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using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using NUnit.Framework;
using Opc.Ua.Bindings;
using Opc.Ua.Pcap.Bindings;
using Opc.Ua.Pcap.Capture;
using Opc.Ua.Pcap.Capture.Sources;
using Opc.Ua.Pcap.Frame;
using Opc.Ua.Pcap.Models;

namespace Opc.Ua.Pcap.Tests.Capture
{
    /// <summary>
    /// Tests that <see cref="InProcessClientCaptureSource"/> honors the
    /// <see cref="StartCaptureRequest.PcapFilePath"/> and
    /// <see cref="StartCaptureRequest.KeyLogFilePath"/> overrides used
    /// by the env-var driven auto-start.
    /// </summary>
    [TestFixture]
    public sealed class InProcessCaptureSourceExplicitPathsTests : TempDirectoryFixture
    {
        [Test]
        public async Task ExplicitPcapFilePathIsHonored()
        {
            var registry = new ChannelCaptureRegistry();
            await using var source = new InProcessClientCaptureSource(registry);

            string explicitPcap = CreateTempPath("explicit.pcap");
            await source.StartAsync(
                new StartCaptureRequest
                {
                    SessionFolder = TempDirectory,
                    PcapFilePath = explicitPcap
                },
                CancellationToken.None).ConfigureAwait(false);

            Assert.That(File.Exists(explicitPcap), Is.True);
            Assert.That(File.Exists(Path.Combine(TempDirectory, "capture.pcap")), Is.False);

            await source.StopAsync(CancellationToken.None).ConfigureAwait(false);

            Assert.That(source.GetRawPcapFilePath(), Is.EqualTo(explicitPcap));
        }

        [Test]
        public async Task ExplicitKeyLogFilePathIsHonored()
        {
            var registry = new ChannelCaptureRegistry();
            await using var source = new InProcessClientCaptureSource(registry);

            string explicitKeyLog = CreateTempPath("explicit.uakeys.json");
            await source.StartAsync(
                new StartCaptureRequest
                {
                    SessionFolder = TempDirectory,
                    KeyLogFilePath = explicitKeyLog
                },
                CancellationToken.None).ConfigureAwait(false);

            Assert.That(File.Exists(explicitKeyLog), Is.True);
            // The text-format sibling is derived by extension swap; for
            // *.uakeys.json that yields *.uakeys.txt next to it.
            Assert.That(File.Exists(CreateTempPath("explicit.uakeys.txt")), Is.True);
            Assert.That(File.Exists(Path.Combine(TempDirectory, "keys.uakeys.json")), Is.False);

            await source.StopAsync(CancellationToken.None).ConfigureAwait(false);

            Assert.That(source.GetKeyLogFilePath(), Is.EqualTo(explicitKeyLog));
        }

        [Test]
        public async Task DefaultsArePreservedWhenExplicitPathsAreNull()
        {
            var registry = new ChannelCaptureRegistry();
            await using var source = new InProcessClientCaptureSource(registry);

            await source.StartAsync(
                new StartCaptureRequest
                {
                    SessionFolder = TempDirectory
                },
                CancellationToken.None).ConfigureAwait(false);

            Assert.That(File.Exists(Path.Combine(TempDirectory, "capture.pcap")), Is.True);
            Assert.That(File.Exists(Path.Combine(TempDirectory, "keys.uakeys.json")), Is.True);
            Assert.That(File.Exists(Path.Combine(TempDirectory, "keys.uakeys.txt")), Is.True);

            await source.StopAsync(CancellationToken.None).ConfigureAwait(false);
        }

        [Test]
        public async Task RelativeExplicitPathsResolveAgainstSessionFolder()
        {
            var registry = new ChannelCaptureRegistry();
            await using var source = new InProcessClientCaptureSource(registry);

            await source.StartAsync(
                new StartCaptureRequest
                {
                    SessionFolder = TempDirectory,
                    PcapFilePath = "relative.pcap",
                    KeyLogFilePath = "relative.uakeys.json"
                },
                CancellationToken.None).ConfigureAwait(false);

            Assert.That(File.Exists(Path.Combine(TempDirectory, "relative.pcap")), Is.True);
            Assert.That(File.Exists(Path.Combine(TempDirectory, "relative.uakeys.json")), Is.True);
            Assert.That(File.Exists(Path.Combine(TempDirectory, "relative.uakeys.txt")), Is.True);

            await source.StopAsync(CancellationToken.None).ConfigureAwait(false);
        }

        [Test]
        public async Task ExplicitPathsCreateMissingParentDirectories()
        {
            var registry = new ChannelCaptureRegistry();
            await using var source = new InProcessClientCaptureSource(registry);

            string nestedDir = Path.Combine(TempDirectory, "nested", "deeper");
            string nestedPcap = Path.Combine(nestedDir, "out.pcap");
            string nestedKeys = Path.Combine(nestedDir, "out.uakeys.json");

