#
# Copyright 2006 sense.lab e.V.
# 
# This file is part of the CryptoBox.
#
# The CryptoBox 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 2 of the License, or
# (at your option) any later version.
# 
# The CryptoBox 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 the CryptoBox; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#


"""The logs feature of the CryptoBox.
"""

__revision__ = "$Id$"

import cryptobox.plugins.base
import re
import datetime
import cherrypy

LOG_LEVELS = [ 'DEBUG', 'INFO', 'NOTICE', 'WARNING', 'ERROR' ]

LINE_REGEX = re.compile(r"(?P<year>\d{4})-(?P<month>\d{2})-(?P<day>\d{2}) " \
        + r"(?P<hour>\d{2}):(?P<minute>\d{2}):\d{2},\d{3} (?P<level>" \
        + "|".join([ "(?:%s)" % e for e in LOG_LEVELS]) + r"): (?P<text>.*)$")

class logs(cryptobox.plugins.base.CryptoBoxPlugin):
    """The logs feature of the CryptoBox.
    """

    plugin_capabilities = [ "system" ]
    plugin_visibility = [ "preferences" ]
    request_auth = False
    rank = 90

    def do_action(self, lines=50, size=3000, level=None):
        """Show the latest part of the log file.
        """
        ## filter input
        try:
            lines = int(lines)
            if lines <= 0:
                raise(ValueError)
        except ValueError:
            self.cbox.log.info("[logs] invalid line number: %s" % str(lines))
            lines = 50
        try:
            size = int(size)
            if size <= 0:
                raise(ValueError)
        except ValueError:
            self.cbox.log.info("[logs] invalid log size: %s" % str(size))
            size = 3000
        if not level is None:
            level = str(level)
            if not level in LOG_LEVELS:
                self.cbox.log.info("[logs] invalid log level: %s" % str(level))
                level = None
        for (index, line) in enumerate(self.__filter_log_content(lines, size, level)):
            self.__set_line_hdf_data(self.hdf_prefix + "Content.%d" % index, line)
            self.hdf[self.hdf_prefix + "Destination"] = \
                self.cbox.prefs["Log"]["Destination"].lower()
        return "show_log"


    @cherrypy.expose
    def download(self, **kargs):
        """Download the complete log file
        **kargs are necessary - we have to ignore 'weblang' and so on ...
        """
        log_file = self.__get_log_destination_file()
        if log_file is None:
            return ""
        else:
            return cherrypy.lib.cptools.serveFile(log_file,
                    disposition="attachment", name="cryptobox_logfile.txt")


    def get_status(self):
        """The current status includes the log configuration details.
        """
        return "%s:%s:%s" % (
                self.cbox.prefs["Log"]["Level"],
                self.cbox.prefs["Log"]["Destination"],
                self.cbox.prefs["Log"]["Details"])


    def get_status(self):
        """The current status includes the log configuration details.
        """
        return "%s:%s:%s" % (
            self.cbox.prefs["Log"]["Level"],
            self.cbox.prefs["Log"]["Destination"],
            self.cbox.prefs["Log"]["Details"])
    

    def __filter_log_content(self, lines, max_size, level):
        """Filter, sort and shorten the log content.
        """
        if level and level in LOG_LEVELS:
            filtered_levels = LOG_LEVELS[:]
            ## only the given and higher levels are accepted
            while filtered_levels[0] != level:
                del filtered_levels[0]
            content = []
            current_length = 0
            for line in self.__get_log_data():
                ## search for matching lines for the given log level
                for one_level in filtered_levels:
                    if line.find(" %s: " % one_level) != -1:
                        break
                else:
                    ## the line does not contain an appropriate level name
                    continue
                ## we found a line that fits
                content.append(line)
                current_length += len(line)
                if lines and len(content) >= lines:
                    break
                if max_size and current_length >= max_size:
                    break
        else:
            content = self.__get_log_data(lines, max_size)
        return content


    def __set_line_hdf_data(self, hdf_prefix, line):
        """Parse the log line for time and log level.

        If parsing fails, then the output line is simply displayed without
        meta information.
        """
        self.hdf[hdf_prefix + ".Text"] = line.strip()
        match = LINE_REGEX.match(line)
        if not match:
            ## we could not parse the line - just return the text without meta info
            return
        ## matching was successful - we can parse the line for details
        ## calculate time difference of log line (aka: age of event)
        try:
            (year, month, day, hour, minute) = match.group(
                    'year', 'month', 'day', 'hour', 'minute')
            (year, month, day, hour, minute) = \
                    (int(year), int(month), int(day), int(hour), int(minute))
            ## timediff is a timedelta object
            timediff = datetime.datetime.today() - \
                    datetime.datetime(year, month, day, hour, minute)
            ## the time units (see below) correspond to the names within the language
            ## file: Text.TimeUnits.Days ...
            if timediff.days >= 1:
                self.hdf[hdf_prefix + ".TimeDiff.Unit"] = 'Days'
                self.hdf[hdf_prefix + ".TimeDiff.Value"] = timediff.days
            elif timediff.seconds >= 3600:
                self.hdf[hdf_prefix + ".TimeDiff.Unit"] = 'Hours'
                self.hdf[hdf_prefix + ".TimeDiff.Value"] = timediff.seconds / 3600
            elif timediff.seconds >= 60:
                self.hdf[hdf_prefix + ".TimeDiff.Unit"] = 'Minutes'
                self.hdf[hdf_prefix + ".TimeDiff.Value"] = timediff.seconds / 60
            else:
                self.hdf[hdf_prefix + ".TimeDiff.Unit"] = 'Seconds'
                self.hdf[hdf_prefix + ".TimeDiff.Value"] = timediff.seconds
        except (OverflowError, TypeError, ValueError, IndexError), err_msg:
            pass
        ## retrieve the level
        try:
            self.hdf[hdf_prefix + ".Level"] = match.group('level')
        except IndexError:
            pass
        try:
            self.hdf[hdf_prefix + ".Text"] = match.group('text').strip()
        except IndexError:
            pass
    

    def __get_log_destination_file(self):
        """For non-file log destinations return 'None' and output a warning
        """
        try:
            if self.cbox.prefs["Log"]["Destination"].upper() == "FILE":
                import os
                return os.path.abspath(self.cbox.prefs["Log"]["Details"])
            else:
                return None
        except KeyError:
            self.cbox.log.error(
                    "could not evaluate one of the following config settings: "
                    + "[Log]->Destination or [Log]->Details")
            return None


    def __get_log_data(self, lines=None, max_size=None):
        """get the most recent log entries of the log file

        the maximum number and size of these entries can be limited by
        'lines' and 'max_size'
        """
        log_file = self.__get_log_destination_file()
        ## return nothing if the currently selected log output is not a file
        if log_file is None:
            return []
        try:
            fdesc = open(log_file, "r")
            if max_size:
                fdesc.seek(-max_size, 2)	# seek relative to the end of the file
            content = fdesc.readlines()
            fdesc.close()
        except IOError:
            self.cbox.log.warn("failed to read the log file (%s)" % log_file)
            return []
        if lines:
            content = content[-lines:]
        content.reverse()
        return content