using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using Junction.Domain;
using Junction.Domain.Models;
using Junction.Domain.Protocols;
using Junction.Persistence;
using Junction.Protocols.MTConnect;
using Xunit;
using Xunit.Abstractions;
using Xunit.Sdk;

namespace Junction.Tests.Integration
{
    /// <summary>
    /// Docker-gated end-to-end integration tests: real <see cref="MtconnectDriver"/> ->
    /// live ladder99 MTConnect agent (docker mock at http://localhost:5000) -> snapshot
    /// round-trip through the real SQLite repository.
    /// <para>
    /// These tests assume the mock is ALREADY running (they do NOT auto-start docker):
    /// <c>docker compose -f mock/docker-compose.yml up -d</c>. When the agent is not
    /// reachable (no docker in CI, mock down) each test SKIPS (never fails), so a CI
    /// without docker stays green.
    /// </para>
    /// xUnit v2 2.9.3 has no <c>Assert.Skip</c> (v3-only), so a self-contained skippable-fact
    /// discoverer (<see cref="DockerFactAttribute"/> + <see cref="SkipTestException"/>) provides a
    /// genuine runtime SKIP result — no extra NuGet package, no csproj change.
    /// <para>Filter with <c>dotnet test --filter Category=Docker</c>.</para>
    /// </summary>
    [Trait("Category", "Docker")]
    public sealed class MtconnectEndToEndTests
    {
        private const string AgentUrl = "http://localhost:5000";

        /// <summary>
        /// Probes the agent's /probe endpoint with a short timeout. Returns true only when the
        /// agent answers with a success status. Never throws — any failure means "not reachable".
        /// </summary>
        private static bool IsAgentReachable()
        {
            try
            {
                using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(2) };
                using var response = http.GetAsync(AgentUrl + "/probe").GetAwaiter().GetResult();
                return response.IsSuccessStatusCode;
            }
            catch
            {
                return false;
            }
        }

        /// <summary>Skips the current test (does not fail) when the docker MTConnect mock is down.</summary>
        private static void SkipIfAgentUnavailable()
        {
            if (!IsAgentReachable())
            {
                throw new SkipTestException(
                    "MTConnect docker mock not reachable at " + AgentUrl +
                    "/probe. Start it with: docker compose -f mock/docker-compose.yml up -d");
            }
        }

        private static Machine NewMtconnectMachine() =>
            new Machine(
                Guid.NewGuid(),
                "IT Mock Mill",
                "mtconnect",
                new Dictionary<string, string> { ["AgentUrl"] = AgentUrl },
                TimeSpan.FromSeconds(1));

        [DockerFact]
        public async Task Driver_ReadsCurrent_FromLiveAgent_VersionAgnostic()
        {
            SkipIfAgentUnavailable();

            var machine = NewMtconnectMachine();

            var factory = new MtconnectDriverFactory();
            Result<IProtocolDriver> created = factory.Create(machine);
            Assert.True(created.IsSuccess, Describe(created));

            IProtocolDriver driver = created.Value;
            try
            {
                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
                Result<MachineSnapshot> read = await driver.ReadCurrentAsync(cts.Token);

                Assert.True(read.IsSuccess, Describe(read));

                var snapshot = read.Value;
                Assert.Equal(machine.Id, snapshot.MachineId);
                Assert.True(snapshot.Items.Count > 0, "expected at least one datum from the live agent");

                // Agent reports AVAILABLE -> Connected. Real MTConnect 2.0 output must parse.
                Assert.Equal(ConnectionState.Connected, snapshot.ConnectionState);

                // A meaningful datum with a non-empty value must be present. The parser is
                // version-agnostic, so match on the datum Name (parsed from the agent's real feed).
                var meaningful = snapshot.Items.FirstOrDefault(i =>
                    !string.IsNullOrWhiteSpace(i.Value) &&
                    (Contains(i.Name, "Position") ||
                     Contains(i.Name, "Execution") ||
                     Contains(i.Name, "Availability")));

                Assert.True(
                    meaningful != null,
                    "expected a Position/Execution/Availability datum with a non-empty value; got: " +
                    string.Join(", ", snapshot.Items.Take(20).Select(i => i.Name + "=" + i.Value)));
            }
            finally
            {
                (driver as IDisposable)?.Dispose();
            }
        }

