using Google.Protobuf;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Admin;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Deploy;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Mesh;
using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
using ZB.MOM.WW.OtOpcUa.Commons.Protos;
using ZB.MOM.WW.OtOpcUa.Commons.Protos.MeshTransport.V1;
using ZB.MOM.WW.OtOpcUa.Commons.Types;

namespace ZB.MOM.WW.OtOpcUa.Commons.Tests;

/// <summary>
///     Round-trip goldens for <see cref="MeshTransportDtoMapper"/> — the mesh gRPC command
///     plane's only data contract. Every golden goes domain → proto → <b>serialized bytes</b> → proto →
///     domain, because the failure class this suite exists to catch is not a mis-assigned property but a
///     member that survives an in-memory copy and vanishes on the wire: proto3 explicit presence is a
///     serialization-level property, so a null-vs-<c>""</c> or absent-vs-epoch mistake is invisible
///     unless the bytes are actually round-tripped.
/// </summary>
/// <remarks>
///     Each record gets one all-members-non-default golden plus a null-variant golden for every
///     nullable member, since a nullable member is exactly where a silent drop hides — the record still
///     compares equal to a fresh instance built with the default, so nothing else in the system notices.
/// </remarks>
public class MeshTransportDtoMapperTests
{
    // Deliberately non-default in every position: distinct GUIDs (so a swapped assignment cannot pass),
    // a real 64-char lowercase SHA-256 hex, and strings that are neither empty nor equal to each other.
    private static readonly Guid DeploymentGuid = Guid.ParseExact("11111111111111111111111111111111", "N");
    private static readonly Guid CorrelationGuid = Guid.ParseExact("22222222222222222222222222222222", "N");
    private static readonly Guid EnvelopeGuid = Guid.ParseExact("33333333333333333333333333333333", "N");

    private const string Sha256Hex = "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08";

    /// <summary>Serializes and re-parses <paramref name="message"/> so presence is proven on the wire.</summary>
    private static T Wire<T>(T message)
        where T : IMessage<T>, new()
        => new MessageParser<T>(() => new T()).ParseFrom(message.ToByteArray());

    // ---------------------------------------------------------------- DispatchDeployment

    [Fact]
    public void DispatchDeployment_RoundTrips_WithEveryMemberSet()
    {
        var domain = new DispatchDeployment(
            new DeploymentId(DeploymentGuid),
            new RevisionHash(Sha256Hex),
            new CorrelationId(CorrelationGuid));

        MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain))).ShouldBe(domain);
    }

    [Fact]
    public void DispatchDeployment_EncodesIdsInTheirHexNForm()
    {
        var proto = MeshTransportDtoMapper.ToProto(new DispatchDeployment(
            new DeploymentId(DeploymentGuid), new RevisionHash(Sha256Hex), new CorrelationId(CorrelationGuid)));

        proto.DeploymentId.ShouldBe(DeploymentGuid.ToString("N"));
        proto.RevisionHash.ShouldBe(Sha256Hex);
        proto.CorrelationId.ShouldBe(CorrelationGuid.ToString("N"));
    }

    // ---------------------------------------------------------------- RestartDriver / ReconnectDriver

    [Fact]
    public void RestartDriver_RoundTrips_WithEveryMemberSet()
    {
        var domain = new RestartDriver("cluster-alpha", "drv-modbus-7", "jdoe@zb.local", CorrelationGuid);

        MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain))).ShouldBe(domain);
    }

    [Fact]
    public void ReconnectDriver_RoundTrips_WithEveryMemberSet()
    {
        var domain = new ReconnectDriver("cluster-beta", "drv-s7-3", "aoperator@zb.local", CorrelationGuid);

        MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain))).ShouldBe(domain);
    }

    // ---------------------------------------------------------------- AlarmCommand

    [Fact]
    public void AlarmCommand_RoundTrips_WithEveryMemberSet()
    {
        var domain = new AlarmCommand(
            "alarm-42",
            "TimedShelve",
            "jdoe@zb.local",
            "shelving for maintenance",
            new DateTime(2026, 8, 6, 13, 45, 12, 345, DateTimeKind.Utc).AddTicks(6789));

        MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain))).ShouldBe(domain);
    }

    [Fact]
    public void AlarmCommand_RoundTrips_WithNullComment()
    {
        var domain = new AlarmCommand("alarm-42", "Acknowledge", "jdoe", null, null);

        var back = MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain)));

        back.ShouldBe(domain);
        back.Comment.ShouldBeNull();
        back.UnshelveAtUtc.ShouldBeNull();
    }

    [Fact]
    public void AlarmCommand_EmptyComment_StaysEmpty_AndIsNotNull()
    {
        // The trap: proto3 without explicit presence decodes an absent string as "", collapsing
        // null and "" onto one value. `optional string comment` keeps them distinct — an operator who
        // acknowledged with a deliberately blank comment must not be reported as having supplied none.
        var domain = new AlarmCommand("alarm-42", "AddComment", "jdoe", "", null);

        var back = MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain)));

        back.ShouldBe(domain);
        back.Comment.ShouldNotBeNull();
        back.Comment.ShouldBeEmpty();
    }

    [Fact]
    public void AlarmCommand_UnshelveAt_RoundTripsAsUtc()
    {
        // DateTime equality compares ticks and ignores Kind, so record equality alone would pass on a
        // Local-Kind result whose instant is hours off once anything re-interprets it. Assert Kind.
        var when = new DateTime(2026, 8, 6, 13, 45, 12, DateTimeKind.Utc).AddTicks(1234567);
        var domain = new AlarmCommand("alarm-42", "TimedShelve", "jdoe", null, when);

        var back = MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain)));

        back.UnshelveAtUtc.ShouldNotBeNull();
        back.UnshelveAtUtc!.Value.Kind.ShouldBe(DateTimeKind.Utc);
        back.UnshelveAtUtc.Value.Ticks.ShouldBe(when.Ticks);
    }

    [Fact]
    public void AlarmCommand_UnrecognizedOperation_RoundTripsVerbatim()
    {
        // Controller decision: `operation` stays a proto string precisely so an operation this build
        // does not know travels intact rather than decoding to an enum's UNSPECIFIED and being dropped.
        var domain = new AlarmCommand("alarm-42", "SomeFutureOperation", "jdoe", null, null);

        var back = MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain)));

        back.ShouldBe(domain);
        back.Operation.ShouldBe("SomeFutureOperation");
    }

    // ---------------------------------------------------------------- ApplyAck

    [Theory]
    [InlineData(ApplyAckOutcome.Applied)]
    [InlineData(ApplyAckOutcome.Failed)]
    public void ApplyAck_RoundTrips_WithEveryMemberSet(ApplyAckOutcome outcome)
    {
        var domain = new ApplyAck(
            new DeploymentId(DeploymentGuid),
            new NodeId("site-a-1"),
            outcome,
            "artifact fetch failed: sha mismatch",
            new CorrelationId(CorrelationGuid));

        MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain))).ShouldBe(domain);
    }

    [Fact]
    public void ApplyAck_RoundTrips_WithNullFailureReason()
    {
        var domain = new ApplyAck(
            new DeploymentId(DeploymentGuid),
            new NodeId("site-a-1"),
            ApplyAckOutcome.Applied,
            null,
            new CorrelationId(CorrelationGuid));

        var back = MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain)));

        back.ShouldBe(domain);
        back.FailureReason.ShouldBeNull();
    }

    [Fact]
    public void ApplyAck_EmptyFailureReason_StaysEmpty_AndIsNotNull()
    {
        var domain = new ApplyAck(
            new DeploymentId(DeploymentGuid),
            new NodeId("site-a-1"),
            ApplyAckOutcome.Failed,
            "",
            new CorrelationId(CorrelationGuid));

        var back = MeshTransportDtoMapper.FromProto(Wire(MeshTransportDtoMapper.ToProto(domain)));

        back.ShouldBe(domain);
        back.FailureReason.ShouldNotBeNull();
        back.FailureReason.ShouldBeEmpty();
    }

