import urllib
from urlparse import urlparse, urlunparse, urlsplit
import sys
import os
import re
import mimetypes
import warnings
try:
    from cStringIO import StringIO
except ImportError:
    from StringIO import StringIO

from django.conf import settings
from django.contrib.auth import authenticate, login
from django.core.handlers.base import BaseHandler
from django.core.handlers.wsgi import WSGIRequest
from django.core.signals import got_request_exception
from django.http import SimpleCookie, HttpRequest, QueryDict
from django.template import TemplateDoesNotExist
from django.test import signals
from django.utils.functional import curry
from django.utils.encoding import smart_str
from django.utils.http import urlencode
from django.utils.importlib import import_module
from django.utils.itercompat import is_iterable
from django.db import transaction, close_connection
from django.test.utils import ContextList

__all__ = ('Client', 'RequestFactory', 'encode_file', 'encode_multipart')


BOUNDARY = 'BoUnDaRyStRiNg'
MULTIPART_CONTENT = 'multipart/form-data; boundary=%s' % BOUNDARY
CONTENT_TYPE_RE = re.compile('.*; charset=([\w\d-]+);?')

class FakePayload(object):
    """
    A wrapper around StringIO that restricts what can be read since data from
    the network can't be seeked and cannot be read outside of its content
    length. This makes sure that views can't do anything under the test client
    that wouldn't work in Real Life.
    """
    def __init__(self, content):
        self.__content = StringIO(content)
        self.__len = len(content)

    def read(self, num_bytes=None):
        if num_bytes is None:
            num_bytes = self.__len or 0
        assert self.__len >= num_bytes, "Cannot read more than the available bytes from the HTTP incoming data."
        content = self.__content.read(num_bytes)
        self.__len -= num_bytes
        return content


class ClientHandler(BaseHandler):
    """
    A HTTP Handler that can be used for testing purposes.
    Uses the WSGI interface to compose requests, but returns
    the raw HttpResponse object
    """
    def __init__(self, enforce_csrf_checks=True, *args, **kwargs):
        self.enforce_csrf_checks = enforce_csrf_checks
        super(ClientHandler, self).__init__(*args, **kwargs)

    def __call__(self, environ):
        from django.conf import settings
        from django.core import signals

        # Set up middleware if needed. We couldn't do this earlier, because
        # settings weren't available.
        if self._request_middleware is None:
            self.load_middleware()

        signals.request_started.send(sender=self.__class__)
        try:
            request = WSGIRequest(environ)
            # sneaky little hack so that we can easily get round
            # CsrfViewMiddleware.  This makes life easier, and is probably
            # required for backwards compatibility with external tests against
            # admin views.
            request._dont_enforce_csrf_checks = not self.enforce_csrf_checks
            response = self.get_response(request)
        finally:
            signals.request_finished.disconnect(close_connection)
            signals.request_finished.send(sender=self.__class__)
            signals.request_finished.connect(close_connection)

        return response

def store_rendered_templates(store, signal, sender, template, context, **kwargs):
    """
    Stores templates and contexts that are rendered.
    """
    store.setdefault('templates', []).append(template)
    store.setdefault('context', ContextList()).append(context)

def encode_multipart(boundary, data):
    """
    Encodes multipart POST data from a dictionary of form values.

    The key will be used as the form data name; the value will be transmitted
    as content. If the value is a file, the contents of the file will be sent
    as an application/octet-stream; otherwise, str(value) will be sent.
    """
    lines = []
    to_str = lambda s: smart_str(s, settings.DEFAULT_CHARSET)

    # Not by any means perfect, but good enough for our purposes.
    is_file = lambda thing: hasattr(thing, "read") and callable(thing.read)

