#!/usr/bin/python

# requires: python-dateutil

import glob, os, sys
import time, datetime
import re
from datetime import datetime
from datetime import timedelta
from optparse import OptionParser

RULES = [
	{'days':14,   'keep':56, 'interval':0},
	{'days':31,   'keep':4,  'interval':1},
	{'days':365,  'keep':6,  'interval':31},
	{'days':3650, 'keep':6,  'interval':365},

	# keep 14 days, 56 copys, all each day
	# keep 31 days, 31 copys, 1 each 7th day
	# keep 365 days, 3 copys, 1 each 31th day
]

TODAY = datetime.today()
VERBOSE = False
NOACTION = False
PREFIX = ''
PATH = ''

def all_files(pattern, search_path, pathsep=os.pathsep):
	""" Given a search path, yield all files matching the pattern. """
	for path in search_path.split(pathsep):
		for match in glob.glob(os.path.join(path, pattern)):
			yield match

def parse_file_dates(list):
    out = []
    # dump_2006.05.02-11:52:01.bz2
    p = re.compile('^\./dump_([0-9]{4})\.([0-9]{2})\.([0-9]{2})-([0-9]{2}):([0-9]{2}):([0-9]{2})(.bz2)?$')
    for file in list:
        m = p.search(file)
        if m:
            d = datetime(int(m.group(1)), int(m.group(2)), int(m.group(3)), int(m.group(4)), int(m.group(5)), int(m.group(6)))
            out.append({'name': file, 'date': d})
    return out

def prepare_rules(rules):
	out = []
	for rule in rules:
		out.append(
				{ 
					'days':timedelta(days=rule['days']),
					'keep':rule['keep'],
					'interval':timedelta(days=rule['interval'])}
			)
	return out

def expire(rules, list):
	t_rules=prepare_rules(rules)
	rule = t_rules.pop(0)
	last = list.pop(0)

	for file in list:
		if VERBOSE:
			print "current file to expire: " + file['name']
			print file['date']
		
		# check if rule applies
		if (file['date'] < (TODAY-rule['days'])):
			if VERBOSE:
				print "move to next rule"
			if t_rules:
				rule = t_rules.pop(0)

		if (last['date'] - file['date']) < rule['interval']:
			if VERBOSE:
				print "unlink file:" + file['name']
			if not NOACTION:
				os.unlink(file['name'])
		else:
			last = file	
			if VERBOSE:
				print "kept file:" + file['name']

			
	
	

parser = OptionParser()
parser.add_option(
			"-p", "--path", dest="path",
      help="path name", metavar="Name")
parser.add_option(
			"-f", "--pattern", dest="pattern",
      help="Pattern maybe some glob", metavar="*.backup")
parser.add_option(
			"-v", "--verbose", action="store_true", dest="verbose", default=False,
      help="verbose")
parser.add_option(
			"-n", "--no-action", action="store_true", dest="noaction", default=False,
      help="just prints what would be done, this implies verbose")

(options, args) = parser.parse_args()

if (not options.path):
	parser.error("no path to check given")

if options.noaction:
	VERBOSE=True
	NOACTION=True

if options.verbose:
	VERBOSE=True

files = sorted( list(all_files(options.pattern,options.path)), reverse=True );
#files = sorted( list(all_files(options.pattern,options.path)) );

if not files:
	sys.exit(0)

files_dates =  parse_file_dates(files);
expire(RULES, files_dates )