_TIMEOUT_SECONDS</c> override — consistent with how
/// every other CLI setting is environment-overridable (<see cref="CliConfig"/>). Runs
/// in the shared "Environment" collection (see <see cref="TestCollections"/>) so it
/// never races another test mutating process-wide environment variables.
/// </summary>
[Collection("Environment")]
public class ManagementHttpClientTimeoutTests
{
    private const string EnvVar = "SCADABRIDGE_HTTP_CONNECT_TIMEOUT_SECONDS";

    [Fact]
    public void DefaultConstructor_LeavesClientTimeoutInfinite()
    {
        using var client = new ManagementHttpClient("http://localhost:9001", "user", "pass");

        Assert.Equal(Timeout.InfiniteTimeSpan, client.EffectiveTimeout);
    }

    [Fact]
    public void ConnectTimeout_DefaultsToThirtySeconds_WhenEnvVarUnset()
    {
        var original = Environment.GetEnvironmentVariable(EnvVar);
        try
        {
            Environment.SetEnvironmentVariable(EnvVar, null);

            Assert.Equal(TimeSpan.FromSeconds(30), ManagementHttpClient.DefaultConnectTimeout);
            Assert.Equal(TimeSpan.FromSeconds(30), ManagementHttpClient.ResolveConnectTimeout());
        }
        finally
        {
            Environment.SetEnvironmentVariable(EnvVar, original);
        }
    }

    [Theory]
    [InlineData("0")]
    [InlineData("-5")]
    [InlineData("not-a-number")]
    [InlineData("")]
    public void InvalidOrNonPositiveEnvValue_FallsBackToDefaultConnectTimeout(string value)
    {
        var original = Environment.GetEnvironmentVariable(EnvVar);
        try
        {
            Environment.SetEnvironmentVariable(EnvVar, value);

            Assert.Equal(TimeSpan.FromSeconds(30), ManagementHttpClient.ResolveConnectTimeout());
        }
        finally
        {
            Environment.SetEnvironmentVariable(EnvVar, original);
        }
    }

    [Fact]
    public void PositiveEnvValue_OverridesDefaultConnectTimeout()
    {
        var original = Environment.GetEnvironmentVariable(EnvVar);
        try
        {
            Environment.SetEnvironmentVariable(EnvVar, "5");

            Assert.Equal(TimeSpan.FromSeconds(5), ManagementHttpClient.ResolveConnectTimeout());
        }
        finally
        {
            Environment.SetEnvironmentVariable(EnvVar, original);
        }
    }

    /// <summary>
    /// The regression that matters: a per-call timeout LONGER than the old 30 s
    /// client cap must actually be honored. Two calls against the same hanging
    /// local listener — one with a short deadline, one with a longer one — must
    /// time out in that order and at their own deadlines, which is only possible
    /// if <see cref="HttpClient.Timeout"/> is not silently capping both. Uses a
    /// real socket (not the stub handler) so the connect + send path is exercised
    /// end to end, and sub-second deadlines so the test stays fast.
    /// </summary>
    [Fact]
    public async Task PerCallTimeoutLongerThanTheOldClientCap_IsHonored()
    {
        // A listener that accepts connections and then never answers: every
        // request hangs until the caller's own deadline fires.
        var listener = new TcpListener(IPAddress.Loopback, 0);
        listener.Start();
        var port = ((IPEndPoint)listener.LocalEndpoint).Port;
        var accepted = new List<TcpClient>();
        var acceptLoop = Task.Run(async () =>
        {
            try
            {
                while (true)
                    accepted.Add(await listener.AcceptTcpClientAsync());
            }
            catch (ObjectDisposedException) { /* listener stopped — expected */ }
            catch (SocketException) { /* listener stopped — expected */ }
        });

        try
        {
            using var client = new ManagementHttpClient($"http://127.0.0.1:{port}", "user", "pass");

            var shortSw = Stopwatch.StartNew();
            var shortResponse = await client.SendCommandAsync("ListSites", new { }, TimeSpan.FromMilliseconds(300));
            shortSw.Stop();

            var longSw = Stopwatch.StartNew();
            var longResponse = await client.SendCommandAsync("ListSites", new { }, TimeSpan.FromMilliseconds(1500));
            longSw.Stop();

            Assert.Equal("TIMEOUT", shortResponse.ErrorCode);
            Assert.Equal("TIMEOUT", longResponse.ErrorCode);

            // The longer deadline must genuinely outlast the shorter one rather
            // than both being clipped to a single client-wide cap.
            Assert.True(
                longSw.Elapsed > TimeSpan.FromMilliseconds(1000),
                $"1.5 s per-call timeout returned after only {longSw.ElapsedMilliseconds} ms — the client cap truncated it.");
            Assert.True(
                shortSw.Elapsed < TimeSpan.FromMilliseconds(1000),
                $"300 ms per-call timeout took {shortSw.ElapsedMilliseconds} ms.");
        }
        finally
        {
            listener.Stop();
            foreach (var c in accepted) c.Dispose();
            await acceptLoop;
        }
    }
}
