# Authors: Jan Cholasta <jcholast@redhat.com>
#
# Copyright (C) 2014  Red Hat
# see file 'COPYING' for use and warranty information
#
# 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, either version 3 of the License, or
# (at your option) any later version.
#
# 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 __future__ import print_function

import os
from optparse import OptionGroup  # pylint: disable=deprecated-module
from cryptography.hazmat.primitives import serialization
import gssapi

from ipapython import admintool, certmonger, ipautil
from ipapython.dn import DN
from ipaplatform.paths import paths
from ipalib import api, errors, x509, certstore
from ipaserver.install import certs, cainstance, installutils


class CACertManage(admintool.AdminTool):
    command_name = 'ipa-cacert-manage'

    usage = "%prog renew [options]\n%prog install [options] CERTFILE"

    description = "Manage CA certificates."

    cert_nickname = 'caSigningCert cert-pki-ca'

    @classmethod
    def add_options(cls, parser):
        super(CACertManage, cls).add_options(parser)

        parser.add_option(
            "-p", "--password", dest='password',
            help="Directory Manager password")

        renew_group = OptionGroup(parser, "Renew options")
        renew_group.add_option(
            "--self-signed", dest='self_signed',
            action='store_true',
            help="Sign the renewed certificate by itself")
        renew_group.add_option(
            "--external-ca", dest='self_signed',
            action='store_false',
            help="Sign the renewed certificate by external CA")
        renew_group.add_option(
            "--external-cert-file", dest="external_cert_files",
            action="append", metavar="FILE",
            help="File containing the IPA CA certificate and the external CA "
                 "certificate chain")
        parser.add_option_group(renew_group)

        install_group = OptionGroup(parser, "Install options")
        install_group.add_option(
            "-n", "--nickname", dest='nickname',
            help="Nickname for the certificate")
        install_group.add_option(
            "-t", "--trust-flags", dest='trust_flags', default='C,,',
            help="Trust flags for the certificate in certutil format")
        parser.add_option_group(install_group)

    def validate_options(self):
        super(CACertManage, self).validate_options(needs_root=True)

        installutils.check_server_configuration()

        parser = self.option_parser

        if not self.args:
            parser.error("command not provided")

        command = self.command = self.args[0]

        if command == 'renew':
            pass
        elif command == 'install':
            if len(self.args) < 2:
                parser.error("certificate file name not provided")
        else:
            parser.error("unknown command \"%s\"" % command)

    def run(self):
        command = self.command

        api.bootstrap(in_server=True)
        api.finalize()

        self.ldap_connect()

        try:
            if command == 'renew':
                rc = self.renew()
            elif command == 'install':
                rc = self.install()
        finally:
            api.Backend.ldap2.disconnect()

        return rc

    def ldap_connect(self):
        password = self.options.password
        if not password:
            try:
                api.Backend.ldap2.connect(ccache=os.environ.get('KRB5CCNAME'))
            except (gssapi.exceptions.GSSError, errors.ACIError):
                pass
            else:
                return

            password = installutils.read_password(
                "Directory Manager", confirm=False, validate=False)
            if password is None:
                raise admintool.ScriptError(
                    "Directory Manager password required")

        api.Backend.ldap2.connect(bind_pw=password)

    def renew(self):
        ca = cainstance.CAInstance(api.env.realm, certs.NSS_DIR)
        if not ca.is_configured():
            raise admintool.ScriptError("CA is not configured on this system")

        criteria = {
            'cert-database': paths.PKI_TOMCAT_ALIAS_DIR,
            'cert-nickname': self.cert_nickname,
            'ca-name': 'dogtag-ipa-ca-renew-agent',
        }
        self.request_id = certmonger.get_request_id(criteria)
        if self.request_id is None:
            raise admintool.ScriptError(
                "CA certificate is not tracked by certmonger")
        self.log.debug(
            "Found certmonger request id %r", self.request_id)

        db = certs.CertDB(api.env.realm, nssdir=paths.PKI_TOMCAT_ALIAS_DIR)
        cert = db.get_cert_from_db(self.cert_nickname, pem=False)

