# -*- coding: utf-8 -*-
#
# This file is part of Radicale Server - Calendar Server
# Copyright © 2011 Guillaume Ayoub
#
# This library 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 library 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 Radicale.  If not, see <http://www.gnu.org/licenses/>.

"""
Radicale executable module.

This module can be executed from a command line with ``$python -m radicale`` or
from a python programme with ``radicale.__main__.run()``.

"""

import atexit
import os
import sys
import optparse
import signal
import threading
from wsgiref.simple_server import make_server

import radicale


def run():
    """Run Radicale as a standalone server."""
    # Get command-line options
    parser = optparse.OptionParser(version=radicale.VERSION)
    parser.add_option(
        "-d", "--daemon", action="store_true",
        default=radicale.config.getboolean("server", "daemon"),
        help="launch as daemon")
    parser.add_option(
        "-p", "--pid",
        default=radicale.config.get("server", "pid"),
        help="set PID filename for daemon mode")
    parser.add_option(
        "-f", "--foreground", action="store_false", dest="daemon",
        help="launch in foreground (opposite of --daemon)")
    parser.add_option(
        "-H", "--hosts",
        default=radicale.config.get("server", "hosts"),
        help="set server hostnames and ports")
    parser.add_option(
        "-s", "--ssl", action="store_true",
        default=radicale.config.getboolean("server", "ssl"),
        help="use SSL connection")
    parser.add_option(
        "-S", "--no-ssl", action="store_false", dest="ssl",
        help="do not use SSL connection (opposite of --ssl)")
    parser.add_option(
        "-k", "--key",
        default=radicale.config.get("server", "key"),
        help="set private key file")
    parser.add_option(
        "-c", "--certificate",
        default=radicale.config.get("server", "certificate"),
        help="set certificate file")
    parser.add_option(
        "-D", "--debug", action="store_true",
        default=radicale.config.getboolean("logging", "debug"),
        help="print debug information")
    options = parser.parse_args()[0]

    # Update Radicale configuration according to options
    for option in parser.option_list:
        key = option.dest
        if key:
            section = "logging" if key == "debug" else "server"
            value = getattr(options, key)
            radicale.config.set(section, key, str(value))

    # Start logging
    radicale.log.start()

    # Fork if Radicale is launched as daemon
    if options.daemon:
        pid = os.fork()
        if pid:
            try:
                if options.pid:
                    open(options.pid, 'w').write(str(pid))
            finally:
                sys.exit()
        sys.stdout = sys.stderr = open(os.devnull, "w")

    # Register exit function
    def cleanup():
        """Remove the PID files."""
        radicale.log.LOGGER.debug("Cleaning up")
        # Remove PID file
        if options.pid and options.daemon:
            os.unlink(options.pid)

    atexit.register(cleanup)
    radicale.log.LOGGER.info("Starting Radicale")

    # Create calendar servers
    servers = []
    server_class = radicale.HTTPSServer if options.ssl else radicale.HTTPServer
    shutdown_program = threading.Event()

    for host in options.hosts.split(','):
        address, port = host.strip().rsplit(':', 1)
        address, port = address.strip('[] '), int(port)
        servers.append(
            make_server(address, port, radicale.Application(),
                        server_class, radicale.RequestHandler))

    # SIGTERM and SIGINT (aka KeyboardInterrupt) should just mark this for
    # shutdown
    signal.signal(signal.SIGTERM, lambda *_: shutdown_program.set())
    signal.signal(signal.SIGINT, lambda *_: shutdown_program.set())

    def serve_forever(server):
        """Serve a server forever, cleanly shutdown when things go wrong."""
        try:
            server.serve_forever()
        finally:
            shutdown_program.set()

    # Start the servers in a different loop to avoid possible race-conditions,
    # when a server exists but another server is added to the list at the same
    # time
    for server in servers:
        radicale.log.LOGGER.debug(
            "Listening to %s port %s" % (
                server.server_name, server.server_port))
        if options.ssl:
            radicale.log.LOGGER.debug("Using SSL")
        threading.Thread(target=serve_forever, args=(server,)).start()

    radicale.log.LOGGER.debug("Radicale server ready")

    # Main loop: wait until all servers are exited
    try:
        # We must do the busy-waiting here, as all ``.join()`` calls completly
        # block the thread, such that signals are not received
        while True:
            # The number is irrelevant, it only needs to be greater than 0.05
            # due to python implementing its own busy-waiting logic
            shutdown_program.wait(5.0)
            if shutdown_program.is_set():
                break
    finally:
        # Ignore signals, so that they cannot interfere
        signal.signal(signal.SIGINT, signal.SIG_IGN)
        signal.signal(signal.SIGTERM, signal.SIG_IGN)

        radicale.log.LOGGER.info("Stopping Radicale")

        for server in servers:
            radicale.log.LOGGER.debug(
                "Closing server listening to %s port %s" % (
                    server.server_name, server.server_port))
            server.shutdown()


if __name__ == '__main__':
    run()
