# Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import errno, logging, os, re, signal, subprocess, time
import common
import constants, cros_logging, cros_ui, cryptohome
from autotest_lib.client.bin import utils
from autotest_lib.client.common_lib import error


_DEFAULT_TIMEOUT = 30
_DEFAULT_OWNERSHIP_TIMEOUT = 60

# Log messages used to signal when we're in a logout situation. Used to detect
# crashes by cros_ui_test.UITest.
LOGOUT_ATTEMPT_MSG = 'cros/login.py: Attempting logout...'
LOGOUT_COMPLETE_MSG = 'cros/login.py: Logout complete.'


class TimeoutError(error.TestError):
    """Error raised when we time out while waiting on a condition."""
    pass


class CrashError(error.TestError):
    """Error raised when a pertinent process crashes while waiting on
    a condition.
    """
    pass


class UnexpectedCondition(error.TestError):
    """Error raised when an expected precondition is not met."""
    pass


def __get_session_manager_pid():
    """Determine the pid of the session manager.

    Returns:
        An integer indicating the current session manager pid, or None if
        it is not running.
    """

    p = subprocess.Popen(["pgrep", "^%s$" % constants.SESSION_MANAGER],
                         stdout=subprocess.PIPE)
    ary = p.communicate()[0].split()
    return int(ary[0]) if ary else None


def __session_manager_restarted(oldpid):
    """Detect if the session manager has restarted.

    Args:
        oldpid: Integer indicating the last known pid of the session_manager.

    Returns:
        True if the session manager is running under a pid other than
        'oldpid', X is running, and there is a window displayed.
    """
    import autox

    newpid = __get_session_manager_pid()
    if newpid and newpid != oldpid:
        try:
            ax = cros_ui.get_autox()
        except autox.Xlib.error.DisplayConnectionError:
            return False

        # When the session manager starts up there is a moment where we can
        # make a connection with autox, but there is no window displayed.  If
        # we start sending keystrokes at this point they get lost.  If we wait
        # for this window to show up, things go much smoother.
        wid = ax.get_top_window_id_at_point(0, 0)
        if not wid:
            return False

        # The login manager displays its widgetry in a second window centered
        # on the screen.  Waiting for this window to show up is also helpful.
        # TODO: perhaps the login manager should emit some more trustworthy
        # signal when it's ready to accept credentials.
        x, y = ax.get_screen_size()
        wid2 = ax.get_top_window_id_at_point(x / 2, y / 2)
        if wid == wid2:
            return False

        return True

    return False


def logged_in():
    # this file is created when the session_manager emits start-user-session
    # and removed when the session_manager emits stop-user-session
    return os.path.exists(constants.LOGGED_IN_MAGIC_FILE)


def process_crashed(process, log_reader):
    """Checks the log watched by |log_reader| to see if a crash was reported
    for |process|.

    Returns True if so, False if not.
    """
    return log_reader.can_find('Received crash notification for %s' % process)


def wait_for_condition(condition, timeout_msg, timeout, process, log_reader,
                       crash_msg):
    try:
        utils.poll_for_condition(
            condition,
            TimeoutError(timeout_msg),
            timeout=timeout)
    except TimeoutError, e:
        # We could fail faster if necessary, but it'd be more complicated.
        if process_crashed(process, log_reader):
            raise CrashError(crash_msg)
        else:
            raise e


def attempt_login(username, password, timeout=_DEFAULT_TIMEOUT):
    """Attempt to log in.

    Args:
        username: str username for login
        password: str password for login
        timeout: float number of seconds to wait

    Raises:
        TimeoutError: login didn't complete before timeout
        UnexpectedCondition: login manager is not running, or user is already
            logged in.
    """
    logging.info("Attempting to login using autox.py and (%s, %s)" %
                 (username, password))

    if not __get_session_manager_pid():
        raise UnexpectedCondition("Session manager is not running")

    if logged_in():
        raise UnexpectedCondition("Already logged in")

    # Mark /var/log/messages now; we'll run through all subsequent log messages
    # if we couldn't log in to see if the browser crashed.
    log_reader = cros_logging.LogReader()
    log_reader.set_start_by_current()

