using System.Net;
using System.Reflection;
using AcDream.Core.Net;
using AcDream.Core.Net.Messages;
using AcDream.Core.Physics;
using AcDream.Headless.Configuration;
using AcDream.Headless.Credentials;
using AcDream.Headless.Diagnostics;
using AcDream.Headless.Hosting;
using AcDream.Runtime;
using AcDream.Runtime.Entities;
using AcDream.Runtime.Session;

namespace AcDream.Headless.Tests;

public sealed class HeadlessSessionIsolationTests
{
    [Theory]
    [InlineData(1)]
    [InlineData(5)]
    [InlineData(10)]
    public void SameServerIdentityStaysIsolatedAcrossActivityPortalAndReconnect(
        int sessionCount)
    {
        const uint sharedPlayerGuid = 0x50000001u;
        var operations = new FixtureOperations(sharedPlayerGuid);
        HeadlessSessionHost[] hosts = Enumerable.Range(0, sessionCount)
            .Select(index => CreateHost(index, operations))
            .ToArray();
        try
        {
            foreach (HeadlessSessionHost host in hosts)
            {
                Assert.Equal(
                    RuntimeSessionStartStatus.Connected,
                    host.Start().Status);
            }

            var firstRecords = new RuntimeEntityRecord[sessionCount];
            for (int index = 0; index < hosts.Length; index++)
            {
                HeadlessSessionHost host = hosts[index];
                WorldSession session =
                    operations.ActiveSession(host.SessionId);
                session.GameActionCapture = _ => { };
                SpawnInto(session, sharedPlayerGuid, index + 1f);
                RuntimeCommandResult selected =
                    host.Commands.Selection.SelectObject(
                        host.Runtime.Generation,
                        sharedPlayerGuid);
                Assert.True(selected.Accepted);
                Assert.True(
                    host.Runtime.EntityObjects.Entities.TryGetActive(
                        sharedPlayerGuid,
                        out RuntimeEntityRecord record));
                firstRecords[index] = record;
                Assert.Equal(
                    index + 1f,
                    record.Snapshot.Position!.Value.PositionX);

                Portal(
                    session,
                    sharedPlayerGuid,
                    index + 20f);
                Assert.True(host.Runtime.Portal.Snapshot.Completed);
                Assert.True(
                    host.Runtime.TransitOwner
                        .CaptureOwnership()
                        .IsSessionIdle);
            }

            Assert.Equal(
                sessionCount,
                firstRecords
                    .Distinct(ReferenceEqualityComparer.Instance)
                    .Count());
            Assert.Equal(
                sessionCount,
                hosts
                    .Select(static host => host.Runtime.Entities)
                    .Distinct(ReferenceEqualityComparer.Instance)
                    .Count());

            for (int index = 0; index < hosts.Length; index++)
            {
                HeadlessSessionHost host = hosts[index];
                ulong priorGeneration = host.Runtime.Generation.Value;
                Assert.Equal(
                    RuntimeSessionStartStatus.Connected,
                    host.Reconnect().Status);
                Assert.True(
                    host.Runtime.Generation.Value > priorGeneration);
                Assert.Equal(0, host.Runtime.Entities.Count);

                WorldSession replacement =
                    operations.ActiveSession(host.SessionId);
                replacement.GameActionCapture = _ => { };
                SpawnInto(
                    replacement,
                    sharedPlayerGuid,
                    index + 101f);
                Assert.True(
                    host.Runtime.EntityObjects.Entities.TryGetActive(
                        sharedPlayerGuid,
                        out RuntimeEntityRecord replacementRecord));
                Assert.NotSame(firstRecords[index], replacementRecord);
                Assert.Equal(
                    index + 101f,
                    replacementRecord.Snapshot.Position!.Value.PositionX);
            }
        }
        finally
        {
            for (int index = hosts.Length - 1; index >= 0; index--)
                hosts[index].Dispose();
        }

        Assert.Equal(sessionCount * 2, operations.CreatedSessionCount);
        Assert.Equal(sessionCount * 2, operations.DisposedSessionCount);
        Assert.All(
            hosts,
            static host =>
                Assert.True(host.Runtime.CaptureOwnership().IsConverged));
    }

    private static HeadlessSessionHost CreateHost(
        int index,
        FixtureOperations operations)
    {
        string id = $"bot-{index}";
        var credential = new HeadlessCredentialSecret(
            $"{id}-credential",
            "fixture-password");
        try
        {
            return new HeadlessSessionHost(
                new HeadlessSessionDescriptor
                {
                    Id = id,
                    Endpoint = new HeadlessEndpointDescriptor
                    {
                        Host = "127.0.0.1",
                        Port = 9000,
                    },
                    Account = id,
                    Character = new HeadlessCharacterSelector
                    {
                        Index = 0,
                    },
                    Policy = new HeadlessBotPolicyDescriptor
                    {
                        Id = "idle",
                    },
                    Credential = new HeadlessCredentialReference
                    {
                        Provider =
                            HeadlessCredentialProviderKind.StandardInput,
                        Reference = $"{id}-credential",
                    },
                },
                credential,
                new HeadlessDiagnosticWriter(TextWriter.Null),
                operations);
        }
        catch
        {
            credential.Dispose();
            throw;
        }
    }