        [DockerFact]
        public async Task Driver_To_Repository_RoundTrip_PersistsSnapshot()
        {
            SkipIfAgentUnavailable();

            var machine = NewMtconnectMachine();

            var dbPath = Path.Combine(
                Path.GetTempPath(),
                "junction_it_" + Guid.NewGuid().ToString("N") + ".db");
            var connectionFactory = new SqliteConnectionFactory("Data Source=" + dbPath);

            try
            {
                Result schema = SqliteSchema.EnsureCreated(connectionFactory);
                Assert.True(schema.IsSuccess, Describe(schema));

                var repo = new SqliteMachineRepository(connectionFactory);

                Result upsert = await repo.UpsertAsync(machine, CancellationToken.None);
                Assert.True(upsert.IsSuccess, Describe(upsert));

                // Take a live snapshot via the real driver.
                var driverFactory = new MtconnectDriverFactory();
                Result<IProtocolDriver> created = driverFactory.Create(machine);
                Assert.True(created.IsSuccess, Describe(created));

                IProtocolDriver driver = created.Value;
                MachineSnapshot snapshot;
                try
                {
                    using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
                    Result<MachineSnapshot> read = await driver.ReadCurrentAsync(cts.Token);
                    Assert.True(read.IsSuccess, Describe(read));
                    snapshot = read.Value;
                }
                finally
                {
                    (driver as IDisposable)?.Dispose();
                }

                Assert.True(snapshot.Items.Count > 0, "live snapshot must carry datums to persist");

                // Persist and read back the latest snapshot.
                Result save = await repo.SaveSnapshotAsync(snapshot, CancellationToken.None);
                Assert.True(save.IsSuccess, Describe(save));

                Result<MachineSnapshot> loadedResult =
                    await repo.GetLatestSnapshotAsync(machine.Id, CancellationToken.None);
                Assert.True(loadedResult.IsSuccess, Describe(loadedResult));

                var loaded = loadedResult.Value;
                Assert.Equal(machine.Id, loaded.MachineId);
                Assert.Equal(snapshot.ConnectionState, loaded.ConnectionState);
                Assert.Equal(snapshot.Items.Count, loaded.Items.Count);

                // Every persisted datum is retrievable with its value intact (last datum).
                var expected = snapshot.Items[0];
                var actual = loaded.TryGetItem(expected.Id);
                Assert.NotNull(actual);
                Assert.Equal(expected.Value, actual!.Value);
                Assert.Equal(expected.Name, actual.Name);
                Assert.Equal(expected.Category, actual.Category);
            }
            finally
            {
                TryDelete(dbPath);
            }
        }

        private static bool Contains(string haystack, string needle) =>
            haystack != null && haystack.IndexOf(needle, StringComparison.OrdinalIgnoreCase) >= 0;

        private static void TryDelete(string path)
        {
            try
            {
                if (File.Exists(path))
                {
                    File.Delete(path);
                }
            }
            catch
            {
                // best-effort cleanup
            }
        }

        private static string Describe<T>(Result<T> result) =>
            result.IsSuccess ? "" : string.Join("; ", result.Errors.Select(e => e.ToString()));

        private static string Describe(Result result) =>
            result.IsSuccess ? "" : string.Join("; ", result.Errors.Select(e => e.ToString()));
    }

    // ---------------------------------------------------------------------------------------
    // Self-contained skippable-fact support for xUnit v2 (no Assert.Skip, no extra package).
    // A test throws SkipTestException at runtime; the custom test case rewrites the resulting
    // TestFailed message into a TestSkipped message, so the runner reports a genuine SKIP.
    // ---------------------------------------------------------------------------------------

    /// <summary>Thrown to skip a test at runtime (dynamic skip for xUnit v2).</summary>
    public sealed class SkipTestException : Exception
    {
        public SkipTestException(string reason) : base(reason) { }
    }

    /// <summary>A <see cref="FactAttribute"/> whose tests may skip at runtime via <see cref="SkipTestException"/>.</summary>
    [XunitTestCaseDiscoverer("Junction.Tests.Integration.DockerFactDiscoverer", "Junction.Tests")]
    [AttributeUsage(AttributeTargets.Method, AllowMultiple = false)]
    public sealed class DockerFactAttribute : FactAttribute
    {
    }

