#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
FDSN Web service client for ObsPy.

:copyright:
    The ObsPy Development Team (devs@obspy.org)
:license:
    GNU Lesser General Public License, Version 3
    (http://www.gnu.org/copyleft/lesser.html)
"""
from __future__ import (absolute_import, division, print_function,
                        unicode_literals)
from future.builtins import *  # NOQA
from future import standard_library
from future.utils import PY2, native_str

import collections
import copy
import io
import os
import textwrap
import threading
import warnings

with standard_library.hooks():
    import queue
    import urllib.error
    import urllib.parse
    import urllib.request
    from collections import OrderedDict

from lxml import etree

import obspy
from obspy import UTCDateTime, read_inventory
from obspy.fdsn.header import (DEFAULT_PARAMETERS, DEFAULT_USER_AGENT, FDSNWS,
                               OPTIONAL_PARAMETERS, PARAMETER_ALIASES,
                               URL_MAPPINGS, WADL_PARAMETERS_NOT_TO_BE_PARSED,
                               FDSNException, FDSNRedirectException)
from obspy.fdsn.wadl_parser import WADLParser


DEFAULT_SERVICE_VERSIONS = {'dataselect': 1, 'station': 1, 'event': 1}


class CustomRedirectHandler(urllib.request.HTTPRedirectHandler):
    """
    Custom redirection handler to also do it for POST requests which the
    standard library does not do by default.
    """
    def redirect_request(self, req, fp, code, msg, headers, newurl):
        """
        Copied and modified from the standard library.
        """
        # Force the same behaviour for GET, HEAD, and POST.
        m = req.get_method()
        if (not (code in (301, 302, 303, 307) and
                 m in ("GET", "HEAD", "POST"))):
            raise urllib.error.HTTPError(req.full_url, code, msg, headers, fp)

        # be conciliant with URIs containing a space
        newurl = newurl.replace(' ', '%20')
        CONTENT_HEADERS = ("content-length", "content-type")
        newheaders = dict((k, v) for k, v in req.headers.items()
                          if k.lower() not in CONTENT_HEADERS)

        # Also redirect the data of the request which the standard library
        # interestingly enough does not do.
        return urllib.request.Request(
            newurl, headers=newheaders,
            data=req.data,
            origin_req_host=req.origin_req_host,
            unverifiable=True)


class NoRedirectionHandler(urllib.request.HTTPRedirectHandler):
    """
    Handler that does not direct!
    """
    def redirect_request(self, req, fp, code, msg, headers, newurl):
        """
        Copied and modified from the standard library.
        """
        raise FDSNRedirectException(
            "Requests with credentials (username, password) are not being "
            "redirected by default to improve security. To force redirects "
            "and if you trust the data center, set `force_redirect` to True "
            "when initializing the Client.")


class Client(object):
    """
    FDSN Web service request client.

    For details see the :meth:`~obspy.fdsn.client.Client.__init__()` method.
    """
    # Dictionary caching any discovered service. Therefore repeatedly
    # initializing a client with the same base URL is cheap.
    __service_discovery_cache = {}

    def __init__(self, base_url="IRIS", major_versions=None, user=None,
                 password=None, user_agent=DEFAULT_USER_AGENT, debug=False,
                 timeout=120, service_mappings=None, force_redirect=False):
        """
        Initializes an FDSN Web Service client.

        >>> client = Client("IRIS")
        >>> print(client)  # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
        FDSN Webservice Client (base url: http://service.iris.edu)
        Available Services: 'dataselect' (v...), 'event' (v...),
        'station' (v...), 'available_event_catalogs',
        'available_event_contributors'
        Use e.g. client.help('dataselect') for the
        parameter description of the individual services
        or client.help() for parameter description of
        all webservices.

        :type base_url: str
        :param base_url: Base URL of FDSN web service compatible server
            (e.g. "http://service.iris.edu") or key string for recognized
            server (one of %s).
        :type major_versions: dict
        :param major_versions: Allows to specify custom major version numbers
            for individual services (e.g.
            `major_versions={'station': 2, 'dataselect': 3}`), otherwise the
            latest version at time of implementation will be used.
        :type user: str
        :param user: User name of HTTP Digest Authentication for access to
            restricted data.
        :type password: str
        :param password: Password of HTTP Digest Authentication for access to
            restricted data.
        :type user_agent: str
        :param user_agent: The user agent for all requests.
        :type debug: bool
        :param debug: Debug flag.
        :type timeout: float
        :param timeout: Maximum time (in seconds) to wait for a single request
            to receive the first byte of the response (after which an exception
            is raised).
        :type service_mappings: dict
        :param service_mappings: For advanced use only. Allows the direct
            setting of the endpoints of the different services. (e.g.
            ``service_mappings={'station': 'http://example.com/test/stat/1'}``)
            Valid keys are ``event``, ``station``, and ``dataselect``. This
            will overwrite the ``base_url`` and ``major_versions`` arguments.
            For all services not specified, the default default locations
            indicated by ``base_url`` and ``major_versions`` will be used. Any
            service that is manually specified as ``None`` (e.g.
            ``service_mappings={'event': None}``) will be deactivated.
        :type force_redirect: bool
        :param force_redirect: By default the client will follow all HTTP
            redirects as long as no credentials (username and password)
            are given. If credentials are given it will raise an exception
            when a redirect is discovered. This is done to improve security.
            Settings this flag to ``True`` will force all redirects to be
            followed even if credentials are given.
        """
        self.debug = debug
        self.user = user
        self.timeout = timeout

        # Cache for the webservice versions. This makes interactive use of
        # the client more convenient.
        self.__version_cache = {}

        if base_url.upper() in URL_MAPPINGS:
            base_url = URL_MAPPINGS[base_url.upper()]

        # Make sure the base_url does not end with a slash.
        base_url = base_url.strip("/")
        self.base_url = base_url

        # Only add the authentication handler if required.
        handlers = []
        if user is not None and password is not None:
            # Create an OpenerDirector for HTTP Digest Authentication
            password_mgr = urllib.request.HTTPPasswordMgrWithDefaultRealm()
            password_mgr.add_password(None, base_url, user, password)
            handlers.append(urllib.request.HTTPDigestAuthHandler(password_mgr))

        if (user is None and password is None) or force_redirect is True:
            # Redirect if no credentials are given or the force_redirect
            # flag is True.
            handlers.append(CustomRedirectHandler())
        else:
            handlers.append(NoRedirectionHandler())

        # Don't install globally to not mess with other codes.
        self._url_opener = urllib.request.build_opener(*handlers)

        self.request_headers = {"User-Agent": user_agent}
        # Avoid mutable kwarg.
        if major_versions is None:
            major_versions = {}
        # Make a copy to avoid overwriting the default service versions.
        self.major_versions = DEFAULT_SERVICE_VERSIONS.copy()
        self.major_versions.update(major_versions)

        # Avoid mutable kwarg.
        if service_mappings is None:
            service_mappings = {}
        self._service_mappings = service_mappings

        if self.debug is True:
            print("Base URL: %s" % self.base_url)
            if self._service_mappings:
                print("Custom service mappings:")
                for key, value in self._service_mappings.items():
                    print("\t%s: '%s'" % (key, value))
            print("Request Headers: %s" % str(self.request_headers))

        self._discover_services()

    def get_events(self, starttime=None, endtime=None, minlatitude=None,
                   maxlatitude=None, minlongitude=None, maxlongitude=None,
                   latitude=None, longitude=None, minradius=None,
                   maxradius=None, mindepth=None, maxdepth=None,
                   minmagnitude=None, maxmagnitude=None, magnitudetype=None,
                   includeallorigins=None, includeallmagnitudes=None,
                   includearrivals=None, eventid=None, limit=None, offset=None,
                   orderby=None, catalog=None, contributor=None,
                   updatedafter=None, filename=None, **kwargs):
        """
        Query the event service of the client.

