# encoding: utf-8
"""
logger.py

Created by Thomas Mangin on 2009-09-06.
Copyright (c) 2009-2017 Exa Networks. All rights reserved.
License: 3-clause BSD. (See the COPYRIGHT file)
"""

from __future__ import print_function

import os
import sys
import stat
import time
import syslog
import logging
import logging.handlers
import pdb
from collections import deque

from exabgp.util.od import od
from exabgp.configuration.environment import environment


def _can_write (location):
	try:
		s  = os.stat(os.path.dirname(location))
	except OSError:
		return None
	mode = s[stat.ST_MODE]
	uid  = os.geteuid()
	gid  = os.getegid()

	return not not (
		((s[stat.ST_UID] == uid) and (mode & stat.S_IWUSR)) or
		((s[stat.ST_GID] == gid) and (mode & stat.S_IWGRP)) or
		(mode & stat.S_IWOTH)
	)


# This delays the evaluation of the od() function which is expensive
# hence why pylint too-few-public-method is disabled

class LazyFormat (object):
	def __init__ (self, prefix, message, formater=od):
		self.prefix = prefix
		self.message = message
		self.formater = formater

	def split (self, char):
		return str(self).split(char)

	def __str__ (self):
		formated = self.formater(self.message)
		return '%s (%4d) %s' % (self.prefix,len(self.message),formated)


class LazyAttribute (object):
	def __init__ (self, flag, aid, length, data):
		self.flag = flag
		self.aid = aid
		self.length = length
		self.data = data

	def split (self, char):
		return str(self).split(char)

	def __str__ (self):
		return 'attribute %-18s flag 0x%02x type 0x%02x len 0x%02x%s' % (
			str(self.aid),
			self.flag,
			int(self.aid),
			self.length,
			' payload %s' % od(self.data) if self.data else ''
		)


class LazyNLRI (object):
	def __init__ (self, afi, safi, addpath, data):
		self.afi = afi
		self.safi = safi
		self.addpath = addpath
		self.data = data

	def split (self, char):
		return str(self).split(char)

	def __str__ (self):
		family = '%s %s' % (self.afi,self.safi)
		path = 'with path-information' if self.addpath else 'without path-information'
		payload = od(self.data) if self.data else 'none'
		return 'NLRI      %-18s %-28s payload %s' % (family,path,payload)


def istty (std):
	try:
		return std.isatty()
	except KeyboardInterrupt:
		raise
	except Exception:
		return False


class Logger (object):
	RECORD = {
		'START':    '\033[01;32m',  # Green
		'DEBUG':    '',
		'INFO':     '\033[01;32m',  # Green
		'NOTICE':   '\033[01;34m',  # Blue
		'WARNING':  '\033[01;33m',  # Yellow
		'ERR':      '\033[01;31m',  # Red
		'CRIT':     '\033[00;31m',  # Strong Red
	}

	MESSAGE = {
		'START':    '\033[1m',  # Green
		'DEBUG':    '',
		'INFO':     '\033[1m',  # Green
		'NOTICE':   '\033[1m',  # Blue
		'WARNING':  '\033[1m',  # Yellow
		'ERR':      '\033[1m',  # Red
		'CRIT':     '\033[1m',  # Strong Red
	}

	END = '\033[0m'

	TTY = {
		'stderr': lambda: istty(sys.stderr),
		'stdout': lambda: istty(sys.stdout),
		'out': lambda: istty(sys.stdout),
	}

	_instance = dict()
	_syslog = None
	_where = ''

	_history = deque()
	_max_history = 20

	_default = None

	_config = ''
	_pid = os.getpid()
	_cwd = os.getcwd()

	def __new__ (cls):
		if cls._instance.get('class',None) is None:
			return super(Logger, cls).__new__(cls)
		else:
			return cls._instance['class']

	# we use os.pid everytime as we may fork and the class is instance before it

	def pdb (self, level):
		if self._option['pdb'] and level == 'CRIT':
			# not sure why, pylint reports an import error here
			pdb.set_trace()

	def config (self, config=None):
		if config is not None:
			self._config = config
		return self._config

	def history (self):
		return "\n".join(self._format(*_) for _ in self._history)

	def _record (self, timestamp, message, source, level):
		if len(self._history) > self._max_history:
			self._history.popleft()
		self._history.append((message,source,level,timestamp))

	def __init__ (self):
		if self._instance.get('class',None) is not None:
			return

		self._instance['class'] = self

		command = environment.settings()
		self.short = command.log.short
		self.level = command.log.level

		self._option = {
			'pdb':           command.debug.pdb,
			'reactor':       command.log.enable and (command.log.all or command.log.reactor),
			'daemon':        command.log.enable and (command.log.all or command.log.daemon),
			'processes':     command.log.enable and (command.log.all or command.log.processes),
			'configuration': command.log.enable and (command.log.all or command.log.configuration),
			'network':       command.log.enable and (command.log.all or command.log.network),
			'wire':          command.log.enable and (command.log.all or command.log.packets),
			'message':       command.log.enable and (command.log.all or command.log.message),
			'rib':           command.log.enable and (command.log.all or command.log.rib),
			'timer':         command.log.enable and (command.log.all or command.log.timers),
			'routes':        command.log.enable and (command.log.all or command.log.routes),
			'parser':        command.log.enable and (command.log.all or command.log.parser),
		}

