using Akka.Actor;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Diagnostics;
using Microsoft.EntityFrameworkCore.Infrastructure;
using Microsoft.EntityFrameworkCore.Storage;
using Microsoft.EntityFrameworkCore.Update;
using Shouldly;
using Xunit;
using ZB.MOM.WW.Audit;
using ZB.MOM.WW.OtOpcUa.Configuration;
using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
using ZB.MOM.WW.OtOpcUa.ControlPlane.Audit;
using ZB.MOM.WW.OtOpcUa.ControlPlane.Tests.Harness;

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

/// <summary>
///     R03:2.6 — one constraint hit used to drop the whole flush. The writer now detaches the rejected
///     row(s) and re-saves, so a duplicate <c>EventId</c> costs exactly that row.
/// </summary>
public sealed class AuditWriterActorRejectedRowTests : ControlPlaneActorTestBase
{
    [Fact]
    public void A_rejected_row_is_dropped_and_the_rest_of_the_batch_is_persisted()
    {
        var dbName = Guid.NewGuid().ToString("N");
        var root = new InMemoryDatabaseRoot();
        var duplicate = Guid.NewGuid();
        var rejecting = new RejectingDbFactory(dbName, root, new RejectOnce(duplicate));
        var actor = Sys.ActorOf(AuditWriterActor.Props(rejecting));

        var ids = Enumerable.Range(0, 20).Select(_ => Guid.NewGuid()).ToList();
        ids.Insert(7, duplicate);
        foreach (var id in ids) actor.Tell(NewEvent(id));

        Watch(actor);
        actor.Tell(PoisonPill.Instance);   // PostStop flushes
        ExpectTerminated(actor);

        using var db = rejecting.CreateDbContext();
        var persisted = db.ConfigAuditLogs.Select(r => r.EventId).ToList();
        persisted.Count.ShouldBe(20, "every row but the rejected one lands");
        persisted.ShouldNotContain(duplicate);
        // Positive control: the rows on either side of the rejected one are present.
        persisted.ShouldContain(ids[6]);
        persisted.ShouldContain(ids[8]);
    }

    /// <summary>A failure that names no entry is a whole-batch failure, exactly as before.</summary>
    [Fact]
    public void A_connection_level_failure_still_drops_the_batch_without_looping()
    {
        var dbName = Guid.NewGuid().ToString("N");
        var root = new InMemoryDatabaseRoot();
        var rejecting = new RejectingDbFactory(dbName, root, new AlwaysFailWithoutEntries());
        var actor = Sys.ActorOf(AuditWriterActor.Props(rejecting));

        for (var i = 0; i < 5; i++) actor.Tell(NewEvent(Guid.NewGuid()));
        Watch(actor);
        actor.Tell(PoisonPill.Instance);
        ExpectTerminated(actor);   // terminates ⇒ the retry loop did not spin

        using var db = rejecting.CreateDbContext();
        db.ConfigAuditLogs.Count().ShouldBe(0);
    }

    private static AuditEvent NewEvent(Guid eventId) => new()
    {
        EventId = eventId, Category = "Config", Action = "Edit", Actor = "joe",
        OccurredAtUtc = DateTimeOffset.UtcNow, Outcome = AuditOutcome.Success,
        DetailsJson = "{}", SourceNode = "node-a", CorrelationId = Guid.NewGuid(),
    };

    /// <summary>Throws a <see cref="DbUpdateException"/> naming the entry for one EventId, the first time it is saved.</summary>
    private sealed class RejectOnce(Guid eventId) : ISaveChangesInterceptor
    {
        private int _fired;

        public InterceptionResult<int> SavingChanges(DbContextEventData eventData, InterceptionResult<int> result)
        {
            if (_fired == 1 || eventData.Context is null) return result;
            var entry = eventData.Context.ChangeTracker.Entries<ConfigAuditLog>()
                .FirstOrDefault(e => e.Entity.EventId == eventId);
            if (entry is null) return result;
            _fired = 1;
            // GetInfrastructure() hands back the pubternal InternalEntityEntry, which is the IUpdateEntry the
            // real provider puts on the exception; the test only needs that one cast.
#pragma warning disable EF1001
            var updateEntry = (IUpdateEntry)entry.GetInfrastructure();
#pragma warning restore EF1001
            throw new DbUpdateException("Cannot insert duplicate key row (simulated 2601)", new[] { updateEntry });
        }
    }

    private sealed class AlwaysFailWithoutEntries : ISaveChangesInterceptor
    {
        public InterceptionResult<int> SavingChanges(DbContextEventData eventData, InterceptionResult<int> result) =>
            throw new DbUpdateException("connection lost (simulated)");
    }

    private sealed class RejectingDbFactory(string dbName, InMemoryDatabaseRoot root, IInterceptor interceptor)
        : IDbContextFactory<OtOpcUaConfigDbContext>
    {
        public OtOpcUaConfigDbContext CreateDbContext() => new(
            new DbContextOptionsBuilder<OtOpcUaConfigDbContext>()
                .UseInMemoryDatabase(dbName, root)
                .AddInterceptors(interceptor)
                .Options);
    }
}