using System.Reflection;
using AcDream.App.Rendering;
using AcDream.App.Net;
using AcDream.Core.Net;
using AcDream.Runtime;
using AcDream.Runtime.Session;

namespace AcDream.App.Tests.Net;

public sealed class GameWindowLiveSessionOwnershipTests
{
    private const BindingFlags PrivateInstance =
        BindingFlags.Instance | BindingFlags.NonPublic;

    [Fact]
    public void GameWindowRetainsCanonicalRuntimeAndFocusedHostButNoMirroredSession()
    {
        FieldInfo[] fields = typeof(GameWindow).GetFields(PrivateInstance);

        Assert.Contains(
            fields,
            field => field.Name == "_runtime"
                && field.FieldType == typeof(GameRuntime));
        Assert.Contains(
            fields,
            field => field.Name == "_liveSessionHost"
                && field.FieldType == typeof(LiveSessionHost));
        Assert.DoesNotContain(
            fields,
            field => field.Name == "_liveSessionController"
                || field.FieldType == typeof(LiveSessionController));
        Assert.DoesNotContain(fields, field => field.Name == "_liveSession");
        Assert.DoesNotContain(fields, field => field.FieldType == typeof(WorldSession));
        Assert.DoesNotContain(fields, field => field.FieldType == typeof(LiveSessionResetPlan));
        Assert.DoesNotContain(fields, field => field.Name == "_liveSessionEvents");
        Assert.DoesNotContain(fields, field => field.Name == "_liveSessionCommands");
    }

    [Fact]
    public void GraphicalSessionSourceBorrowsCanonicalRuntimeState()
    {
        FieldInfo[] fields = typeof(LiveSessionAppSource).GetFields(PrivateInstance);

        Assert.Equal(2, fields.Length);
        Assert.Contains(
            fields,
            field => field.Name == "_session"
                && field.FieldType == typeof(LiveSessionController));
        Assert.Contains(
            fields,
            field => field.Name == "_commands"
                && field.FieldType == typeof(LiveSessionCommandSurface));
        Assert.DoesNotContain(fields, field => field.FieldType == typeof(WorldSession));
        Assert.DoesNotContain(fields, field => field.FieldType == typeof(bool));
        Assert.DoesNotContain(
            fields,
            field => field.FieldType == typeof(RuntimeGenerationToken)
                || field.FieldType == typeof(ulong));
    }

    [Fact]
    public void ProductionWindowConstructsOnlyTheCanonicalRuntimeRoot()
    {
        string root = FindRepositoryRoot();
        string source = File.ReadAllText(Path.Combine(
            root,
            "src",
            "AcDream.App",
            "Rendering",
            "GameWindow.cs"));

        Assert.Equal(
            1,
            CountOccurrences(source, "new GameRuntime("));
        Assert.Contains(
            "private readonly GameRuntime _runtime;",
            source,
            StringComparison.Ordinal);
        Assert.Contains(
            "_runtimeHostLease = _runtime.AcquireHostLease(",
            source,
            StringComparison.Ordinal);
        string[] forbidden =
        [
            "new RuntimeEntityObjectLifetime(",
            "new RuntimeInventoryState(",
            "new RuntimeCharacterState(",
            "new RuntimeCommunicationState(",
            "new RuntimeActionState(",
            "new RuntimeLocalPlayerMovementState(",
            "new RuntimeWorldTransitState(",
            "new LiveSessionController(",
            "new GameRuntimeClock(",
        ];
        Assert.All(
            forbidden,
            value => Assert.DoesNotContain(
                value,
                source,
                StringComparison.Ordinal));
    }

    [Theory]
    [InlineData("TryStartLiveSession")]
    [InlineData("ClearInboundEntityState")]
    [InlineData("WireLiveSessionEvents")]
    [InlineData("DisposeLiveSessionRouting")]
    [InlineData("CreateLiveSessionBinding")]
    [InlineData("ApplyLiveSessionSelection")]
    [InlineData("ApplyLiveSessionEnteredWorld")]
    public void DisplacedLifecycleBodiesAreAbsent(string methodName)
    {
        Assert.Null(typeof(GameWindow).GetMethod(methodName, PrivateInstance));
    }

    private static int CountOccurrences(string source, string value)
    {
        int count = 0;
        int cursor = 0;
        while ((cursor = source.IndexOf(
                   value,
                   cursor,
                   StringComparison.Ordinal)) >= 0)
        {
            count++;
            cursor += value.Length;
        }
        return count;
    }

    private static string FindRepositoryRoot()
    {
        var current = new DirectoryInfo(AppContext.BaseDirectory);
        while (current is not null)
        {
            if (File.Exists(Path.Combine(current.FullName, "AcDream.slnx")))
                return current.FullName;
            current = current.Parent;
        }

        throw new DirectoryNotFoundException("AcDream.slnx was not found.");
    }
}