# vi: ts=4 expandtab
#
#    Copyright (C) 2012 Canonical Ltd.
#    Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
#    Copyright (C) 2012 Yahoo! Inc.
#
#    Author: Scott Moser <scott.moser@canonical.com>
#    Author: Juerg Haefliger <juerg.haefliger@hp.com>
#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
#    Author: Ben Howard <ben.howard@canonical.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License version 3, as
#    published by the Free Software Foundation.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

from StringIO import StringIO

import abc
import grp
import os
import pwd
import re

from cloudinit import importer
from cloudinit import log as logging
from cloudinit import ssh_util
from cloudinit import util

# TODO(harlowja): Make this via config??
IFACE_ACTIONS = {
    'up': ['ifup', '--all'],
    'down': ['ifdown', '--all'],
}

LOG = logging.getLogger(__name__)


class Distro(object):

    __metaclass__ = abc.ABCMeta
    default_user = None

    def __init__(self, name, cfg, paths):
        self._paths = paths
        self._cfg = cfg
        self.name = name

    def add_default_user(self):
        # Adds the distro user using the rules:
        #  - Password is same as username but is locked
        #  - nopasswd sudo access

        user = self.get_default_user()
        if not user:
            raise NotImplementedError("No Default user")

        self.create_user(user,
                        plain_text_passwd=user,
                        home="/home/%s" % user,
                        shell="/bin/bash",
                        lockpasswd=True,
                        gecos="%s%s" % (user[0:1].upper(), user[1:]),
                        sudo="ALL=(ALL) NOPASSWD:ALL")

        LOG.info("Added default '%s' user with passwordless sudo", user)

    @abc.abstractmethod
    def install_packages(self, pkglist):
        raise NotImplementedError()

    @abc.abstractmethod
    def _write_network(self, settings):
        # In the future use the http://fedorahosted.org/netcf/
        # to write this blob out in a distro format
        raise NotImplementedError()

    def get_option(self, opt_name, default=None):
        return self._cfg.get(opt_name, default)

    @abc.abstractmethod
    def set_hostname(self, hostname):
        raise NotImplementedError()

    @abc.abstractmethod
    def update_hostname(self, hostname, prev_hostname_fn):
        raise NotImplementedError()

    @abc.abstractmethod
    def package_command(self, cmd, args=None):
        raise NotImplementedError()

    @abc.abstractmethod
    def update_package_sources(self):
        raise NotImplementedError()

    def get_primary_arch(self):
        arch = os.uname[4]
        if arch in ("i386", "i486", "i586", "i686"):
            return "i386"
        return arch

    def _get_arch_package_mirror_info(self, arch=None):
        mirror_info = self.get_option("package_mirrors", None)
        if arch == None:
            arch = self.get_primary_arch()
        return _get_arch_package_mirror_info(mirror_info, arch)

    def get_package_mirror_info(self, arch=None,
                                availability_zone=None):
        # this resolves the package_mirrors config option
        # down to a single dict of {mirror_name: mirror_url}
        arch_info = self._get_arch_package_mirror_info(arch)

        return _get_package_mirror_info(availability_zone=availability_zone,
                                        mirror_info=arch_info)

    def apply_network(self, settings, bring_up=True):
        # Write it out
        self._write_network(settings)
        # Now try to bring them up
        if bring_up:
            return self._interface_action('up')
        return False

    @abc.abstractmethod
    def apply_locale(self, locale, out_fn=None):
        raise NotImplementedError()

    @abc.abstractmethod
    def set_timezone(self, tz):
        raise NotImplementedError()

    def _get_localhost_ip(self):
        return "127.0.0.1"