    # Up our priority so we don't get descheduled in the middle of sending key
    # press and key release events.
    ax = cros_ui.get_autox()
    # navigate to login screen
    ax.send_hotkey("Ctrl+Alt+L")
    # escape out of any login screen menus (e.g., the network select menu)
    ax.send_hotkey("Escape")
    time.sleep(0.5)
    if (username):
        # focus username
        ax.send_hotkey("Alt+U")
        ax.send_text(username)
        # focus password
        ax.send_hotkey("Alt+P")
        ax.send_text(password)
        ax.send_hotkey("Return")
    else:
        ax.send_hotkey("Alt+B")  # Browse without signing-in

    wait_for_condition(condition=logged_in,
                       timeout_msg='Timed out waiting for login',
                       timeout=timeout,
                       process='chrome',
                       log_reader=log_reader,
                       crash_msg='Chrome crashed during login')
    if (username):
        # We don't take ownership on Guest login; Otherwise we SIGABRT keygen
        wait_for_ownership()


def attempt_logout(timeout=_DEFAULT_TIMEOUT):
    """Attempt to log out by killing Chrome.

    Args:
        timeout: float number of seconds to wait

    Raises:
        TimeoutError: logout didn't complete before timeout
        UnexpectedCondition: user is not logged in
    """
    if not logged_in():
        raise UnexpectedCondition('Already logged out')

    # Log what we're about to do to /var/log/messages. Used to log crashes later
    # in cleanup by cros_ui_test.UITest.
    utils.system('logger "%s"' % LOGOUT_ATTEMPT_MSG)

    try:
      oldpid = __get_session_manager_pid()

      # Mark /var/log/messages now; we'll run through all subsequent log
      # messages if we couldn't TERM and restart the session manager.

      log_reader = cros_logging.LogReader()
      log_reader.set_start_by_current()

      # Gracefully exiting the session manager causes the user's session to end.
      utils.system('pkill -TERM -o ^%s$' % constants.SESSION_MANAGER)

      wait_for_condition(
          condition=lambda: __session_manager_restarted(oldpid),
          timeout_msg='Timed out waiting for logout',
          timeout=timeout,
          process='session_manager',
          log_reader=log_reader,
          crash_msg='session_manager crashed while shutting down.')
    finally:
      utils.system('logger "%s"' % LOGOUT_COMPLETE_MSG)


def wait_for_browser(timeout=_DEFAULT_TIMEOUT):
    """Wait until a Chrome process is running.

    Args:
        timeout: float number of seconds to wait

    Raises:
        TimeoutError: Chrome didn't start before timeout
    """
    # Mark /var/log/messages now; we'll run through all subsequent log messages
    # if we couldn't start chrome to see if the browser crashed.
    log_reader = cros_logging.LogReader()
    log_reader.set_start_by_current()
    wait_for_condition(
        lambda: os.system('pgrep ^%s$' % constants.BROWSER) == 0,
        timeout_msg='Timed out waiting for Chrome to start',
        timeout=timeout,
        process='chrome',
        log_reader=log_reader,
        crash_msg='Chrome crashed while starting up.')


def wait_for_cryptohome(timeout=_DEFAULT_TIMEOUT):
    """Wait until cryptohome is mounted.

    Args:
        timeout: float number of seconds to wait

    Raises:
        TimeoutError: cryptohome wasn't mounted before timeout
    """
    # Mark /var/log/messages now; we'll run through all subsequent log messages
    # if we couldn't get the browser up to see if the browser crashed.
    log_reader = cros_logging.LogReader()
    log_reader.set_start_by_current()
    wait_for_condition(
        condition=lambda: cryptohome.is_mounted(),
        timeout_msg='Timed out waiting for cryptohome to be mounted',
        timeout=timeout,
        process='cryptohomed',
        log_reader=log_reader,
        crash_msg='cryptohomed crashed during mount attempt')


def wait_for_login_prompt(timeout=_DEFAULT_TIMEOUT):
    """Wait the login prompt is on screen and ready

    Args:
        timeout: float number of seconds to wait

    Raises:
        TimeoutError: Login prompt didn't get up before timeout
    """
    # Mark /var/log/messages now; we'll run through all subsequent log messages
    # if we couldn't get the browser up to see if the browser crashed.
    log_reader = cros_logging.LogReader()
    log_reader.set_start_by_current()
    wait_for_condition(
        condition=lambda: os.access(
            constants.LOGIN_PROMPT_READY_MAGIC_FILE, os.F_OK),
        timeout_msg='Timed out waiting for login prompt',
        timeout=timeout,
        process='chrome',
        log_reader=log_reader,
        crash_msg='Chrome crashed before the login prompt.')


def wait_for_window_manager(timeout=_DEFAULT_TIMEOUT):
    """Wait until the window manager is running.