    [Fact]
    public void ApplyAck_UnspecifiedOutcome_Throws_RatherThanDecodingToAMeaningfulValue()
    {
        // The single highest-stakes decode in this contract. proto3 hands back 0 for an absent enum
        // field, and the deploy path seals on Applied — so 0 must never resolve to Applied (or to
        // Failed, which would fail a deployment that actually succeeded). ApplyAckOutcome has no
        // Unknown member to land on, so refusal is the only honest answer.
        var proto = new ApplyAckMessage
        {
            DeploymentId = DeploymentGuid.ToString("N"),
            NodeId = "site-a-1",
            Outcome = ApplyOutcome.Unspecified,
            CorrelationId = CorrelationGuid.ToString("N"),
        };

        var ex = Should.Throw<InvalidOperationException>(() => MeshTransportDtoMapper.FromProto(proto));
        ex.Message.ShouldContain(nameof(ApplyOutcome.Unspecified));
    }

    [Fact]
    public void ApplyAck_UnknownOutcomeValue_Throws()
    {
        // A peer built against a newer contract with a third outcome. Same rule: refuse, do not guess.
        var proto = new ApplyAckMessage
        {
            DeploymentId = DeploymentGuid.ToString("N"),
            NodeId = "site-a-1",
            Outcome = (ApplyOutcome)99,
            CorrelationId = CorrelationGuid.ToString("N"),
        };

        Should.Throw<InvalidOperationException>(() => MeshTransportDtoMapper.FromProto(proto))
            .Message.ShouldContain("99");
    }

    [Fact]
    public void ApplyAck_UnknownClrOutcome_ThrowsOnEncode()
    {
        var domain = new ApplyAck(
            new DeploymentId(DeploymentGuid),
            new NodeId("site-a-1"),
            (ApplyAckOutcome)99,
            null,
            new CorrelationId(CorrelationGuid));

        Should.Throw<ArgumentOutOfRangeException>(() => MeshTransportDtoMapper.ToProto(domain));
    }

    // ---------------------------------------------------------------- Envelope

    [Fact]
    public void Envelope_RoundTrips_DispatchDeployment()
    {
        var domain = new DispatchDeployment(
            new DeploymentId(DeploymentGuid), new RevisionHash(Sha256Hex), new CorrelationId(CorrelationGuid));

        var envelope = Wire(MeshTransportDtoMapper.ToEnvelope(domain));

        envelope.CommandCase.ShouldBe(CommandEnvelope.CommandOneofCase.DispatchDeployment);
        MeshTransportDtoMapper.FromEnvelope(envelope).ShouldBe(domain);
    }

    [Fact]
    public void Envelope_RoundTrips_RestartDriver()
    {
        var domain = new RestartDriver("cluster-alpha", "drv-modbus-7", "jdoe", CorrelationGuid);

        var envelope = Wire(MeshTransportDtoMapper.ToEnvelope(domain));

        envelope.CommandCase.ShouldBe(CommandEnvelope.CommandOneofCase.RestartDriver);
        MeshTransportDtoMapper.FromEnvelope(envelope).ShouldBe(domain);
    }

    [Fact]
    public void Envelope_RoundTrips_ReconnectDriver()
    {
        var domain = new ReconnectDriver("cluster-beta", "drv-s7-3", "jdoe", CorrelationGuid);

        var envelope = Wire(MeshTransportDtoMapper.ToEnvelope(domain));

        envelope.CommandCase.ShouldBe(CommandEnvelope.CommandOneofCase.ReconnectDriver);
        MeshTransportDtoMapper.FromEnvelope(envelope).ShouldBe(domain);
    }