        >>> client = Client("IRIS")
        >>> cat = client.get_events(eventid=609301)
        >>> print(cat)
        1 Event(s) in Catalog:
        1997-10-14T09:53:11.070000Z | -22.145, -176.720 | 7.8 mw

        The return value is a :class:`~obspy.core.event.Catalog` object
        which can contain any number of events.

        >>> t1 = UTCDateTime("2001-01-07T00:00:00")
        >>> t2 = UTCDateTime("2001-01-07T03:00:00")
        >>> cat = client.get_events(starttime=t1, endtime=t2, minmagnitude=4,
        ...                         catalog="ISC")
        >>> print(cat)
        3 Event(s) in Catalog:
        2001-01-07T02:55:59.290000Z |  +9.801,  +76.548 | 4.9 mb
        2001-01-07T02:35:35.170000Z | -21.291,  -68.308 | 4.4 mb
        2001-01-07T00:09:25.630000Z | +22.946, -107.011 | 4.0 mb

        :type starttime: :class:`~obspy.core.utcdatetime.UTCDateTime`, optional
        :param starttime: Limit to events on or after the specified start time.
        :type endtime: :class:`~obspy.core.utcdatetime.UTCDateTime`, optional
        :param endtime: Limit to events on or before the specified end time.
        :type minlatitude: float, optional
        :param minlatitude: Limit to events with a latitude larger than the
            specified minimum.
        :type maxlatitude: float, optional
        :param maxlatitude: Limit to events with a latitude smaller than the
            specified maximum.
        :type minlongitude: float, optional
        :param minlongitude: Limit to events with a longitude larger than the
            specified minimum.
        :type maxlongitude: float, optional
        :param maxlongitude: Limit to events with a longitude smaller than the
            specified maximum.
        :type latitude: float, optional
        :param latitude: Specify the latitude to be used for a radius search.
        :type longitude: float, optional
        :param longitude: Specify the longitude to the used for a radius
            search.
        :type minradius: float, optional
        :param minradius: Limit to events within the specified minimum number
            of degrees from the geographic point defined by the latitude and
            longitude parameters.
        :type maxradius: float, optional
        :param maxradius: Limit to events within the specified maximum number
            of degrees from the geographic point defined by the latitude and
            longitude parameters.
        :type mindepth: float, optional
        :param mindepth: Limit to events with depth more than the specified
            minimum.
        :type maxdepth: float, optional
        :param maxdepth: Limit to events with depth less than the specified
            maximum.
        :type minmagnitude: float, optional
        :param minmagnitude: Limit to events with a magnitude larger than the
            specified minimum.
        :type maxmagnitude: float, optional
        :param maxmagnitude: Limit to events with a magnitude smaller than the
            specified maximum.
        :type magnitudetype: str, optional
        :param magnitudetype: Specify a magnitude type to use for testing the
            minimum and maximum limits.
        :type includeallorigins: bool, optional
        :param includeallorigins: Specify if all origins for the event should
            be included, default is data center dependent but is suggested to
            be the preferred origin only.
        :type includeallmagnitudes: bool, optional
        :param includeallmagnitudes: Specify if all magnitudes for the event
            should be included, default is data center dependent but is
            suggested to be the preferred magnitude only.
        :type includearrivals: bool, optional
        :param includearrivals: Specify if phase arrivals should be included.
        :type eventid: str (or int, dependent on data center), optional
        :param eventid: Select a specific event by ID; event identifiers are
            data center specific.
        :type limit: int, optional
        :param limit: Limit the results to the specified number of events.
        :type offset: int, optional
        :param offset: Return results starting at the event count specified,
            starting at 1.
        :type orderby: str, optional
        :param orderby: Order the result by time or magnitude with the
            following possibilities:

            * time: order by origin descending time
            * time-asc: order by origin ascending time
            * magnitude: order by descending magnitude
            * magnitude-asc: order by ascending magnitude

        :type catalog: str, optional
        :param catalog: Limit to events from a specified catalog
        :type contributor: str, optional
        :param contributor: Limit to events contributed by a specified
            contributor.
        :type updatedafter: :class:`~obspy.core.utcdatetime.UTCDateTime`,
            optional
        :param updatedafter: Limit to events updated after the specified time.
        :type filename: str or file
        :param filename: If given, the downloaded data will be saved there
            instead of being parse to an ObsPy object. Thus it will contain the
            raw data from the webservices.


        Any additional keyword arguments will be passed to the webservice as
        additional arguments. If you pass one of the default parameters and the
        webservice does not support it, a warning will be issued. Passing any
        non-default parameters that the webservice does not support will raise
        an error.
        """
        if "event" not in self.services:
            msg = "The current client does not have an event service."
            raise ValueError(msg)

        locs = locals()
        setup_query_dict('event', locs, kwargs)

        url = self._create_url_from_parameters(
            "event", DEFAULT_PARAMETERS['event'], kwargs)

        data_stream = self._download(url)
        data_stream.seek(0, 0)
        if filename:
            self._write_to_file_object(filename, data_stream)
            data_stream.close()
        else:
            cat = obspy.readEvents(data_stream, format="quakeml")
            data_stream.close()
            return cat

    def get_stations(self, starttime=None, endtime=None, startbefore=None,
                     startafter=None, endbefore=None, endafter=None,
                     network=None, station=None, location=None, channel=None,
                     minlatitude=None, maxlatitude=None, minlongitude=None,
                     maxlongitude=None, latitude=None, longitude=None,
                     minradius=None, maxradius=None, level=None,
                     includerestricted=None, includeavailability=None,
                     updatedafter=None, matchtimeseries=None, filename=None,
                     **kwargs):
        """
        Query the station service of the FDSN client.

        >>> client = Client("IRIS")
        >>> starttime = UTCDateTime("2001-01-01")
        >>> endtime = UTCDateTime("2001-01-02")
        >>> inventory = client.get_stations(network="IU", station="A*",
        ...                                 starttime=starttime,
        ...                                 endtime=endtime)
        >>> print(inventory)  # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
        Inventory created at ...
            Created by: IRIS WEB SERVICE: fdsnws-station | version: ...
                        http://service.iris.edu/fdsnws/station/1/query...
            Sending institution: IRIS-DMC (IRIS-DMC)
            Contains:
                    Networks (1):
                            IU
                    Stations (3):
                            IU.ADK (Adak, Aleutian Islands, Alaska)
                            IU.AFI (Afiamalu, Samoa)
                            IU.ANMO (Albuquerque, New Mexico, USA)
                    Channels (0):
        >>> inventory.plot()  # doctest: +SKIP

        .. plot::

            from obspy import UTCDateTime
            from obspy.fdsn import Client
            client = Client()
            starttime = UTCDateTime("2001-01-01")
            endtime = UTCDateTime("2001-01-02")
            inventory = client.get_stations(network="IU", station="A*",
                                            starttime=starttime,
                                            endtime=endtime)
            inventory.plot()


        The result is an :class:`~obspy.station.inventory.Inventory` object
        which models a StationXML file.

