using System;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

public class JustifiedWorkerEngine
{
    private readonly string _binaryPath;
    private readonly string _licenseKey;
    private static readonly SemaphoreSlim _asyncPipeLock = new SemaphoreSlim(1, 1);

    public JustifiedWorkerEngine(string binaryPath, string licenseKey)
    {
        _binaryPath = binaryPath;
        _licenseKey = licenseKey;
    }

    public async Task<string> ExecuteTransformationAsync(string inputJsonPayload)
    {
        await _asyncPipeLock.WaitAsync();
        try {
            string singleLinePayload = inputJsonPayload.Replace("\r", "").Replace("\n", "\\n");

            var startInfo = new ProcessStartInfo
            {
                FileName = _binaryPath,
                Arguments = $"--pipe --license {_licenseKey}",
                RedirectStandardInput = true,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                UseShellExecute = false,
                CreateNoWindow = true,
                StandardOutputEncoding = Encoding.UTF8
            };

            using var process = new Process { StartInfo = startInfo };
            process.Start();

            using (var writer = process.StandardInput)
            {
                await writer.WriteLineAsync(singleLinePayload);
            }

            string resultJson = await process.StandardOutput.ReadLineAsync();
            await process.WaitForExitAsync();

            try {
                if (resultJson != null && resultJson.Contains("[DATA_INSUFFICIENT_HALT]")) {
                    throw new InvalidOperationException($"Diagnostic Halt: {resultJson}");
                }
                return resultJson;
            } catch (Exception ex) {
                Console.WriteLine($"[DIAGNOSTIC INTERCEPT] Client UI preserved. {ex.Message}");
                return null;
            }
        } finally {
            _asyncPipeLock.Release();
        }
    }
}