    /// <summary>Discovers <see cref="DockerFactAttribute"/>-decorated methods as skippable test cases.</summary>
    public sealed class DockerFactDiscoverer : IXunitTestCaseDiscoverer
    {
        private static readonly string[] SkippingExceptionNames = { typeof(SkipTestException).FullName! };

        private readonly IMessageSink _diagnosticMessageSink;

        public DockerFactDiscoverer(IMessageSink diagnosticMessageSink)
        {
            _diagnosticMessageSink = diagnosticMessageSink;
        }

        public IEnumerable<IXunitTestCase> Discover(
            ITestFrameworkDiscoveryOptions discoveryOptions,
            ITestMethod testMethod,
            IAttributeInfo factAttribute)
        {
            yield return new SkippableFactTestCase(
                SkippingExceptionNames,
                _diagnosticMessageSink,
                discoveryOptions.MethodDisplayOrDefault(),
                discoveryOptions.MethodDisplayOptionsOrDefault(),
                testMethod);
        }
    }

    /// <summary>Test case that converts a designated exception into a skip result.</summary>
    public sealed class SkippableFactTestCase : XunitTestCase
    {
        private string[] _skippingExceptionNames = Array.Empty<string>();

        [EditorBrowsable(EditorBrowsableState.Never)]
        [Obsolete("Called by the de-serializer; should only be called by deriving classes for de-serialization purposes")]
        public SkippableFactTestCase()
        {
        }

        public SkippableFactTestCase(
            string[] skippingExceptionNames,
            IMessageSink diagnosticMessageSink,
            TestMethodDisplay defaultMethodDisplay,
            TestMethodDisplayOptions defaultMethodDisplayOptions,
            ITestMethod testMethod,
            object[]? testMethodArguments = null)
            : base(diagnosticMessageSink, defaultMethodDisplay, defaultMethodDisplayOptions, testMethod, testMethodArguments)
        {
            _skippingExceptionNames = skippingExceptionNames;
        }

        public override void Serialize(IXunitSerializationInfo data)
        {
            base.Serialize(data);
            data.AddValue(nameof(_skippingExceptionNames), _skippingExceptionNames);
        }

        public override void Deserialize(IXunitSerializationInfo data)
        {
            base.Deserialize(data);
            _skippingExceptionNames = data.GetValue<string[]>(nameof(_skippingExceptionNames));
        }

        public override async Task<RunSummary> RunAsync(
            IMessageSink diagnosticMessageSink,
            IMessageBus messageBus,
            object[] constructorArguments,
            ExceptionAggregator aggregator,
            CancellationTokenSource cancellationTokenSource)
        {
            var interceptor = new SkippableTestMessageBus(messageBus, _skippingExceptionNames);
            var result = await base.RunAsync(
                diagnosticMessageSink, interceptor, constructorArguments, aggregator, cancellationTokenSource);

            result.Failed -= interceptor.SkippedCount;
            result.Skipped += interceptor.SkippedCount;
            return result;
        }
    }

    /// <summary>Rewrites <see cref="ITestFailed"/> carrying a skipping exception into <see cref="ITestSkipped"/>.</summary>
    public sealed class SkippableTestMessageBus : IMessageBus
    {
        private readonly IMessageBus _inner;
        private readonly string[] _skippingExceptionNames;

        public SkippableTestMessageBus(IMessageBus inner, string[] skippingExceptionNames)
        {
            _inner = inner;
            _skippingExceptionNames = skippingExceptionNames;
        }

        public int SkippedCount { get; private set; }

        public bool QueueMessage(IMessageSinkMessage message)
        {
            if (message is ITestFailed failed)
            {
                var exceptionType = failed.ExceptionTypes.FirstOrDefault();
                if (exceptionType != null && _skippingExceptionNames.Contains(exceptionType))
                {
                    SkippedCount++;
                    var reason = failed.Messages != null && failed.Messages.Length > 0
                        ? failed.Messages[0]
                        : "skipped";
                    return _inner.QueueMessage(new TestSkipped(failed.Test, reason));
                }
            }

            return _inner.QueueMessage(message);
        }

        public void Dispose() => _inner.Dispose();
    }
}