#!/usr/bin/python
#
# Copyright (C) 2014  Simo Sorce <simo@redhat.com>
#
# 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 ipsilon.tools.saml2metadata import Metadata
from ipsilon.tools.saml2metadata import SAML2_NAMEID_MAP
from ipsilon.tools.saml2metadata import SAML2_SERVICE_MAP
from ipsilon.tools.certs import Certificate
from string import Template
import argparse
import logging
import os
import pwd
import requests
import shutil
import socket
import sys


HTTPDCONFD = '/etc/httpd/conf.d'
SAML2_TEMPLATE = '/usr/share/ipsilon/templates/install/saml2/sp.conf'
SAML2_CONFFILE = '/etc/httpd/conf.d/ipsilon-saml.conf'
SAML2_HTTPDIR = '/etc/httpd/saml2'
SAML2_PROTECTED = '/saml2protected'

#Installation arguments
args = dict()

# Regular logging
logger = logging.getLogger()


def openlogs():
    global logger  # pylint: disable=W0603
    logger = logging.getLogger()
    lh = logging.StreamHandler(sys.stderr)
    logger.addHandler(lh)


def saml2():
    logger.info('Installing SAML2 Service Provider')

    if args['saml_idp_metadata'] is None:
        #TODO: detect via SRV records ?
        raise ValueError('An IDP metadata file/url is required.')

    idpmeta = None

    try:
        if os.path.exists(args['saml_idp_metadata']):
            with open(args['saml_idp_metadata']) as f:
                idpmeta = f.read()
        elif args['saml_idp_metadata'].startswith('file://'):
            with open(args['saml_idp_metadata'][7:]) as f:
                idpmeta = f.read()
        else:
            r = requests.get(args['saml_idp_metadata'])
            r.raise_for_status()
            idpmeta = r.content
    except Exception, e:  # pylint: disable=broad-except
        logger.error("Failed to retrieve IDP Metadata file!\n" +
                     "Error: [%s]" % repr(e))
        raise

    path = None
    if args['saml_httpd']:
        path = os.path.join(SAML2_HTTPDIR, args['hostname'])
        os.makedirs(path, 0750)
    else:
        path = os.getcwd()

    url = 'https://' + args['hostname']
    url_sp = url + args['saml_sp']
    url_logout = url + args['saml_sp_logout']
    url_post = url + args['saml_sp_post']

    # Generate metadata
    m = Metadata('sp')
    c = Certificate(path)
    c.generate('certificate', args['hostname'])
    m.set_entity_id(url_sp)
    m.add_certs(c)
    m.add_service(SAML2_SERVICE_MAP['logout-redirect'], url_logout)
    m.add_service(SAML2_SERVICE_MAP['response-post'], url_post, index="0")
    sp_metafile = os.path.join(path, 'metadata.xml')
    m.output(sp_metafile)

    if args['saml_httpd']:
        idp_metafile = os.path.join(path, 'idp-metadata.xml')
        with open(idp_metafile, 'w+') as f:
            f.write(idpmeta)

        saml_protect = 'auth'
        saml_auth=''
        if args['saml_base'] != args['saml_auth']:
            saml_protect = 'info'
            saml_auth = '<Location %s>\n' \
                        '    MellonEnable "auth"\n' \
                        '</Location>\n' % args['saml_auth']

        psp = '# '
        if args['saml_auth'] == SAML2_PROTECTED:
            # default location, enable the default page
            psp = ''

        with open(SAML2_TEMPLATE) as f:
            template = f.read()
        t = Template(template)
        hunk = t.substitute(saml_base=args['saml_base'],
                            saml_protect=saml_protect,
                            saml_sp_key=c.key,
                            saml_sp_cert=c.cert,
                            saml_sp_meta=sp_metafile,
                            saml_idp_meta=idp_metafile,
                            saml_sp=args['saml_sp'],
                            saml_auth=saml_auth, sp=psp)

        with open(SAML2_CONFFILE, 'w+') as f:
            f.write(hunk)

