#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Basic logger, storing data in /var/log/clogger/*.log
# Author    : Pierre-Elliott Bécue <becue@crans.org>
# License   : GPLv3
# Date      : 27/04/2014

import os
import datetime
import pytz
import logging

TZ = pytz.timezone('Europe/Paris')
LDIRPATH = os.getenv('DBG_CLOGGER_PATH', '/var/log/clogger')

class CLogger(logging.Logger):
    """
    Crans logger.
    """

    def __init__(self, loggerName, service=None, level="info", debug=False):
        """
        Initializes logger. The debug variable is useful to have a print to stdout (when debugging)
        """
        super(CLogger, self).__init__(loggerName)

        self.c_formatter = None
        self.c_file_handler = None
        self.c_sh = None
        self.c_level = level

        # When no service is specified, we don't put the reference in the format.
        if service is None:
            self.c_format = "%(asctime)s - %(name)s - %(levelname)s - %(message)s"
        else:
            self.c_format = "%%(asctime)s - %%(name)s - %(service)s - %%(levelname)s - %%(message)s" % {'service': service}

        self.create_formatter()
        self.apply_file_handler(loggerName)
        if debug:
            self.apply_stream_handler()

    def get_file_handler_path(self):
        """Returns the file handler path"""
        if self.__file_handler_path is None:
            return ''
        return self.__file_handler_path

    def create_formatter(self):
        """Creates a formatter based on CFormatter class.
        It uses self.format as a source."""

        if self.c_formatter is not None:
            return

        # Creates formatter
        self.c_formatter = CFormatter(self.c_format, "%Y-%m-%dT%H:%M:%S.%f%z")

    def apply_stream_handler(self):
        """Creates a streamhandler that prints to stdout.
        Its level is debug"""
        self.c_sh = logging.StreamHandler()
        self.c_shlevel = logging.DEBUG
        self.c_sh.setLevel(self.c_shlevel)
        self.c_sh.setFormatter(self.c_formatter)
        self.addHandler(self.c_sh)

    def apply_file_handler(self, loggerName):
        """Creates a file handler which level is given by self.c_level"""
        if self.c_file_handler is not None:
            return

        # Computes the file handler name using service name.
        self.__file_handler_path = os.path.join(LDIRPATH, "%s.log" % (loggerName,))

        # Creates FileHandler
        self.c_file_handler = logging.FileHandler(self.__file_handler_path)

        # Catches appropriate level in logging.
        self.c_file_handler_level = getattr(logging, self.c_level.upper(), logging.INFO)
        self.c_file_handler.setLevel(self.c_file_handler_level)

        # Adds formatter to FileHandler
        self.c_file_handler.setFormatter(self.c_formatter)

        # Adds FileHandler to Handlers
        self.addHandler(self.c_file_handler)

class CFormatter(logging.Formatter):
    """
    This Formatter subclasses the classic formatter to provide a
    timezone-aware logging.
    """

    converter = datetime.datetime.fromtimestamp

    def formatTime(self, record, datefmt=None):
        """
        Return the creation time of the specified LogRecord as formatted text.

        This method should be called from format() by a formatter which
        wants to make use of a formatted time. This method can be overridden
        in formatters to provide for any specific requirement, but the
        basic behaviour is as follows: if datefmt (a string) is specified,
        it is used with time.strftime() to format the creation time of the
        record. Otherwise, the ISO8601 format is used. The resulting
        string is returned. This function uses a user-configurable function
        to convert the creation time to a tuple. By default, time.localtime()
        is used; to change this for a particular formatter instance, set the
        'converter' attribute to a function with the same signature as
        time.localtime() or time.gmtime(). To change it for all formatters,
        for example if you want all logging times to be shown in GMT,
        set the 'converter' attribute in the Formatter class.
        """
        ct = self.converter(record.created, TZ)
        ct = ct.replace(microsecond=int(record.msecs * 1000))
        if datefmt:
            s = ct.strftime(datefmt)
        else:
            s = ct.strftime("%Y-%m-%d %H:%M:%S.%f")
        return s