using Akka.Actor;
using Akka.TestKit.Xunit2;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using NSubstitute;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.SecuredWrites;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Sites;
using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.DataConnection;
using ZB.MOM.WW.ScadaBridge.Commons.Messages.Management;
using ZB.MOM.WW.ScadaBridge.Commons.Types;
using ZB.MOM.WW.ScadaBridge.Communication;

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

/// <summary>
/// Handler tests for the two-person ("secured") write submit/reject/list flow
/// (M7 OPC UA / MxGateway UX, Task T14b). Submit is gated to Operator, reject to
/// Verifier; the no-self-approval rule and the MxGateway-protocol precondition
/// are enforced inside the handlers and surface as ManagementError.
/// </summary>
public class SecuredWriteHandlerTests : TestKit, IDisposable
{
    private readonly ISiteRepository _siteRepo;
    private readonly ISecuredWriteRepository _securedWriteRepo;
    private readonly StubCommunicationService _comms;
    private readonly ServiceCollection _services;

    public SecuredWriteHandlerTests()
    {
        _siteRepo = Substitute.For<ISiteRepository>();
        _securedWriteRepo = Substitute.For<ISecuredWriteRepository>();
        _comms = new StubCommunicationService();

        _services = new ServiceCollection();
        _services.AddScoped(_ => _siteRepo);
        _services.AddScoped(_ => _securedWriteRepo);
        _services.AddSingleton<CommunicationService>(_comms);
    }

    /// <summary>
    /// Test double for the site-write seam. <see cref="CommunicationService.WriteTagAsync"/>
    /// is virtual so the approve relay can be exercised without a live actor system;
    /// records the relayed request and returns a canned response.
    /// </summary>
    private sealed class StubCommunicationService : CommunicationService
    {
        public StubCommunicationService()
            : base(Options.Create(new CommunicationOptions()), NullLogger<CommunicationService>.Instance)
        {
        }

        public WriteTagRequest? LastRequest { get; private set; }

        public int CallCount { get; private set; }

        public Func<WriteTagRequest, WriteTagResponse> Responder { get; set; } =
            req => new WriteTagResponse(req.CorrelationId, Success: true, ErrorMessage: null, DateTimeOffset.UtcNow);

        public Exception? ThrowOnWrite { get; set; }

        public override Task<WriteTagResponse> WriteTagAsync(
            string siteId, WriteTagRequest request, CancellationToken ct = default)
        {
            CallCount++;
            LastRequest = request;
            if (ThrowOnWrite is not null)
            {
                return Task.FromException<WriteTagResponse>(ThrowOnWrite);
            }

            return Task.FromResult(Responder(request));
        }
    }

    private IActorRef CreateActor()
    {
        var sp = _services.BuildServiceProvider();
        return Sys.ActorOf(Props.Create(() => new ManagementActor(
            sp, NullLogger<ManagementActor>.Instance)));
    }

    private static ManagementEnvelope Envelope(object command, string username, params string[] roles) =>
        new(new AuthenticatedUser(username, username, roles, Array.Empty<string>()),
            command, Guid.NewGuid().ToString("N"));

    void IDisposable.Dispose() => Shutdown();

    /// <summary>Wires a site whose single connection uses the given protocol.</summary>
    private void SeedSiteWithConnection(int siteId, string identifier, string connectionName, string protocol)
    {
        _siteRepo.GetSiteByIdentifierAsync(identifier, Arg.Any<CancellationToken>())
            .Returns(new Site($"Site{siteId}", identifier) { Id = siteId });
        _siteRepo.GetDataConnectionsBySiteIdAsync(siteId, Arg.Any<CancellationToken>())
            .Returns(new List<DataConnection>
            {
                new(connectionName, protocol, siteId) { Id = 100 }
            });
    }

    // ------------------------------------------------------------------------
    // Submit
    // ------------------------------------------------------------------------

    [Fact]
    public void Submit_OnNonMxGatewayConnection_ReturnsError_NoRowInserted()
    {
        SeedSiteWithConnection(1, "SITE1", "Plc1", "OpcUa");

        var actor = CreateActor();
        var envelope = Envelope(
            new SubmitSecuredWriteCommand("SITE1", "Plc1", "Tag.A", "true", "Boolean", "go"),
            "alice", "Operator");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementError>(TimeSpan.FromSeconds(5));
        Assert.Equal("COMMAND_FAILED", response.ErrorCode);
        Assert.Contains("MxGateway", response.Error);
        _securedWriteRepo.DidNotReceiveWithAnyArgs().AddAsync(default!, default);
    }

