# Copyright 2002 Ben Escoto
#
# This file is part of rdiff-backup.
#
# rdiff-backup is free software; you can redistribute it and/or modify
# 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.
#
# rdiff-backup 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 rdiff-backup; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
# USA

"""Provide time related exceptions and functions"""

import time, types, re
import Globals


class TimeException(Exception): pass

_interval_conv_dict = {"s": 1, "m": 60, "h": 3600, "D": 86400,
					   "W": 7*86400, "M": 30*86400, "Y": 365*86400}
_integer_regexp = re.compile("^[0-9]+$")
_interval_regexp = re.compile("^([0-9]+)([smhDWMY])")
_genstr_date_regexp1 = re.compile("^(?P<year>[0-9]{4})[-/]"
					   "(?P<month>[0-9]{1,2})[-/](?P<day>[0-9]{1,2})$")
_genstr_date_regexp2 = re.compile("^(?P<month>[0-9]{1,2})[-/]"
					   "(?P<day>[0-9]{1,2})[-/](?P<year>[0-9]{4})$")
curtime = curtimestr = None
been_awake_since = None # stores last time sleep() was run

def setcurtime(curtime = None):
	"""Sets the current time in curtime and curtimestr on all systems"""
	t = curtime or time.time()
	for conn in Globals.connections:
		conn.Time.setcurtime_local(long(t))

def setcurtime_local(timeinseconds):
	"""Only set the current time locally"""
	global curtime, curtimestr
	curtime, curtimestr = timeinseconds, timetostring(timeinseconds)

def setprevtime(timeinseconds):
	"""Sets the previous inc time in prevtime and prevtimestr"""
	assert timeinseconds > 0, timeinseconds
	timestr = timetostring(timeinseconds)
	for conn in Globals.connections:
		conn.Time.setprevtime_local(timeinseconds, timestr)

def setprevtime_local(timeinseconds, timestr):
	"""Like setprevtime but only set the local version"""
	global prevtime, prevtimestr
	prevtime, prevtimestr = timeinseconds, timestr

def timetostring(timeinseconds):
	"""Return w3 datetime compliant listing of timeinseconds"""
	s = time.strftime("%Y-%m-%dT%H:%M:%S", time.localtime(timeinseconds))
	return s + gettzd()

def stringtotime(timestring):
	"""Return time in seconds from w3 timestring

	If there is an error parsing the string, or it doesn't look
	like a w3 datetime string, return None.

	"""
	try:
		date, daytime = timestring[:19].split("T")
		year, month, day = map(int, date.split("-"))
		hour, minute, second = map(int, daytime.split(":"))
		assert 1900 < year < 2100, year
		assert 1 <= month <= 12
		assert 1 <= day <= 31
		assert 0 <= hour <= 23
		assert 0 <= minute <= 59
		assert 0 <= second <= 61  # leap seconds
		timetuple = (year, month, day, hour, minute, second, -1, -1, -1)
		if time.daylight:
			utc_in_secs = time.mktime(timetuple) - time.altzone
		else: utc_in_secs = time.mktime(timetuple) - time.timezone

		return long(utc_in_secs) + tzdtoseconds(timestring[19:])
	except (TypeError, ValueError, AssertionError): return None

def timetopretty(timeinseconds):
	"""Return pretty version of time"""
	return time.asctime(time.localtime(timeinseconds))

def stringtopretty(timestring):
	"""Return pretty version of time given w3 time string"""
	return timetopretty(stringtotime(timestring))

def inttopretty(seconds):
	"""Convert num of seconds to readable string like "2 hours"."""
	partlist = []
	hours, seconds = divmod(seconds, 3600)
	if hours > 1: partlist.append("%d hours" % hours)
	elif hours == 1: partlist.append("1 hour")

	minutes, seconds = divmod(seconds, 60)
	if minutes > 1: partlist.append("%d minutes" % minutes)
	elif minutes == 1: partlist.append("1 minute")

	if seconds == 1: partlist.append("1 second")
	elif not partlist or seconds > 1:
		if isinstance(seconds, int) or isinstance(seconds, long):
			partlist.append("%s seconds" % seconds)
		else: partlist.append("%.2f seconds" % seconds)
	return " ".join(partlist)

def intstringtoseconds(interval_string):
	"""Convert a string expressing an interval (e.g. "4D2s") to seconds"""
	def error():
		raise TimeException("""Bad interval string "%s"

