"""A simple log mechanism styled after PEP 282."""

# The class here is styled after PEP 282 so that it could later be
# replaced with a standard Python logging implementation.

DEBUG = 1
INFO = 2
WARN = 3
ERROR = 4
FATAL = 5

import sys

class Log:

def __init__(self, threshold=WARN):
self.threshold = threshold

def _log(self, level, msg, args):
if level not in (DEBUG, INFO, WARN, ERROR, FATAL):
raise ValueError('%s wrong log level' % str(level))

if level >= self.threshold:
if args:
msg = msg % args
if level in (WARN, ERROR, FATAL):
stream = sys.stderr
else:
stream = sys.stdout
stream.write('%s\n' % msg)
stream.flush()

def log(self, level, msg, *args):
self._log(level, msg, args)

def debug(self, msg, *args):
self._log(DEBUG, msg, args)

def info(self, msg, *args):
self._log(INFO, msg, args)

def warn(self, msg, *args):
self._log(WARN, msg, args)

def error(self, msg, *args):
self._log(ERROR, msg, args)

def fatal(self, msg, *args):
self._log(FATAL, msg, args)

_global_log = Log()
log = _global_log.log
debug = _global_log.debug
info = _global_log.info
warn = _global_log.warn
error = _global_log.error
fatal = _global_log.fatal

def set_threshold(level):
# return the old threshold for use from tests
old = _global_log.threshold
_global_log.threshold = level
return old

def set_verbosity(v):
if v <= 0:
set_threshold(WARN)
elif v == 1:
set_threshold(INFO)
elif v >= 2:
set_threshold(DEBUG)