#!/usr/bin/env python

import gettext
import os.path
import pwd
import subprocess
import sys
import syslog

PERSISTENCE_DIR = "/live/persistence/TailsData_unlocked"
PACKAGES_LIST_FILE = PERSISTENCE_DIR + "/live-additional-software.conf"
ACTIVATION_FILE = "/var/run/live-additional-software/activated"

def _launch_apt_get(specific_args):
    """Launch apt-get with given args
    
    Launch apt-get with given arguments list, log its standard and error output
    and return its returncode"""
    apt_get_env = os.environ.copy()
    # The environnment provided in GDM PostLogin hooks doesn't contain /sbin/
    # which is required by dpkg. Let's use the default path for root in Tails.
    apt_get_env['PATH'] = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
    # We will log the output and want it in English when included in bug reports
    apt_get_env['LANG'] = "C"
    args = ["apt-get", "--quiet", "--yes"]
    args.extend(specific_args)
    apt_get = subprocess.Popen(
        args,
        env=apt_get_env,
        stderr=subprocess.STDOUT,
        stdout=subprocess.PIPE)
    for line in iter(apt_get.stdout.readline, ''):
        if not line.startswith('('):
            syslog.syslog(line.rstrip())
    apt_get.wait()
    if apt_get.returncode:
        syslog.syslog(syslog.LOG_WARNING,
            "apt-get exited with returncode %i" % apt_get.returncode)
    return apt_get.returncode

def _notify(title, body):
    """Display a notification to the user of the live system
    """
    cmd = "/usr/local/sbin/tails-notify-user"
    try:
        # XXX: replace with check_output when Tails will be based on Wheezy
        # (which includes Python 2.7)
        notify_user = subprocess.Popen([cmd, title, body],
                                       stderr=subprocess.STDOUT, stdout=subprocess.PIPE)
        notify_user_output = notify_user.stdout.read()
        notify_user.wait()
        if notify_user.returncode != 0:
            syslog.syslog(syslog.LOG_WARNING, "Warning: unable to notify the user. %s returned with exit code %s"
                 % (cmd, notify_user.returncode))
            syslog.syslog(syslog.LOG_WARNING, "%s output follows: %s."
                 % (cmd, notify_user_output))
            syslog.syslog(syslog.LOG_WARNING, "The notification was: %s %s" % (title, body))
    except OSError, e:
        syslog.syslog(syslog.LOG_WARNING, "Warning: unable to notify the user. %s" % e)
        syslog.syslog(syslog.LOG_WARNING, "The notification was: %s %s" % (title, body))

def has_additional_packages_list():
    """Return true iff PACKAGES_LIST_FILE exists
    """
    return os.path.isfile(PACKAGES_LIST_FILE)

def get_additional_packages():
    """Returns the list of all the additional packages
    """
    packages = []
    if has_additional_packages_list():
        with open(PACKAGES_LIST_FILE) as f:
            for line in f:
                line = line.strip()
                if line: packages.append(line)
        f.closed
    return packages

def install_additional_packages():
    """The subcommand which activates and installs all additional packages
    """
    syslog.syslog("Starting to install additional software...")
    if has_additional_packages_list():
        syslog.syslog("Found additional packages list")
    elif os.path.isdir(PERSISTENCE_DIR):
        syslog.syslog(syslog.LOG_WARNING, "Warning: no configuration file found, creating an empty one.")
        create_additional_packages_list()
        return True
    else:
        syslog.syslog(syslog.LOG_WARNING, "Warning: persistence is not mounted, exiting")
        return True
    packages = get_additional_packages()
    if not packages:
        syslog.syslog(syslog.LOG_WARNING, "Warning: no packages to install, exiting")
        return True
    set_activated()
    syslog.syslog("Will install the following packages: %s" % " ".join(packages))
    apt_get_returncode = _launch_apt_get(["--no-remove",
        "--option", "DPkg::Options::=--force-confold",
        "install"] + packages)
    if apt_get_returncode:
        syslog.syslog(syslog.LOG_WARNING, "Warning: installation of %s failed" % " ".join(packages))
        return False
    else:
        syslog.syslog("Installation completed successfully.")
        return True

def upgrade_additional_packages():
    """The subcommand which upgrades all additional packages if they are activated
    """
    if not is_activated():
        syslog.syslog(syslog.LOG_WARNING, "Warning: additional packages not activated, exiting")
        return True
    syslog.syslog("Starting to upgrade additional software...")
    apt_get_returncode = _launch_apt_get(["update"])
    if apt_get_returncode:
        syslog.syslog(syslog.LOG_WARNING, "Warning: the update failed.")
        _notify(_("Your additional software"),
             _("The upgrade failed. This might be due to a network problem. \
Please check your network connection, try to restart Tails, or read the system \
log to understand better the problem."))
        return False
    if install_additional_packages():
        _notify(_("Your additional software"),
             _("The upgrade was successful."))
        return True
    else:
        _notify(_("Your additional software"),
             _("The upgrade failed. This might be due to a network problem. \
Please check your network connection, try to restart Tails, or read the system \
log to understand better the problem."))
        return False

def create_additional_packages_list():
    """Creates the additional packages list

    Creates the additional packages list file with the right permissions.
    The caller must ensure the file doesn't already exist.
    """
    assert not has_additional_packages_list(), "%s already exists" % PACKAGES_LIST_FILE
    syslog.syslog("Creating additional software configuration file")
    f = open(PACKAGES_LIST_FILE, 'w')
    f.closed
    os.chmod(PACKAGES_LIST_FILE, 0600)
    os.chown(PACKAGES_LIST_FILE,
             pwd.getpwnam('tails-persistence-setup').pw_uid,
             pwd.getpwnam('tails-persistence-setup').pw_gid)

def is_activated():
    """Check if additional software has been activated
    """
    return os.path.isfile(ACTIVATION_FILE)

def set_activated():
    """Save that additional software has been activated
    """
    syslog.syslog("Activating persistent software packages")
    activation_file_dir = os.path.dirname(ACTIVATION_FILE)
    if not os.path.exists(activation_file_dir):
        os.makedirs(activation_file_dir)
    try:
        f = open(ACTIVATION_FILE, 'w')
    finally:
        if f: f.close()

def print_help():
    """The subcommand which displays help
    """
    sys.stderr.write("Usage: %s <subcommand>\n" % program_name)
    sys.stderr.write("""Subcommands:
    install: activate and install additional software
    upgrade: upgrade additional software if activated\n""")

if __name__ == "__main__":
    program_name = os.path.basename(sys.argv[0])

    syslog.openlog("%s[%i]" % (program_name, os.getpid()))
    gettext.install("tails")

    if len(sys.argv) < 2:
         print_help()
         sys.exit(4)

    if sys.argv[1] == "install":
        if not install_additional_packages():
            sys.exit(1)
    elif sys.argv[1] == "upgrade":
        if not upgrade_additional_packages():
            sys.exit(2)
    else:
        print_help()
        sys.exit(4)