        pw = pwd.getpwnam(args['httpd_user'])
        for root, dirs, files in os.walk(SAML2_HTTPDIR):
            for name in dirs:
                target = os.path.join(root, name)
                os.chown(target, pw.pw_uid, pw.pw_gid)
                os.chmod(target, 0700)
            for name in files:
                target = os.path.join(root, name)
                os.chown(target, pw.pw_uid, pw.pw_gid)
                os.chmod(target, 0600)

        logger.info('SAML Service Provider configured.')
        logger.info('You should be able to restart the HTTPD server and' +
                    ' then access it at %s%s' % (url, args['saml_auth']))
    else:
        logger.info('SAML Service Provider configuration ready.')
        logger.info('Use the certificate, key and metadata.xml files to' +
                    ' configure your Service Provider')


def install():
    if args['saml']:
        saml2()


def saml2_uninstall():
    try:
        shutil.rmtree(os.path.join(SAML2_HTTPDIR, args['hostname']))
    except Exception, e:  # pylint: disable=broad-except
        log_exception(e)
    try:
        os.remove(SAML2_CONFFILE)
    except Exception, e:  # pylint: disable=broad-except
        log_exception(e)


def uninstall():
    logger.info('Uninstalling Service Provider')
    #FXIME: ask confirmation
    saml2_uninstall()
    logger.info('Uninstalled SAML2 data')


def log_exception(e):
    if 'debug' in args and args['debug']:
        logger.exception(e)
    else:
        logger.error(e)


def parse_args():
    global args

    fc = argparse.ArgumentDefaultsHelpFormatter
    parser = argparse.ArgumentParser(description='Client Install Options',
                                     formatter_class=fc)
    parser.add_argument('--version',
                        action='version', version='%(prog)s 0.1')
    parser.add_argument('--hostname', default=socket.getfqdn(),
                        help="Machine's fully qualified host name")
    parser.add_argument('--admin-user', default='admin',
                        help="Account allowed to create a SP")
    parser.add_argument('--httpd-user', default='apache',
                        help="Web server account used to read certs")
    parser.add_argument('--saml', action='store_true', default=False,
                        help="Whether to install a saml2 SP")
    parser.add_argument('--saml-idp-metadata', default=None,
                        help="A URL pointing at the IDP Metadata (FILE or HTTP)")
    parser.add_argument('--saml-httpd', action='store_true', default=False,
                        help="Automatically configure httpd")
    parser.add_argument('--saml-base', default='/',
                        help="Where saml2 authdata is available")
    parser.add_argument('--saml-auth', default=SAML2_PROTECTED,
                        help="Where saml2 authentication is enforced")
    parser.add_argument('--saml-sp', default='/saml2',
                        help="Where saml communication happens")
    parser.add_argument('--saml-sp-logout', default='/saml2/logout',
                        help="Single Logout URL")
    parser.add_argument('--saml-sp-post', default='/saml2/postResponse',
                        help="Post response URL")
    parser.add_argument('--debug', action='store_true', default=False,
                        help="Turn on script debugging")
    parser.add_argument('--uninstall', action='store_true',
                        help="Uninstall the server and all data")

    args = vars(parser.parse_args())

    if len(args['hostname'].split('.')) < 2:
        raise ValueError('Hostname: %s is not a FQDN.')

    # At least one on this list needs to be specified or we do nothing
    sp_list = ['saml']
    present = False
    for sp in sp_list:
        if args[sp]:
            present = True
    if not present and not args['uninstall']:
        raise ValueError('Nothing to install, please select a Service type.')


if __name__ == '__main__':
    out = 0
    openlogs()
    try:
        parse_args()

        if 'uninstall' in args and args['uninstall'] is True:
            uninstall()

        install()
    except Exception, e:  # pylint: disable=broad-except
        log_exception(e)
        if 'uninstall' in args and args['uninstall'] is True:
            print 'Uninstallation aborted.'
        else:
            print 'Installation aborted.'
        out = 1
    finally:
        if out == 0:
            if 'uninstall' in args and args['uninstall'] is True:
                print 'Uninstallation complete.'
            else:
                print 'Installation complete.'
    sys.exit(out)