Intervals are specified like 2Y (2 years) or 2h30m (2.5 hours).  The
allowed special characters are s, m, h, D, W, M, and Y.  See the man
page for more information.
""" % interval_string)
	if len(interval_string) < 2: error()

	total = 0
	while interval_string:
		match = _interval_regexp.match(interval_string)
		if not match: error()
		num, ext = int(match.group(1)), match.group(2)
		if not ext in _interval_conv_dict or num < 0: error()
		total += num*_interval_conv_dict[ext]
		interval_string = interval_string[match.end(0):]
	return total

def gettzd():
	"""Return w3's timezone identification string.

	Expresed as [+/-]hh:mm.  For instance, PST is -08:00.  Zone is
	coincides with what localtime(), etc., use.

	"""
	if time.daylight: offset = -1 * time.altzone/60
	else: offset = -1 * time.timezone/60
	if offset > 0: prefix = "+"
	elif offset < 0: prefix = "-"
	else: return "Z" # time is already in UTC

	hours, minutes = map(abs, divmod(offset, 60))
	assert 0 <= hours <= 23
	assert 0 <= minutes <= 59
	return "%s%02d:%02d" % (prefix, hours, minutes)

def tzdtoseconds(tzd):
	"""Given w3 compliant TZD, return how far ahead UTC is"""
	if tzd == "Z": return 0
	assert len(tzd) == 6 # only accept forms like +08:00 for now
	assert (tzd[0] == "-" or tzd[0] == "+") and tzd[3] == ":"
	return -60 * (60 * int(tzd[:3]) + int(tzd[4:]))

def cmp(time1, time2):
	"""Compare time1 and time2 and return -1, 0, or 1"""
	if type(time1) is types.StringType:
		time1 = stringtotime(time1)
		assert time1 is not None
	if type(time2) is types.StringType:
		time2 = stringtotime(time2)
		assert time2 is not None

	if time1 < time2: return -1
	elif time1 == time2: return 0
	else: return 1


def sleep(sleep_ratio):
	"""Sleep for period to maintain given sleep_ratio

	On my system sleeping for periods less than 1/20th of a second
	doesn't seem to work very accurately, so accumulate at least that
	much time before sleeping.

	"""
	global been_awake_since
	if been_awake_since is None: # first running
		been_awake_since = time.time()
	else:
		elapsed_time = time.time() - been_awake_since
		sleep_time = elapsed_time * (sleep_ratio/(1-sleep_ratio))
		if sleep_time >= 0.05:
			time.sleep(sleep_time)
			been_awake_since = time.time()

def genstrtotime(timestr, curtime = None):
	"""Convert a generic time string to a time in seconds"""
	if curtime is None: curtime = globals()['curtime']
	if timestr == "now": return curtime

	def error():
		raise TimeException("""Bad time string "%s"

The acceptible time strings are intervals (like "3D64s"), w3-datetime
strings, like "2002-04-26T04:22:01-07:00" (strings like
"2002-04-26T04:22:01" are also acceptable - rdiff-backup will use the
current time zone), or ordinary dates like 2/4/1997 or 2001-04-23
(various combinations are acceptable, but the month always precedes
the day).""" % timestr)

	# Test for straight integer
	if _integer_regexp.search(timestr): return int(timestr)

	# Test for w3-datetime format, possibly missing tzd
	t = stringtotime(timestr) or stringtotime(timestr+gettzd())
	if t: return t

	try: # test for an interval, like "2 days ago"
		return curtime - intstringtoseconds(timestr)
	except TimeException: pass

	# Now check for dates like 2001/3/23
	match = _genstr_date_regexp1.search(timestr) or \
			_genstr_date_regexp2.search(timestr)
	if not match: error()
	timestr = "%s-%02d-%02dT00:00:00%s" % (match.group('year'),
			     int(match.group('month')), int(match.group('day')), gettzd())
	t = stringtotime(timestr)
	if t: return t
	else: error()