        The ``level`` argument determines the amount of returned information.
        ``level="station"`` is useful for availability queries whereas
        ``level="response"`` returns the full response information for the
        requested channels. ``level`` can furthermore be set to ``"network"``
        and ``"channel"``.

        >>> inventory = client.get_stations(
        ...     starttime=starttime, endtime=endtime,
        ...     network="IU", sta="ANMO", loc="00", channel="*Z",
        ...     level="response")
        >>> print(inventory)  # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
        Inventory created at ...
            Created by: IRIS WEB SERVICE: fdsnws-station | version: ...
                    http://service.iris.edu/fdsnws/station/1/query?...
            Sending institution: IRIS-DMC (IRIS-DMC)
            Contains:
                Networks (1):
                    IU
                Stations (1):
                    IU.ANMO (Albuquerque, New Mexico, USA)
                Channels (4):
                    IU.ANMO.00.BHZ, IU.ANMO.00.LHZ, IU.ANMO.00.UHZ,
                    IU.ANMO.00.VHZ
        >>> inventory[0].plot_response(min_freq=1E-4)  # doctest: +SKIP

        .. plot::

            from obspy import UTCDateTime
            from obspy.fdsn import Client
            client = Client()
            starttime = UTCDateTime("2001-01-01")
            endtime = UTCDateTime("2001-01-02")
            inventory = client.get_stations(
                starttime=starttime, endtime=endtime,
                network="IU", sta="ANMO", loc="00", channel="*Z",
                level="response")
            inventory[0].plot_response(min_freq=1E-4)

        :type starttime: :class:`~obspy.core.utcdatetime.UTCDateTime`
        :param starttime: Limit to metadata epochs starting on or after the
            specified start time.
        :type endtime: :class:`~obspy.core.utcdatetime.UTCDateTime`
        :param endtime: Limit to metadata epochs ending on or before the
            specified end time.
        :type startbefore: :class:`~obspy.core.utcdatetime.UTCDateTime`
        :param startbefore: Limit to metadata epochs starting before specified
            time.
        :type startafter: :class:`~obspy.core.utcdatetime.UTCDateTime`
        :param startafter: Limit to metadata epochs starting after specified
            time.
        :type endbefore: :class:`~obspy.core.utcdatetime.UTCDateTime`
        :param endbefore: Limit to metadata epochs ending before specified
            time.
        :type endafter: :class:`~obspy.core.utcdatetime.UTCDateTime`
        :param endafter: Limit to metadata epochs ending after specified time.
        :type network: str
        :param network: Select one or more network codes. Can be SEED network
            codes or data center defined codes. Multiple codes are
            comma-separated.
        :type station: str
        :param station: Select one or more SEED station codes. Multiple codes
            are comma-separated.
        :type location: str
        :param location: Select one or more SEED location identifiers. Multiple
            identifiers are comma-separated. As a special case ``“--“`` (two
            dashes) will be translated to a string of two space characters to
            match blank location IDs.
        :type channel: str
        :param channel: Select one or more SEED channel codes. Multiple codes
            are comma-separated.
        :type minlatitude: float
        :param minlatitude: Limit to stations with a latitude larger than the
            specified minimum.
        :type maxlatitude: float
        :param maxlatitude: Limit to stations with a latitude smaller than the
            specified maximum.
        :type minlongitude: float
        :param minlongitude: Limit to stations with a longitude larger than the
            specified minimum.
        :type maxlongitude: float
        :param maxlongitude: Limit to stations with a longitude smaller than
            the specified maximum.
        :type latitude: float
        :param latitude: Specify the latitude to be used for a radius search.
        :type longitude: float
        :param longitude: Specify the longitude to the used for a radius
            search.
        :type minradius: float
        :param minradius: Limit results to stations within the specified
            minimum number of degrees from the geographic point defined by the
            latitude and longitude parameters.
        :type maxradius: float
        :param maxradius: Limit results to stations within the specified
            maximum number of degrees from the geographic point defined by the
            latitude and longitude parameters.
        :type level: str
        :param level: Specify the level of detail for the results ("network",
            "station", "channel", "response"), e.g. specify "response" to get
            full information including instrument response for each channel.
        :type includerestricted: bool
        :param includerestricted: Specify if results should include information
            for restricted stations.
        :type includeavailability: bool
        :param includeavailability: Specify if results should include
            information about time series data availability.
        :type updatedafter: :class:`~obspy.core.utcdatetime.UTCDateTime`
        :param updatedafter: Limit to metadata updated after specified date;
            updates are data center specific.
        :type matchtimeseries: bool
        :param matchtimeseries: Only include data for which matching time
            series data is available.
        :type filename: str or file
        :param filename: If given, the downloaded data will be saved there
            instead of being parse to an ObsPy object. Thus it will contain the
            raw data from the webservices.
        :rtype: :class:`~obspy.station.inventory.Inventory`
        :returns: Inventory with requested station information.

        Any additional keyword arguments will be passed to the webservice as
        additional arguments. If you pass one of the default parameters and the
        webservice does not support it, a warning will be issued. Passing any
        non-default parameters that the webservice does not support will raise
        an error.
        """
        if "station" not in self.services:
            msg = "The current client does not have a station service."
            raise ValueError(msg)

        locs = locals()
        setup_query_dict('station', locs, kwargs)

        url = self._create_url_from_parameters(
            "station", DEFAULT_PARAMETERS['station'], kwargs)

        data_stream = self._download(url)
        data_stream.seek(0, 0)
        if filename:
            self._write_to_file_object(filename, data_stream)
            data_stream.close()
        else:
            inventory = read_inventory(data_stream, format="STATIONXML")
            data_stream.close()
            return inventory

    def get_waveforms(self, network, station, location, channel, starttime,
                      endtime, quality=None, minimumlength=None,
                      longestonly=None, filename=None, attach_response=False,
                      **kwargs):
        """
        Query the dataselect service of the client.

        >>> client = Client("IRIS")
        >>> t1 = UTCDateTime("2010-02-27T06:30:00.000")
        >>> t2 = t1 + 5
        >>> st = client.get_waveforms("IU", "ANMO", "00", "LHZ", t1, t2)
        >>> print(st)  # doctest: +ELLIPSIS
        1 Trace(s) in Stream:
        IU.ANMO.00.LHZ | 2010-02-27T06:30:00.069538Z - ... | 1.0 Hz, 5 samples

        The services can deal with UNIX style wildcards.

        >>> st = client.get_waveforms("IU", "A*", "1?", "LHZ", t1, t2)
        >>> print(st)  # doctest: +ELLIPSIS
        3 Trace(s) in Stream:
        IU.ADK.10.LHZ  | 2010-02-27T06:30:00.069538Z - ... | 1.0 Hz, 5 samples
        IU.AFI.10.LHZ  | 2010-02-27T06:30:00.069538Z - ... | 1.0 Hz, 5 samples
        IU.ANMO.10.LHZ | 2010-02-27T06:30:00.069538Z - ... | 1.0 Hz, 5 samples

        Use ``attach_response=True`` to automatically add response information
        to each trace. This can be used to remove response using
        :meth:`~obspy.core.stream.Stream.remove_response`.

