import os
import sys

from optparse import OptionParser
from StringIO import StringIO

from twisted.internet.threads import deferToThread
from twisted.internet.defer import DeferredList


class FetchError(Exception):
pass


class HTTPCodeError(FetchError):

def __init__(self, http_code, body):
self.http_code = http_code
self.body = body

def __str__(self):
return "Server returned HTTP code %d" % self.http_code

def __repr__(self):
return "<HTTPCodeError http_code=%d>" % self.http_code


class PyCurlError(FetchError):

def __init__(self, error_code, message):
self.error_code = error_code
self._message = message

def __str__(self):
return "Error %d: %s" % (self.error_code, self.message)

def __repr__(self):
return "<PyCurlError args=(%d, '%s')>" % (self.error_code,
self.message)

@property
def message(self):
return self._message


def fetch(url, post=False, data="", headers={}, cainfo=None, curl=None,
connect_timeout=30, total_timeout=600, insecure=False, follow=True):
"""Retrieve a URL and return the content.

@param url: The url to be fetched.
@param post: If true, the POST method will be used (defaults to GET).
@param data: Data to be sent to the server as the POST content.
@param headers: Dictionary of header => value entries to be used
on the request.
@param cainfo: Path to the file with CA certificates.
@param insecure: If true, perform curl using insecure option which will
not attempt to verify authenticity of the peer's
certificate. (Used during autodiscovery)
@param follow: If True, follow HTTP redirects (default True).
"""
import pycurl
output = StringIO(data)
input = StringIO()

if curl is None:
curl = pycurl.Curl()

if post:
curl.setopt(pycurl.POST, True)

if data:
curl.setopt(pycurl.POSTFIELDSIZE, len(data))
curl.setopt(pycurl.READFUNCTION, output.read)

if cainfo and url.startswith("https:"):
curl.setopt(pycurl.CAINFO, cainfo)

if headers:
curl.setopt(pycurl.HTTPHEADER,
["%s: %s" % pair for pair in sorted(headers.iteritems())])

if insecure:
curl.setopt(pycurl.SSL_VERIFYPEER, False)

curl.setopt(pycurl.URL, str(url))
if follow:
curl.setopt(pycurl.FOLLOWLOCATION, 1)

curl.setopt(pycurl.MAXREDIRS, 5)
curl.setopt(pycurl.CONNECTTIMEOUT, connect_timeout)
curl.setopt(pycurl.LOW_SPEED_LIMIT, 1)
curl.setopt(pycurl.LOW_SPEED_TIME, total_timeout)
curl.setopt(pycurl.NOSIGNAL, 1)
curl.setopt(pycurl.WRITEFUNCTION, input.write)
curl.setopt(pycurl.DNS_CACHE_TIMEOUT, 0)
curl.setopt(pycurl.ENCODING, "gzip,deflate")

try:
curl.perform()
except pycurl.error, e:
raise PyCurlError(e.args[0], e.args[1])

body = input.getvalue()

http_code = curl.getinfo(pycurl.HTTP_CODE)
if http_code != 200:
raise HTTPCodeError(http_code, body)

return body


def test(args):
parser = OptionParser()
parser.add_option("--post", action="store_true")
parser.add_option("--data", default="")
parser.add_option("--cainfo")
options, (url,) = parser.parse_args(args)
print fetch(url, post=options.post, data=options.data,
cainfo=options.cainfo)


def fetch_async(*args, **kwargs):
"""Retrieve a URL asynchronously.

@return: A C{Deferred} resulting in the URL content.
"""
return deferToThread(fetch, *args, **kwargs)


def fetch_many_async(urls, callback=None, errback=None, **kwargs):
"""
Retrieve a list of URLs asynchronously.

@param callback: Optionally, a function that will be fired one time for
each successful URL, and will be passed its content and the URL itself.
@param errback: Optionally, a function that will be fired one time for each
failing URL, and will be passed the failure and the URL itself.
@return: A C{DeferredList} whose callback chain will be fired as soon as
all downloads have terminated. If an error occurs, the errback chain
of the C{DeferredList} will be fired immediatly.
"""
results = []
for url in urls:
result = fetch_async(url, **kwargs)
if callback:
result.addCallback(callback, url)
if errback:
result.addErrback(errback, url)
results.append(result)
return DeferredList(results, fireOnOneErrback=True, consumeErrors=True)


def url_to_filename(url, directory=None):
"""Return the last component of the given C{url}.

@param url: The URL to get the filename from.
@param directory: Optionally a path to prepend to the returned filename.

@note: Any trailing slash in the C{url} will be removed
"""
filename = url.rstrip("/").split("/")[-1]
if directory is not None:
filename = os.path.join(directory, filename)
return filename


def fetch_to_files(urls, directory, logger=None, **kwargs):
"""
Retrieve a list of URLs and save their content as files in a directory.

@param urls: The list URLs to fetch.
@param directory: The directory to save the files to, the name of the file
will equal the last fragment of the URL.
@param logger: Optional function to be used to log errors for failed URLs.
"""

def write(data, url):
filename = url_to_filename(url, directory=directory)
fd = open(filename, "w")
fd.write(data)
fd.close()

def log_error(failure, url):
if logger:
logger("Couldn't fetch file from %s (%s)" % (
url, str(failure.value)))
return failure

return fetch_many_async(urls, callback=write, errback=log_error, **kwargs)


if __name__ == "__main__":
test(sys.argv[1:])