using Akka.Actor;
using Akka.TestKit.Xunit2;
using Microsoft.Extensions.Logging.Abstractions;
using Akka.TestKit;
using ScadaLink.Commons.Messages.DataConnection;
using ScadaLink.Commons.Messages.Instance;
using ScadaLink.Commons.Types.Flattening;
using ScadaLink.SiteRuntime.Actors;
using ScadaLink.SiteRuntime.Persistence;
using ScadaLink.SiteRuntime.Scripts;
using System.Text.Json;

namespace ScadaLink.SiteRuntime.Tests.Actors;

/// <summary>
/// Regression tests for SiteRuntime-001: Instance.SetAttribute must route writes
/// to the Data Connection Layer for data-sourced attributes instead of persisting
/// a local static override.
/// </summary>
public class InstanceActorSetAttributeTests : TestKit, IDisposable
{
    private readonly SiteStorageService _storage;
    private readonly ScriptCompilationService _compilationService;
    private readonly SharedScriptLibrary _sharedScriptLibrary;
    private readonly SiteRuntimeOptions _options;
    private readonly string _dbFile;

    public InstanceActorSetAttributeTests()
    {
        _dbFile = Path.Combine(Path.GetTempPath(), $"instance-setattr-test-{Guid.NewGuid():N}.db");
        _storage = new SiteStorageService(
            $"Data Source={_dbFile}",
            NullLogger<SiteStorageService>.Instance);
        _storage.InitializeAsync().GetAwaiter().GetResult();
        _compilationService = new ScriptCompilationService(
            NullLogger<ScriptCompilationService>.Instance);
        _sharedScriptLibrary = new SharedScriptLibrary(
            _compilationService, NullLogger<SharedScriptLibrary>.Instance);
        _options = new SiteRuntimeOptions();
    }

    void IDisposable.Dispose()
    {
        Shutdown();
        try { File.Delete(_dbFile); } catch { /* cleanup */ }
    }

    private IActorRef CreateInstanceActor(string instanceName, FlattenedConfiguration config, IActorRef? dclManager)
    {
        return ActorOf(Props.Create(() => new InstanceActor(
            instanceName,
            JsonSerializer.Serialize(config),
            _storage,
            _compilationService,
            _sharedScriptLibrary,
            null,
            _options,
            NullLogger<InstanceActor>.Instance,
            dclManager)));
    }

    /// <summary>
    /// Drains the startup <see cref="SubscribeTagsRequest"/> the Instance Actor emits
    /// to the DCL in PreStart, then returns the next <see cref="WriteTagRequest"/>.
    /// </summary>
    private static WriteTagRequest ExpectWriteTag(TestProbe dclProbe)
        => dclProbe.FishForMessage<WriteTagRequest>(_ => true, TimeSpan.FromSeconds(5));

    private static FlattenedConfiguration DataSourcedConfig(string instanceName) => new()
    {
        InstanceUniqueName = instanceName,
        Attributes =
        [
            new ResolvedAttribute
            {
                CanonicalName = "Setpoint",
                Value = "10",
                DataType = "Double",
                DataSourceReference = "/Motor/Setpoint",
                BoundDataConnectionName = "OpcServer1"
            }
        ]
    };

    [Fact]
    public async Task SetAttribute_DataSourcedAttribute_IssuesDclWriteAndDoesNotPersistOverride()
    {
        var config = DataSourcedConfig("PumpDcl1");
        var dclProbe = CreateTestProbe();
        var actor = CreateInstanceActor("PumpDcl1", config, dclProbe.Ref);

        actor.Tell(new SetStaticAttributeCommand(
            "corr-dcl", "PumpDcl1", "Setpoint", "55", DateTimeOffset.UtcNow));

        // The Instance Actor must forward a WriteTagRequest to the DCL manager.
        var write = ExpectWriteTag(dclProbe);
        Assert.Equal("OpcServer1", write.ConnectionName);
        Assert.Equal("/Motor/Setpoint", write.TagPath);
        Assert.Equal("55", write.Value);