        >>> t = UTCDateTime("2012-12-14T10:36:01.6Z")
        >>> st = client.get_waveforms("TA", "E42A", "*", "BH?", t+300, t+400,
        ...                           attach_response=True)
        >>> st.remove_response(output="VEL") # doctest: +ELLIPSIS
        <obspy.core.stream.Stream object at ...>
        >>> st.plot()  # doctest: +SKIP

        .. plot::

            from obspy import UTCDateTime
            from obspy.fdsn import Client
            client = Client("IRIS")
            t = UTCDateTime("2012-12-14T10:36:01.6Z")
            st = client.get_waveforms("TA", "E42A", "*", "BH?", t+300, t+400,
                                      attach_response=True)
            st.remove_response(output="VEL")
            st.plot()

        :type network: str
        :param network: Select one or more network codes. Can be SEED network
            codes or data center defined codes. Multiple codes are
            comma-separated. Wildcards are allowed.
        :type station: str
        :param station: Select one or more SEED station codes. Multiple codes
            are comma-separated. Wildcards are allowed.
        :type location: str
        :param location: Select one or more SEED location identifiers. Multiple
            identifiers are comma-separated. Wildcards are allowed.
        :type channel: str
        :param channel: Select one or more SEED channel codes. Multiple codes
            are comma-separated.
        :type starttime: :class:`~obspy.core.utcdatetime.UTCDateTime`
        :param starttime: Limit results to time series samples on or after the
            specified start time
        :type endtime: :class:`~obspy.core.utcdatetime.UTCDateTime`
        :param endtime: Limit results to time series samples on or before the
            specified end time
        :type quality: str, optional
        :param quality: Select a specific SEED quality indicator, handling is
            data center dependent.
        :type minimumlength: float, optional
        :param minimumlength: Limit results to continuous data segments of a
            minimum length specified in seconds.
        :type longestonly: bool, optional
        :param longestonly: Limit results to the longest continuous segment per
            channel.
        :type filename: str or file
        :param filename: If given, the downloaded data will be saved there
            instead of being parse to an ObsPy object. Thus it will contain the
            raw data from the webservices.
        :type attach_response: bool
        :param attach_response: Specify whether the station web service should
            be used to automatically attach response information to each trace
            in the result set. A warning will be shown if a response can not be
            found for a channel. Does nothing if output to a file was
            specified.

        Any additional keyword arguments will be passed to the webservice as
        additional arguments. If you pass one of the default parameters and the
        webservice does not support it, a warning will be issued. Passing any
        non-default parameters that the webservice does not support will raise
        an error.
        """
        if "dataselect" not in self.services:
            msg = "The current client does not have a dataselect service."
            raise ValueError(msg)

        locs = locals()
        setup_query_dict('dataselect', locs, kwargs)

        # Special location handling. Convert empty strings to "--".
        if "location" in kwargs and not kwargs["location"]:
            kwargs["location"] = "--"

        url = self._create_url_from_parameters(
            "dataselect", DEFAULT_PARAMETERS['dataselect'], kwargs)

        data_stream = self._download(url)
        data_stream.seek(0, 0)
        if filename:
            self._write_to_file_object(filename, data_stream)
            data_stream.close()
        else:
            st = obspy.read(data_stream, format="MSEED")
            data_stream.close()
            if attach_response:
                self._attach_responses(st)
            return st

    def _attach_responses(self, st):
        """
        Helper method to fetch response via get_stations() and attach it to
        each trace in stream.
        """
        netids = {}
        for tr in st:
            if tr.id not in netids:
                netids[tr.id] = (tr.stats.starttime, tr.stats.endtime)
                continue
            netids[tr.id] = (
                min(tr.stats.starttime, netids[tr.id][0]),
                max(tr.stats.endtime, netids[tr.id][1]))

        inventories = []
        for key, value in netids.items():
            net, sta, loc, chan = key.split(".")
            starttime, endtime = value
            try:
                inventories.append(self.get_stations(
                    network=net, station=sta, location=loc, channel=chan,
                    starttime=starttime, endtime=endtime, level="response"))
            except Exception as e:
                warnings.warn(str(e))
        st.attach_response(inventories)

    def get_waveforms_bulk(self, bulk, quality=None, minimumlength=None,
                           longestonly=None, filename=None,
                           attach_response=False, **kwargs):
        r"""
        Query the dataselect service of the client. Bulk request.

        Send a bulk request for waveforms to the server. `bulk` can either be
        specified as a filename, a file-like object or a string (with
        information formatted according to the FDSN standard) or a list of
        lists (each specifying network, station, location, channel, starttime
        and endtime). See examples and parameter description for more
        details.

        `bulk` can be provided in the following forms:

        (1) As a list of lists. Each list item has to be list of network,
            station, location, channel, starttime and endtime.

        (2) As a valid request string/file as defined in the
            `FDSNWS documentation <http://www.fdsn.org/webservices/>`_.
            The request information can be provided as a..

            - a string containing the request information
            - a string with the path to a local file with the request
            - an open file handle (or file-like object) with the request

        >>> client = Client("IRIS")
        >>> t1 = UTCDateTime("2010-02-27T06:30:00.000")
        >>> t2 = t1 + 1
        >>> t3 = t1 + 3
        >>> bulk = [("IU", "ANMO", "*", "BHZ", t1, t2),
        ...         ("IU", "AFI", "1?", "BHE", t1, t3),
        ...         ("GR", "GRA1", "*", "BH*", t2, t3)]
        >>> st = client.get_waveforms_bulk(bulk)
        >>> print(st)  # doctest: +ELLIPSIS
        5 Trace(s) in Stream:
        GR.GRA1..BHE   | 2010-02-27T06:30:01... | 20.0 Hz, 40 samples
        GR.GRA1..BHN   | 2010-02-27T06:30:01... | 20.0 Hz, 40 samples
        GR.GRA1..BHZ   | 2010-02-27T06:30:01... | 20.0 Hz, 40 samples
        IU.ANMO.00.BHZ | 2010-02-27T06:30:00... | 20.0 Hz, 20 samples
        IU.ANMO.10.BHZ | 2010-02-27T06:30:00... | 40.0 Hz, 40 samples
        >>> bulk = 'quality=B\n' + \
        ...        'longestonly=false\n' + \
        ...        'IU ANMO * BHZ 2010-02-27 2010-02-27T00:00:02\n' + \
        ...        'IU AFI 1? BHE 2010-02-27 2010-02-27T00:00:04\n' + \
        ...        'GR GRA1 * BH? 2010-02-27 2010-02-27T00:00:02\n'
        >>> st = client.get_waveforms_bulk(bulk)
        >>> print(st)  # doctest: +ELLIPSIS
        5 Trace(s) in Stream:
        GR.GRA1..BHE   | 2010-02-27T00:00:00... | 20.0 Hz, 40 samples
        GR.GRA1..BHN   | 2010-02-27T00:00:00... | 20.0 Hz, 40 samples
        GR.GRA1..BHZ   | 2010-02-27T00:00:00... | 20.0 Hz, 40 samples
        IU.ANMO.00.BHZ | 2010-02-27T00:00:00... | 20.0 Hz, 40 samples
        IU.ANMO.10.BHZ | 2010-02-27T00:00:00... | 40.0 Hz, 80 samples
        >>> st = client.get_waveforms_bulk("/tmp/request.txt") \
        ...     # doctest: +SKIP
        >>> print(st)  # doctest: +SKIP
        5 Trace(s) in Stream:
        GR.GRA1..BHE   | 2010-02-27T00:00:00... | 20.0 Hz, 40 samples
        GR.GRA1..BHN   | 2010-02-27T00:00:00... | 20.0 Hz, 40 samples
        GR.GRA1..BHZ   | 2010-02-27T00:00:00... | 20.0 Hz, 40 samples
        IU.ANMO.00.BHZ | 2010-02-27T00:00:00... | 20.0 Hz, 40 samples
        IU.ANMO.10.BHZ | 2010-02-27T00:00:00... | 40.0 Hz, 80 samples
        >>> t = UTCDateTime("2012-12-14T10:36:01.6Z")
        >>> t1 = t + 300
        >>> t2 = t + 400
        >>> bulk = [("TA", "S42A", "*", "BHZ", t1, t2),
        ...         ("TA", "W42A", "*", "BHZ", t1, t2),
        ...         ("TA", "Z42A", "*", "BHZ", t1, t2)]
        >>> st = client.get_waveforms_bulk(bulk, attach_response=True)
        >>> st.remove_response(output="VEL") # doctest: +ELLIPSIS
        <obspy.core.stream.Stream object at ...>
        >>> st.plot()  # doctest: +SKIP

