// "linux": ["gnome-terminal", "konsole", "xfce4-terminal", "terminator", "xterm", "uxterm"],
// "win32": ["cmd","powershell","bash"],
// "darwin": ["bash"],

class Terminal {
  constructor() {
     this.get_linux_terminal = function () {
      switch (process.env.GDMSESSION) {
        // if session is using gtk
        case 'ubuntu':
        case 'ubuntu-2d':
        case 'gnome':
        case 'gnome-shell':
        case 'gnome-classic':
        case 'gnome-fallback':
        case 'cinnamon':
          return "gnome-terminal";
        // xfce session has its own terminal, xfce is gtk compatible
        case 'xfce':
          return "xfce4-terminal";
        // if session is using qt, kde and lxde are qt compatible
        case 'kde-plasma':
          return "konsole";
        case 'Lubuntu':
          return "lxterminal";
        // if unknown session, default to xterm
        default:
          // attempt to determine desktop session
          switch (process.env.XDG_CURRENT_DESKTOP) {
            case 'Unity':
            case 'GNOME':
            case 'X-Cinnamon':
              return "gnome-terminal";
            case 'XFCE':
              return "xfce4-terminal";
            case 'KDE':
              return "konsole";
            case 'LXDE':
              return "lxterminal";
            default:
              return "xterm";
          }
        return ""; // redundant LBYL response
      }
    };

    this.set_linux_terminal = function (shell) {
      // creates an object containing the environments
      // default shell and execute option
      switch (shell) {
        case 'gnome-terminal':
        case 'xfce4-terminal':
          return {
            'shell': shell,
            'option': '-x'
          };
        case 'konsole':
        case 'lxterminal':
        case 'xterm':
          return {
            'shell': shell,
            'option': '-e'
          };
        default:
          return {
            'shell': "xterm",
            'option': '-e'
          };
        return ""; // redundant LBYL response
      }
    };

    this.get_tty = function () {
      if ("linux" == process.platform) {
        // linux has a mass variety of environments and a variety of ways
        // for determining those environments. best to go for the base
        // environments by depending on the most common builtin shells instead.
        // https://askubuntu.com/questions/72549/how-to-determine-which-window-manager-is-running
        return this.set_linux_terminal(
          this.get_linux_terminal()
        );
      }

      if ("darwin" == process.platform){
        // even though mac os x supports other shells, i assume that they
        // support the command option as $SHELL -c "command string".
        // some users report that $SHELL fails and that osascript works.
        // https://ss64.com/osx/osascript.html
        // return {
        //   'shell': process.env.SHELL,
        //   'option': '-c'
        // };
        return {
          'shell': 'osascript',
          'option': '-e',
          'command': 'tell app "Terminal" to do script',
        };
      }

      if ("win32" == process.platform) {
        // windows xp and up can be gaurenteed to have the cmd.exe shell.
        // %comspec% should default to %windir%system32cmd.exe unless
        // otherwise modified by the end user.
        // https://en.wikipedia.org/wiki/Environment_variable#Windows
        return {
          'shell': process.env.COMSPEC,
          'option': '/c',
          'command': 'start',
        };
      }

      return {}; // redundant LBYL response
    };
  }
}

exports.cli = cli = new Terminal()
exports.has_a_tty = cli.get_tty()

const terminal = require('./terminal');

const spawn = require('child_process').spawn;

switch (process.platform) {
  case 'linux':
    var echo = spawn(
      terminal.has_a_tty.shell,
      [
        terminal.has_a_tty.option,
        "python",
        "-c",
        "print('Hello, World');input('...enter to continue...')",
      ]
    );
    break;
  case 'win32':
  case 'darwin':
    var echo = spawn(
      terminal.has_a_tty.shell,
      [
        terminal.has_a_tty.option,
        terminal.has_a_tty.command,
        "python",
        "-c",
        "print('Hello, World');input('...enter to continue...')",
      ]
    );
    break;
  default:
    console.error(
      new Error("Error: Could not determine the OS platform type.")
    );
    break;
}

echo.stdout.on('data', (data) => {
  console.log(`stdout: ${data}`);
});

echo.stderr.on('data', (data) => {
  console.log(`stderr: ${data}`);
});

echo.on('close', (code) => {
  console.log(`child process exited with code ${code}`);
});