    def update_etc_hosts(self, hostname, fqdn):
        # Format defined at
        # http://unixhelp.ed.ac.uk/CGI/man-cgi?hosts
        header = "# Added by cloud-init"
        real_header = "%s on %s" % (header, util.time_rfc2822())
        local_ip = self._get_localhost_ip()
        hosts_line = "%s\t%s %s" % (local_ip, fqdn, hostname)
        new_etchosts = StringIO()
        need_write = False
        need_change = True
        hosts_ro_fn = self._paths.join(True, "/etc/hosts")
        for line in util.load_file(hosts_ro_fn).splitlines():
            if line.strip().startswith(header):
                continue
            if not line.strip() or line.strip().startswith("#"):
                new_etchosts.write("%s\n" % (line))
                continue
            split_line = [s.strip() for s in line.split()]
            if len(split_line) < 2:
                new_etchosts.write("%s\n" % (line))
                continue
            (ip, hosts) = split_line[0], split_line[1:]
            if ip == local_ip:
                if sorted([hostname, fqdn]) == sorted(hosts):
                    need_change = False
                if need_change:
                    line = "%s\n%s" % (real_header, hosts_line)
                    need_change = False
                    need_write = True
            new_etchosts.write("%s\n" % (line))
        if need_change:
            new_etchosts.write("%s\n%s\n" % (real_header, hosts_line))
            need_write = True
        if need_write:
            contents = new_etchosts.getvalue()
            util.write_file(self._paths.join(False, "/etc/hosts"),
                            contents, mode=0644)

    def _interface_action(self, action):
        if action not in IFACE_ACTIONS:
            raise NotImplementedError("Unknown interface action %s" % (action))
        cmd = IFACE_ACTIONS[action]
        try:
            LOG.debug("Attempting to run %s interface action using command %s",
                      action, cmd)
            (_out, err) = util.subp(cmd)
            if len(err):
                LOG.warn("Running %s resulted in stderr output: %s", cmd, err)
            return True
        except util.ProcessExecutionError:
            util.logexc(LOG, "Running interface command %s failed", cmd)
            return False

    def isuser(self, name):
        try:
            if pwd.getpwnam(name):
                return True
        except KeyError:
            return False

    def get_default_user(self):
        return self.default_user

    def create_user(self, name, **kwargs):
        """
            Creates users for the system using the GNU passwd tools. This
            will work on an GNU system. This should be overriden on
            distros where useradd is not desirable or not available.
        """

        adduser_cmd = ['useradd', name]
        x_adduser_cmd = ['useradd', name]

        # Since we are creating users, we want to carefully validate the
        # inputs. If something goes wrong, we can end up with a system
        # that nobody can login to.
        adduser_opts = {
                "gecos": '--comment',
                "homedir": '--home',
                "primarygroup": '--gid',
                "groups": '--groups',
                "passwd": '--password',
                "shell": '--shell',
                "expiredate": '--expiredate',
                "inactive": '--inactive',
                }

        adduser_opts_flags = {
                "nousergroup": '--no-user-group',
                "system": '--system',
                "nologinit": '--no-log-init',
                "nocreatehome": "-M",
                }

        # Now check the value and create the command
        for option in kwargs:
            value = kwargs[option]
            if option in adduser_opts and value \
                and isinstance(value, str):
                adduser_cmd.extend([adduser_opts[option], value])

                # Redact the password field from the logs
                if option != "password":
                    x_adduser_cmd.extend([adduser_opts[option], value])
                else:
                    x_adduser_cmd.extend([adduser_opts[option], 'REDACTED'])

            elif option in adduser_opts_flags and value:
                adduser_cmd.append(adduser_opts_flags[option])
                x_adduser_cmd.append(adduser_opts_flags[option])

        # Default to creating home directory unless otherwise directed
        #  Also, we do not create home directories for system users.
        if "nocreatehome" not in kwargs and "system" not in kwargs:
            adduser_cmd.append('-m')

        # Create the user
        if self.isuser(name):
            LOG.warn("User %s already exists, skipping." % name)
        else:
            LOG.debug("Creating name %s" % name)
            try:
                util.subp(adduser_cmd, logstring=x_adduser_cmd)
            except Exception as e:
                util.logexc(LOG, "Failed to create user %s due to error.", e)
                raise e

        # Set password if plain-text password provided
        if 'plain_text_passwd' in kwargs and kwargs['plain_text_passwd']:
            self.set_passwd(name, kwargs['plain_text_passwd'])

        # Default locking down the account.
        if ('lockpasswd' not in kwargs and
            ('lockpasswd' in kwargs and kwargs['lockpasswd']) or
            'system' not in kwargs):
            try:
                util.subp(['passwd', '--lock', name])
            except Exception as e:
                util.logexc(LOG, ("Failed to disable password logins for"
                            "user %s" % name), e)
                raise e

