using System.Net.Sockets;
using Xunit;
using Xunit.Sdk;

namespace ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests;

/// <summary>
///     Reachability probe for the <c>ab_server</c> Docker container (libplctag's CIP
///     simulator built via <c>Docker/Dockerfile</c>) or any real AB PLC the
///     <c>AB_SERVER_ENDPOINT</c> env var points at. Parses
///     <c>AB_SERVER_ENDPOINT</c> (default <c>localhost:44818</c>) + TCP-connects
///     once at fixture construction. Tests skip via <see cref="AbServerFactAttribute"/>
///     / <see cref="AbServerTheoryAttribute"/> when the port isn't live, so
///     <c>dotnet test</c> stays green on a fresh clone without Docker running.
///     Matches the <see cref="ModbusSimulatorFixture"/> / <c>Snap7ServerFixture</c> /
///     <c>OpcPlcFixture</c> shape.
/// </summary>
/// <remarks>
///     Docker is the only supported launch path — no native-binary spawn + no
///     PATH lookup. Bring the container up before <c>dotnet test</c>:
///     <c>docker compose -f Docker/docker-compose.yml --profile controllogix up</c>.
/// </remarks>
public sealed class AbServerFixture : IAsyncLifetime
{
    private const string EndpointEnvVar = "AB_SERVER_ENDPOINT";

    /// <summary>The profile this fixture instance represents. Parallel family smoke tests
    /// instantiate the fixture with the profile matching their compose-file service.</summary>
    public AbServerProfile Profile { get; }

    public string Host { get; } = "127.0.0.1";
    public int Port { get; } = AbServerProfile.DefaultPort;

    public AbServerFixture() : this(KnownProfiles.ControlLogix) { }

    public AbServerFixture(AbServerProfile profile)
    {
        Profile = profile ?? throw new ArgumentNullException(nameof(profile));

        // Endpoint override applies to both host + port — targeting a real PLC at
        // non-default host or port shouldn't need fixture changes.
        if (Environment.GetEnvironmentVariable(EndpointEnvVar) is { Length: > 0 } raw)
        {
            var parts = raw.Split(':', 2);
            Host = parts[0];
            if (parts.Length == 2 && int.TryParse(parts[1], out var p)) Port = p;
        }
    }

    public ValueTask InitializeAsync() => ValueTask.CompletedTask;
    public ValueTask DisposeAsync() => ValueTask.CompletedTask;

    /// <summary>
    ///     <c>true</c> when ab_server is reachable at this fixture's Host/Port. Used by
    ///     <see cref="AbServerFactAttribute"/> / <see cref="AbServerTheoryAttribute"/>
    ///     to decide whether to skip tests on a fresh clone without a running container.
    /// </summary>
    public static bool IsServerAvailable() =>
        TcpProbe(ResolveHost(), ResolvePort());

    private static string ResolveHost() =>
        Environment.GetEnvironmentVariable(EndpointEnvVar)?.Split(':', 2)[0] ?? "127.0.0.1";

    private static int ResolvePort()
    {
        var raw = Environment.GetEnvironmentVariable(EndpointEnvVar);
        if (raw is null) return AbServerProfile.DefaultPort;
        var parts = raw.Split(':', 2);
        return parts.Length == 2 && int.TryParse(parts[1], out var p) ? p : AbServerProfile.DefaultPort;
    }

    /// <summary>One-shot TCP probe; 500 ms budget so a missing container fails the probe fast.</summary>
    private static bool TcpProbe(string host, int port)
    {
        try
        {
            using var client = new TcpClient();
            var task = client.ConnectAsync(host, port);
            return task.Wait(TimeSpan.FromMilliseconds(500)) && client.Connected;
        }
        catch { return false; }
    }
}

/// <summary>
///     <c>[Fact]</c>-equivalent that skips when ab_server isn't reachable — accepts a
///     live Docker listener on <c>localhost:44818</c> or an <c>AB_SERVER_ENDPOINT</c>
///     override pointing at a real PLC.
/// </summary>
public sealed class AbServerFactAttribute : FactAttribute
{
    public AbServerFactAttribute()
    {
        if (!AbServerFixture.IsServerAvailable())
            Skip = "ab_server not reachable. Start the Docker container " +
                   "(docker compose -f Docker/docker-compose.yml --profile controllogix up) " +
                   "or set AB_SERVER_ENDPOINT to a real PLC.";
    }
}

/// <summary>
///     <c>[Theory]</c>-equivalent with the same availability rules as
///     <see cref="AbServerFactAttribute"/>. Pair with
///     <c>[MemberData(nameof(KnownProfiles.All))]</c>-style providers to run one theory
///     row per family.
/// </summary>
public sealed class AbServerTheoryAttribute : TheoryAttribute
{
    public AbServerTheoryAttribute()
    {
        if (!AbServerFixture.IsServerAvailable())
            Skip = "ab_server not reachable. Start the Docker container " +
                   "(docker compose -f Docker/docker-compose.yml --profile controllogix up) " +
                   "or set AB_SERVER_ENDPOINT to a real PLC.";
    }
}
