#!/usr/bin/python
# Authors:
#     Endi S. Dewata <edewata@redhat.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# Copyright (C) 2013 Red Hat, Inc.
# All rights reserved.
#

from lxml import etree
import getpass
import grp
import io
import ldap
import operator
import os
import pwd
import re
import shutil
import subprocess
import tempfile

import pki

INSTANCE_BASE_DIR = '/var/lib/pki'
REGISTRY_DIR = '/etc/sysconfig/pki'
SUBSYSTEM_TYPES = ['ca', 'kra', 'ocsp', 'tks', 'tps']
SUBSYSTEM_CLASSES = {}

class PKIServer(object):

    @classmethod
    def instances(cls):

        instances = []

        if not os.path.exists(os.path.join(REGISTRY_DIR, 'tomcat')):
            return instances

        for instance_name in os.listdir(pki.server.INSTANCE_BASE_DIR):
            instance = pki.server.PKIInstance(instance_name)
            instance.load()
            instances.append(instance)

        return instances


class PKISubsystem(object):

    def __init__(self, instance, subsystem_name):

        self.instance = instance
        self.name = subsystem_name
        self.type = instance.type

        if self.type >= 10:
            self.base_dir = os.path.join(self.instance.base_dir, self.name)
        else:
            self.base_dir = instance.base_dir

        self.conf_dir = os.path.join(self.base_dir, 'conf')
        self.cs_conf = os.path.join(self.conf_dir, 'CS.cfg')

        self.context_xml_template = os.path.join(
            pki.SHARE_DIR, self.name, 'conf', 'Catalina', 'localhost', self.name + '.xml')

        self.context_xml = os.path.join(
            instance.conf_dir, 'Catalina', 'localhost', self.name + '.xml')

        self.config = {}
        self.type = None
        self.prefix = None

        # custom subsystem location
        self.doc_base = os.path.join(self.base_dir, 'webapps', self.name)

    def load(self):
        self.config.clear()

        lines = open(self.cs_conf).read().splitlines()

        for line in lines:
            parts = line.split('=', 1)
            name = parts[0]
            value = parts[1]
            self.config[name] = value

        self.type = self.config['cs.type']
        self.prefix = self.type.lower()

    def find_subsystem_certs(self):
        certs = []

        cert_ids = self.config['%s.cert.list' % self.name].split(',')
        for cert_id in cert_ids:
            cert = self.create_subsystem_cert_object(cert_id)
            certs.append(cert)

        return certs

    def get_subsystem_cert(self, cert_id):
        return self.create_subsystem_cert_object(cert_id)

    def create_subsystem_cert_object(self, cert_id):
        cert = {}
        cert['id'] = cert_id
        cert['nickname'] = self.config.get('%s.%s.nickname' % (self.name, cert_id), None)
        cert['token'] = self.config.get('%s.%s.tokenname' % (self.name, cert_id), None)
        cert['data'] = self.config.get('%s.%s.cert' % (self.name, cert_id), None)
        cert['request'] = self.config.get('%s.%s.certreq' % (self.name, cert_id), None)
        return cert

    def update_subsystem_cert(self, cert):
        cert_id = cert['id']
        self.config['%s.%s.nickname' % (self.name, cert_id)] = cert.get('nickname', None)
        self.config['%s.%s.tokenname' % (self.name, cert_id)] = cert.get('token', None)
        self.config['%s.%s.cert' % (self.name, cert_id)] = cert.get('data', None)
        self.config['%s.%s.certreq' % (self.name, cert_id)] = cert.get('request', None)

    def save(self):
        sorted_config = sorted(self.config.items(), key=operator.itemgetter(0))
        with io.open(self.cs_conf, 'wb') as f:
            for (key, value) in sorted_config:
                f.write('%s=%s\n' % (key, value))

    def is_valid(self):
        return os.path.exists(self.conf_dir)

    def validate(self):
        if not self.is_valid():
            raise pki.PKIException(
                'Invalid subsystem: ' + self.__repr__(),
                None, self.instance)

    def is_enabled(self):
        return self.instance.is_deployed(self.name)

    def enable(self):
        if os.path.exists(self.doc_base):
            # deploy custom subsystem if exists
            doc_base = self.doc_base

        else:
            # otherwise deploy default subsystem directly from
            # /usr/share/pki/<subsystem>/webapps/<subsystem>
            doc_base = None

        self.instance.deploy(self.name, self.context_xml_template, doc_base)

    def disable(self):
        self.instance.undeploy(self.name)

    def open_database(self, name='internaldb'):