        .. plot::

            from obspy import UTCDateTime
            from obspy.fdsn import Client
            client = Client("IRIS")
            t = UTCDateTime("2012-12-14T10:36:01.6Z")
            t1 = t + 300
            t2 = t + 400
            bulk = [("TA", "S42A", "*", "BHZ", t1, t2),
                    ("TA", "W42A", "*", "BHZ", t1, t2),
                    ("TA", "Z42A", "*", "BHZ", t1, t2)]
            st = client.get_waveforms_bulk(bulk, attach_response=True)
            st.remove_response(output="VEL")
            st.plot()

        .. note::

            Use `attach_response=True` to automatically add response
            information to each trace. This can be used to remove response
            using :meth:`~obspy.core.stream.Stream.remove_response`.

        :type bulk: str, file or list of lists
        :param bulk: Information about the requested data. See above for
            details.
        :type quality: str, optional
        :param quality: Select a specific SEED quality indicator, handling is
            data center dependent. Ignored when `bulk` is provided as a
            request string/file.
        :type minimumlength: float, optional
        :param minimumlength: Limit results to continuous data segments of a
            minimum length specified in seconds. Ignored when `bulk` is
            provided as a request string/file.
        :type longestonly: bool, optional
        :param longestonly: Limit results to the longest continuous segment per
            channel. Ignored when `bulk` is provided as a request string/file.
        :type filename: str or file
        :param filename: If given, the downloaded data will be saved there
            instead of being parse to an ObsPy object. Thus it will contain the
            raw data from the webservices.
        :type attach_response: bool
        :param attach_response: Specify whether the station web service should
            be used to automatically attach response information to each trace
            in the result set. A warning will be shown if a response can not be
            found for a channel. Does nothing if output to a file was
            specified.

        Any additional keyword arguments will be passed to the webservice as
        additional arguments. If you pass one of the default parameters and the
        webservice does not support it, a warning will be issued. Passing any
        non-default parameters that the webservice does not support will raise
        an error.
        """
        if "dataselect" not in self.services:
            msg = "The current client does not have a dataselect service."
            raise ValueError(msg)

        arguments = OrderedDict(
            quality=quality,
            minimumlength=minimumlength,
            longestonly=longestonly
        )
        bulk = self._get_bulk_string(bulk, arguments)

        url = self._build_url("dataselect", "query")

        data_stream = self._download(url,
                                     data=bulk.encode('ascii', 'strict'))
        data_stream.seek(0, 0)
        if filename:
            self._write_to_file_object(filename, data_stream)
            data_stream.close()
        else:
            st = obspy.read(data_stream, format="MSEED")
            data_stream.close()
            if attach_response:
                self._attach_responses(st)
            return st

    def get_stations_bulk(self, bulk, level=None, includerestricted=None,
                          includeavailability=None, filename=None, **kwargs):
        r"""
        Query the station service of the client. Bulk request.

        Send a bulk request for stations to the server. `bulk` can either be
        specified as a filename, a file-like object or a string (with
        information formatted according to the FDSN standard) or a list of
        lists (each specifying network, station, location, channel, starttime
        and endtime). See examples and parameter description for more
        details.

        `bulk` can be provided in the following forms:

        (1) As a list of lists. Each list item has to be list of network,
            station, location, channel, starttime and endtime.

        (2) As a valid request string/file as defined in the
            `FDSNWS documentation <http://www.fdsn.org/webservices/>`_.
            The request information can be provided as a..

            - a string containing the request information
            - a string with the path to a local file with the request
            - an open file handle (or file-like object) with the request

        >>> client = Client("IRIS")
        >>> t1 = UTCDateTime("2010-02-27T06:30:00.000")
        >>> t2 = t1 + 1
        >>> t3 = t1 + 3
        >>> bulk = [("IU", "ANMO", "*", "BHZ", t1, t2),
        ...         ("IU", "AFI", "1?", "BHE", t1, t3),
        ...         ("GR", "GRA1", "*", "BH*", t2, t3)]
        >>> inv = client.get_stations_bulk(bulk)
        >>> print(inv)  # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
        Inventory created at ...
            Created by: IRIS WEB SERVICE: fdsnws-station | version: ...
                     http://service.iris.edu/fdsnws/station/1/query?
            Sending institution: IRIS-DMC (IRIS-DMC)
            Contains:
                Networks (2):
                    GR
                    IU
                Stations (2):
                    GR.GRA1 (GRAFENBERG ARRAY, BAYERN)
                    IU.ANMO (Albuquerque, New Mexico, USA)
                Channels (0):
        >>> inv.plot()  # doctest: +SKIP

        .. plot::

            from obspy import UTCDateTime
            from obspy.fdsn import Client

            client = Client("IRIS")
            t1 = UTCDateTime("2010-02-27T06:30:00.000")
            t2 = t1 + 1
            t3 = t1 + 3
            bulk = [("IU", "ANMO", "*", "BHZ", t1, t2),
                    ("IU", "AFI", "1?", "BHE", t1, t3),
                    ("GR", "GRA1", "*", "BH*", t2, t3)]
            inv = client.get_stations_bulk(bulk)
            inv.plot()

        >>> inv = client.get_stations_bulk(bulk, level="channel")
        >>> print(inv)  # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
        Inventory created at ...
            Created by: IRIS WEB SERVICE: fdsnws-station | version: ...
                     http://service.iris.edu/fdsnws/station/1/query?
            Sending institution: IRIS-DMC (IRIS-DMC)
            Contains:
                Networks (2):
                    GR
                    IU
                Stations (2):
                    GR.GRA1 (GRAFENBERG ARRAY, BAYERN)
                    IU.ANMO (Albuquerque, New Mexico, USA)
                Channels (5):
                    GR.GRA1..BHE, GR.GRA1..BHN, GR.GRA1..BHZ, IU.ANMO.00.BHZ,
                    IU.ANMO.10.BHZ
        >>> inv = client.get_stations_bulk("/tmp/request.txt") \
        ...     # doctest: +SKIP
        >>> print(inv)  # doctest: +SKIP
        Inventory created at 2014-04-28T14:42:26.000000Z
            Created by: IRIS WEB SERVICE: fdsnws-station | version: 1.0.14
                    None
            Sending institution: IRIS-DMC (IRIS-DMC)
            Contains:
                Networks (2):
                    GR
                    IU
                Stations (2):
                    GR.GRA1 (GRAFENBERG ARRAY, BAYERN)
                    IU.ANMO (Albuquerque, New Mexico, USA)
                Channels (5):
                    GR.GRA1..BHE, GR.GRA1..BHN, GR.GRA1..BHZ, IU.ANMO.00.BHZ,
                    IU.ANMO.10.BHZ

