"""Utilities to get a password and/or the current user name.

getpass(prompt) - prompt for a password, with echo turned off

getuser() - get the user name from the environment or password database

On Windows, the msvcrt module will be used.

On the Mac EasyDialogs.AskPassword is used, if available.

"""

# Authors: Piers Lauder (original)

#          Guido van Rossum (Windows support and cleanup)

import sys

__all__ = ["getpass","getuser"]

def unix_getpass(prompt='Password: ', stream=None):

    """Prompt for a password, with echo turned off.

    The prompt is written on stream, by default stdout.

    Restore terminal settings at end.

    """

    if stream is None:

        stream = sys.stdout

    try:

        fd = sys.stdin.fileno()

    except:

        return default_getpass(prompt)

    old = termios.tcgetattr(fd)     # a copy to save

    new = old[:]

    new[3] = new[3] & ~termios.ECHO # 3 == 'lflags'

    try:

        termios.tcsetattr(fd, termios.TCSADRAIN, new)

        passwd = _raw_input(prompt, stream)

    finally:

        termios.tcsetattr(fd, termios.TCSADRAIN, old)

    stream.write('\n')

    return passwd

def win_getpass(prompt='Password: ', stream=None):

    """Prompt for password with echo off, using Windows getch()."""

    if sys.stdin is not sys.__stdin__:

        return default_getpass(prompt, stream)

    import msvcrt

    for c in prompt:

        msvcrt.putch(c)

    pw = ""

    while 1:

        c = msvcrt.getch()

        if c == '\r' or c == '\n':

            break

        if c == '\003':

            raise KeyboardInterrupt

        if c == '\b':

            pw = pw[:-1]

        else:

            pw = pw + c

    msvcrt.putch('\r')

    msvcrt.putch('\n')

    return pw

def default_getpass(prompt='Password: ', stream=None):

    print >>sys.stderr, "Warning: Problem with getpass. Passwords may be echoed."

    return _raw_input(prompt, stream)

def _raw_input(prompt="", stream=None):

    # A raw_input() replacement that doesn't save the string in the

    # GNU readline history.

    if stream is None:

        stream = sys.stdout

    prompt = str(prompt)

    if prompt:

        stream.write(prompt)

    line = sys.stdin.readline()

    if not line:

        raise EOFError

    if line[-1] == '\n':

        line = line[:-1]

    return line

def getuser():

    """Get the username from the environment or password database.

    First try various environment variables, then the password

    database.  This works on Windows as long as USERNAME is set.

    """

    import os

    for name in ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):

        user = os.environ.get(name)

        if user:

            return user

    # If this fails, the exception will "explain" why

    import pwd

    return pwd.getpwuid(os.getuid())[0]

# Bind the name getpass to the appropriate function

try:

    import termios

    # it's possible there is an incompatible termios from the

    # McMillan Installer, make sure we have a UNIX-compatible termios

    termios.tcgetattr, termios.tcsetattr

except (ImportError, AttributeError):

    try:

        import msvcrt

    except ImportError:

        try:

            from EasyDialogs import AskPassword

        except ImportError:

            getpass = default_getpass

        else:

            getpass = AskPassword

    else:

        getpass = win_getpass

else:

    getpass = unix_getpass