    # Each bit of the multipart form data could be either a form value or a
    # file, or a *list* of form values and/or files. Remember that HTTP field
    # names can be duplicated!
    for (key, value) in data.items():
        if is_file(value):
            lines.extend(encode_file(boundary, key, value))
        elif not isinstance(value, basestring) and is_iterable(value):
            for item in value:
                if is_file(item):
                    lines.extend(encode_file(boundary, key, item))
                else:
                    lines.extend([
                        '--' + boundary,
                        'Content-Disposition: form-data; name="%s"' % to_str(key),
                        '',
                        to_str(item)
                    ])
        else:
            lines.extend([
                '--' + boundary,
                'Content-Disposition: form-data; name="%s"' % to_str(key),
                '',
                to_str(value)
            ])

    lines.extend([
        '--' + boundary + '--',
        '',
    ])
    return '\r\n'.join(lines)

def encode_file(boundary, key, file):
    to_str = lambda s: smart_str(s, settings.DEFAULT_CHARSET)
    if hasattr(file, 'content_type'):
        content_type = file.content_type
    else:
        content_type = mimetypes.guess_type(file.name)[0]
    if content_type is None:
        content_type = 'application/octet-stream'
    return [
        '--' + boundary,
        'Content-Disposition: form-data; name="%s"; filename="%s"' \
            % (to_str(key), to_str(os.path.basename(file.name))),
        'Content-Type: %s' % content_type,
        '',
        file.read()
    ]



class RequestFactory(object):
    """
    Class that lets you create mock Request objects for use in testing.

    Usage:

    rf = RequestFactory()
    get_request = rf.get('/hello/')
    post_request = rf.post('/submit/', {'foo': 'bar'})

    Once you have a request object you can pass it to any view function,
    just as if that view had been hooked up using a URLconf.
    """
    def __init__(self, **defaults):
        self.defaults = defaults
        self.cookies = SimpleCookie()
        self.errors = StringIO()

    def _base_environ(self, **request):
        """
        The base environment for a request.
        """
        environ = {
            'HTTP_COOKIE':       self.cookies.output(header='', sep='; '),
            'PATH_INFO':         '/',
            'QUERY_STRING':      '',
            'REMOTE_ADDR':       '127.0.0.1',
            'REQUEST_METHOD':    'GET',
            'SCRIPT_NAME':       '',
            'SERVER_NAME':       'testserver',
            'SERVER_PORT':       '80',
            'SERVER_PROTOCOL':   'HTTP/1.1',
            'wsgi.version':      (1,0),
            'wsgi.url_scheme':   'http',
            'wsgi.errors':       self.errors,
            'wsgi.multiprocess': True,
            'wsgi.multithread':  False,
            'wsgi.run_once':     False,
        }
        environ.update(self.defaults)
        environ.update(request)
        return environ

    def request(self, **request):
        "Construct a generic request object."
        return WSGIRequest(self._base_environ(**request))

    def _get_path(self, parsed):
        # If there are parameters, add them
        if parsed[3]:
            return urllib.unquote(parsed[2] + ";" + parsed[3])
        else:
            return urllib.unquote(parsed[2])

    def get(self, path, data={}, **extra):
        "Construct a GET request"

        parsed = urlparse(path)
        r = {
            'CONTENT_TYPE':    'text/html; charset=utf-8',
            'PATH_INFO':       self._get_path(parsed),
            'QUERY_STRING':    urlencode(data, doseq=True) or parsed[4],
            'REQUEST_METHOD': 'GET',
            'wsgi.input':      FakePayload('')
        }
        r.update(extra)
        return self.request(**r)

    def post(self, path, data={}, content_type=MULTIPART_CONTENT,
             **extra):
        "Construct a POST request."