        :type bulk: str, file or list of lists
        :param bulk: Information about the requested data. See above for
            details.
        :type quality: str, optional
        :param quality: Select a specific SEED quality indicator, handling is
            data center dependent. Ignored when `bulk` is provided as a
            request string/file.
        :type minimumlength: float, optional
        :param minimumlength: Limit results to continuous data segments of a
            minimum length specified in seconds. Ignored when `bulk` is
            provided as a request string/file.
        :type longestonly: bool, optional
        :param longestonly: Limit results to the longest continuous segment per
            channel. Ignored when `bulk` is provided as a request string/file.
        :type filename: str or file
        :param filename: If given, the downloaded data will be saved there
            instead of being parse to an ObsPy object. Thus it will contain the
            raw data from the webservices.
        :type attach_response: bool
        :param attach_response: Specify whether the station web service should
            be used to automatically attach response information to each trace
            in the result set. A warning will be shown if a response can not be
            found for a channel. Does nothing if output to a file was
            specified.

        Any additional keyword arguments will be passed to the webservice as
        additional arguments. If you pass one of the default parameters and the
        webservice does not support it, a warning will be issued. Passing any
        non-default parameters that the webservice does not support will raise
        an error.
        """
        if "dataselect" not in self.services:
            msg = "The current client does not have a dataselect service."
            raise ValueError(msg)

        arguments = OrderedDict(
            level=level,
            includerestriced=includerestricted,
            includeavailability=includeavailability
        )
        bulk = self._get_bulk_string(bulk, arguments)

        url = self._build_url("station", "query")

        data_stream = self._download(url,
                                     data=bulk.encode('ascii', 'strict'))
        data_stream.seek(0, 0)
        if filename:
            self._write_to_file_object(filename, data_stream)
            data_stream.close()
            return
        else:
            inv = obspy.read_inventory(data_stream, format="stationxml")
            data_stream.close()
            return inv

    def _get_bulk_string(self, bulk, arguments):
        locs = locals()
        # If its an iterable, we build up the query string from it
        # StringIO objects also have __iter__ so check for 'read' as well
        if isinstance(bulk, collections.Iterable) \
                and not hasattr(bulk, "read") \
                and not isinstance(bulk, (str, native_str)):
            tmp = ["%s=%s" % (key, convert_to_string(value))
                   for key, value in arguments.items() if value is not None]
            # empty location codes have to be represented by two dashes
            tmp += [" ".join((net, sta, loc or "--", cha,
                              convert_to_string(t1), convert_to_string(t2)))
                    for net, sta, loc, cha, t1, t2 in bulk]
            bulk = "\n".join(tmp)
        else:
            if any([value is not None for value in arguments.values()]):
                msg = ("Parameters %s are ignored when request data is "
                       "provided as a string or file!")
                warnings.warn(msg % arguments.keys())
            # if it has a read method, read data from there
            if hasattr(bulk, "read"):
                bulk = bulk.read()
            elif isinstance(bulk, (str, native_str)):
                # check if bulk is a local file
                if "\n" not in bulk and os.path.isfile(bulk):
                    with open(bulk, 'r') as fh:
                        tmp = fh.read()
                    bulk = tmp
                # just use bulk as input data
                else:
                    pass
            else:
                msg = ("Unrecognized input for 'bulk' argument. Please "
                       "contact developers if you think this is a bug.")
                raise NotImplementedError(msg)
        return bulk

    def _write_to_file_object(self, filename_or_object, data_stream):
        if hasattr(filename_or_object, "write"):
            filename_or_object.write(data_stream.read())
            return
        with open(filename_or_object, "wb") as fh:
            fh.write(data_stream.read())

    def _create_url_from_parameters(self, service, default_params, parameters):
        """
        """
        service_params = self.services[service]
        # Get all required parameters and make sure they are available!
        required_parameters = [
            key for key, value in service_params.items()
            if value["required"] is True]
        for req_param in required_parameters:
            if req_param not in parameters:
                msg = "Parameter '%s' is required." % req_param
                raise TypeError(msg)

        final_parameter_set = {}

        # Now loop over all parameters, convert them and make sure they are
        # accepted by the service.
        for key, value in parameters.items():
            if key not in service_params:
                # If it is not in the service but in the default parameters
                # raise a warning.
                if key in default_params:
                    msg = ("The standard parameter '%s' is not supported by "
                           "the webservice. It will be silently ignored." %
                           key)
                    warnings.warn(msg)
                    continue
                elif key in WADL_PARAMETERS_NOT_TO_BE_PARSED:
                    msg = ("The parameter '%s' is ignored because it is not "
                           "useful within ObsPy")
                    warnings.warn(msg % key)
                    continue
                # Otherwise raise an error.
                else:
                    msg = \
                        "The parameter '%s' is not supported by the service." \
                        % key
                    raise TypeError(msg)
            # Now attempt to convert the parameter to the correct type.
            this_type = service_params[key]["type"]
            try:
                value = this_type(value)
            except:
                msg = "'%s' could not be converted to type '%s'." % (
                    str(value), this_type.__name__)
                raise TypeError(msg)
            # Now convert to a string that is accepted by the webservice.
            value = convert_to_string(value)
            if isinstance(value, (str, native_str)):
                if not value:
                    continue
            final_parameter_set[key] = value

        return self._build_url(service, "query",
                               parameters=final_parameter_set)

    def __str__(self):
        versions = dict([(s, self._get_webservice_versionstring(s))
                         for s in self.services if s in FDSNWS])
        services_string = ["'%s' (v%s)" % (s, versions[s])
                           for s in FDSNWS if s in self.services]
        other_services = sorted([s for s in self.services if s not in FDSNWS])
        services_string += ["'%s'" % s for s in other_services]
        services_string = ", ".join(services_string)
        ret = ("FDSN Webservice Client (base url: {url})\n"
               "Available Services: {services}\n\n"
               "Use e.g. client.help('dataselect') for the\n"
               "parameter description of the individual services\n"
               "or client.help() for parameter description of\n"
               "all webservices.".format(url=self.base_url,
                                         services=services_string))
        return ret

    def _repr_pretty_(self, p, cycle):
        p.text(str(self))

    def help(self, service=None):
        """
        Print a more extensive help for a given service.

