# -*- coding: utf-8 -*-

#  This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)
#    Copyright (C) 2012-2019 janeczku, OzzieIsaacs, andrerfcsantos, idalin
#
#  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 division, print_function, unicode_literals
import sys
import os
import errno
import signal
import socket

try:
    from gevent.pywsgi import WSGIServer
    from gevent.pool import Pool
    from gevent import __version__ as _version
    VERSION = 'Gevent ' + _version
    _GEVENT = True
except ImportError:
    from tornado.wsgi import WSGIContainer
    from tornado.httpserver import HTTPServer
    from tornado.ioloop import IOLoop
    from tornado import version as _version
    VERSION = 'Tornado ' + _version
    _GEVENT = False

from . import logger


log = logger.create()



def _readable_listen_address(address, port):
    if ':' in address:
        address = "[" + address + "]"
    return '%s:%s' % (address, port)


class WebServer(object):

    def __init__(self):
        signal.signal(signal.SIGINT, self._killServer)
        signal.signal(signal.SIGTERM, self._killServer)

        self.wsgiserver = None
        self.access_logger = None
        self.restart = False
        self.app = None
        self.listen_address = None
        self.listen_port = None
        self.unix_socket_file = None
        self.ssl_args = None

    def init_app(self, application, config):
        self.app = application
        self.listen_address = config.get_config_ipaddress()
        self.listen_port = config.config_port

        if config.config_access_log:
            log_name = "gevent.access" if _GEVENT else "tornado.access"
            formatter = logger.ACCESS_FORMATTER_GEVENT if _GEVENT else logger.ACCESS_FORMATTER_TORNADO
            self.access_logger = logger.create_access_log(config.config_access_logfile, log_name, formatter)
        else:
            if not _GEVENT:
                logger.get('tornado.access').disabled = True

        certfile_path = config.get_config_certfile()
        keyfile_path = config.get_config_keyfile()
        if certfile_path and keyfile_path:
            if os.path.isfile(certfile_path) and os.path.isfile(keyfile_path):
                self.ssl_args = dict(certfile=certfile_path, keyfile=keyfile_path)
            else:
                log.warning('The specified paths for the ssl certificate file and/or key file seem to be broken. Ignoring ssl.')
                log.warning('Cert path: %s', certfile_path)
                log.warning('Key path:  %s', keyfile_path)

    def _make_gevent_unix_socket(self, socket_file):
        # the socket file must not exist prior to bind()
        if os.path.exists(socket_file):
            # avoid nuking regular files and symbolic links (could be a mistype or security issue)
            if os.path.isfile(socket_file) or os.path.islink(socket_file):
                raise OSError(errno.EEXIST, os.strerror(errno.EEXIST), socket_file)
            os.remove(socket_file)

        unix_sock = WSGIServer.get_listener(socket_file, family=socket.AF_UNIX)
        self.unix_socket_file = socket_file

        # ensure current user and group have r/w permissions, no permissions for other users
        # this way the socket can be shared in a semi-secure manner
        # between the user running calibre-web and the user running the fronting webserver
        os.chmod(socket_file, 0o660)

        return unix_sock

    def _make_gevent_socket(self):
        if os.name != 'nt':
            unix_socket_file = os.environ.get("CALIBRE_UNIX_SOCKET")
            if unix_socket_file:
                return self._make_gevent_unix_socket(unix_socket_file), "unix:" + unix_socket_file

        if self.listen_address:
            return (self.listen_address, self.listen_port), None

        if os.name == 'nt':
            self.listen_address = '0.0.0.0'
            return (self.listen_address, self.listen_port), None

        try:
            address = ('::', self.listen_port)
            sock = WSGIServer.get_listener(address, family=socket.AF_INET6)
        except socket.error as ex:
            log.error('%s', ex)
            log.warning('Unable to listen on "", trying on IPv4 only...')
            address = ('', self.listen_port)
            sock = WSGIServer.get_listener(address, family=socket.AF_INET)

        return sock, _readable_listen_address(*address)

    def _start_gevent(self):
        ssl_args = self.ssl_args or {}

        try:
            sock, output = self._make_gevent_socket()
            if output is None:
                output = _readable_listen_address(self.listen_address, self.listen_port)
            log.info('Starting Gevent server on %s', output)
            self.wsgiserver = WSGIServer(sock, self.app, log=self.access_logger, spawn=Pool(), **ssl_args)
            self.wsgiserver.serve_forever()
        finally:
            if self.unix_socket_file:
                os.remove(self.unix_socket_file)
                self.unix_socket_file = None

    def _start_tornado(self):
        if os.name == 'nt' and sys.version_info > (3, 7):
            import asyncio
            asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
        log.info('Starting Tornado server on %s', _readable_listen_address(self.listen_address, self.listen_port))

        # Max Buffersize set to 200MB            )
        http_server = HTTPServer(WSGIContainer(self.app),
                                 max_buffer_size=209700000,
                                 ssl_options=self.ssl_args)
        http_server.listen(self.listen_port, self.listen_address)
        self.wsgiserver = IOLoop.current()
        self.wsgiserver.start()
        # wait for stop signal
        self.wsgiserver.close(True)

    def start(self):
        try:
            if _GEVENT:
                # leave subprocess out to allow forking for fetchers and processors
                self._start_gevent()
            else:
                self._start_tornado()
        except Exception as ex:
            log.error("Error starting server: %s", ex)
            print("Error starting server: %s" % ex)
            self.stop()
            return False
        finally:
            self.wsgiserver = None

        if not self.restart:
            log.info("Performing shutdown of Calibre-Web")
            # prevent irritiating log of pending tasks message from asyncio
            logger.get('asyncio').setLevel(logger.logging.CRITICAL)
            return True

        log.info("Performing restart of Calibre-Web")
        arguments = list(sys.argv)
        arguments.insert(0, sys.executable)
        if os.name == 'nt':
            arguments = ["\"%s\"" % a for a in arguments]
        os.execv(sys.executable, arguments)
        return True

    def _killServer(self, ignored_signum, ignored_frame):
        self.stop()

    def stop(self, restart=False):
        from . import updater_thread
        updater_thread.stop()

        log.info("webserver stop (restart=%s)", restart)
        self.restart = restart
        if self.wsgiserver:
            if _GEVENT:
                self.wsgiserver.close()
            else:
                self.wsgiserver.add_callback_from_signal(self.wsgiserver.stop)
