import re
import six
import datetime

from django.conf import settings
from django.http import HttpResponse
from django.core.urlresolvers import reverse

from tastypie.api import Api
from tastypie.serializers import Serializer
from tastypie.exceptions import BadRequest, ApiFieldError
from tastypie.utils.mime import determine_format, build_content_type
from tastypie.utils import is_valid_jsonp_callback_value
from tastypie.fields import ApiField

import debug                            # pyflakes:ignore

_api_list = []

for _app in settings.INSTALLED_APPS:
    _module_dict = globals()
    if '.' in _app:
        _root, _name = _app.split('.', 1)
        if _root == 'ietf':
            if not '.' in _name:

                _api = Api(api_name=_name)
                _module_dict[_name] = _api
                _api_list.append((_name, _api))

def top_level(request):
    available_resources = {}

    apitop = reverse('ietf.api.top_level')

    for name in sorted([ name for name, api in _api_list if len(api._registry) > 0 ]):
        available_resources[name] = {
            'list_endpoint': '%s/%s/' % (apitop, name),
        }

    serializer = Serializer()
    desired_format = determine_format(request, serializer)

    options = {}

    if 'text/javascript' in desired_format:
        callback = request.GET.get('callback', 'callback')

        if not is_valid_jsonp_callback_value(callback):
            raise BadRequest('JSONP callback name is invalid.')

        options['callback'] = callback

    serialized = serializer.serialize(available_resources, desired_format, options)
    return HttpResponse(content=serialized, content_type=build_content_type(desired_format))

def autodiscover():
    """
    Auto-discover INSTALLED_APPS resources.py modules and fail silently when
    not present. This forces an import on them to register any admin bits they
    may want.
    """

    from django.conf import settings
    from django.utils.importlib import import_module
    from django.utils.module_loading import module_has_submodule

    for app in settings.INSTALLED_APPS:
        mod = import_module(app)
        # Attempt to import the app's admin module.
        try:
            import_module('%s.resources' % (app, ))
        except:
            # Decide whether to bubble up this error. If the app just
            # doesn't have an admin module, we can ignore the error
            # attempting to import it, otherwise we want it to bubble up.
            if module_has_submodule(mod, "resources"):
                raise

TIMEDELTA_REGEX = re.compile('^(?P<days>\d+d)?\s?(?P<hours>\d+h)?\s?(?P<minutes>\d+m)?\s?(?P<seconds>\d+s?)$')

class TimedeltaField(ApiField):
    dehydrated_type = 'timedelta'
    help_text = "A timedelta field, with duration expressed in seconds. Ex: 132"

    def convert(self, value):
        if value is None:
            return None

        if isinstance(value, six.string_types):
            match = TIMEDELTA_REGEX.search(value)

            if match:
                data = match.groupdict()
                return datetime.timedelta(int(data['days']), int(data['hours']), int(data['minutes']), int(data['seconds']))
            else:
                raise ApiFieldError("Timedelta provided to '%s' field doesn't appear to be a valid timedelta string: '%s'" % (self.instance_name, value))

        return value

    def hydrate(self, bundle):
        value = super(TimedeltaField, self).hydrate(bundle)

        if value and not hasattr(value, 'seconds'):
            if isinstance(value, six.string_types):
                try:
                    match = TIMEDELTA_REGEX.search(value)

                    if match:
                        data = match.groupdict()
                        value = datetime.timedelta(int(data['days']), int(data['hours']), int(data['minutes']), int(data['seconds']))
                    else:
                        raise ValueError()
                except (ValueError, TypeError):
                    raise ApiFieldError("Timedelta provided to '%s' field doesn't appear to be a valid datetime string: '%s'" % (self.instance_name, value))

            else:
                raise ApiFieldError("Datetime provided to '%s' field must be a string: %s" % (self.instance_name, value))

        return value