        This will use the already parsed WADL files and be specific for each
        data center and always up-to-date.
        """
        if service is not None and service not in self.services:
            msg = "Service '%s' not available for current client." % service
            raise ValueError(msg)

        if service is None:
            services = list(self.services.keys())
        elif service in FDSNWS:
            services = [service]
        else:
            msg = "Service '%s is not a valid FDSN web service." % service
            raise ValueError(msg)

        msg = []
        for service in services:
            if service not in FDSNWS:
                continue
            SERVICE_DEFAULT = DEFAULT_PARAMETERS[service]
            SERVICE_OPTIONAL = OPTIONAL_PARAMETERS[service]

            msg.append("Parameter description for the "
                       "'%s' service (v%s) of '%s':" % (
                           service,
                           self._get_webservice_versionstring(service),
                           self.base_url))

            # Loop over all parameters and group them in four lists: available
            # default parameters, missing default parameters, optional
            # parameters and additional parameters.
            available_default_parameters = []
            missing_default_parameters = []
            optional_parameters = []
            additional_parameters = []

            printed_something = False

            for name in SERVICE_DEFAULT:
                if name in self.services[service]:
                    available_default_parameters.append(name)
                else:
                    missing_default_parameters.append(name)

            for name in SERVICE_OPTIONAL:
                if name in self.services[service]:
                    optional_parameters.append(name)

            defined_parameters = SERVICE_DEFAULT + SERVICE_OPTIONAL
            for name in self.services[service].keys():
                if name not in defined_parameters:
                    additional_parameters.append(name)

            def _param_info_string(name):
                param = self.services[service][name]
                name = "%s (%s)" % (name, param["type"].__name__.replace(
                    'new', ''))
                req_def = ""
                if param["required"]:
                    req_def = "Required Parameter"
                elif param["default_value"]:
                    req_def = "Default value: %s" % str(param["default_value"])
                if param["options"]:
                    req_def += ", Choices: %s" % \
                        ", ".join(map(str, param["options"]))
                if req_def:
                    req_def = ", %s" % req_def
                if param["doc_title"]:
                    doc_title = textwrap.fill(param["doc_title"], width=79,
                                              initial_indent="        ",
                                              subsequent_indent="        ",
                                              break_long_words=False)
                    doc_title = "\n" + doc_title
                else:
                    doc_title = ""

                return "    {name}{req_def}{doc_title}".format(
                    name=name, req_def=req_def, doc_title=doc_title)

            if optional_parameters:
                printed_something = True
                msg.append("The service offers the following optional "
                           "standard parameters:")
                for name in optional_parameters:
                    msg.append(_param_info_string(name))

            if additional_parameters:
                printed_something = True
                msg.append("The service offers the following "
                           "non-standard parameters:")
                for name in additional_parameters:
                    msg.append(_param_info_string(name))

            if missing_default_parameters:
                printed_something = True
                msg.append("WARNING: The service does not offer the following "
                           "standard parameters: %s" %
                           ", ".join(missing_default_parameters))

            if service == "event" and \
                    "available_event_catalogs" in self.services:
                printed_something = True
                msg.append("Available catalogs: %s" %
                           ", ".join(
                               self.services["available_event_catalogs"]))

            if service == "event" and \
                    "available_event_contributors" in self.services:
                printed_something = True
                msg.append("Available contributors: %s" %
                           ", ".join(
                               self.services["available_event_contributors"]))

            if printed_something is False:
                msg.append("No derivations from standard detected")

        print("\n".join(msg))

    def _download(self, url, return_string=False, data=None):
        code, data = download_url(
            url, opener=self._url_opener, headers=self.request_headers,
            debug=self.debug, return_string=return_string, data=data,
            timeout=self.timeout)
        # get detailed server response message
        if code != 200:
            try:
                server_info = "\n".join([
                    line for line in data.read().splitlines() if line])
            except:
                server_info = None

        # No data.
        if code == 204:
            raise FDSNException("No data available for request.", server_info)
        elif code == 400:
            msg = ("Bad request. If you think your request was valid "
                   "please contact the developers.")
            raise FDSNException(msg, server_info)
        elif code == 401:
            raise FDSNException("Unauthorized, authentication required.",
                                server_info)
        elif code == 403:
            raise FDSNException("Authentication failed.", server_info)
        elif code == 413:
            raise FDSNException("Request would result in too much data. "
                                "Denied by the datacenter. Split the request "
                                "in smaller parts", server_info)
        # Request URI too large.
        elif code == 414:
            msg = ("The request URI is too large. Please contact the ObsPy "
                   "developers.", server_info)
            raise NotImplementedError(msg)
        elif code == 500:
            raise FDSNException("Service responds: Internal server error",
                                server_info)
        elif code == 503:
            raise FDSNException("Service temporarily unavailable", server_info)
        # Catch any non 200 codes.
        elif code != 200:
            raise FDSNException("Unknown HTTP code: %i" % code, server_info)
        return data

    def _build_url(self, service, resource_type, parameters={}):
        """
        Builds the correct URL.

        Replaces "query" with "queryauth" if client has authentication
        information.
        """
        # authenticated dataselect queries have different target URL
        if self.user is not None:
            if service == "dataselect" and resource_type == "query":
                resource_type = "queryauth"
        return build_url(self.base_url, service, self.major_versions[service],
                         resource_type, parameters,
                         service_mappings=self._service_mappings)

    def _discover_services(self):
        """
        Automatically discovers available services.

        They are discovered by downloading the corresponding WADL files. If a
        WADL does not exist, the services are assumed to be non-existent.
        """
        services = ["dataselect", "event", "station"]
        # omit manually deactivated services
        for service, custom_target in self._service_mappings.items():
            if custom_target is None:
                services.remove(service)
        urls = [self._build_url(service, "application.wadl")
                for service in services]
        if "event" in services:
            urls.append(self._build_url("event", "catalogs"))
            urls.append(self._build_url("event", "contributors"))

        # Access cache if available.
        url_hash = frozenset(urls)
        if url_hash in self.__service_discovery_cache:
            if self.debug is True:
                print("Loading discovered services from cache.")
            self.services = copy.deepcopy(
                self.__service_discovery_cache[url_hash])
            return

        # Request all in parallel.
        wadl_queue = queue.Queue()

        headers = self.request_headers
        debug = self.debug
        opener = self._url_opener

        def get_download_thread(url):
            class ThreadURL(threading.Thread):
                def run(self):
                    # Catch 404s.
                    try:
                        code, data = download_url(
                            url, opener=opener, headers=headers,
                            debug=debug)
                        if code == 200:
                            wadl_queue.put((url, data))
                        # Pass on the redirect exception.
                        elif code is None and isinstance(
                                data, FDSNRedirectException):
                            wadl_queue.put((url, data))
                        else:
                            wadl_queue.put((url, None))
                    except urllib.request.HTTPError as e:
                        if e.code == 404:
                            wadl_queue.put((url, None))
                        else:
                            raise
            return ThreadURL()

        threads = list(map(get_download_thread, urls))
        for thread in threads:
            thread.start()
        for thread in threads:
            thread.join(15)

        self.services = {}

        # Collect the redirection exceptions to be able to raise nicer
        # exceptions.
        redirect_messages = set()

        for _ in range(wadl_queue.qsize()):
            item = wadl_queue.get()
            url, wadl = item

            if wadl is None:
                continue
            elif isinstance(wadl, FDSNRedirectException):
                redirect_messages.add(str(wadl))
                continue

            if "dataselect" in url:
                self.services["dataselect"] = WADLParser(wadl).parameters
                if self.debug is True:
                    print("Discovered dataselect service")
            elif "event" in url and "application.wadl" in url:
                self.services["event"] = WADLParser(wadl).parameters
                if self.debug is True:
                    print("Discovered event service")
            elif "station" in url:
                self.services["station"] = WADLParser(wadl).parameters
                if self.debug is True:
                    print("Discovered station service")
            elif "event" in url and "catalogs" in url:
                try:
                    self.services["available_event_catalogs"] = \
                        parse_simple_xml(wadl)["catalogs"]
                except ValueError:
                    msg = "Could not parse the catalogs at '%s'." % url
                    warnings.warn(msg)

            elif "event" in url and "contributors" in url:
                try:
                    self.services["available_event_contributors"] = \
                        parse_simple_xml(wadl)["contributors"]
                except ValueError:
                    msg = "Could not parse the contributors at '%s'." % url
                    warnings.warn(msg)
        if not self.services:
            if redirect_messages:
                raise FDSNRedirectException(", ".join(redirect_messages))

            msg = ("No FDSN services could be discovered at '%s'. This could "
                   "be due to a temporary service outage or an invalid FDSN "
                   "service address." % self.base_url)
            raise FDSNException(msg)

        # Cache.
        if self.debug is True:
            print("Storing discovered services in cache.")
        self.__service_discovery_cache[url_hash] = \
            copy.deepcopy(self.services)

    def get_webservice_version(self, service):
        """
        Get full version information of webservice (as a tuple of ints).

