from __future__ import unicode_literals

import json
import mimetypes
import os
import re
import sys
from copy import copy
from importlib import import_module
from io import BytesIO

from django.apps import apps
from django.conf import settings
from django.core import urlresolvers
from django.core.handlers.base import BaseHandler
from django.core.handlers.wsgi import ISO_8859_1, UTF_8, WSGIRequest
from django.core.signals import (
    got_request_exception, request_finished, request_started,
)
from django.db import close_old_connections
from django.http import HttpRequest, QueryDict, SimpleCookie
from django.template import TemplateDoesNotExist
from django.test import signals
from django.test.utils import ContextList
from django.utils import six
from django.utils.encoding import force_bytes, force_str, uri_to_iri
from django.utils.functional import SimpleLazyObject, curry
from django.utils.http import urlencode
from django.utils.itercompat import is_iterable
from django.utils.six.moves.urllib.parse import urljoin, urlparse, urlsplit

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


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


class RedirectCycleError(Exception):
    """
    The test client has been asked to follow a redirect loop.
    """
    def __init__(self, message, last_response):
        super(RedirectCycleError, self).__init__(message)
        self.last_response = last_response
        self.redirect_chain = last_response.redirect_chain


class FakePayload(object):
    """
    A wrapper around BytesIO 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=None):
        self.__content = BytesIO()
        self.__len = 0
        self.read_started = False
        if content is not None:
            self.write(content)

    def __len__(self):
        return self.__len

    def read(self, num_bytes=None):
        if not self.read_started:
            self.__content.seek(0)
            self.read_started = True
        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

    def write(self, content):
        if self.read_started:
            raise ValueError("Unable to write a payload after he's been read")
        content = force_bytes(content)
        self.__content.write(content)
        self.__len += len(content)


def closing_iterator_wrapper(iterable, close):
    try:
        for item in iterable:
            yield item
    finally:
        request_finished.disconnect(close_old_connections)
        close()                                 # will fire request_finished
        request_finished.connect(close_old_connections)


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 with
    the originating WSGIRequest attached to its ``wsgi_request`` attribute.
    """
    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):
        # 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()

        request_started.disconnect(close_old_connections)
        request_started.send(sender=self.__class__, environ=environ)
        request_started.connect(close_old_connections)
        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

        # Request goes through middleware.
        response = self.get_response(request)
        # Attach the originating request to the response so that it could be
        # later retrieved.
        response.wsgi_request = request

        # We're emulating a WSGI server; we must call the close method
        # on completion.
        if response.streaming:
            response.streaming_content = closing_iterator_wrapper(
                response.streaming_content, response.close)
        else:
            request_finished.disconnect(close_old_connections)
            response.close()                    # will fire request_finished
            request_finished.connect(close_old_connections)

        return response


def store_rendered_templates(store, signal, sender, template, context, **kwargs):
    """
    Stores templates and contexts that are rendered.

    The context is copied so that it is an accurate representation at the time
    of rendering.
    """
    store.setdefault('templates', []).append(template)
    store.setdefault('context', ContextList()).append(copy(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_bytes = lambda s: force_bytes(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, six.string_types) and is_iterable(value):
            for item in value:
                if is_file(item):
                    lines.extend(encode_file(boundary, key, item))
                else:
                    lines.extend(to_bytes(val) for val in [
                        '--%s' % boundary,
                        'Content-Disposition: form-data; name="%s"' % key,
                        '',
                        item
                    ])
        else:
            lines.extend(to_bytes(val) for val in [
                '--%s' % boundary,
                'Content-Disposition: form-data; name="%s"' % key,
                '',
                value
            ])

    lines.extend([
        to_bytes('--%s--' % boundary),
        b'',
    ])
    return b'\r\n'.join(lines)


def encode_file(boundary, key, file):
    to_bytes = lambda s: force_bytes(s, settings.DEFAULT_CHARSET)
    filename = os.path.basename(file.name) if hasattr(file, 'name') else ''
    if hasattr(file, 'content_type'):
        content_type = file.content_type
    elif filename:
        content_type = mimetypes.guess_type(filename)[0]
    else:
        content_type = None

    if content_type is None:
        content_type = 'application/octet-stream'
    if not filename:
        filename = key
    return [
        to_bytes('--%s' % boundary),
        to_bytes('Content-Disposition: form-data; name="%s"; filename="%s"'
                 % (key, filename)),
        to_bytes('Content-Type: %s' % content_type),
        b'',
        to_bytes(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 = BytesIO()

    def _base_environ(self, **request):
        """
        The base environment for a request.
        """
        # This is a minimal valid WSGI environ dictionary, plus:
        # - HTTP_COOKIE: for cookie support,
        # - REMOTE_ADDR: often useful, see #8551.
        # See http://www.python.org/dev/peps/pep-3333/#environ-variables
        environ = {
            'HTTP_COOKIE': self.cookies.output(header='', sep='; '),
            'PATH_INFO': str('/'),
            'REMOTE_ADDR': str('127.0.0.1'),
            'REQUEST_METHOD': str('GET'),
            'SCRIPT_NAME': str(''),
            'SERVER_NAME': str('testserver'),
            'SERVER_PORT': str('80'),
            'SERVER_PROTOCOL': str('HTTP/1.1'),
            'wsgi.version': (1, 0),
            'wsgi.url_scheme': str('http'),
            'wsgi.input': FakePayload(b''),
            '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 _encode_data(self, data, content_type):
        if content_type is MULTIPART_CONTENT:
            return 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
            return force_bytes(data, encoding=charset)

    def _get_path(self, parsed):
        path = force_str(parsed[2])
        # If there are parameters, add them
        if parsed[3]:
            path += str(";") + force_str(parsed[3])
        path = uri_to_iri(path).encode(UTF_8)
        # Under Python 3, non-ASCII values in the WSGI environ are arbitrarily
        # decoded with ISO-8859-1. We replicate this behavior here.
        # Refs comment in `get_bytes_from_wsgi()`.
        return path.decode(ISO_8859_1) if six.PY3 else path

    def get(self, path, data=None, secure=False, **extra):
        "Construct a GET request."

        data = {} if data is None else data
        r = {
            'QUERY_STRING': urlencode(data, doseq=True),
        }
        r.update(extra)
        return self.generic('GET', path, secure=secure, **r)

    def post(self, path, data=None, content_type=MULTIPART_CONTENT,
             secure=False, **extra):
        "Construct a POST request."

        data = {} if data is None else data
        post_data = self._encode_data(data, content_type)

        return self.generic('POST', path, post_data, content_type,
                            secure=secure, **extra)

    def head(self, path, data=None, secure=False, **extra):
        "Construct a HEAD request."

        data = {} if data is None else data
        r = {
            'QUERY_STRING': urlencode(data, doseq=True),
        }
        r.update(extra)
        return self.generic('HEAD', path, secure=secure, **r)

    def trace(self, path, secure=False, **extra):
        "Construct a TRACE request."
        return self.generic('TRACE', path, secure=secure, **extra)

    def options(self, path, data='', content_type='application/octet-stream',
                secure=False, **extra):
        "Construct an OPTIONS request."
        return self.generic('OPTIONS', path, data, content_type,
                            secure=secure, **extra)

    def put(self, path, data='', content_type='application/octet-stream',
            secure=False, **extra):
        "Construct a PUT request."
        return self.generic('PUT', path, data, content_type,
                            secure=secure, **extra)

    def patch(self, path, data='', content_type='application/octet-stream',
              secure=False, **extra):
        "Construct a PATCH request."
        return self.generic('PATCH', path, data, content_type,