        // DCL confirms the write.
        dclProbe.Reply(new WriteTagResponse(write.CorrelationId, true, null, DateTimeOffset.UtcNow));
        var response = ExpectMsg<SetStaticAttributeResponse>(TimeSpan.FromSeconds(5));
        Assert.True(response.Success);

        // No static override should be persisted for a data-sourced attribute.
        await Task.Delay(300);
        var overrides = await _storage.GetStaticOverridesAsync("PumpDcl1");
        Assert.Empty(overrides);
    }

    [Fact]
    public void SetAttribute_DataSourcedAttribute_DoesNotOptimisticallyUpdateMemory()
    {
        var config = DataSourcedConfig("PumpDcl2");
        var dclProbe = CreateTestProbe();
        var actor = CreateInstanceActor("PumpDcl2", config, dclProbe.Ref);

        actor.Tell(new SetStaticAttributeCommand(
            "corr-dcl2", "PumpDcl2", "Setpoint", "999", DateTimeOffset.UtcNow));

        var write = ExpectWriteTag(dclProbe);
        dclProbe.Reply(new WriteTagResponse(write.CorrelationId, true, null, DateTimeOffset.UtcNow));
        ExpectMsg<SetStaticAttributeResponse>(TimeSpan.FromSeconds(5));

        // In-memory value must still be the original config value — it is only
        // updated when the subscription delivers the confirmed device value.
        actor.Tell(new GetAttributeRequest("corr-get", "PumpDcl2", "Setpoint", DateTimeOffset.UtcNow));
        var get = ExpectMsg<GetAttributeResponse>(TimeSpan.FromSeconds(5));
        Assert.Equal("10", get.Value?.ToString());
    }

    [Fact]
    public void SetAttribute_DataSourcedAttribute_DclWriteFailure_ReturnedToCaller()
    {
        var config = DataSourcedConfig("PumpDcl3");
        var dclProbe = CreateTestProbe();
        var actor = CreateInstanceActor("PumpDcl3", config, dclProbe.Ref);

        actor.Tell(new SetStaticAttributeCommand(
            "corr-dcl3", "PumpDcl3", "Setpoint", "42", DateTimeOffset.UtcNow));

        var write = ExpectWriteTag(dclProbe);
        dclProbe.Reply(new WriteTagResponse(write.CorrelationId, false, "device rejected write", DateTimeOffset.UtcNow));

        var response = ExpectMsg<SetStaticAttributeResponse>(TimeSpan.FromSeconds(5));
        Assert.False(response.Success);
        Assert.Contains("device rejected write", response.ErrorMessage);
    }

    [Fact]
    public async Task SetAttribute_StaticAttribute_StillPersistsOverrideAndDoesNotCallDcl()
    {
        var config = new FlattenedConfiguration
        {
            InstanceUniqueName = "PumpStatic1",
            Attributes =
            [
                new ResolvedAttribute { CanonicalName = "Label", Value = "Main", DataType = "String" }
            ]
        };
        var dclProbe = CreateTestProbe();
        var actor = CreateInstanceActor("PumpStatic1", config, dclProbe.Ref);

        actor.Tell(new SetStaticAttributeCommand(
            "corr-static", "PumpStatic1", "Label", "Backup", DateTimeOffset.UtcNow));

        var response = ExpectMsg<SetStaticAttributeResponse>(TimeSpan.FromSeconds(5));
        Assert.True(response.Success);

        // DCL must NOT receive a write for a static attribute.
        dclProbe.ExpectNoMsg(TimeSpan.FromMilliseconds(300));

        await Task.Delay(300);
        var overrides = await _storage.GetStaticOverridesAsync("PumpStatic1");
        Assert.Single(overrides);
        Assert.Equal("Backup", overrides["Label"]);
    }
}