# Copyright 2012-2019 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

import io
import sys
from datetime import datetime
from time import mktime
from email.utils import formatdate, parsedate

try:
	from urllib.request import urlopen as _urlopen
	import urllib.parse as urllib_parse
	import urllib.request as urllib_request
except ImportError:
	from urllib import urlopen as _urlopen
	import urlparse as urllib_parse
	import urllib2 as urllib_request

if sys.hexversion >= 0x3000000:
	# pylint: disable=W0622
	long = int

# to account for the difference between TIMESTAMP of the index' contents
#  and the file-'mtime'
TIMESTAMP_TOLERANCE = 5


def have_pep_476():
	"""
	Test whether ssl certificate verification is enabled by default for
	stdlib http clients (PEP 476).

	@returns: bool, True if ssl certificate verification is enabled by
		default
	"""
	return hasattr(__import__('ssl'), '_create_unverified_context')


def urlopen(url, if_modified_since=None):
	parse_result = urllib_parse.urlparse(url)
	if parse_result.scheme not in ("http", "https"):
		return _urlopen(url)
	else:
		netloc = parse_result.netloc.rpartition('@')[-1]
		url = urllib_parse.urlunparse((parse_result.scheme, netloc, parse_result.path, parse_result.params, parse_result.query, parse_result.fragment))
		password_manager = urllib_request.HTTPPasswordMgrWithDefaultRealm()
		request = urllib_request.Request(url)
		request.add_header('User-Agent', 'Gentoo Portage')
		if if_modified_since:
			request.add_header('If-Modified-Since', _timestamp_to_http(if_modified_since))
		if parse_result.username is not None:
			password_manager.add_password(None, url, parse_result.username, parse_result.password)
		auth_handler = CompressedResponseProcessor(password_manager)
		opener = urllib_request.build_opener(auth_handler)
		hdl = opener.open(request)
		if hdl.headers.get('last-modified', ''):
			try:
				add_header = hdl.headers.add_header
			except AttributeError:
				# Python 2
				add_header = hdl.headers.addheader
			add_header('timestamp', _http_to_timestamp(hdl.headers.get('last-modified')))
		return hdl

def _timestamp_to_http(timestamp):
	dt = datetime.fromtimestamp(float(long(timestamp)+TIMESTAMP_TOLERANCE))
	stamp = mktime(dt.timetuple())
	return formatdate(timeval=stamp, localtime=False, usegmt=True)

def _http_to_timestamp(http_datetime_string):
	tuple = parsedate(http_datetime_string)
	timestamp = mktime(tuple)
	return str(long(timestamp))

class CompressedResponseProcessor(urllib_request.HTTPBasicAuthHandler):
	# Handler for compressed responses.

	def http_request(self, req):
		req.add_header('Accept-Encoding', 'bzip2,gzip,deflate')
		return req
	https_request = http_request

	def http_response(self, req, response):
		decompressed = None
		if response.headers.get('content-encoding') == 'bzip2':
			import bz2
			decompressed = io.BytesIO(bz2.decompress(response.read()))
		elif response.headers.get('content-encoding') == 'gzip':
			from gzip import GzipFile
			decompressed = GzipFile(fileobj=io.BytesIO(response.read()), mode='r')
		elif response.headers.get('content-encoding') == 'deflate':
			import zlib
			try:
				decompressed = io.BytesIO(zlib.decompress(response.read()))
			except zlib.error: # they ignored RFC1950
				decompressed = io.BytesIO(zlib.decompress(response.read(), -zlib.MAX_WBITS))
		if decompressed:
			old_response = response
			response = urllib_request.addinfourl(decompressed, old_response.headers, old_response.url, old_response.code)
			response.msg = old_response.msg
		return response
	https_response = http_response