Simple logging decorator for python

verbose.py

#!/usr/bin/env python3

# +------------------------------------------------------------------------------+
# |                     HOW TO USE: from verbose import Log                      |
# +=================================== Basics ===================================+
# | <Inputs>                                                                     |
# |   msg : used as the main message to output (this is the only required field) |
# |   tag : used to conceptually group messages or add string identifier         |
# |                                                                              |
# | <Functions>                                                                  |
# |   note()  : use instead of print()                                           |
# |   wrap()  : decorator for methods (the message will be shown for each call)  |
# |   write() : writes messages to a log file (with timestamps)                  |
# |   hack()  : display the source of wrapped function as if it were being typed |
# |             (this is a novelty wrapper to look like a "movie hacker")        |
# |                                                                              |
# | <Levels (colors)>                                                            |
# |   DEFAULT   : standard (default terminal text color)                         |
# |   INFO      : grey,    use to show general notes                             |
# |   DEBUG     : blue,    use to show debugging info                            |
# |   ERROR     : red,     use to indicate errors                                |
# |   SUCCESS   : green,   use to indicate success                               |
# |   WARNING   : yellow,  use to indicate warnings                              |
# |   IMPORTANT : magenta, use to bring attention to but not for errors          |
# |   HEADER    : bblack,  use to display function wrappers                      |
# |                                                                              |
# +================================== Advanced ==================================+
# | <Inputs>                                                                     |
# |   force : always print the log message (default=False)                       |
# |   pad   :   character used to pad message to 80 characters (default=None)    |
# |   fmt   :   python format string (the following variables can be used)       |
# |     {tag}    - the tag field                                                 |
# |     {msg}    - the msg field                                                 |
# |     {args}   - required function arguments                                   |
# |     {kwargs} - optional function arguments                                   |
# |     {pad}    - character used to pad to 80 bytes                             |
# |                                                                              |
# | <Temporarily disable logging>                                                |
# |   Log.ENABLED = False                                                        |
# |                                                                              |
# | <Print the first argument to a function>                                     |
# |   @Log.wrap('argument1', fmt='{msg}: {args[0]}')                             |
# |   def foo(x):                                                                |
# |     pass # the value of x will now be logged when foo() is called            |
# |                                                                              |
# +------------------------------------------------------------------------------+

import os, sys
import time
from functools import wraps

# for movie hacker wrapper
import inspect
try: # pip install Pygments
	from pygments import highlight
	from pygments.lexers import PythonLexer
	from pygments.formatters import TerminalFormatter
except ModuleNotFoundError:
	COLOR = False
else:
	COLOR = True


class Log:
	ENABLED = True

	FILE_PATH = os.path.curdir # set to None to disable file log
	FILE_LINE_LIMIT = 1000     # set to 0 for no limit

	def __make_color(code):
		return '\033[' + str(code) + 'm'
	DEFAULT   = {'name': 'DEFAULT',   'color': __make_color( 0)} # (terminal text)
	INFO      = {'name': 'INFO',      'color': __make_color( 1)} # grey
	ERROR     = {'name': 'ERROR',     'color': __make_color(31)} # red
	SUCCESS   = {'name': 'SUCCESS',   'color': __make_color(32)} # green
	WARN      = {'name': 'WARN',      'color': __make_color(33)} # yellow
	DEBUG     = {'name': 'DEBUG',     'color': __make_color(34)} # blue
	IMPORTANT = {'name': 'IMPORTANT', 'color': __make_color(35)} # magenta
	HEADER    = {'name': 'HEADER',    'color': __make_color('30;1')} # bright black (requires 16 color support)

	@staticmethod
	def note(msg, tag='>', fmt='{tag} {msg}', args=[], kwargs={}, level=INFO, pad=None, force=False):
		def color(msg):
			"""Add color to strings"""
			if os.name == 'posix':
				return level['color'] + msg + Log.DEFAULT['color']
			else:
				return msg
		if Log.ENABLED or force:
			formatted_msg = fmt.format(tag=tag, msg=msg, args=args, kwargs=kwargs)
			if pad:
				formatted_msg += ' '
				formatted_msg = formatted_msg.ljust(80, pad)
			print(color(formatted_msg))

	@staticmethod
	def wrap(msg, tag=None, fmt='[{tag}] {msg}: {args}{kwargs}', level=HEADER):
		"""Decorator used to display log as '[tag] msg'"""
		def print_msg(func):
			@wraps(func)
			def wrapper(*args, **kwargs):
				Log.note(msg, tag=tag or func.__name__, fmt=fmt, args=args, kwargs=kwargs, level=level)
				return func(*args, **kwargs)
			return wrapper
		return print_msg

	@staticmethod
	def write(msg, tag='*', fmt='[{tag}] {msg}', level=INFO, args=[]):
		"""Write log to file"""
		if not Log.FILE_PATH: return
		timestamp = time.strftime('%Y-%m-%d_%H:%M:%S')
		log_msg = ' - '.join([timestamp, level['name'], fmt.format(tag=tag, msg=msg)])
		filename = os.path.join(Log.FILE_PATH, 'log')
		if not os.path.isfile(filename):
			Log.note('creating log file...', tag='+')
			with open(filename, 'w'): pass
		with open(filename, 'r+') as f:
			data = f.readlines()
			data.append(log_msg + os.linesep)
			f.seek(0)
			f.truncate()
			f.writelines(data[-Log.FILE_LINE_LIMIT:])

	@staticmethod
	def hack(func):
		def print_type(s, speed=0.0003, force=False):
			if not Log.ENABLED and not force: return
			if COLOR:
				s = highlight(s, PythonLexer(), TerminalFormatter(linenos=True))
			else: # green text
				print('\033[32m', end='')
			line = lambda c: Log.note('', tag='---', fmt='', pad=c)
			line('~')
			for c in s:
				print(c, end='', flush=True)
				time.sleep(speed)
			line('~')

		@wraps(func)
		def wrapper(*args, **kwargs):
			src = inspect.getsource(func)
			# TODO: remove @Log.hack from src
			try:
				print_type(src)
			except KeyboardInterrupt:
				pass
			finally:
				print('\033[0m') # reset terminal color
			return func(*args, **kwargs)
		return wrapper

if __name__ == '__main__':
	# sample usage
	Log.ENABLED = True # comment this line to turn off logging
	@Log.hack
	@Log.wrap('this is a messages for the method')
	def hello_world(an_arg, opt=None):
		Log.note('hello world')
		Log.note('a padded note', pad='*', level=Log.IMPORTANT)
		Log.note('this will always be printed', level=Log.DEBUG, force=True)
		Log.write('done', tag='verbose test', level=Log.SUCCESS)
	hello_world(5, opt=1)