    Args:
        timeout: float number of seconds to wait

    Raises:
        TimeoutError: window manager didn't start before timeout
    """
    utils.poll_for_condition(
        lambda: not os.system('pgrep ^%s$' % constants.WINDOW_MANAGER),
        TimeoutError('Timed out waiting for window manager to start'),
        timeout=timeout)


def wait_for_initial_chrome_window(timeout=_DEFAULT_TIMEOUT):
    """Wait until the initial Chrome window is mapped.

    Args:
      timeout: float number of seconds to wait

    Raises:
        TimeoutError: Chrome window wasn't mapped before timeout
    """
    # Mark /var/log/messages now; we'll run through all subsequent log messages
    # if we couldn't get the browser up to see if the browser crashed.
    log_reader = cros_logging.LogReader()
    log_reader.set_start_by_current()
    wait_for_condition(
        lambda: os.access(
            constants.CHROME_WINDOW_MAPPED_MAGIC_FILE, os.F_OK),
        'Timed out waiting for initial Chrome window',
        timeout=timeout,
        process='chrome',
        log_reader=log_reader,
        crash_msg='Chrome crashed before first tab rendered.')


def wait_for_ownership(timeout=_DEFAULT_OWNERSHIP_TIMEOUT):
    log_reader = cros_logging.LogReader()
    log_reader.set_start_by_current()
    wait_for_condition(
        condition=lambda: os.access(constants.OWNER_KEY_FILE, os.F_OK),
        timeout_msg='Timed out waiting for ownership',
        timeout=timeout,
        process=constants.BROWSER,
        log_reader=log_reader,
        crash_msg='Chrome crashed before ownership could be taken.')


def nuke_login_manager():
    nuke_process_by_name('session_manager')
    wait_for_browser()


def nuke_process_by_name(name, with_prejudice=False):
    pid = int(utils.system_output('pgrep -o ^%s$' % name).split()[0])
    if with_prejudice:
        utils.nuke_pid(pid, [signal.SIGKILL])
    else:
        utils.nuke_pid(pid)


def refresh_window_manager(timeout=_DEFAULT_TIMEOUT):
    """Clear state that tracks what WM has done, kill it, and wait until
    the window manager is running.

    Args:
        timeout: float number of seconds to wait

    Raises:
        TimeoutError: window manager didn't start before timeout
    """
    os.unlink(constants.CHROME_WINDOW_MAPPED_MAGIC_FILE)
    nuke_process_by_name(constants.WINDOW_MANAGER)
    wait_for_window_manager()


def refresh_login_screen(timeout=_DEFAULT_TIMEOUT):
    """Clear any runtime state that chrome has built up at the login screen.

    Args:
        timeout: float number of seconds to wait

    Raises:
        UnexpectedCondition: called while already logged in
        TimeoutError: chrome didn't start before timeout
    """
    if logged_in():
        raise UnexpectedCondition('Already logged in')
    wait_for_browser()
    wait_for_login_prompt()
    oldpid = __get_session_manager_pid()

    # Clear breadcrumb that shows we've emitted login-prompt-ready.
    try:
        os.unlink(constants.LOGIN_PROMPT_READY_MAGIC_FILE)
    except OSError, e:
        if e.errno != errno.ENOENT:
            raise e

    # Clear old log files.
    logpath = constants.CHROME_LOG_DIR
    try:
        for file in os.listdir(logpath):
            fullpath = os.path.join(logpath, file)
            if os.path.isfile(fullpath):
                os.unlink(fullpath)

    except (IOError, OSError) as error:
        logging.error(error)

    # Restart the UI.
    nuke_login_manager()
    utils.poll_for_condition(
        lambda: __session_manager_restarted(oldpid),
        TimeoutError('Timed out waiting for logout'),
        timeout)
    wait_for_login_prompt()