#!/usr/bin/python

# Copyright (c) 2009 Benjamin Drung <bdrung@ubuntu.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

# Reference: https://developer.mozilla.org/en/Toolkit_version_format

import getopt
import sys

# error codes
COMMAND_LINE_SYNTAX_ERROR = 2
INVALID_COMPARATOR = 3
EMPTY_VERSION_STRING = 4

def decode_part(part):
	"""Decodes a version part (like 5pre4) to <number-a><string-b><number-c><string-d>"""
	subpart = [0,"",0,""]

	# Split <number-a>
	length = 0
	for i in xrange(len(part)):
		if part[i].isdigit() or part[i] in ("-"):
			length += 1
		else:
			break
	if length > 0:
		subpart[0] = int(part[0:length])
	part = part[length:]

	# Split <string-b>
	length = 0
	for i in xrange(len(part)):
		if not (part[i].isdigit() or part[i] in ("-")):
			length += 1
		else:
			break
	subpart[1] = part[0:length]
	part = part[length:]

	# Split <number-c>
	length = 0
	for i in xrange(len(part)):
		if part[i].isdigit() or part[i] in ("-"):
			length += 1
		else:
			break
	if length > 0:
		subpart[2] = int(part[0:length])
	subpart[3] = part[length:]

	# if string-b is a plus sign, number-a is incremented to be compatible with
	# the Firefox 1.0.x version format: 1.0+ is the same as 1.1pre
	if subpart[1] == "+":
		subpart[0] += 1
		subpart[1] = "pre"

	# if the version part is a single asterisk, it is interpreted as an
	# infinitely-large number: 1.5.0.* is the same as 1.5.0.(infinity)
	if subpart[1] == "*":
		subpart[0] = sys.maxint
		subpart[1] = ""

	return subpart

def decode_version(version, verbose=False):
	"""Decodes a version string like 1.1pre1a"""
	parts = version.split(".")
	decoded_parts = map(decode_part, parts)
	if verbose:
		print "I: Split %s up into %s." % (version, decoded_parts)
	return decoded_parts

def compare_subpart((a, b)):
	# A string-part that exists is always less-then a nonexisting string-part
	if a == "":
		if b == "":
			return 0
		else:
			return 1
	elif b == "":
		if a == "":
			return 0
		else:
			return -1
	else:
		return cmp(a, b)

def compare_part((x, y)):
	compared_subparts = filter(lambda x: x != 0, map(compare_subpart, zip(x, y)))
	if compared_subparts:
		return compared_subparts[0]
	else:
		return 0

def compare_versions(a, b):
	if len(a) < len(b):
		a.extend((len(b) - len(a)) * [[0,"",0,""]])
	if len(b) < len(a):
		b.extend((len(a) - len(b)) * [[0,"",0,""]])

	result = filter(lambda x: x != 0, map(compare_part, zip(a, b)))
	if result:
		return result[0]
	else:
		return 0

comparators = ("lt", "le", "eq", "ne", "ge", "gt")

def moz_version_compare(version1, comparator, version2, silent=False, verbose=False):
	"""Return true if the expression version1 comparator version2 is valid, otherwise false"""
	if comparator not in comparators:
		if not silent:
			print >> sys.stderr, "E: The comparator " + comparator + \
				" is not valid. It should one of " + ", ".join(comparators) + "."
		sys.exit(INVALID_COMPARATOR)

	if version1.strip() == "" or version2.strip() == "":
		if not silent:
			print >> sys.stderr, "E: At least one version string is empty."
		sys.exit(EMPTY_VERSION_STRING)

	if verbose:
		symbol = {"lt": "<", "le": "<=", "eq": "=", "ne": "!=", "ge": ">=", "gt": ">"}
		print "I: Comparing %s %s %s." % (version1, symbol[comparator], version2)

	a = decode_version(version1, verbose)
	b = decode_version(version2, verbose)

	if comparator == "lt":
		return compare_versions(a, b) < 0
	elif comparator == "le":
		return compare_versions(a, b) <= 0
	elif comparator == "eq":
		return compare_versions(a, b) == 0
	elif comparator == "ne":
		return compare_versions(a, b) != 0
	elif comparator == "ge":
		return compare_versions(a, b) >= 0
	elif comparator == "gt":
		return compare_versions(a, b) > 0


def usage(output):
	print >> output, """Usage: %s --compare version1 comparator version2

  -h, --help         display this help and exit
  -s, --silent       do not print anything and die silent on errors
  -v, --verbose      print more information

comparator must be one of %s.""" % (sys.argv[0], ", ".join(comparators))


if __name__ == "__main__":
	try:
		long_opts = ["compare", "help", "silent", "verbose"]
		opts, args = getopt.gnu_getopt(sys.argv[1:], "chsv", long_opts)
	except getopt.GetoptError, e:
		# print help information and exit:
		print >> sys.stderr, str(e) # will print something like "option -a not recognized"
		usage(sys.stderr)
		sys.exit(COMMAND_LINE_SYNTAX_ERROR)

	compare = False
	silent = False
	verbose = False

	for o, a in opts:
		if o in ("-c", "--compare"):
			compare = True
		elif o in ("-h", "--help"):
			usage(sys.stdout)
			sys.exit()
		elif o in ("-s", "--silent"):
			silent = True
		elif o in ("-v", "--verbose"):
			verbose = True
		else:
			assert False, "unhandled option"

	if compare:
		if len(args) != 3:
			if not silent:
				usage(sys.stderr)
			sys.exit(COMMAND_LINE_SYNTAX_ERROR)
		if moz_version_compare(args[0], args[1], args[2], silent, verbose):
			if verbose:
				print "I: Compare expression true."
			sys.exit(0)
		else:
			if verbose:
				print "I: Compare expression false."
			sys.exit(1)
	else:
		if not silent:
			print >> sys.stderr, "E: You should specify the command --compare."
			usage(sys.stderr)
		sys.exit(COMMAND_LINE_SYNTAX_ERROR)