    [Fact]
    public void Submit_OnUnknownConnection_ReturnsError_NoRowInserted()
    {
        SeedSiteWithConnection(1, "SITE1", "Plc1", "MxGateway");

        var actor = CreateActor();
        var envelope = Envelope(
            new SubmitSecuredWriteCommand("SITE1", "DoesNotExist", "Tag.A", "true", "Boolean", null),
            "alice", "Operator");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementError>(TimeSpan.FromSeconds(5));
        Assert.Equal("COMMAND_FAILED", response.ErrorCode);
        _securedWriteRepo.DidNotReceiveWithAnyArgs().AddAsync(default!, default);
    }

    [Fact]
    public void Submit_OnMxGatewayConnection_InsertsPendingRowWithOperatorUser()
    {
        SeedSiteWithConnection(1, "SITE1", "Mx1", "MxGateway");

        PendingSecuredWrite? inserted = null;
        _securedWriteRepo
            .When(r => r.AddAsync(Arg.Any<PendingSecuredWrite>(), Arg.Any<CancellationToken>()))
            .Do(ci => inserted = ci.Arg<PendingSecuredWrite>());
        _securedWriteRepo.AddAsync(Arg.Any<PendingSecuredWrite>(), Arg.Any<CancellationToken>())
            .Returns(55L);

        var actor = CreateActor();
        var envelope = Envelope(
            new SubmitSecuredWriteCommand("SITE1", "Mx1", "Tag.Setpoint", "42.5", "Double", "raise setpoint"),
            "alice", "Operator");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementSuccess>(TimeSpan.FromSeconds(5));
        Assert.Equal(envelope.CorrelationId, response.CorrelationId);
        Assert.NotNull(inserted);
        Assert.Equal("Pending", inserted!.Status);
        Assert.Equal("alice", inserted.OperatorUser);
        Assert.Equal("Mx1", inserted.ConnectionName);
        Assert.Equal("SITE1", inserted.SiteId);
        Assert.Equal("Tag.Setpoint", inserted.TagPath);
        Assert.Equal("42.5", inserted.ValueJson);
        Assert.Equal("Double", inserted.ValueType);
        Assert.Equal("raise setpoint", inserted.OperatorComment);
        // The returned DTO carries the store-assigned id and operator.
        Assert.Contains("\"id\":55", response.JsonData);
        Assert.Contains("alice", response.JsonData);
    }

    // ------------------------------------------------------------------------
    // Reject
    // ------------------------------------------------------------------------

    private PendingSecuredWrite SeedPendingWrite(long id, string operatorUser)
    {
        var row = new PendingSecuredWrite
        {
            Id = id,
            SiteId = "SITE1",
            ConnectionName = "Mx1",
            TagPath = "Tag.A",
            ValueJson = "true",
            ValueType = "Boolean",
            Status = "Pending",
            OperatorUser = operatorUser,
            SubmittedAtUtc = DateTime.UtcNow
        };
        _securedWriteRepo.GetAsync(id, Arg.Any<CancellationToken>()).Returns(row);
        return row;
    }

    [Fact]
    public void Reject_BySubmittingUser_ReturnsError_StatusUnchanged()
    {
        SeedPendingWrite(7, operatorUser: "alice");

        var actor = CreateActor();
        // Same principal that submitted attempts to reject — separation of duties.
        var envelope = Envelope(new RejectSecuredWriteCommand(7, "no"), "alice", "Verifier");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementError>(TimeSpan.FromSeconds(5));
        Assert.Equal("COMMAND_FAILED", response.ErrorCode);
        _securedWriteRepo.DidNotReceiveWithAnyArgs().UpdateAsync(default!, default);
    }

    [Fact]
    public void Reject_ByDifferentUser_FlipsStatusToRejected()
    {
        SeedPendingWrite(7, operatorUser: "alice");

        PendingSecuredWrite? updated = null;
        _securedWriteRepo
            .When(r => r.UpdateAsync(Arg.Any<PendingSecuredWrite>(), Arg.Any<CancellationToken>()))
            .Do(ci => updated = ci.Arg<PendingSecuredWrite>());

        var actor = CreateActor();
        var envelope = Envelope(new RejectSecuredWriteCommand(7, "not authorized"), "bob", "Verifier");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementSuccess>(TimeSpan.FromSeconds(5));
        Assert.Equal(envelope.CorrelationId, response.CorrelationId);
        Assert.NotNull(updated);
        Assert.Equal("Rejected", updated!.Status);
        Assert.Equal("bob", updated.VerifierUser);
        Assert.Equal("not authorized", updated.VerifierComment);
        Assert.NotNull(updated.DecidedAtUtc);
        // Operator fields are preserved (fully-populated update).
        Assert.Equal("alice", updated.OperatorUser);
    }

