# This file is part of Radicale Server - Calendar Server
# Copyright © 2011-2017 Guillaume Ayoub
# Copyright © 2017-2019 Unrud <unrud@outlook.com>
#
# 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``.
Uses the built-in WSGI server.

"""

import argparse
import contextlib
import os
import signal
import socket
import sys
from types import FrameType
from typing import Dict, List, cast

from radicale import VERSION, config, log, server, storage
from radicale.log import logger


def run() -> None:
    """Run Radicale as a standalone server."""
    exit_signal_numbers = [signal.SIGTERM, signal.SIGINT]
    if os.name == "posix":
        exit_signal_numbers.append(signal.SIGHUP)
        exit_signal_numbers.append(signal.SIGQUIT)
    if sys.platform == "win32":
        exit_signal_numbers.append(signal.SIGBREAK)

    # Raise SystemExit when signal arrives to run cleanup code
    # (like destructors, try-finish etc.), otherwise the process exits
    # without running any of them
    def exit_signal_handler(signal_number: "signal.Signals",
                            stack_frame: FrameType) -> None:
        sys.exit(1)
    for signal_number in exit_signal_numbers:
        signal.signal(signal_number, exit_signal_handler)

    log.setup()

    # Get command-line arguments
    parser = argparse.ArgumentParser(
        prog="radicale", usage="%(prog)s [OPTIONS]", allow_abbrev=False)

    parser.add_argument("--version", action="version", version=VERSION)
    parser.add_argument("--verify-storage", action="store_true",
                        help="check the storage for errors and exit")
    parser.add_argument("-C", "--config",
                        help="use specific configuration files", nargs="*")
    parser.add_argument("-D", "--debug", action="store_true",
                        help="print debug information")

    groups: Dict["argparse._ArgumentGroup", List[str]] = {}
    for section, values in config.DEFAULT_CONFIG_SCHEMA.items():
        if section.startswith("_"):
            continue
        group = parser.add_argument_group(section)
        groups[group] = []
        for option, data in values.items():
            if option.startswith("_"):
                continue
            kwargs = data.copy()
            long_name = "--%s-%s" % (section, option.replace("_", "-"))
            args: List[str] = list(kwargs.pop("aliases", ()))
            args.append(long_name)
            kwargs["dest"] = "%s_%s" % (section, option)
            groups[group].append(kwargs["dest"])
            del kwargs["value"]
            with contextlib.suppress(KeyError):
                del kwargs["internal"]

            if kwargs["type"] == bool:
                del kwargs["type"]
                kwargs["action"] = "store_const"
                kwargs["const"] = "True"
                opposite_args = list(kwargs.pop("opposite_aliases", ()))
                opposite_args.append("--no%s" % long_name[1:])
                group.add_argument(*args, **kwargs)

                kwargs["const"] = "False"
                kwargs["help"] = "do not %s (opposite of %s)" % (
                    kwargs["help"], long_name)
                group.add_argument(*opposite_args, **kwargs)
            else:
                del kwargs["type"]
                group.add_argument(*args, **kwargs)

    args_ns = parser.parse_args()

    # Preliminary configure logging
    if args_ns.debug:
        args_ns.logging_level = "debug"
    with contextlib.suppress(ValueError):
        log.set_level(config.DEFAULT_CONFIG_SCHEMA["logging"]["level"]["type"](
            args_ns.logging_level))

    # Update Radicale configuration according to arguments
    arguments_config = {}
    for group, actions in groups.items():
        section = group.title or ""
        section_config = {}
        for action in actions:
            value = getattr(args_ns, action)
            if value is not None:
                section_config[action.split('_', 1)[1]] = value
        if section_config:
            arguments_config[section] = section_config

    try:
        configuration = config.load(config.parse_compound_paths(
            config.DEFAULT_CONFIG_PATH,
            os.environ.get("RADICALE_CONFIG"),
            os.pathsep.join(args_ns.config) if args_ns.config else None))
        if arguments_config:
            configuration.update(arguments_config, "command line arguments")
    except Exception as e:
        logger.critical("Invalid configuration: %s", e, exc_info=True)
        sys.exit(1)

    # Configure logging
    log.set_level(cast(str, configuration.get("logging", "level")))

    # Log configuration after logger is configured
    for source, miss in configuration.sources():
        logger.info("%s %s", "Skipped missing" if miss else "Loaded", source)

    if args_ns.verify_storage:
        logger.info("Verifying storage")
        try:
            storage_ = storage.load(configuration)
            with storage_.acquire_lock("r"):
                if not storage_.verify():
                    logger.critical("Storage verifcation failed")
                    sys.exit(1)
        except Exception as e:
            logger.critical("An exception occurred during storage "
                            "verification: %s", e, exc_info=True)
            sys.exit(1)
        return

    # Create a socket pair to notify the server of program shutdown
    shutdown_socket, shutdown_socket_out = socket.socketpair()

    # Shutdown server when signal arrives
    def shutdown_signal_handler(signal_number: "signal.Signals",
                                stack_frame: FrameType) -> None:
        shutdown_socket.close()
    for signal_number in exit_signal_numbers:
        signal.signal(signal_number, shutdown_signal_handler)

    try:
        server.serve(configuration, shutdown_socket_out)
    except Exception as e:
        logger.critical("An exception occurred during server startup: %s", e,
                        exc_info=True)
        sys.exit(1)


if __name__ == "__main__":
    run()