        options = self.options
        if options.external_cert_files:
            return self.renew_external_step_2(ca, cert)

        if options.self_signed is not None:
            self_signed = options.self_signed
        else:
            self_signed = x509.is_self_signed(cert, x509.DER)

        if self_signed:
            return self.renew_self_signed(ca)
        else:
            return self.renew_external_step_1(ca)

    def renew_self_signed(self, ca):
        print("Renewing CA certificate, please wait")

        try:
            ca.set_renewal_master()
        except errors.NotFound:
            raise admintool.ScriptError("CA renewal master not found")

        self.resubmit_request(ca, 'caCACert')

        print("CA certificate successfully renewed")

    def renew_external_step_1(self, ca):
        print("Exporting CA certificate signing request, please wait")

        self.resubmit_request(ca, 'ipaCSRExport')

        print(("The next step is to get %s signed by your CA and re-run "
              "ipa-cacert-manage as:" % paths.IPA_CA_CSR))
        print("ipa-cacert-manage renew "
              "--external-cert-file=/path/to/signed_certificate "
              "--external-cert-file=/path/to/external_ca_certificate")

    def renew_external_step_2(self, ca, old_cert_der):
        print("Importing the renewed CA certificate, please wait")

        options = self.options
        conn = api.Backend.ldap2
        cert_file, ca_file = installutils.load_external_cert(
            options.external_cert_files, x509.subject_base())

        old_cert_obj = x509.load_certificate(old_cert_der, x509.DER)
        old_der_subject = x509.get_der_subject(old_cert_der, x509.DER)
        old_spki = old_cert_obj.public_key().public_bytes(
            serialization.Encoding.DER,
            serialization.PublicFormat.SubjectPublicKeyInfo
        )

        with open(cert_file.name) as f:
            new_cert_data = f.read()
        new_cert_der = x509.normalize_certificate(new_cert_data)
        new_cert_obj = x509.load_certificate(new_cert_der, x509.DER)
        new_der_subject = x509.get_der_subject(new_cert_der, x509.DER)
        new_spki = new_cert_obj.public_key().public_bytes(
            serialization.Encoding.DER,
            serialization.PublicFormat.SubjectPublicKeyInfo
        )

        if new_cert_obj.subject != old_cert_obj.subject:
            raise admintool.ScriptError(
                "Subject name mismatch (visit "
                "http://www.freeipa.org/page/Troubleshooting for "
                "troubleshooting guide)")
        if new_der_subject != old_der_subject:
            raise admintool.ScriptError(
                "Subject name encoding mismatch (visit "
                "http://www.freeipa.org/page/Troubleshooting for "
                "troubleshooting guide)")
        if new_spki != old_spki:
            raise admintool.ScriptError(
                "Subject public key info mismatch (visit "
                "http://www.freeipa.org/page/Troubleshooting for "
                "troubleshooting guide)")

        with certs.NSSDatabase() as tmpdb:
            pw = ipautil.write_tmp_file(ipautil.ipa_generate_password())
            tmpdb.create_db(pw.name)
            tmpdb.add_cert(old_cert_der, 'IPA CA', 'C,,')

            try:
                tmpdb.add_cert(new_cert_der, 'IPA CA', 'C,,')
            except ipautil.CalledProcessError as e:
                raise admintool.ScriptError(
                    "Not compatible with the current CA certificate: %s" % e)

            ca_certs = x509.load_certificate_list_from_file(ca_file.name)
            for ca_cert in ca_certs:
                data = ca_cert.public_bytes(serialization.Encoding.DER)
                tmpdb.add_cert(data, str(DN(ca_cert.subject)), 'C,,')

            try:
                tmpdb.verify_ca_cert_validity('IPA CA')
            except ValueError as e:
                raise admintool.ScriptError(
                    "Not a valid CA certificate: %s (visit "
                    "http://www.freeipa.org/page/Troubleshooting for "
                    "troubleshooting guide)" % e)

