#!/usr/bin/env python3
#
# Copyright (C) 2019-2022 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later 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/>.

import os
import sys

from copy import deepcopy

import vyos.defaults
import vyos.certbot_util

from vyos.config import Config
from vyos.configverify import verify_vrf
from vyos import ConfigError
from vyos.pki import wrap_certificate
from vyos.pki import wrap_private_key
from vyos.template import render
from vyos.utils.process import call
from vyos.utils.network import check_port_availability
from vyos.utils.network import is_listen_port_bind_service
from vyos.utils.file import write_file

from vyos import airbag
airbag.enable()

config_file = '/etc/nginx/sites-available/default'
systemd_override = r'/run/systemd/system/nginx.service.d/override.conf'
cert_dir = '/etc/ssl/certs'
key_dir = '/etc/ssl/private'
certbot_dir = vyos.defaults.directories['certbot']

# https config needs to coordinate several subsystems: api, certbot,
# self-signed certificate, as well as the virtual hosts defined within the
# https config definition itself. Consequently, one needs a general dict,
# encompassing the https and other configs, and a list of such virtual hosts
# (server blocks in nginx terminology) to pass to the jinja2 template.
default_server_block = {
    'id'        : '',
    'address'   : '*',
    'port'      : '443',
    'name'      : ['_'],
    'api'       : {},
    'vyos_cert' : {},
    'certbot'   : False
}

def get_config(config=None):
    if config:
        conf = config
    else:
        conf = Config()

    base = ['service', 'https']
    if not conf.exists(base):
        return None

    https = conf.get_config_dict(base, get_first_key=True)

    if https:
        https['pki'] = conf.get_config_dict(['pki'], key_mangling=('-', '_'),
                                get_first_key=True, no_tag_node_value_mangle=True)

    return https

def verify(https):
    if https is None:
        return None

    if 'certificates' in https:
        certificates = https['certificates']

        if 'certificate' in certificates:
            if not https['pki']:
                raise ConfigError("PKI is not configured")

            cert_name = certificates['certificate']

            if cert_name not in https['pki']['certificate']:
                raise ConfigError("Invalid certificate on https configuration")

            pki_cert = https['pki']['certificate'][cert_name]

            if 'certificate' not in pki_cert:
                raise ConfigError("Missing certificate on https configuration")

            if 'private' not in pki_cert or 'key' not in pki_cert['private']:
                raise ConfigError("Missing certificate private key on https configuration")

        if 'certbot' in https['certificates']:
            vhost_names = []
            for vh, vh_conf in https.get('virtual-host', {}).items():
                vhost_names += vh_conf.get('server-name', [])
            domains = https['certificates']['certbot'].get('domain-name', [])
            domains_found = [domain for domain in domains if domain in vhost_names]
            if not domains_found:
                raise ConfigError("At least one 'virtual-host <id> server-name' "
                              "matching the 'certbot domain-name' is required.")

    server_block_list = []

    # organize by vhosts
    vhost_dict = https.get('virtual-host', {})

    if not vhost_dict:
        # no specified virtual hosts (server blocks); use default
        server_block_list.append(default_server_block)
    else:
        for vhost in list(vhost_dict):
            server_block = deepcopy(default_server_block)
            data = vhost_dict.get(vhost, {})
            server_block['address'] = data.get('listen-address', '*')
            server_block['port'] = data.get('port', '443')
            server_block_list.append(server_block)

    for entry in server_block_list:
        _address = entry.get('address')
        _address = '0.0.0.0' if _address == '*' else _address
        _port = entry.get('port')
        proto = 'tcp'
        if check_port_availability(_address, int(_port), proto) is not True and \
                not is_listen_port_bind_service(int(_port), 'nginx'):
            raise ConfigError(f'"{proto}" port "{_port}" is used by another service')

    verify_vrf(https)
    return None

def generate(https):
    if https is None:
        return None

    server_block_list = []

    # organize by vhosts

    vhost_dict = https.get('virtual-host', {})

    if not vhost_dict:
        # no specified virtual hosts (server blocks); use default
        server_block_list.append(default_server_block)
    else:
        for vhost in list(vhost_dict):
            server_block = deepcopy(default_server_block)
            server_block['id'] = vhost
            data = vhost_dict.get(vhost, {})
            server_block['address'] = data.get('listen-address', '*')
            server_block['port'] = data.get('port', '443')
            name = data.get('server-name', ['_'])
            server_block['name'] = name
            allow_client = data.get('allow-client', {})
            server_block['allow_client'] = allow_client.get('address', [])
            server_block_list.append(server_block)

    # get certificate data

    cert_dict = https.get('certificates', {})

    if 'certificate' in cert_dict:
        cert_name = cert_dict['certificate']
        pki_cert = https['pki']['certificate'][cert_name]

        cert_path = os.path.join(cert_dir, f'{cert_name}.pem')
        key_path = os.path.join(key_dir, f'{cert_name}.pem')

        server_cert = str(wrap_certificate(pki_cert['certificate']))
        if 'ca-certificate' in cert_dict:
            ca_cert = cert_dict['ca-certificate']
            server_cert += '\n' + str(wrap_certificate(https['pki']['ca'][ca_cert]['certificate']))

        write_file(cert_path, server_cert)
        write_file(key_path, wrap_private_key(pki_cert['private']['key']))

        vyos_cert_data = {
            'crt': cert_path,
            'key': key_path
        }

        for block in server_block_list:
            block['vyos_cert'] = vyos_cert_data

    # letsencrypt certificate using certbot

    certbot = False
    cert_domains = cert_dict.get('certbot', {}).get('domain-name', [])
    if cert_domains:
        certbot = True
        for domain in cert_domains:
            sub_list = vyos.certbot_util.choose_server_block(server_block_list,
                                                             domain)
            if sub_list:
                for sb in sub_list:
                    sb['certbot'] = True
                    sb['certbot_dir'] = certbot_dir
                    # certbot organizes certificates by first domain
                    sb['certbot_domain_dir'] = cert_domains[0]

    # get api data

    api_set = False
    api_data = {}
    if 'api' in list(https):
        api_set = True
        api_data = vyos.defaults.api_data
    api_settings = https.get('api', {})
    if api_settings:
        vhosts = https.get('api-restrict', {}).get('virtual-host', [])
        if vhosts:
            api_data['vhost'] = vhosts[:]

    if api_data:
        vhost_list = api_data.get('vhost', [])
        if not vhost_list:
            for block in server_block_list:
                block['api'] = api_data
        else:
            for block in server_block_list:
                if block['id'] in vhost_list:
                    block['api'] = api_data

    if 'server_block_list' not in https or not https['server_block_list']:
        https['server_block_list'] = [default_server_block]

    data = {
        'server_block_list': server_block_list,
        'api_set': api_set,
        'certbot': certbot
    }

    render(config_file, 'https/nginx.default.j2', data)
    render(systemd_override, 'https/override.conf.j2', https)
    return None

def apply(https):
    # Reload systemd manager configuration
    call('systemctl daemon-reload')
    if https is not None:
        call('systemctl restart nginx.service')
    else:
        call('systemctl stop nginx.service')

if __name__ == '__main__':
    try:
        c = get_config()
        verify(c)
        generate(c)
        apply(c)
    except ConfigError as e:
        print(e)
        sys.exit(1)