        if content_type is MULTIPART_CONTENT:
            post_data = encode_multipart(BOUNDARY, data)
        else:
            # Encode the content so that the byte representation is correct.
            match = CONTENT_TYPE_RE.match(content_type)
            if match:
                charset = match.group(1)
            else:
                charset = settings.DEFAULT_CHARSET
            post_data = smart_str(data, encoding=charset)

        parsed = urlparse(path)
        r = {
            'CONTENT_LENGTH': len(post_data),
            'CONTENT_TYPE':   content_type,
            'PATH_INFO':      self._get_path(parsed),
            'QUERY_STRING':   parsed[4],
            'REQUEST_METHOD': 'POST',
            'wsgi.input':     FakePayload(post_data),
        }
        r.update(extra)
        return self.request(**r)

    def head(self, path, data={}, **extra):
        "Construct a HEAD request."

        parsed = urlparse(path)
        r = {
            'CONTENT_TYPE':    'text/html; charset=utf-8',
            'PATH_INFO':       self._get_path(parsed),
            'QUERY_STRING':    urlencode(data, doseq=True) or parsed[4],
            'REQUEST_METHOD': 'HEAD',
            'wsgi.input':      FakePayload('')
        }
        r.update(extra)
        return self.request(**r)

    def options(self, path, data={}, **extra):
        "Constrict an OPTIONS request"

        parsed = urlparse(path)
        r = {
            'PATH_INFO':       self._get_path(parsed),
            'QUERY_STRING':    urlencode(data, doseq=True) or parsed[4],
            'REQUEST_METHOD': 'OPTIONS',
            'wsgi.input':      FakePayload('')
        }
        r.update(extra)
        return self.request(**r)

    def put(self, path, data={}, content_type=MULTIPART_CONTENT,
            **extra):
        "Construct a PUT request."

        if content_type is MULTIPART_CONTENT:
            post_data = encode_multipart(BOUNDARY, data)
        else:
            post_data = data

        # Make `data` into a querystring only if it's not already a string. If
        # it is a string, we'll assume that the caller has already encoded it.
        query_string = None
        if not isinstance(data, basestring):
            query_string = urlencode(data, doseq=True)

        parsed = urlparse(path)
        r = {
            'CONTENT_LENGTH': len(post_data),
            'CONTENT_TYPE':   content_type,
            'PATH_INFO':      self._get_path(parsed),
            'QUERY_STRING':   query_string or parsed[4],
            'REQUEST_METHOD': 'PUT',
            'wsgi.input':     FakePayload(post_data),
        }
        r.update(extra)
        return self.request(**r)

    def delete(self, path, data={}, **extra):
        "Construct a DELETE request."

        parsed = urlparse(path)
        r = {
            'PATH_INFO':       self._get_path(parsed),
            'QUERY_STRING':    urlencode(data, doseq=True) or parsed[4],
            'REQUEST_METHOD': 'DELETE',
            'wsgi.input':      FakePayload('')
        }
        r.update(extra)
        return self.request(**r)


class Client(RequestFactory):
    """
    A class that can act as a client for testing purposes.

    It allows the user to compose GET and POST requests, and
    obtain the response that the server gave to those requests.
    The server Response objects are annotated with the details
    of the contexts and templates that were rendered during the
    process of serving the request.

    Client objects are stateful - they will retain cookie (and
    thus session) details for the lifetime of the Client instance.

    This is not intended as a replacement for Twill/Selenium or
    the like - it is here to allow testing against the
    contexts and templates produced by a view, rather than the
    HTML rendered to the end-user.
    """
    def __init__(self, enforce_csrf_checks=False, **defaults):
        super(Client, self).__init__(**defaults)
        self.handler = ClientHandler(enforce_csrf_checks)
        self.exc_info = None

    def store_exc_info(self, **kwargs):
        """
        Stores exceptions when they are generated by a view.
        """
        self.exc_info = sys.exc_info()

    def _session(self):
        """
        Obtains the current session variables.
        """
        if 'django.contrib.sessions' in settings.INSTALLED_APPS:
            engine = import_module(settings.SESSION_ENGINE)
            cookie = self.cookies.get(settings.SESSION_COOKIE_NAME, None)
            if cookie:
                return engine.SessionStore(cookie.value)
        return {}
    session = property(_session)