    [Fact]
    public void Envelope_RoundTrips_AlarmCommand()
    {
        var domain = new AlarmCommand("alarm-42", "Acknowledge", "jdoe", "ack'd", null);

        var envelope = Wire(MeshTransportDtoMapper.ToEnvelope(domain, new CorrelationId(EnvelopeGuid)));

        envelope.CommandCase.ShouldBe(CommandEnvelope.CommandOneofCase.AlarmCommand);
        envelope.CorrelationId.ShouldBe(EnvelopeGuid.ToString("N"));
        MeshTransportDtoMapper.FromEnvelope(envelope).ShouldBe(domain);
    }

    [Fact]
    public void Envelope_SetsBothCorrelationIds_ForTheThreeSelfCorrelatingCommands()
    {
        // Encode writes envelope and inner correlation from the record's own member, so the two can
        // only diverge if a peer produced them apart — see the decode-precedence golden below.
        var dispatch = MeshTransportDtoMapper.ToEnvelope(new DispatchDeployment(
            new DeploymentId(DeploymentGuid), new RevisionHash(Sha256Hex), new CorrelationId(CorrelationGuid)));
        dispatch.CorrelationId.ShouldBe(CorrelationGuid.ToString("N"));
        dispatch.DispatchDeployment.CorrelationId.ShouldBe(CorrelationGuid.ToString("N"));

        var restart = MeshTransportDtoMapper.ToEnvelope(
            new RestartDriver("c", "d", "u", CorrelationGuid));
        restart.CorrelationId.ShouldBe(CorrelationGuid.ToString("N"));
        restart.RestartDriver.CorrelationId.ShouldBe(CorrelationGuid.ToString("N"));

        var reconnect = MeshTransportDtoMapper.ToEnvelope(
            new ReconnectDriver("c", "d", "u", CorrelationGuid));
        reconnect.CorrelationId.ShouldBe(CorrelationGuid.ToString("N"));
        reconnect.ReconnectDriver.CorrelationId.ShouldBe(CorrelationGuid.ToString("N"));
    }

    [Fact]
    public void Envelope_InnerCorrelationWins_OnDecode()
    {
        // Controller decision: the inner field is the domain member, the envelope's is transport
        // metadata. If a peer ever writes them apart, the record must carry what the record declared.
        var envelope = Wire(new CommandEnvelope
        {
            CorrelationId = EnvelopeGuid.ToString("N"),
            DispatchDeployment = new DispatchDeploymentCommand
            {
                DeploymentId = DeploymentGuid.ToString("N"),
                RevisionHash = Sha256Hex,
                CorrelationId = CorrelationGuid.ToString("N"),
            },
        });

        var decoded = MeshTransportDtoMapper.FromEnvelope(envelope).ShouldBeOfType<DispatchDeployment>();
        decoded.CorrelationId.Value.ShouldBe(CorrelationGuid);
        decoded.CorrelationId.Value.ShouldNotBe(EnvelopeGuid);
    }

    [Fact]
    public void Envelope_InnerCorrelationWins_OnDecode_ForDriverCommands()
    {
        var restart = Wire(new CommandEnvelope
        {
            CorrelationId = EnvelopeGuid.ToString("N"),
            RestartDriver = new RestartDriverCommand
            {
                ClusterId = "c",
                DriverInstanceId = "d",
                ActorByUserName = "u",
                CorrelationId = CorrelationGuid.ToString("N"),
            },
        });
        MeshTransportDtoMapper.FromEnvelope(restart).ShouldBeOfType<RestartDriver>()
            .CorrelationId.ShouldBe(CorrelationGuid);

        var reconnect = Wire(new CommandEnvelope
        {
            CorrelationId = EnvelopeGuid.ToString("N"),
            ReconnectDriver = new ReconnectDriverCommand
            {
                ClusterId = "c",
                DriverInstanceId = "d",
                ActorByUserName = "u",
                CorrelationId = CorrelationGuid.ToString("N"),
            },
        });
        MeshTransportDtoMapper.FromEnvelope(reconnect).ShouldBeOfType<ReconnectDriver>()
            .CorrelationId.ShouldBe(CorrelationGuid);
    }