        # TODO: add LDAPI support
        hostname = self.config['%s.ldapconn.host' % name]
        port = self.config['%s.ldapconn.port' % name]
        secure = self.config['%s.ldapconn.secureConn' % name]

        if secure == 'true':
            url = 'ldaps://%s:%s' % (hostname, port)

        elif secure == 'false':
            url = 'ldap://%s:%s' % (hostname, port)

        else:
            raise Exception('Invalid parameter value in %s.ldapconn.secureConn: %s' % (name, secure))

        connection = PKIDatabaseConnection(url)

        connection.set_security_database(self.instance.nssdb_dir)

        auth_type = self.config['%s.ldapauth.authtype' % name]
        if auth_type == 'BasicAuth':
            connection.set_credentials(
                bind_dn=self.config['%s.ldapauth.bindDN' % name],
                bind_password=self.instance.get_password(name)
            )

        elif auth_type == 'SslClientAuth':
            connection.set_credentials(
                client_cert_nickname=self.config['%s.ldapauth.clientCertNickname' % name],
                nssdb_password=self.instance.get_password('internal')
            )

        else:
            raise Exception('Invalid parameter value in %s.ldapauth.authtype: %s' % (name, auth_type))

        connection.open()

        return connection

    def __repr__(self):
        return str(self.instance) + '/' + self.name


class PKIInstance(object):

    def __init__(self, name, instanceType=10):

        self.name = name
        self.type = instanceType

        if self.type >= 10:
            self.base_dir = os.path.join(INSTANCE_BASE_DIR, name)
        else:
            self.base_dir = os.path.join(pki.BASE_DIR, name)

        self.conf_dir = os.path.join(self.base_dir, 'conf')
        self.password_conf = os.path.join(self.conf_dir, 'password.conf')

        self.nssdb_dir = os.path.join(self.base_dir, 'alias')
        self.lib_dir = os.path.join(self.base_dir, 'lib')

        self.registry_dir = os.path.join(pki.server.REGISTRY_DIR, 'tomcat', self.name)
        self.registry_file = os.path.join(self.registry_dir, self.name)

        self.service_name = 'pki-tomcatd@%s.service' % self.name

        self.user = None
        self.group = None

        self.uid = None
        self.gid = None

        self.passwords = {}

        self.subsystems = []

    def is_valid(self):
        return os.path.exists(self.conf_dir)

    def validate(self):
        if not self.is_valid():
            raise pki.PKIException(
                'Invalid instance: ' + self.__repr__(), None)

    def start(self):
        subprocess.check_call(['systemctl', 'start', self.service_name])

    def stop(self):
        subprocess.check_call(['systemctl', 'stop', self.service_name])

    def is_active(self):
        rc = subprocess.call(['systemctl', '--quiet', 'is-active', self.service_name])
        return rc == 0

    def load(self):
        # load UID and GID
        with open(self.registry_file, 'r') as registry:
            lines = registry.readlines()

        for line in lines:

            m = re.search('^PKI_USER=(.*)$', line)
            if m:
                self.user = m.group(1)
                self.uid = pwd.getpwnam(self.user).pw_uid

            m = re.search('^PKI_GROUP=(.*)$', line)
            if m:
                self.group = m.group(1)
                self.gid = grp.getgrnam(self.group).gr_gid

        # load passwords
        self.passwords.clear()
        lines = open(self.password_conf).read().splitlines()

        for line in lines:
            parts = line.split('=', 1)
            name = parts[0]
            value = parts[1]
            self.passwords[name] = value

        # load subsystems
        for subsystem_name in os.listdir(self.registry_dir):
            if subsystem_name in SUBSYSTEM_TYPES:
                if subsystem_name in SUBSYSTEM_CLASSES:
                    subsystem = SUBSYSTEM_CLASSES[subsystem_name](self)
                else:
                    subsystem = PKISubsystem(self, subsystem_name)
                subsystem.load()
                self.subsystems.append(subsystem)

    def get_password(self, name):
        if name in self.passwords:
            return self.passwords[name]

        password = getpass.getpass(prompt='Enter password for %s: ' % name)
        self.passwords[name] = password

        return password

    def get_subsystem(self, name):
        for subsystem in self.subsystems:
            if name == subsystem.name:
                return subsystem
        return None

    def is_deployed(self, webapp_name):
        context_xml = os.path.join(
            self.conf_dir, 'Catalina', 'localhost', webapp_name + '.xml')
        return os.path.exists(context_xml)

    def deploy(self, webapp_name, descriptor, doc_base=None):
        """
        Deploy a web application into a Tomcat instance.

