#!/usr/bin/env python3
#
# Copyright (C) 2019 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 sys
import os
from copy import deepcopy

import jinja2

import vyos.defaults
import vyos.certbot_util
from vyos.config import Config
from vyos import ConfigError

config_file = '/etc/nginx/sites-available/default'

# Please be careful if you edit the template.
config_tmpl = """

### Autogenerated by https.py ###
# Default server configuration
#
server {
        listen 80 default_server;
        listen [::]:80 default_server;
        server_name _;
        return 301 https://$server_name$request_uri;
}

{% for server in server_block_list %}
server {

        # SSL configuration
        #
{% if server.address == '*' %}
        listen {{ server.port }} ssl;
        listen [::]:{{ server.port }} ssl;
{% else %}
        listen {{ server.address }}:{{ server.port }} ssl;
{% endif %}

{% for name in server.name %}
        server_name {{ name }};
{% endfor %}

{% if server.certbot %}
        ssl_certificate /etc/letsencrypt/live/{{ server.certbot_dir }}/fullchain.pem;
        ssl_certificate_key /etc/letsencrypt/live/{{ server.certbot_dir }}/privkey.pem;
        include /etc/letsencrypt/options-ssl-nginx.conf;
        ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
{% elif server.vyos_cert %}
        include {{ server.vyos_cert.conf }};
{% else %}
        #
        # Self signed certs generated by the ssl-cert package
        # Don't use them in a production server!
        #
        include snippets/snakeoil.conf;
{% endif %}

        # proxy settings for HTTP API, if enabled; 503, if not
        location ~ /(retrieve|configure|config-file|image|generate|show) {
{% if server.api %}
                proxy_pass http://localhost:{{ server.api.port }};
                proxy_buffering off;
{% else %}
                return 503;
{% endif %}
        }

        error_page 501 502 503 =200 @50*_json;

        location @50*_json {
                default_type application/json;
                return 200 '{"error": "Start service in configuration mode: set service https api"}';
        }

}

{% endfor %}
"""

default_server_block = {
    'address'   : '*',
    'port'      : '443',
    'name'      : ['_'],
    'api'       : {},
    'vyos_cert' : {},
    'certbot'   : False
}

def get_config():
    server_block_list = []
    conf = Config()
    if not conf.exists('service https'):
        return None
    else:
        conf.set_level('service https')

    if not conf.exists('virtual-host'):
        server_block_list.append(default_server_block)
    else:
        for vhost in conf.list_nodes('virtual-host'):
            server_block = deepcopy(default_server_block)
            if conf.exists(f'virtual-host {vhost} listen-address'):
                addr = conf.return_value(f'virtual-host {vhost} listen-address')
                server_block['address'] = addr
            if conf.exists(f'virtual-host {vhost} listen-port'):
                port = conf.return_value(f'virtual-host {vhost} listen-port')
                server_block['port'] = port
            if conf.exists(f'virtual-host {vhost} server-name'):
                names = conf.return_values(f'virtual-host {vhost} server-name')
                server_block['name'] = names[:]
            server_block_list.append(server_block)

    vyos_cert_data = {}
    if conf.exists('certificates system-generated-certificate'):
        vyos_cert_data = vyos.defaults.vyos_cert_data
    if vyos_cert_data:
        for block in server_block_list:
            block['vyos_cert'] = vyos_cert_data

    certbot = False
    certbot_domains = []
    if conf.exists('certificates certbot domain-name'):
        certbot_domains = conf.return_values('certificates certbot domain-name')
    if certbot_domains:
        certbot = True
        for domain in certbot_domains:
            sub_list = vyos.certbot_util.choose_server_block(server_block_list,
                                                             domain)
            if sub_list:
                for sb in sub_list:
                    sb['certbot'] = True
                    # certbot organizes certificates by first domain
                    sb['certbot_dir'] = certbot_domains[0]

    api_data = {}
    if conf.exists('api'):
        api_data = vyos.defaults.api_data
        if conf.exists('api port'):
            port = conf.return_value('api port')
            api_data['port'] = port
    if api_data:
        for block in server_block_list:
            block['api'] = api_data

    https = {'server_block_list' : server_block_list, 'certbot': certbot}
    return https

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

    if https['certbot']:
        for sb in https['server_block_list']:
            if sb['certbot']:
                return None
        raise ConfigError("At least one 'virtual-host <id> server-name' "
                          "matching the 'certbot domain-name' is required.")
    return None

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

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

    tmpl = jinja2.Template(config_tmpl, trim_blocks=True)
    config_text = tmpl.render(https)
    with open(config_file, 'w') as f:
        f.write(config_text)

    return None

def apply(https):
    if https is not None:
        os.system('sudo systemctl restart nginx.service')
    else:
        os.system('sudo 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)