# urllib3/poolmanager.py
# Copyright 2008-2013 Andrey Petrov and contributors (see CONTRIBUTORS.txt)
#
# This module is part of urllib3 and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php

import logging

try: # Python 3
from urllib.parse import urljoin
except ImportError:
from urlparse import urljoin

from ._collections import RecentlyUsedContainer
from .connectionpool import HTTPConnectionPool, HTTPSConnectionPool
from .connectionpool import port_by_scheme
from .request import RequestMethods
from .util import parse_url


__all__ = ['PoolManager', 'ProxyManager', 'proxy_from_url']


pool_classes_by_scheme = {
'http': HTTPConnectionPool,
'https': HTTPSConnectionPool,
}

log = logging.getLogger(__name__)

SSL_KEYWORDS = ('key_file', 'cert_file', 'cert_reqs', 'ca_certs',
'ssl_version')


class PoolManager(RequestMethods):
"""
Allows for arbitrary requests while transparently keeping track of
necessary connection pools for you.

:param num_pools:
Number of connection pools to cache before discarding the least
recently used pool.

:param headers:
Headers to include with all requests, unless other headers are given
explicitly.

:param \**connection_pool_kw:
Additional parameters are used to create fresh
:class:`urllib3.connectionpool.ConnectionPool` instances.

Example: ::

>>> manager = PoolManager(num_pools=2)
>>> r = manager.request('GET', 'http://google.com/')
>>> r = manager.request('GET', 'http://google.com/mail')
>>> r = manager.request('GET', 'http://yahoo.com/')
>>> len(manager.pools)
2

"""

proxy = None

def __init__(self, num_pools=10, headers=None, **connection_pool_kw):
RequestMethods.__init__(self, headers)
self.connection_pool_kw = connection_pool_kw
self.pools = RecentlyUsedContainer(num_pools,
dispose_func=lambda p: p.close())

def _new_pool(self, scheme, host, port):
"""
Create a new :class:`ConnectionPool` based on host, port and scheme.

This method is used to actually create the connection pools handed out
by :meth:`connection_from_url` and companion methods. It is intended
to be overridden for customization.
"""
pool_cls = pool_classes_by_scheme[scheme]
kwargs = self.connection_pool_kw
if scheme == 'http':
kwargs = self.connection_pool_kw.copy()
for kw in SSL_KEYWORDS:
kwargs.pop(kw, None)

return pool_cls(host, port, **kwargs)

def clear(self):
"""
Empty our store of pools and direct them all to close.

This will not affect in-flight connections, but they will not be
re-used after completion.
"""
self.pools.clear()

def connection_from_host(self, host, port=None, scheme='http'):
"""
Get a :class:`ConnectionPool` based on the host, port, and scheme.

If ``port`` isn't given, it will be derived from the ``scheme`` using
``urllib3.connectionpool.port_by_scheme``.
"""

scheme = scheme or 'http'

port = port or port_by_scheme.get(scheme, 80)

pool_key = (scheme, host, port)

with self.pools.lock:
# If the scheme, host, or port doesn't match existing open
# connections, open a new ConnectionPool.
pool = self.pools.get(pool_key)
if pool:
return pool

# Make a fresh ConnectionPool of the desired type
pool = self._new_pool(scheme, host, port)
self.pools[pool_key] = pool
return pool

def connection_from_url(self, url):
"""
Similar to :func:`urllib3.connectionpool.connection_from_url` but
doesn't pass any additional parameters to the
:class:`urllib3.connectionpool.ConnectionPool` constructor.

Additional parameters are taken from the :class:`.PoolManager`
constructor.
"""
u = parse_url(url)
return self.connection_from_host(u.host, port=u.port, scheme=u.scheme)

def urlopen(self, method, url, redirect=True, **kw):
"""
Same as :meth:`urllib3.connectionpool.HTTPConnectionPool.urlopen`
with custom cross-host redirect logic and only sends the request-uri
portion of the ``url``.