    [Fact]
    public void Reject_NonPendingRow_ReturnsError()
    {
        var row = SeedPendingWrite(7, operatorUser: "alice");
        row.Status = "Approved";

        var actor = CreateActor();
        var envelope = Envelope(new RejectSecuredWriteCommand(7, null), "bob", "Verifier");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementError>(TimeSpan.FromSeconds(5));
        Assert.Equal("COMMAND_FAILED", response.ErrorCode);
        _securedWriteRepo.DidNotReceiveWithAnyArgs().UpdateAsync(default!, default);
    }

    [Fact]
    public void Reject_MissingRow_ReturnsError()
    {
        _securedWriteRepo.GetAsync(99, Arg.Any<CancellationToken>()).Returns((PendingSecuredWrite?)null);

        var actor = CreateActor();
        var envelope = Envelope(new RejectSecuredWriteCommand(99, null), "bob", "Verifier");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementError>(TimeSpan.FromSeconds(5));
        Assert.Equal("COMMAND_FAILED", response.ErrorCode);
    }

    // ------------------------------------------------------------------------
    // List
    // ------------------------------------------------------------------------

    [Fact]
    public void List_FiltersByStatusAndSite()
    {
        _securedWriteRepo.QueryAsync("Pending", "SITE1", 0, 200, Arg.Any<CancellationToken>())
            .Returns(new List<PendingSecuredWrite>
            {
                new()
                {
                    Id = 3, SiteId = "SITE1", ConnectionName = "Mx1", TagPath = "Tag.A",
                    ValueJson = "true", ValueType = "Boolean", Status = "Pending",
                    OperatorUser = "alice", SubmittedAtUtc = DateTime.UtcNow
                }
            });

        var actor = CreateActor();
        var envelope = Envelope(new ListSecuredWritesCommand("Pending", "SITE1"), "carol", "Viewer");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementSuccess>(TimeSpan.FromSeconds(5));
        Assert.Equal(envelope.CorrelationId, response.CorrelationId);
        Assert.Contains("\"id\":3", response.JsonData);
        Assert.Contains("alice", response.JsonData);
        _securedWriteRepo.Received(1).QueryAsync("Pending", "SITE1", 0, 200, Arg.Any<CancellationToken>());
    }

    [Fact]
    public void List_NoFilters_PassesNullsToRepository()
    {
        _securedWriteRepo.QueryAsync(null, null, 0, 200, Arg.Any<CancellationToken>())
            .Returns(new List<PendingSecuredWrite>());

        var actor = CreateActor();
        var envelope = Envelope(new ListSecuredWritesCommand(null, null), "carol");

        actor.Tell(envelope);

        ExpectMsg<ManagementSuccess>(TimeSpan.FromSeconds(5));
        _securedWriteRepo.Received(1).QueryAsync(null, null, 0, 200, Arg.Any<CancellationToken>());
    }

    // ------------------------------------------------------------------------
    // Approve (execute) — Task C3
    // ------------------------------------------------------------------------

    /// <summary>Arms the CAS to succeed (a different verifier wins the race).</summary>
    private void ArmCasSuccess(long id) =>
        _securedWriteRepo.TryMarkApprovedAsync(
                id, Arg.Any<string>(), Arg.Any<string?>(), Arg.Any<DateTime>(), Arg.Any<CancellationToken>())
            .Returns(true);

    [Fact]
    public void Approve_ByDifferentVerifier_RelaysWrite_FlipsStatusToExecuted()
    {
        SeedPendingWrite(7, operatorUser: "alice");
        ArmCasSuccess(7);

        PendingSecuredWrite? updated = null;
        _securedWriteRepo
            .When(r => r.UpdateAsync(Arg.Any<PendingSecuredWrite>(), Arg.Any<CancellationToken>()))
            .Do(ci => updated = ci.Arg<PendingSecuredWrite>());

        var actor = CreateActor();
        var envelope = Envelope(new ApproveSecuredWriteCommand(7, "approved"), "bob", "Verifier");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementSuccess>(TimeSpan.FromSeconds(5));
        Assert.Equal(envelope.CorrelationId, response.CorrelationId);

        // The CAS guarded the transition (exactly once).
        _securedWriteRepo.Received(1).TryMarkApprovedAsync(
            7, "bob", "approved", Arg.Any<DateTime>(), Arg.Any<CancellationToken>());

        // The write was relayed to the site MxGateway connection.
        Assert.Equal(1, _comms.CallCount);
        Assert.NotNull(_comms.LastRequest);
        Assert.Equal("Mx1", _comms.LastRequest!.ConnectionName);
        Assert.Equal("Tag.A", _comms.LastRequest.TagPath);

        Assert.NotNull(updated);
        Assert.Equal("Executed", updated!.Status);
        Assert.NotNull(updated.ExecutedAtUtc);
        Assert.Null(updated.ExecutionError);
    }