    [Fact]
    public void FromEnvelope_UnsetOneof_Throws()
    {
        // Unreachable while MeshTransportProtoContractTests holds the oneof locked, which is exactly
        // why it must throw rather than return null: the alternative is a command that crosses the
        // mesh, decodes to nothing and is dropped without a trace.
        var ex = Should.Throw<InvalidOperationException>(
            () => MeshTransportDtoMapper.FromEnvelope(new CommandEnvelope { CorrelationId = "x" }));

        ex.Message.ShouldContain(nameof(CommandEnvelope.CommandOneofCase.None));
    }

    [Fact]
    public void ToEnvelope_UnknownMessageType_Throws()
    {
        Should.Throw<ArgumentOutOfRangeException>(
            () => MeshTransportDtoMapper.ToEnvelope("not a command", new CorrelationId(EnvelopeGuid)));
    }

    [Fact]
    public void EveryHandledOneofCase_DecodesToADomainRecord()
    {
        // Ties the mapper to the contract-lock list: a fifth oneof case added to the proto and to
        // HandledCases without a mapper arm fails here rather than at runtime on the far side.
        var samples = new Dictionary<CommandEnvelope.CommandOneofCase, CommandEnvelope>
        {
            [CommandEnvelope.CommandOneofCase.DispatchDeployment] = MeshTransportDtoMapper.ToEnvelope(
                new DispatchDeployment(new DeploymentId(DeploymentGuid), new RevisionHash(Sha256Hex),
                    new CorrelationId(CorrelationGuid))),
            [CommandEnvelope.CommandOneofCase.RestartDriver] = MeshTransportDtoMapper.ToEnvelope(
                new RestartDriver("c", "d", "u", CorrelationGuid)),
            [CommandEnvelope.CommandOneofCase.ReconnectDriver] = MeshTransportDtoMapper.ToEnvelope(
                new ReconnectDriver("c", "d", "u", CorrelationGuid)),
            [CommandEnvelope.CommandOneofCase.AlarmCommand] = MeshTransportDtoMapper.ToEnvelope(
                new AlarmCommand("a", "Acknowledge", "u", null, null), new CorrelationId(EnvelopeGuid)),
        };

        samples.Keys.ShouldBe(MeshTransportProtoContract.HandledCases, ignoreOrder: true);

        foreach (var (expectedCase, envelope) in samples)
        {
            envelope.CommandCase.ShouldBe(expectedCase);
            MeshTransportDtoMapper.FromEnvelope(Wire(envelope)).ShouldNotBeNull();
        }
    }

    // ---------------------------------------------------------------- ToEnvelope(object …) dispatch

    [Fact]
    public void ToEnvelope_ObjectDispatch_MatchesTheTypedOverloads()
    {
        // The router holds its command as MeshCommand.Message (an object), so the untyped entry point
        // must produce byte-identical envelopes to the typed ones it delegates to.
        var alarmCorrelation = new CorrelationId(EnvelopeGuid);

        object[] commands =
        [
            new DispatchDeployment(new DeploymentId(DeploymentGuid), new RevisionHash(Sha256Hex),
                new CorrelationId(CorrelationGuid)),
            new RestartDriver("c", "d", "u", CorrelationGuid),
            new ReconnectDriver("c", "d", "u", CorrelationGuid),
            new AlarmCommand("a", "Acknowledge", "u", "note", null),
        ];

        CommandEnvelope[] typed =
        [
            MeshTransportDtoMapper.ToEnvelope((DispatchDeployment)commands[0]),
            MeshTransportDtoMapper.ToEnvelope((RestartDriver)commands[1]),
            MeshTransportDtoMapper.ToEnvelope((ReconnectDriver)commands[2]),
            MeshTransportDtoMapper.ToEnvelope((AlarmCommand)commands[3], alarmCorrelation),
        ];

        for (var i = 0; i < commands.Length; i++)
        {
            MeshTransportDtoMapper.ToEnvelope(commands[i], alarmCorrelation).ShouldBe(typed[i]);
        }
    }
}