using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using Microsoft.Extensions.Logging;

namespace AyaNova.Util
{
    public static class RunProgram
    {


        /// <summary>
        /// Run a program directly, no shell: each argument is passed as-is (no quoting or escaping needed, nothing is interpreted by a shell)
        /// and extra environment variables are set for this process only (e.g. PGPASSWORD so a password never appears on a command line)
        /// Returns empty string on success (exit code 0) or the error text otherwise, same convention as the backup job expects
        /// </summary>
        public static string RunNoShell(string fileName, IEnumerable<string> arguments, IDictionary<string, string> environment = null, ILogger log = null, int waitForExitTimeOut = int.MaxValue)
        {
            try
            {
                using (var process = new Process())
                {
                    process.StartInfo = new ProcessStartInfo
                    {
                        FileName = fileName,
                        RedirectStandardOutput = true,
                        RedirectStandardError = true,
                        UseShellExecute = false,
                        CreateNoWindow = true,
                    };
                    foreach (var a in arguments)
                        process.StartInfo.ArgumentList.Add(a);
                    if (environment != null)
                        foreach (var e in environment)
                            process.StartInfo.Environment[e.Key] = e.Value;

                    process.Start();
                    //read both streams at once, reading one to the end first can deadlock if the other fills its buffer
                    var stdOut = process.StandardOutput.ReadToEndAsync();
                    var stdErr = process.StandardError.ReadToEndAsync();
                    if (!process.WaitForExit(waitForExitTimeOut))
                    {
                        process.Kill(true);
                        return $"ERROR: TIMED OUT {waitForExitTimeOut}ms BEFORE COMPLETION running {fileName}";
                    }
                    process.WaitForExit();//ensures output streams are fully read after the timed wait above
                    if (process.ExitCode != 0)
                        return $"ERROR: {Path.GetFileName(fileName)} exit code {process.ExitCode}: {stdErr.Result}{stdOut.Result}".Trim();
                    return string.Empty;
                }
            }
            catch (Exception ex)
            {
                //arguments deliberately not logged, they can contain connection details
                if (log != null)
                {
                    log.LogError(ex, $"RunProgram error running command:{fileName}");
                }
                throw;
            }
        }

    }
}