        This method will copy the specified deployment descriptor into
        <instance>/conf/Catalina/localhost/<name>.xml and point the docBase
        to the specified location. The web application will become available
        under "/<name>" URL path.

        See also: http://tomcat.apache.org/tomcat-7.0-doc/config/context.html

        :param webapp_name: Web application name.
        :type webapp_name: str
        :param descriptor: Path to deployment descriptor (context.xml).
        :type descriptor: str
        :param doc_base: Path to web application content.
        :type doc_base: str
        """

        context_xml = os.path.join(
            self.conf_dir, 'Catalina', 'localhost', webapp_name + '.xml')

        # read deployment descriptor
        parser = etree.XMLParser(remove_blank_text=True)
        document = etree.parse(descriptor, parser)

        if doc_base:
            # customize docBase
            context = document.getroot()
            context.set('docBase', doc_base)

        # write deployment descriptor
        with open(context_xml, 'w') as f:
            f.write(etree.tostring(document, pretty_print=True))

        # set deployment descriptor ownership and permission
        os.chown(context_xml, self.uid, self.gid)
        os.chmod(context_xml, 00660)

    def undeploy(self, webapp_name):
        context_xml = os.path.join(
            self.conf_dir, 'Catalina', 'localhost', webapp_name + '.xml')
        os.remove(context_xml)

    def __repr__(self):
        if self.type == 9:
            return "Dogtag 9 " + self.name
        return self.name


class PKIDatabaseConnection(object):

    def __init__(self, url='ldap://localhost:389'):

        self.url = url

        self.nssdb_dir = None

        self.bind_dn = None
        self.bind_password = None

        self.client_cert_nickname = None
        self.nssdb_password = None

        self.temp_dir = None
        self.ldap = None

    def set_security_database(self, nssdb_dir=None):
        self.nssdb_dir = nssdb_dir

    def set_credentials(self, bind_dn=None, bind_password=None,
            client_cert_nickname=None, nssdb_password=None):
        self.bind_dn = bind_dn
        self.bind_password = bind_password
        self.client_cert_nickname = client_cert_nickname
        self.nssdb_password = nssdb_password

    def open(self):

        self.temp_dir = tempfile.mkdtemp()

        if self.nssdb_dir:

            ldap.set_option(ldap.OPT_X_TLS_CACERTDIR, self.nssdb_dir)

        if self.client_cert_nickname:

            password_file = os.path.join(self.temp_dir, 'password.txt')
            with open(password_file, 'w') as f:
                f.write(self.nssdb_password)

            ldap.set_option(ldap.OPT_X_TLS_CERTFILE, self.client_cert_nickname)
            ldap.set_option(ldap.OPT_X_TLS_KEYFILE, password_file)

        self.ldap = ldap.initialize(self.url)

        if self.bind_dn and self.bind_password:
            self.ldap.simple_bind_s(self.bind_dn, self.bind_password)

    def close(self):

        if self.ldap:
            self.ldap.unbind_s()

        if self.temp_dir:
            shutil.rmtree(self.temp_dir)


class PKIServerException(pki.PKIException):

    def __init__(self, message, exception=None,
                 instance=None, subsystem=None):

        pki.PKIException.__init__(self, message, exception)

        self.instance = instance
        self.subsystem = subsystem


class Tomcat(object):

    @classmethod
    def get_major_version(self):

        # run "tomcat version"
        output = subprocess.check_output(['/usr/sbin/tomcat', 'version'])

        # find "Server version: Apache Tomcat/<major version>.<minor version>"
        match = re.search(r'^Server version:[^/]*/(\d+).*$', output, re.MULTILINE)

        if not match:
            raise Exception('Unable to determine Tomcat version')

        # return major version
        return match.group(1)