using System.Text.Json;
using System.Text.Json.Nodes;
using DotCraft.Unity;

namespace Agc.Unity.Attach;

public sealed record EditorTarget(int Pid, DateTime StartedUtc, string? ProjectPath, string? EditorPath);

public interface IEditorBackend : IAsyncDisposable
{
    Task<IReadOnlyList<EditorTarget>> DetectAsync(CancellationToken cancellationToken);
    Task<JsonObject> ConnectAsync(EditorTarget target, CancellationToken cancellationToken);
    Task<JsonObject> StatusAsync(CancellationToken cancellationToken);
    Task<JsonObject> ExecuteAsync(string code, Action onDispatch, CancellationToken cancellationToken);
    Task<JsonObject> WaitAsync(string executionId, CancellationToken cancellationToken);
    Task DisconnectAsync(CancellationToken cancellationToken);
    void ForgetSelection();
}

internal sealed class AttachBackend : IEditorBackend
{
    private readonly string session = Guid.NewGuid().ToString("N");
    private readonly UnityAttachService service = new(
        Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "Genarrative", "UnityAttach"), "");

    public Task<IReadOnlyList<EditorTarget>> DetectAsync(CancellationToken cancellationToken)
    {
        if (!OperatingSystem.IsWindows() || !Environment.Is64BitProcess)
            throw new HostException("UnityPlatformUnsupported", "Unity Attach requires Windows x64.");
        cancellationToken.ThrowIfCancellationRequested();
        var values = JsonSerializer.SerializeToNode(service.List())!.AsArray();
        IReadOnlyList<EditorTarget> targets = values.Select(value => new EditorTarget(
            value!["pid"]!.GetValue<int>(), value["startedUtc"]!.GetValue<DateTime>().ToUniversalTime(),
            value["project"]?.GetValue<string>(), value["editor"]?.GetValue<string>())).ToArray();
        cancellationToken.ThrowIfCancellationRequested();
        return Task.FromResult(targets);
    }

    public Task<JsonObject> ConnectAsync(EditorTarget target, CancellationToken cancellationToken) =>
        service.Connect(session, target.Pid, cancellationToken);
    public Task<JsonObject> StatusAsync(CancellationToken cancellationToken) => service.Status(session, cancellationToken);
    public Task<JsonObject> ExecuteAsync(string code, Action onDispatch, CancellationToken cancellationToken) =>
        service.Execute(session, code, null, true, 0, cancellationToken, onDispatch);
    public Task<JsonObject> WaitAsync(string executionId, CancellationToken cancellationToken) =>
        service.Wait(session, executionId, 250, false, cancellationToken);
    public async Task DisconnectAsync(CancellationToken cancellationToken) =>
        await service.Disconnect(session, cancellationToken);
    public void ForgetSelection() => service.ForgetSelection(session);
    public ValueTask DisposeAsync() => service.DisposeAsync();
}

public sealed class HostException(string code, string message) : Exception(message)
{
    public string Code { get; } = code;
}