            Assert.That(Directory.Exists(nestedDir), Is.False);

            await source.StartAsync(
                new StartCaptureRequest
                {
                    SessionFolder = TempDirectory,
                    PcapFilePath = nestedPcap,
                    KeyLogFilePath = nestedKeys
                },
                CancellationToken.None).ConfigureAwait(false);

            Assert.That(File.Exists(nestedPcap), Is.True);
            Assert.That(File.Exists(nestedKeys), Is.True);

            await source.StopAsync(CancellationToken.None).ConfigureAwait(false);
        }

        [Test]
        public void ConstructorRejectsNullRegistry()
        {
            Assert.That(
                () => new InProcessClientCaptureSource(null!),
                Throws.TypeOf<System.ArgumentNullException>().With.Property("ParamName").EqualTo("registry"));
        }

        [Test]
        public async Task StartAsyncRejectsNullAndMissingSessionFolder()
        {
            var registry = new ChannelCaptureRegistry();
            await using var source = new InProcessClientCaptureSource(registry);

            Assert.That(
                async () => await source.StartAsync(null!, CancellationToken.None).ConfigureAwait(false),
                Throws.TypeOf<System.ArgumentNullException>().With.Property("ParamName").EqualTo("request"));
            Assert.That(
                async () => await source.StartAsync(new StartCaptureRequest(), CancellationToken.None)
                    .ConfigureAwait(false),
                Throws.TypeOf<PcapDiagnosticsException>().With.Message.Contains("sessionFolder"));
        }

        [Test]
        public async Task StartAsyncTwiceThrowsAndStopAsyncIsIdempotent()
        {
            var registry = new ChannelCaptureRegistry();
            await using var source = new InProcessClientCaptureSource(registry);
            await source.StartAsync(
                new StartCaptureRequest
                {
                    SessionFolder = TempDirectory
                },
                CancellationToken.None).ConfigureAwait(false);

            Assert.That(
                async () => await source.StartAsync(
                    new StartCaptureRequest
                    {
                        SessionFolder = TempDirectory
                    },
                    CancellationToken.None).ConfigureAwait(false),
                Throws.TypeOf<PcapDiagnosticsException>().With.Message.Contains("cannot be started twice"));

            await source.StopAsync(CancellationToken.None).ConfigureAwait(false);
            await source.StopAsync(CancellationToken.None).ConfigureAwait(false);
        }

        [Test]
        public async Task FrameSinkWritesSentAndReceivedFramesToPcap()
        {
            var registry = new ChannelCaptureRegistry();
            await using var source = new InProcessServerCaptureSource(registry);
            await source.StartAsync(
                new StartCaptureRequest
                {
                    SessionFolder = TempDirectory
                },
                CancellationToken.None).ConfigureAwait(false);

            var sink = (IFrameCaptureSink)source;
            sink.OnFrameSent(0x11111111, new byte[] { 1, 2, 3 });
            sink.OnFrameReceived(0x22222222, new byte[] { 4, 5 });
            sink.OnFrameReceived(0x33333333, ReadOnlySpan<byte>.Empty);

            await source.StopAsync(CancellationToken.None).ConfigureAwait(false);
            List<CaptureFrame> frames = await PcapTestHelpers.ToListAsync(
                source.ReadCapturedFramesAsync(maxFrames: 2, CancellationToken.None)).ConfigureAwait(false);

            Assert.That(registry.CurrentObserver, Is.Null);
            Assert.That(source.FrameCount, Is.EqualTo(2));
            Assert.That(source.ByteCount, Is.EqualTo(5));
            Assert.That(frames, Has.Count.EqualTo(2));
            Assert.That(frames[0].Data.Length, Is.GreaterThan(3));
            Assert.That(frames[1].Data.Length, Is.GreaterThan(2));
        }

        [Test]
        public async Task MaxFramesCapClearsObserverButFlushesQueuedFrame()
        {
            var registry = new ChannelCaptureRegistry();
            await using var source = new InProcessClientCaptureSource(registry);
            await source.StartAsync(
                new StartCaptureRequest
                {
                    SessionFolder = TempDirectory,
                    MaxFrames = 1
                },
                CancellationToken.None).ConfigureAwait(false);

            var sink = (IFrameCaptureSink)source;
            sink.OnFrameSent(0x11111111, new byte[] { 1 });
            sink.OnFrameSent(0x11111111, new byte[] { 2 });

            await source.StopAsync(CancellationToken.None).ConfigureAwait(false);
            List<CaptureFrame> frames = await PcapTestHelpers.ToListAsync(
                source.ReadCapturedFramesAsync(maxFrames: 1, CancellationToken.None)).ConfigureAwait(false);

            Assert.That(registry.CurrentObserver, Is.Null);
            Assert.That(source.FrameCount, Is.EqualTo(2));
            Assert.That(source.ByteCount, Is.EqualTo(2));
            Assert.That(frames, Has.Count.EqualTo(1));
        }
    }
}