#!/usr/bin/python3
#
# Copyright (c) 2013 Mikkel Schubert <MikkelSch@gmail.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
import errno
import itertools
import logging
import os
import time

import coloredlogs


_LOG_LEVELS = {
    "info": logging.INFO,
    "warning": logging.WARNING,
    "error": logging.ERROR,
    "debug": logging.DEBUG,
}


_CONSOLE_MESSAGE_FORMAT = "%(asctime)s %(levelname)s %(message)s"
_CONSOLE_DATE_FORMAT = "%H:%M:%S"
_FILE_MESSAGE_FORMAT = "%(asctime)s %(name)s %(levelname)s %(message)s"

_LOG_ENABLED = False


def initialize_console_logging():
    global _LOG_ENABLED

    if not _LOG_ENABLED:
        coloredlogs.install(fmt=_CONSOLE_MESSAGE_FORMAT, datefmt=_CONSOLE_DATE_FORMAT)
        _LOG_ENABLED = True


def initialize(log_level="error", log_file=None, name="paleomix"):
    initialize_console_logging()

    log_level = _LOG_LEVELS[log_level.lower()]
    root = logging.getLogger()
    root.setLevel(logging.NOTSET)

    if log_file:
        handler = logging.FileHandler(log_file)
        handler.setFormatter(logging.Formatter(_FILE_MESSAGE_FORMAT))
        handler.setLevel(log_level)
        root.addHandler(handler)
    elif name:
        template = "%s.%s_%%02i.log" % (name, time.strftime("%Y%m%d_%H%M%S"))
        handler = LazyLogfile(template, log_level=log_level)
        handler.setFormatter(logging.Formatter(_FILE_MESSAGE_FORMAT))
        handler.setLevel(log_level)
        root.addHandler(handler)


def add_argument_group(parser, default="error"):
    """Adds an option-group to an OptionParser object, with options
    pertaining to logging. Note that 'initialize' expects the config
    object to have these options."""
    group = parser.add_argument_group("Logging")
    group.add_argument(
        "--log-file",
        default=None,
        help="Write log-messages to this file.",
    )
    group.add_argument(
        "--log-level",
        default=default,
        choices=("info", "warning", "error", "debug"),
        type=str.lower,
        help="Log messages at the specified level. If a filename is not specified with "
        "--log-file, PALEOMIX will automatically create a log file in the current "
        "directory should events be logged at this level or above",
    )


def get_logfiles():
    root = logging.getLogger()
    for handler in root.handlers:
        if isinstance(handler, logging.FileHandler) and handler.stream:
            yield handler.baseFilename


class LazyLogfile(logging.FileHandler):
    def __init__(self, template, log_level):
        logging.FileHandler.__init__(self, template, delay=True)
        # Use absolute path for template
        self._template = self.baseFilename
        self._log_level = log_level

    def emit(self, record):
        # Don't try to log self-emitted log events, to avoid recursive loops
        if record.name != __name__:
            super().emit(record)

    def _open(self):
        """Try to open a new logfile, taking steps to ensure that
        existing logfiles using the same template are not clobbered."""
        flags = os.O_WRONLY | os.O_CREAT | os.O_EXCL

        for start in itertools.count(start=1):
            filename = self._template % (start,)
            os.makedirs(os.path.dirname(filename), exist_ok=True)

            try:
                stream = os.fdopen(os.open(filename, flags), "w")
                logger = logging.getLogger(__name__)
                level_name = logging.getLevelName(self._log_level).lower()
                logger.info("Saving %s logs to %r", level_name, filename)

                self.baseFilename = filename
                return stream
            except OSError as error:
                if error.errno != errno.EEXIST:
                    raise