The given ``url`` parameter must be absolute, such that an appropriate
:class:`urllib3.connectionpool.ConnectionPool` can be chosen for it.
"""
u = parse_url(url)
conn = self.connection_from_host(u.host, port=u.port, scheme=u.scheme)

kw['assert_same_host'] = False
kw['redirect'] = False
if 'headers' not in kw:
kw['headers'] = self.headers

if self.proxy is not None and u.scheme == "http":
response = conn.urlopen(method, url, **kw)
else:
response = conn.urlopen(method, u.request_uri, **kw)

redirect_location = redirect and response.get_redirect_location()
if not redirect_location:
return response

# Support relative URLs for redirecting.
redirect_location = urljoin(url, redirect_location)

# RFC 2616, Section 10.3.4
if response.status == 303:
method = 'GET'

log.info("Redirecting %s -> %s" % (url, redirect_location))
kw['retries'] = kw.get('retries', 3) - 1 # Persist retries countdown
kw['redirect'] = redirect
return self.urlopen(method, redirect_location, **kw)


class ProxyManager(PoolManager):
"""
Behaves just like :class:`PoolManager`, but sends all requests through
the defined proxy, using the CONNECT method for HTTPS URLs.

:param poxy_url:
The URL of the proxy to be used.

:param proxy_headers:
A dictionary contaning headers that will be sent to the proxy. In case
of HTTP they are being sent with each request, while in the
HTTPS/CONNECT case they are sent only once. Could be used for proxy
authentication.

Example:
>>> proxy = urllib3.ProxyManager('http://localhost:3128/')
>>> r1 = proxy.request('GET', 'http://google.com/')
>>> r2 = proxy.request('GET', 'http://httpbin.org/')
>>> len(proxy.pools)
1
>>> r3 = proxy.request('GET', 'https://httpbin.org/')
>>> r4 = proxy.request('GET', 'https://twitter.com/')
>>> len(proxy.pools)
3

"""

def __init__(self, proxy_url, num_pools=10, headers=None,
proxy_headers=None, **connection_pool_kw):

if isinstance(proxy_url, HTTPConnectionPool):
proxy_url = '%s://%s:%i' % (proxy_url.scheme, proxy_url.host,
proxy_url.port)
proxy = parse_url(proxy_url)
if not proxy.port:
port = port_by_scheme.get(proxy.scheme, 80)
proxy = proxy._replace(port=port)
self.proxy = proxy
self.proxy_headers = proxy_headers or {}
assert self.proxy.scheme in ("http", "https"), \
'Not supported proxy scheme %s' % self.proxy.scheme
connection_pool_kw['_proxy'] = self.proxy
connection_pool_kw['_proxy_headers'] = self.proxy_headers
super(ProxyManager, self).__init__(
num_pools, headers, **connection_pool_kw)

def connection_from_host(self, host, port=None, scheme='http'):
if scheme == "https":
return super(ProxyManager, self).connection_from_host(
host, port, scheme)

return super(ProxyManager, self).connection_from_host(
self.proxy.host, self.proxy.port, self.proxy.scheme)

def _set_proxy_headers(self, url, headers=None):
"""
Sets headers needed by proxies: specifically, the Accept and Host
headers. Only sets headers not provided by the user.
"""
headers_ = {'Accept': '*/*'}

netloc = parse_url(url).netloc
if netloc:
headers_['Host'] = netloc

if headers:
headers_.update(headers)
return headers_

def urlopen(self, method, url, redirect=True, **kw):
"Same as HTTP(S)ConnectionPool.urlopen, ``url`` must be absolute."
u = parse_url(url)

if u.scheme == "http":
# It's too late to set proxy headers on per-request basis for
# tunnelled HTTPS connections, should use
# constructor's proxy_headers instead.
kw['headers'] = self._set_proxy_headers(url, kw.get('headers',
self.headers))
kw['headers'].update(self.proxy_headers)

return super(ProxyManager, self).urlopen(method, url, redirect, **kw)


def proxy_from_url(url, **kw):
return ProxyManager(proxy_url=url, **kw)