		if not command.log.enable:
			self.destination = ''
			return

		self.destination = command.log.destination

		self.restart(True)

	def _local_syslog (self):
		if sys.platform == "darwin":
			address = '/var/run/syslog'
		else:
			address = '/dev/log'
		if not os.path.exists(address):
			address = ('localhost', 514)
		handler = logging.handlers.SysLogHandler(address)

		self._syslog.addHandler(handler)
		return True

	def _remote_syslog (self, destination):
		# If the address is invalid, each syslog call will print an error.
		# See how it can be avoided, as the socket error is encapsulated and not returned
		address = (destination, 514)
		handler = logging.handlers.SysLogHandler(address)

		self._syslog.addHandler(handler)
		return True

	def _standard (self, facility):
		handler = logging.StreamHandler(getattr(sys,facility))

		self._syslog.addHandler(handler)
		return True

	def _file (self, destination):
		# folder
		logfile = os.path.realpath(os.path.normpath(os.path.join(self._cwd,destination)))
		can = _can_write(logfile)
		if can is True:
			handler = logging.handlers.RotatingFileHandler(logfile, maxBytes=5*1024*1024, backupCount=5)
		elif can is None:
			self.critical('ExaBGP can not access (perhaps as it does not exist) the log folder provided','logger')
			return False
		else:
			self.critical('ExaBGP does not have the right to write in the requested log directory','logger')
			return False

		self._syslog.addHandler(handler)
		return True

	def restart (self, first=False):
		try:
			if first:
				self._where = 'stdout'
				self._default = logging.StreamHandler(sys.stdout)
				self._syslog = logging.getLogger()
				self._syslog.setLevel(logging.DEBUG)
				self._syslog.addHandler(self._default)
				return True
		except IOError:
			# no way to report anything via stdout, silently failing
			return False

		if not self._syslog:
			# no way to report anything via stdout, silently failing
			return False

		for handler in self._syslog.handlers:
			self._syslog.removeHandler(handler)
		self._syslog.addHandler(self._default)

		try:
			if self.destination == 'stderr':
				self._where = 'stderr'
				return True
			elif self.destination == 'stdout':
				self._where = 'out'
				result = self._standard(self.destination)
			elif self.destination in ('','syslog'):
				self._where = 'syslog'
				result = self._local_syslog()
			elif self.destination.startswith('host:'):
				self._where = 'syslog'
				result = self._remote_syslog(self.destination[5:].strip())
			else:
				self._where = 'file'
				result = self._file(self.destination)

			if result:
				self._syslog.removeHandler(self._default)
			return result
		except IOError:
			self.critical('Can not set logging (are stdout/stderr closed?)','logger')
			return False

	def _format (self, message, source, level,timestamp=None):
		if timestamp is None:
			timestamp = time.localtime()
			self._record(timestamp,message,source,level)

		if self.short:
			return message

		if self._where in ['stdout','stderr','out']:
			now = time.strftime('%H:%M:%S',timestamp)
			if not self.TTY[self._where]():
				return "%s | %-6d | %-15s | %s" % (now,self._pid,source,message)
			return "%s | %-6d | %s%-13s%s | %s%-8s%s" % (
				now,
				self._pid,
				self.RECORD.get(level,''),source,self.END,
				self.MESSAGE.get(level,''),message,self.END
			)
		elif self._where in ['syslog',]:
			return "%s[%d]: %-13s %s" % (environment.application,self._pid,source,message)
		elif self._where in ['file',]:
			now = time.strftime('%a, %d %b %Y %H:%M:%S',timestamp)
			return "%s %-6d %-13s %s" % (now,self._pid,source,message)
		else:
			# failsafe
			return "%s | %-8s | %-6d | %-13s | %s" % (now,level,self._pid,source,message)

	def _report (self, message, source, level):
		if source.startswith('incoming-'):
			src = 'wire'
		elif source.startswith('outgoing-'):
			src = 'wire'
		elif source.startswith('peer-'):
			src = 'network'
		else:
			src = source

		log = self._option.get(src,True) and getattr(syslog,'LOG_%s' % level) <= self.level

		if not log:
			return

		for line in message.split('\n'):
			if self._syslog:
				self._syslog.debug(self._format(line,source,level))
			else:
				print(self._format(line,source,level))
				sys.stdout.flush()

	def debug (self, message, source='', level='DEBUG'):
		self._report(message,source,level)

	def info (self, message, source='', level='INFO'):
		self._report(message,source,level)

	def notice (self, message, source='', level='NOTICE'):
		self._report(message,source,level)

	def warning (self, message, source='', level='WARNING'):
		self._report(message,source,level)

	def error (self, message, source='', level='ERR'):
		self._report(message,source,level)

	def critical (self, message, source='', level='CRIT'):
		self._report(message,source,level)


class FakeLogger (object):
	def __getattr__ (self, name):
		def printf (data, _=None):
			sys.stdout.write('Fake logger [%s]\n' % str(data))
		return printf