    private static void SpawnInto(
        WorldSession session,
        uint guid,
        float positionX) =>
        EventDelegate<Action<WorldSession.EntitySpawn>>(
            session,
            nameof(session.EntitySpawned))(
                Spawn(guid, positionX));

    private static void Portal(
        WorldSession session,
        uint guid,
        float positionX)
    {
        EventDelegate<Action<uint>>(
            session,
            nameof(session.TeleportStarted))(1u);
        EventDelegate<Action<WorldSession.EntityPositionUpdate>>(
            session,
            nameof(session.PositionUpdated))(
                new WorldSession.EntityPositionUpdate(
                    guid,
                    Position(positionX) with
                    {
                        LandblockId = 0x01020001u,
                    },
                    Velocity: null,
                    PlacementId: null,
                    IsGrounded: true,
                    InstanceSequence: 1,
                    PositionSequence: 2,
                    TeleportSequence: 1,
                    ForcePositionSequence: 0));
    }

    private static WorldSession.EntitySpawn Spawn(
        uint guid,
        float positionX)
    {
        CreateObject.ServerPosition position = Position(positionX);
        var timestamps = new PhysicsTimestamps(
            Position: 1,
            Movement: 1,
            State: 1,
            Vector: 1,
            Teleport: 0,
            ServerControlledMove: 1,
            ForcePosition: 0,
            ObjDesc: 1,
            Instance: 1);
        var physics = new PhysicsSpawnData(
            RawState: (uint)PhysicsStateFlags.ReportCollisions,
            Position: position,
            Movement: null,
            AnimationFrame: null,
            SetupTableId: 0x02000001u,
            MotionTableId: null,
            SoundTableId: null,
            PhysicsScriptTableId: null,
            Parent: null,
            Children: null,
            Scale: null,
            Friction: null,
            Elasticity: null,
            Translucency: null,
            Velocity: null,
            Acceleration: null,
            AngularVelocity: null,
            DefaultScriptType: null,
            DefaultScriptIntensity: null,
            Timestamps: timestamps);
        return new WorldSession.EntitySpawn(
            guid,
            position,
            0x02000001u,
            [],
            [],
            [],
            null,
            null,
            "Headless",
            null,
            null,
            null,
            PhysicsState: physics.RawState,
            InstanceSequence: 1,
            MovementSequence: 1,
            ServerControlSequence: 1,
            PositionSequence: 1,
            Physics: physics);
    }

    private static CreateObject.ServerPosition Position(float positionX) =>
        new(
            0x01010001u,
            positionX,
            10f,
            5f,
            1f,
            0f,
            0f,
            0f);

    private static TDelegate EventDelegate<TDelegate>(
        WorldSession session,
        string eventName)
        where TDelegate : Delegate =>
        Assert.IsType<TDelegate>(
            typeof(WorldSession).GetField(
                eventName,
                BindingFlags.Instance | BindingFlags.NonPublic)
            ?.GetValue(session));

    private sealed class FixtureOperations(uint sharedPlayerGuid)
        : ILiveSessionOperations
    {
        private readonly Dictionary<string, WorldSession> _active =
            new(StringComparer.Ordinal);

        public int CreatedSessionCount { get; private set; }
        public int DisposedSessionCount { get; private set; }

        public WorldSession ActiveSession(string account) =>
            _active[account];

        public IPEndPoint ResolveEndpoint(string host, int port) =>
            new(IPAddress.Loopback, port);

        public WorldSession CreateSession(IPEndPoint endpoint)
        {
            CreatedSessionCount++;
            return new WorldSession(endpoint, new FixtureTransport());
        }

        public void Connect(
            WorldSession session,
            string user,
            string password) =>
            _active[user] = session;

        public CharacterList.Parsed GetCharacters(
            WorldSession session) =>
            new(
                0u,
                [
                    new CharacterList.Character(
                        sharedPlayerGuid,
                        "Headless",
                        0u),
                ],
                [],
                11,
                "account",
                true,
                true);

        public void EnterWorld(
            WorldSession session,
            int activeCharacterIndex)
        {
        }

        public void Tick(WorldSession session)
        {
        }

        public void DisposeSession(WorldSession session)
        {
            DisposedSessionCount++;
            session.Dispose();
        }
    }

    private sealed class FixtureTransport : IWorldSessionTransport
    {
        public void Send(ReadOnlySpan<byte> datagram)
        {
        }

        public void Send(
            IPEndPoint remote,
            ReadOnlySpan<byte> datagram)
        {
        }

        public int Receive(
            Span<byte> destination,
            TimeSpan timeout,
            out IPEndPoint? from)
        {
            from = null;
            return -1;
        }

        public ValueTask<NetReceiveResult> ReceiveAsync(
            Memory<byte> destination,
            CancellationToken cancellationToken) =>
            ValueTask.FromException<NetReceiveResult>(
                new OperationCanceledException(cancellationToken));

        public void Dispose()
        {
        }
    }
}