namespace Zcbot.WindowsNode.Tests;

public sealed class NodeApplicationControllerTests : IDisposable
{
    private readonly string root = Path.Combine(
        Path.GetTempPath(), "zcbot-windows-node-tests", Guid.NewGuid().ToString("N"));

    [Fact]
    public void StartWithoutIdentityRemainsNotRegistered()
    {
        var store = new FakeConfigStore();
        var connections = new List<FakeConnection>();
        using var controller = CreateController(store, connections);

        controller.Start();

        Assert.Equal(NodeState.NotRegistered, controller.CurrentStatus.State);
        Assert.Null(controller.CurrentConfig);
        Assert.Empty(connections);
    }

    [Fact]
    public async Task ReconnectWaitsForOldSessionAndStartsOneReplacement()
    {
        var store = new FakeConfigStore { Config = CreateConfig() };
        var connections = new List<FakeConnection>();
        using var controller = CreateController(store, connections);
        controller.Start();
        Assert.Single(connections);

        var reconnected = await controller.ReconnectAsync();

        Assert.True(reconnected);
        Assert.Equal(2, connections.Count);
        Assert.True(connections[0].Completed);
        Assert.False(connections[1].Completed);
        await controller.StopAsync(NodeShutdownMode.WaitForJobs);
    }

    [Fact]
    public async Task CancelStopIsIdempotentAndCancelsJobsOnce()
    {
        var store = new FakeConfigStore { Config = CreateConfig() };
        var connections = new List<FakeConnection>();
        using var controller = CreateController(store, connections);
        controller.Start();

        var first = controller.StopAsync(NodeShutdownMode.CancelJobs);
        var second = controller.StopAsync(NodeShutdownMode.WaitForJobs);
        await Task.WhenAll(first, second);

        Assert.Same(first, second);
        Assert.Equal(1, connections[0].CancelJobsCalls);
        Assert.True(connections[0].Completed);
        Assert.Equal(NodeState.Stopped, controller.CurrentStatus.State);
    }

    [Fact]
    public async Task FailedMigrationRestartsTheExistingConfiguration()
    {
        var store = new FakeConfigStore { Config = CreateConfig() };
        var connections = new List<FakeConnection>();
        using var controller = CreateController(
            store,
            connections,
            migrate: (_, _, _) => throw new IOException("copy failed"));
        controller.Start();

        await Assert.ThrowsAsync<IOException>(
            () => controller.MigrateDataRootAsync(Path.Combine(root, "new-root")));

        Assert.Equal(2, connections.Count);
        Assert.True(connections[0].Completed);
        Assert.False(connections[1].Completed);
        await controller.StopAsync(NodeShutdownMode.WaitForJobs);
    }

    [Fact]
    public async Task ResetIdentityWaitsForSessionBeforeDeletingIdentity()
    {
        var store = new FakeConfigStore { Config = CreateConfig() };
        var connections = new List<FakeConnection>();
        using var controller = CreateController(store, connections);
        controller.Start();

        await controller.ResetIdentityAsync();

        Assert.True(connections[0].Completed);
        Assert.True(store.IdentityDeleted);
        Assert.Null(controller.CurrentConfig);
        Assert.Equal(NodeState.NotRegistered, controller.CurrentStatus.State);
    }

    public void Dispose()
    {
        if (Directory.Exists(root))
        {
            Directory.Delete(root, recursive: true);
        }
    }

    private NodeApplicationController CreateController(
        FakeConfigStore store,
        List<FakeConnection> connections,
        Func<string, string, CancellationToken, Task<NodeDataMigrationResult>>? migrate = null)
    {
        var paths = new NodePaths(
            root,
            Path.Combine(root, "node.json"),
            Path.Combine(root, "jobs"),
            Path.Combine(root, "workspaces"));
        return new NodeApplicationController(
            store,
            paths,
            (_, _) =>
            {
                var connection = new FakeConnection();
                connections.Add(connection);
                return connection;
            },
            (_, _, _) => Task.CompletedTask,
            migrate ?? ((source, target, _) => Task.FromResult(
                new NodeDataMigrationResult(source, target, 0, 0))),
            _ => { });
    }

    private static NodeConfig CreateConfig() => new(
        new Uri("https://zcbot.example/"),
        Guid.NewGuid(),
        Guid.NewGuid(),
        "test-node",
        "secret",
        30,
        []);

    private sealed class FakeConfigStore : INodeConfigStore
    {
        public NodeConfig? Config { get; set; }
        public bool IdentityDeleted { get; private set; }
        public bool Exists => Config is not null;
        public string ConfigPath => "node.json";

        public void Save(NodeConfig config) => Config = config;

        public NodeConfig Load() => Config
            ?? throw new NodeConfigurationException("missing identity");

        public void DeleteLocalIdentity()
        {
            IdentityDeleted = true;
            Config = null;
        }
    }

    private sealed class FakeConnection : INodeConnection
    {
        public int CancelJobsCalls { get; private set; }
        public bool Completed { get; private set; }

        public async Task RunAsync(CancellationToken cancellationToken)
        {
            try
            {
                await Task.Delay(Timeout.InfiniteTimeSpan, cancellationToken);
            }
            finally
            {
                Completed = true;
            }
        }

        public void CancelActiveJobsForExit() => CancelJobsCalls++;
    }
}