using System;
using System.Diagnostics;
using System.Threading.Tasks;

namespace WebTerminalServer
{
    public class EasyTerminal
    {
        private readonly string _cmdExe;
        private Process _process;

        public EasyTerminal(string cmdExe)
        {
            _cmdExe = cmdExe;
        }

        public EventHandler<byte[]> DataReceived { get; set; }
        public EventHandler<uint> CloseReceived { get; set; }

        public void OnInput(byte[] ee)
        {
            if (ee == null) throw new ArgumentException();

            if (ee.Length == 1 && ee[0] == 13)
            {
                _process.StandardInput.WriteLine();
                _process.StandardInput.Flush();
                _process.StandardInput.BaseStream.Flush();
                return;
            }
            _process.StandardInput.BaseStream.Write(ee, 0, ee.Length);
            _process.StandardInput.BaseStream.Flush();
        }

        public void OnClose()
        {
            _process?.Kill();
        }

        public void Run()
        {
            _process = new Process
            {
                StartInfo =
                {
                    FileName = _cmdExe,
                    RedirectStandardError = true,
                    RedirectStandardInput = true,
                    RedirectStandardOutput = true,
                    UseShellExecute = false
                },
                EnableRaisingEvents = true
            };

            _process.Exited += delegate { CloseReceived?.Invoke(this, (uint)_process.ExitCode); };

            _process.Start();

            Task.Run(async delegate
            {
                var s = _process.StandardOutput.BaseStream;
                var buf = new byte[1024];
                while (_process.HasExited == false)
                {
                    var count = await s.ReadAsync(buf, 0, buf.Length);
                    var outBuf = new byte[count];
                    Buffer.BlockCopy(buf, 0, outBuf, 0, count);
                    DataReceived?.Invoke(this, outBuf);
                }
            });

            Task.Run(async delegate
            {
                var s = _process.StandardError.BaseStream;
                var buf = new byte[1024];
                while (_process.HasExited == false)
                {
                    var count = await s.ReadAsync(buf, 0, buf.Length);
                    var outBuf = new byte[count];
                    Buffer.BlockCopy(buf, 0, outBuf, 0, count);
                    DataReceived?.Invoke(this, outBuf);
                }
            });
        }
    }
}