// Launch a child process and put it in the job immediately, redirecting its
// stdout/stderr to log files (matches the pod_out/err.txt + bridge_out/err.txt
// the old launch_pod.ps1 produced).
//
// The assign happens right after Start(), before DOSBox/pythonw has a chance to
// spawn anything, so the whole tree is captured. (A CREATE_SUSPENDED launch
// would close even that microscopic gap; neither of these children forks at
// startup, so Start()+assign is sufficient here.)

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;

namespace VwePod
{
    internal static class ChildProcess
    {
        public static Process StartInJob(
            JobObject job, string exe, string args,
            IDictionary<string, string> extraEnv,
            string outPath, string errPath, string workingDir)
        {
            var psi = new ProcessStartInfo
            {
                FileName = exe,
                Arguments = args,
                UseShellExecute = false,          // inherit our env; allow job assign
                CreateNoWindow = false,           // children make their own windows
                RedirectStandardOutput = true,
                RedirectStandardError = true,
            };
            if (!string.IsNullOrEmpty(workingDir)) psi.WorkingDirectory = workingDir;
            if (extraEnv != null)
                foreach (var kv in extraEnv) psi.Environment[kv.Key] = kv.Value;

            var proc = new Process { StartInfo = psi };

            var outWriter = new StreamWriter(outPath, false) { AutoFlush = true };
            var errWriter = new StreamWriter(errPath, false) { AutoFlush = true };
            proc.OutputDataReceived += (s, e) => { if (e.Data != null) lock (outWriter) outWriter.WriteLine(e.Data); };
            proc.ErrorDataReceived  += (s, e) => { if (e.Data != null) lock (errWriter) errWriter.WriteLine(e.Data); };
            proc.Exited += (s, e) => { try { outWriter.Dispose(); errWriter.Dispose(); } catch { } };
            proc.EnableRaisingEvents = true;

            proc.Start();
            job.Add(proc.Handle);         // capture before it can spawn a child
            proc.BeginOutputReadLine();
            proc.BeginErrorReadLine();
            return proc;
        }
    }
}