# -*- coding: utf-8 -*-
# Copyright 2014-2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from ._base import Config
from synapse.util.logcontext import LoggingContextFilter
from twisted.logger import globalLogBeginner, STDLibLogObserver
import logging
import logging.config
import yaml
from string import Template
import os
import signal


DEFAULT_LOG_CONFIG = Template("""
version: 1

formatters:
    precise:
        format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - \
%(request)s - %(message)s'

filters:
    context:
        (): synapse.util.logcontext.LoggingContextFilter
        request: ""

handlers:
    file:
        class: logging.handlers.RotatingFileHandler
        formatter: precise
        filename: ${log_file}
        maxBytes: 104857600
        backupCount: 10
        filters: [context]
    console:
        class: logging.StreamHandler
        formatter: precise
        filters: [context]

loggers:
    synapse:
        level: INFO

    synapse.storage.SQL:
        # beware: increasing this to DEBUG will make synapse log sensitive
        # information such as access tokens.
        level: INFO

root:
    level: INFO
    handlers: [file, console]
""")


class LoggingConfig(Config):

    def read_config(self, config):
        self.verbosity = config.get("verbose", 0)
        self.no_redirect_stdio = config.get("no_redirect_stdio", False)
        self.log_config = self.abspath(config.get("log_config"))
        self.log_file = self.abspath(config.get("log_file"))

    def default_config(self, config_dir_path, server_name, **kwargs):
        log_config = self.abspath(
            os.path.join(config_dir_path, server_name + ".log.config")
        )
        return """
        # A yaml python logging config file
        log_config: "%(log_config)s"
        """ % locals()

    def read_arguments(self, args):
        if args.verbose is not None:
            self.verbosity = args.verbose
        if args.no_redirect_stdio is not None:
            self.no_redirect_stdio = args.no_redirect_stdio
        if args.log_config is not None:
            self.log_config = args.log_config
        if args.log_file is not None:
            self.log_file = args.log_file

    def add_arguments(cls, parser):
        logging_group = parser.add_argument_group("logging")
        logging_group.add_argument(
            '-v', '--verbose', dest="verbose", action='count',
            help="The verbosity level. Specify multiple times to increase "
            "verbosity. (Ignored if --log-config is specified.)"
        )
        logging_group.add_argument(
            '-f', '--log-file', dest="log_file",
            help="File to log to. (Ignored if --log-config is specified.)"
        )
        logging_group.add_argument(
            '--log-config', dest="log_config", default=None,
            help="Python logging config file"
        )
        logging_group.add_argument(
            '-n', '--no-redirect-stdio',
            action='store_true', default=None,
            help="Do not redirect stdout/stderr to the log"
        )

    def generate_files(self, config):
        log_config = config.get("log_config")
        if log_config and not os.path.exists(log_config):
            log_file = self.abspath("homeserver.log")
            with open(log_config, "wb") as log_config_file:
                log_config_file.write(
                    DEFAULT_LOG_CONFIG.substitute(log_file=log_file)
                )


def setup_logging(config, use_worker_options=False):
    """ Set up python logging

    Args:
        config (LoggingConfig | synapse.config.workers.WorkerConfig):
            configuration data

        use_worker_options (bool): True to use 'worker_log_config' and
            'worker_log_file' options instead of 'log_config' and 'log_file'.
    """
    log_config = (config.worker_log_config if use_worker_options
                  else config.log_config)
    log_file = (config.worker_log_file if use_worker_options
                else config.log_file)

    log_format = (
        "%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(request)s"
        " - %(message)s"
    )

    if log_config is None:
        # We don't have a logfile, so fall back to the 'verbosity' param from
        # the config or cmdline. (Note that we generate a log config for new
        # installs, so this will be an unusual case)
        level = logging.INFO
        level_for_storage = logging.INFO
        if config.verbosity:
            level = logging.DEBUG
            if config.verbosity > 1:
                level_for_storage = logging.DEBUG

        logger = logging.getLogger('')
        logger.setLevel(level)

        logging.getLogger('synapse.storage.SQL').setLevel(level_for_storage)

        formatter = logging.Formatter(log_format)
        if log_file:
            # TODO: Customisable file size / backup count
            handler = logging.handlers.RotatingFileHandler(
                log_file, maxBytes=(1000 * 1000 * 100), backupCount=3
            )

            def sighup(signum, stack):
                logger.info("Closing log file due to SIGHUP")
                handler.doRollover()
                logger.info("Opened new log file due to SIGHUP")
        else:
            handler = logging.StreamHandler()

            def sighup(signum, stack):
                pass

        handler.setFormatter(formatter)

        handler.addFilter(LoggingContextFilter(request=""))

        logger.addHandler(handler)
    else:
        def load_log_config():
            with open(log_config, 'r') as f:
                logging.config.dictConfig(yaml.load(f))

        def sighup(signum, stack):
            # it might be better to use a file watcher or something for this.
            logging.info("Reloading log config from %s due to SIGHUP",
                         log_config)
            load_log_config()

        load_log_config()

    # TODO(paul): obviously this is a terrible mechanism for
    #   stealing SIGHUP, because it means no other part of synapse
    #   can use it instead. If we want to catch SIGHUP anywhere
    #   else as well, I'd suggest we find a nicer way to broadcast
    #   it around.
    if getattr(signal, "SIGHUP"):
        signal.signal(signal.SIGHUP, sighup)

    # It's critical to point twisted's internal logging somewhere, otherwise it
    # stacks up and leaks kup to 64K object;
    # see: https://twistedmatrix.com/trac/ticket/8164
    #
    # Routing to the python logging framework could be a performance problem if
    # the handlers blocked for a long time as python.logging is a blocking API
    # see https://twistedmatrix.com/documents/current/core/howto/logger.html
    # filed as https://github.com/matrix-org/synapse/issues/1727
    #
    # However this may not be too much of a problem if we are just writing to a file.
    observer = STDLibLogObserver()
    globalLogBeginner.beginLoggingTo(
        [observer],
        redirectStandardIO=not config.no_redirect_stdio,
    )