    [Fact]
    public void Approve_BySubmittingUser_ReturnsError_CasNotCalled_NoRelay()
    {
        SeedPendingWrite(7, operatorUser: "alice");

        var actor = CreateActor();
        // Same principal that submitted attempts to approve — separation of duties.
        var envelope = Envelope(new ApproveSecuredWriteCommand(7, "self"), "alice", "Verifier");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementError>(TimeSpan.FromSeconds(5));
        Assert.Equal("COMMAND_FAILED", response.ErrorCode);
        _securedWriteRepo.DidNotReceiveWithAnyArgs().TryMarkApprovedAsync(
            default, default!, default, default, default);
        Assert.Equal(0, _comms.CallCount);
    }

    [Fact]
    public void Approve_WhenCasLosesRace_ReturnsError_NoRelay()
    {
        SeedPendingWrite(7, operatorUser: "alice");
        _securedWriteRepo.TryMarkApprovedAsync(
                7, Arg.Any<string>(), Arg.Any<string?>(), Arg.Any<DateTime>(), Arg.Any<CancellationToken>())
            .Returns(false);

        var actor = CreateActor();
        var envelope = Envelope(new ApproveSecuredWriteCommand(7, "race"), "bob", "Verifier");

        actor.Tell(envelope);

        var response = ExpectMsg<ManagementError>(TimeSpan.FromSeconds(5));
        Assert.Equal("COMMAND_FAILED", response.ErrorCode);
        Assert.Contains("already decided", response.Error);
        Assert.Equal(0, _comms.CallCount);
    }

    [Fact]
    public void Approve_WhenRelayFails_FlipsStatusToFailed_WithError()
    {
        SeedPendingWrite(7, operatorUser: "alice");
        ArmCasSuccess(7);
        _comms.Responder = req =>
            new WriteTagResponse(req.CorrelationId, Success: false, ErrorMessage: "device offline", DateTimeOffset.UtcNow);

        PendingSecuredWrite? updated = null;
        _securedWriteRepo
            .When(r => r.UpdateAsync(Arg.Any<PendingSecuredWrite>(), Arg.Any<CancellationToken>()))
            .Do(ci => updated = ci.Arg<PendingSecuredWrite>());

        var actor = CreateActor();
        var envelope = Envelope(new ApproveSecuredWriteCommand(7, "approved"), "bob", "Verifier");

        actor.Tell(envelope);

        // The approve itself succeeds (the row was decided); the relay outcome is recorded on the row.
        ExpectMsg<ManagementSuccess>(TimeSpan.FromSeconds(5));
        Assert.Equal(1, _comms.CallCount);
        Assert.NotNull(updated);
        Assert.Equal("Failed", updated!.Status);
        Assert.Equal("device offline", updated.ExecutionError);
        Assert.NotNull(updated.ExecutedAtUtc);
    }

    [Fact]
    public void Approve_WhenRelayThrows_FlipsStatusToFailed_WithExceptionMessage()
    {
        SeedPendingWrite(7, operatorUser: "alice");
        ArmCasSuccess(7);
        _comms.ThrowOnWrite = new InvalidOperationException("transport down");

        PendingSecuredWrite? updated = null;
        _securedWriteRepo
            .When(r => r.UpdateAsync(Arg.Any<PendingSecuredWrite>(), Arg.Any<CancellationToken>()))
            .Do(ci => updated = ci.Arg<PendingSecuredWrite>());

        var actor = CreateActor();
        var envelope = Envelope(new ApproveSecuredWriteCommand(7, "approved"), "bob", "Verifier");

        actor.Tell(envelope);

        ExpectMsg<ManagementSuccess>(TimeSpan.FromSeconds(5));
        Assert.NotNull(updated);
        Assert.Equal("Failed", updated!.Status);
        Assert.Contains("transport down", updated.ExecutionError);
    }

    [Fact]
    public void Approve_UnknownValueType_FlipsStatusToFailed_NoRelay()
    {
        var row = SeedPendingWrite(7, operatorUser: "alice");
        row.ValueType = "Bogus";
        ArmCasSuccess(7);

        PendingSecuredWrite? updated = null;
        _securedWriteRepo
            .When(r => r.UpdateAsync(Arg.Any<PendingSecuredWrite>(), Arg.Any<CancellationToken>()))
            .Do(ci => updated = ci.Arg<PendingSecuredWrite>());

        var actor = CreateActor();
        var envelope = Envelope(new ApproveSecuredWriteCommand(7, "approved"), "bob", "Verifier");

        actor.Tell(envelope);

        ExpectMsg<ManagementSuccess>(TimeSpan.FromSeconds(5));
        Assert.Equal(0, _comms.CallCount);
        Assert.NotNull(updated);
        Assert.Equal("Failed", updated!.Status);
        Assert.Equal("unknown value type", updated.ExecutionError);
    }
}