        # Configure sudo access
        if 'sudo' in kwargs:
            self.write_sudo_rules(name, kwargs['sudo'])

        # Import SSH keys
        if 'sshauthorizedkeys' in kwargs:
            keys = set(kwargs['sshauthorizedkeys']) or []
            ssh_util.setup_user_keys(keys, name, None, self._paths)

        return True

    def set_passwd(self, user, passwd, hashed=False):
        pass_string = '%s:%s' % (user, passwd)
        cmd = ['chpasswd']

        if hashed:
            cmd.append('--encrypted')

        try:
            util.subp(cmd, pass_string, logstring="chpasswd for %s" % user)
        except Exception as e:
            util.logexc(LOG, "Failed to set password for %s" % user)
            raise e

        return True

    def write_sudo_rules(self,
        user,
        rules,
        sudo_file="/etc/sudoers.d/90-cloud-init-users",
        ):

        content_header = "# user rules for %s" % user
        content = "%s\n%s %s\n\n" % (content_header, user, rules)

        if isinstance(rules, list):
            content = "%s\n" % content_header
            for rule in rules:
                content += "%s %s\n" % (user, rule)
            content += "\n"

        if not os.path.exists(sudo_file):
            util.write_file(sudo_file, content, 0644)

        else:
            try:
                with open(sudo_file, 'a') as f:
                    f.write(content)
            except IOError as e:
                util.logexc(LOG, "Failed to write %s" % sudo_file, e)
                raise e

    def isgroup(self, name):
        try:
            if grp.getgrnam(name):
                return True
        except:
            return False

    def create_group(self, name, members):
        group_add_cmd = ['groupadd', name]

        # Check if group exists, and then add it doesn't
        if self.isgroup(name):
            LOG.warn("Skipping creation of existing group '%s'" % name)
        else:
            try:
                util.subp(group_add_cmd)
                LOG.info("Created new group %s" % name)
            except Exception as e:
                util.logexc("Failed to create group %s" % name, e)

        # Add members to the group, if so defined
        if len(members) > 0:
            for member in members:
                if not self.isuser(member):
                    LOG.warn("Unable to add group member '%s' to group '%s'"
                            "; user does not exist." % (member, name))
                    continue

                util.subp(['usermod', '-a', '-G', name, member])
                LOG.info("Added user '%s' to group '%s'" % (member, name))


def _get_package_mirror_info(mirror_info, availability_zone=None,
                             mirror_filter=util.search_for_mirror):
    # given a arch specific 'mirror_info' entry (from package_mirrors)
    # search through the 'search' entries, and fallback appropriately
    # return a dict with only {name: mirror} entries.

    ec2_az_re = ("^[a-z][a-z]-(%s)-[1-9][0-9]*[a-z]$" %
        "north|northeast|east|southeast|south|southwest|west|northwest")

    subst = {}
    if availability_zone:
        subst['availability_zone'] = availability_zone

    if availability_zone and re.match(ec2_az_re, availability_zone):
        subst['ec2_region'] = "%s" % availability_zone[0:-1]

    results = {}
    for (name, mirror) in mirror_info.get('failsafe', {}).iteritems():
        results[name] = mirror

    for (name, searchlist) in mirror_info.get('search', {}).iteritems():
        mirrors = []
        for tmpl in searchlist:
            try:
                mirrors.append(tmpl % subst)
            except KeyError:
                pass

        found = mirror_filter(mirrors)
        if found:
            results[name] = found

    LOG.debug("filtered distro mirror info: %s" % results)

    return results


def _get_arch_package_mirror_info(package_mirrors, arch):
    # pull out the specific arch from a 'package_mirrors' config option
    default = None
    for item in package_mirrors:
        arches = item.get("arches")
        if arch in arches:
            return item
        if "default" in arches:
            default = item
    return default


def fetch(name):
    locs = importer.find_module(name,
                                ['', __name__],
                                ['Distro'])
    if not locs:
        raise ImportError("No distribution found for distro %s"
                           % (name))
    mod = importer.import_module(locs[0])
    cls = getattr(mod, 'Distro')
    return cls