            trust_chain = tmpdb.get_trust_chain('IPA CA')[:-1]
            for nickname in trust_chain:
                try:
                    ca_cert = tmpdb.get_cert(nickname)
                except RuntimeError:
                    break
                certstore.put_ca_cert_nss(
                    conn, api.env.basedn, ca_cert, nickname, ',,')

        dn = DN(('cn', self.cert_nickname), ('cn', 'ca_renewal'),
                ('cn', 'ipa'), ('cn', 'etc'), api.env.basedn)
        try:
            entry = conn.get_entry(dn, ['usercertificate'])
            entry['usercertificate'] = [new_cert_der]
            conn.update_entry(entry)
        except errors.NotFound:
            entry = conn.make_entry(
                dn,
                objectclass=['top', 'pkiuser', 'nscontainer'],
                cn=[self.cert_nickname],
                usercertificate=[new_cert_der])
            conn.add_entry(entry)
        except errors.EmptyModlist:
            pass

        try:
            ca.set_renewal_master()
        except errors.NotFound:
            raise admintool.ScriptError("CA renewal master not found")

        self.resubmit_request(ca, 'ipaRetrieval')

        print("CA certificate successfully renewed")

    def resubmit_request(self, ca, profile):
        timeout = api.env.startup_timeout + 60

        self.log.debug("resubmitting certmonger request '%s'", self.request_id)
        certmonger.resubmit_request(self.request_id, profile=profile)
        try:
            state = certmonger.wait_for_request(self.request_id, timeout)
        except RuntimeError:
            raise admintool.ScriptError(
                "Resubmitting certmonger request '%s' timed out, "
                "please check the request manually" % self.request_id)
        ca_error = certmonger.get_request_value(self.request_id, 'ca-error')
        if state != 'MONITORING' or ca_error:
            raise admintool.ScriptError(
                "Error resubmitting certmonger request '%s', "
                "please check the request manually" % self.request_id)

        self.log.debug("modifying certmonger request '%s'", self.request_id)
        certmonger.modify(self.request_id, profile='ipaCACertRenewal')

    def install(self):
        print("Installing CA certificate, please wait")

        options = self.options
        cert_filename = self.args[1]

        try:
            cert_obj = x509.load_certificate_from_file(cert_filename)
        except IOError as e:
            raise admintool.ScriptError(
                "Can't open \"%s\": %s" % (cert_filename, e))
        except (TypeError, ValueError) as e:
            raise admintool.ScriptError("Not a valid certificate: %s" % e)
        cert = cert_obj.public_bytes(serialization.Encoding.DER)

        nickname = options.nickname or str(DN(cert_obj.subject))

        ca_certs = certstore.get_ca_certs_nss(api.Backend.ldap2,
                                              api.env.basedn,
                                              api.env.realm,
                                              False)

        with certs.NSSDatabase() as tmpdb:
            pw = ipautil.write_tmp_file(ipautil.ipa_generate_password())
            tmpdb.create_db(pw.name)
            tmpdb.add_cert(cert, nickname, 'C,,')
            for ca_cert, ca_nickname, ca_trust_flags in ca_certs:
                tmpdb.add_cert(ca_cert, ca_nickname, ca_trust_flags)

            try:
                tmpdb.verify_ca_cert_validity(nickname)
            except ValueError as e:
                raise admintool.ScriptError(
                    "Not a valid CA certificate: %s (visit "
                    "http://www.freeipa.org/page/Troubleshooting for "
                    "troubleshooting guide)" % e)

        trust_flags = options.trust_flags
        if ((set(trust_flags) - set(',CPTcgpuw')) or
            len(trust_flags.split(',')) != 3):
            raise admintool.ScriptError("Invalid trust flags")

        try:
            certstore.put_ca_cert_nss(
                api.Backend.ldap2, api.env.basedn, cert, nickname, trust_flags)
        except ValueError as e:
            raise admintool.ScriptError(
                "Failed to install the certificate: %s" % e)

        print("CA certificate successfully installed")