        This method is cached and will only be called once for each service
        per client object.
        """
        if service is not None and service not in self.services:
            msg = "Service '%s' not available for current client." % service
            raise ValueError(msg)

        if service not in FDSNWS:
            msg = "Service '%s is not a valid FDSN web service." % service
            raise ValueError(msg)

        # Access cache.
        if service in self.__version_cache:
            return self.__version_cache[service]

        url = self._build_url(service, "version")
        version = self._download(url, return_string=True)
        version = list(map(int, version.split(b".")))

        # Store in cache.
        self.__version_cache[service] = version

        return version

    def _get_webservice_versionstring(self, service):
        """
        Get full version information of webservice as a string.
        """
        version = self.get_webservice_version(service)
        return ".".join(map(str, version))


def convert_to_string(value):
    """
    Takes any value and converts it to a string compliant with the FDSN
    webservices.

    Will raise a ValueError if the value could not be converted.

    >>> print(convert_to_string("abcd"))
    abcd
    >>> print(convert_to_string(1))
    1
    >>> print(convert_to_string(1.2))
    1.2
    >>> print(convert_to_string( \
              UTCDateTime(2012, 1, 2, 3, 4, 5, 666666)))
    2012-01-02T03:04:05.666666
    >>> print(convert_to_string(True))
    true
    >>> print(convert_to_string(False))
    false
    """
    if isinstance(value, (str, native_str)):
        return value
    # Boolean test must come before integer check!
    elif isinstance(value, bool):
        return str(value).lower()
    elif isinstance(value, int):
        return str(value)
    elif isinstance(value, float):
        return str(value)
    elif isinstance(value, UTCDateTime):
        return str(value).replace("Z", "")
    elif PY2 and isinstance(value, bytes):
        return value
    else:
        raise TypeError("Unexpected type %s" % repr(value))


def build_url(base_url, service, major_version, resource_type,
              parameters=None, service_mappings=None):
    """
    URL builder for the FDSN webservices.

    Built as a separate function to enhance testability.

    >>> print(build_url("http://service.iris.edu", "dataselect", 1, \
                        "application.wadl"))
    http://service.iris.edu/fdsnws/dataselect/1/application.wadl

    >>> print(build_url("http://service.iris.edu", "dataselect", 1, \
                        "query", {"cha": "EHE"}))
    http://service.iris.edu/fdsnws/dataselect/1/query?cha=EHE
    """
    # Avoid mutable kwargs.
    if parameters is None:
        parameters = {}
    if service_mappings is None:
        service_mappings = {}

    # Only allow certain resource types.
    if service not in ["dataselect", "event", "station"]:
        msg = "Resource type '%s' not allowed. Allowed types: \n%s" % \
            (service, ",".join(("dataselect", "event", "station")))
        raise ValueError(msg)

    # Special location handling.
    if "location" in parameters:
        loc = parameters["location"].replace(" ", "")
        # Empty location.
        if not loc:
            loc = "--"
        # Empty location at start of list.
        if loc.startswith(','):
            loc = "--" + loc
        # Empty location at end of list.
        if loc.endswith(','):
            loc += "--"
        # Empty location in middle of list.
        loc = loc.replace(",,", ",--,")
        parameters["location"] = loc

    # Apply per-service mappings if any.
    if service in service_mappings:
        url = "/".join((service_mappings[service], resource_type))
    else:
        url = "/".join((base_url, "fdsnws", service,
                        str(major_version), resource_type))

    if parameters:
        # Strip parameters.
        for key, value in parameters.items():
            try:
                parameters[key] = value.strip()
            except:
                pass
        url = "?".join((url, urllib.parse.urlencode(parameters)))
    return url


def download_url(url, opener, timeout=10, headers={}, debug=False,
                 return_string=True, data=None):
    """
    Returns a pair of tuples.

    The first one is the returned HTTP code and the second the data as
    string.

    Will return a tuple of Nones if the service could not be found.
    All encountered exceptions will get raised unless `debug=True` is
    specified.

    Performs a http GET if data=None, otherwise a http POST.
    """
    if debug is True:
        print("Downloading %s" % url)

    try:
        url_obj = opener.open(
            urllib.request.Request(url=url, headers=headers),
            timeout=timeout,
            data=data)
    # Catch HTTP errors.
    except urllib.request.HTTPError as e:
        if debug is True:
            msg = "HTTP error %i, reason %s, while downloading '%s': %s" % \
                  (e.code, str(e.reason), url, e.read())
            print(msg)
        return e.code, e
    except Exception as e:
        if debug is True:
            print("Error while downloading: %s" % url)
        return None, e

    code = url_obj.getcode()
    if return_string is False:
        data = io.BytesIO(url_obj.read())
    else:
        data = url_obj.read()

    if debug is True:
        print("Downloaded %s with HTTP code: %i" % (url, code))

    return code, data


def setup_query_dict(service, locs, kwargs):
    """
    """
    # check if alias is used together with the normal parameter
    for key in kwargs:
        if key in PARAMETER_ALIASES:
            if locs[PARAMETER_ALIASES[key]] is not None:
                msg = ("two parameters were provided for the same option: "
                       "%s, %s" % (key, PARAMETER_ALIASES[key]))
                raise FDSNException(msg)
    # short aliases are not mentioned in the downloaded WADLs, so we have
    # to map it here according to the official FDSN WS documentation
    for key in kwargs.keys():
        if key in PARAMETER_ALIASES:
            value = kwargs.pop(key)
            if value is not None:
                kwargs[PARAMETER_ALIASES[key]] = value

    for param in DEFAULT_PARAMETERS[service] + OPTIONAL_PARAMETERS[service]:
        param = PARAMETER_ALIASES.get(param, param)
        value = locs[param]
        if value is not None:
            kwargs[param] = value


def parse_simple_xml(xml_string):
    """
    Simple helper function for parsing the Catalog and Contributor availability
    files.

    Parses XMLs of the form::

        <Bs>
            <total>4</total>
            <B>1</B>
            <B>2</B>
            <B>3</B>
            <B>4</B>
        </Bs>

    and return a dictionary with a single item::

        {"Bs": set(("1", "2", "3", "4"))}
    """
    root = etree.fromstring(xml_string.strip())

    if not root.tag.endswith("s"):
        msg = "Could not parse the XML."
        raise ValueError(msg)
    child_tag = root.tag[:-1]
    children = [i.text for i in root if i.tag == child_tag]

    return {root.tag.lower(): set(children)}


if __name__ == '__main__':
    import doctest
    doctest.testmod(exclude_empty=True)
