#!/usr/bin/env python3
#
# Copyright (C) 2020 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
import grp
import re
import json
import logging
import signal
import importlib.util
import zmq

from vyos.defaults import directories
from vyos.configsource import ConfigSourceString
from vyos.config import Config
from vyos import ConfigError

CFG_GROUP = 'vyattacfg'

debug = True

logger = logging.getLogger(__name__)
logs_handler = logging.StreamHandler()
logger.addHandler(logs_handler)

if debug:
    logger.setLevel(logging.DEBUG)
else:
    logger.setLevel(logging.INFO)

SOCKET_PATH = "ipc:///run/vyos-configd.sock"

# Response error codes
R_SUCCESS = 1
R_ERROR_COMMIT = 2
R_ERROR_DAEMON = 4
R_PASS = 8

vyos_conf_scripts_dir = directories['conf_mode']
configd_include_file = os.path.join(directories['data'], 'configd-include.json')
configd_env_set_file = os.path.join(directories['data'], 'vyos-configd-env-set')
configd_env_unset_file = os.path.join(directories['data'], 'vyos-configd-env-unset')
# sourced on entering config session
configd_env_file = '/etc/default/vyos-configd-env'

active_string = ''
session_string = ''

session_tty = None

def key_name_from_file_name(f):
    return os.path.splitext(f)[0]

def module_name_from_key(k):
    return k.replace('-', '_')

def path_from_file_name(f):
    return os.path.join(vyos_conf_scripts_dir, f)

# opt-in to be run by daemon
with open(configd_include_file) as f:
    try:
        include = json.load(f)
    except OSError as e:
        logger.critical(f"configd include file error: {e}")
        sys.exit(1)
    except json.JSONDecodeError as e:
        logger.critical(f"JSON load error: {e}")
        sys.exit(1)

# import conf_mode scripts
(_, _, filenames) = next(iter(os.walk(vyos_conf_scripts_dir)))
filenames.sort()

load_filenames = [f for f in filenames if f in include]
imports = [key_name_from_file_name(f) for f in load_filenames]
module_names = [module_name_from_key(k) for k in imports]
paths = [path_from_file_name(f) for f in load_filenames]
to_load = list(zip(module_names, paths))

modules = []

for x in to_load:
    spec = importlib.util.spec_from_file_location(x[0], x[1])
    module = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(module)
    modules.append(module)

conf_mode_scripts = dict(zip(imports, modules))

exclude_set = {key_name_from_file_name(f) for f in filenames if f not in include}
include_set = {key_name_from_file_name(f) for f in filenames if f in include}

def explicit_print(t, m):
    try:
        with open(t, 'w') as f:
            f.write(m)
            f.write("\n")
            f.flush()
    except Exception:
        pass

def run_script(script, config) -> int:
    config.set_level([])
    try:
        c = script.get_config(config)
        script.verify(c)
        script.generate(c)
        script.apply(c)
    except ConfigError as e:
        logger.critical(e)
        explicit_print(session_tty, str(e))
        return R_ERROR_COMMIT
    except Exception:
        return R_ERROR_DAEMON

    return R_SUCCESS

def initialization(socket):
    global session_tty
    # Reset config strings:
    active_string = ''
    session_string = ''
    # zmq synchronous for ipc from single client:
    active_string = socket.recv().decode()
    resp = "active"
    socket.send(resp.encode())
    session_string = socket.recv().decode()
    resp = "session"
    socket.send(resp.encode())
    pid_string = socket.recv().decode()
    resp = "pid"
    socket.send(resp.encode())

    logger.debug(f"config session pid is {pid_string}")
    try:
        session_tty = os.readlink(f"/proc/{pid_string}/fd/1")
    except FileNotFoundError:
        session_tty = None

    configsource = ConfigSourceString(running_config_text=active_string,
                                      session_config_text=session_string)

    config = Config(config_source=configsource)

    return config

def process_node_data(config, data) -> int:
    if not config:
        logger.critical(f"Empty config")
        return R_ERROR_DAEMON

    script_name = None

    res = re.match(r'^.+\/([^/].+).py(VYOS_TAGNODE_VALUE=.+)?', data)
    if res.group(1):
        script_name = res.group(1)
    if res.group(2):
        env = res.group(2).split('=')
        os.environ[env[0]] = env[1]

    if not script_name:
        logger.critical(f"Missing script_name")
        return R_ERROR_DAEMON

    if script_name in exclude_set:
        return R_PASS

    result = run_script(conf_mode_scripts[script_name], config)

    return result

def remove_if_file(f: str):
    try:
        os.remove(f)
    except FileNotFoundError:
        pass
    except OSError:
        raise

def shutdown():
    remove_if_file(configd_env_file)
    os.symlink(configd_env_unset_file, configd_env_file)
    sys.exit(0)

if __name__ == '__main__':
    context = zmq.Context()
    socket = context.socket(zmq.REP)

    # Set the right permissions on the socket, then change it back
    o_mask = os.umask(0)
    socket.bind(SOCKET_PATH)
    os.umask(o_mask)

    cfg_group = grp.getgrnam(CFG_GROUP)
    os.setgid(cfg_group.gr_gid)

    os.environ['SUDO_USER'] = 'vyos'
    os.environ['SUDO_GID'] = str(cfg_group.gr_gid)

    def sig_handler(signum, frame):
        shutdown()

    signal.signal(signal.SIGTERM, sig_handler)
    signal.signal(signal.SIGINT, sig_handler)

    # Define the vyshim environment variable
    remove_if_file(configd_env_file)
    os.symlink(configd_env_set_file, configd_env_file)

    config = None

    while True:
        #  Wait for next request from client
        msg = socket.recv().decode()
        logger.debug(f"Received message: {msg}")
        message = json.loads(msg)

        if message["type"] == "init":
            resp = "init"
            socket.send(resp.encode())
            config = initialization(socket)
        elif message["type"] == "node":
            res = process_node_data(config, message["data"])
            response = res.to_bytes(1, byteorder=sys.byteorder)
            logger.debug(f"Sending response {res}")
            socket.send(response)
        else:
            logger.critical(f"Unexpected message: {message}")