from collections import OrderedDict

import graphene
from graphene import Field, InputField
from graphene.relay.mutation import ClientIDMutation
from graphene.types.mutation import MutationOptions
from graphene.types.utils import yank_fields_from_attrs
from graphene_django.registry import get_global_registry

from .converter import convert_form_field
from .types import ErrorType


def fields_for_form(form, only_fields, exclude_fields):
    fields = OrderedDict()
    for name, field in form.fields.items():
        is_not_in_only = only_fields and name not in only_fields
        is_excluded = (
            name in exclude_fields  # or
            # name in already_created_fields
        )

        if is_not_in_only or is_excluded:
            continue

        fields[name] = convert_form_field(field)
    return fields


class BaseDjangoFormMutation(ClientIDMutation):
    class Meta:
        abstract = True

    @classmethod
    def mutate_and_get_payload(cls, root, info, **input):
        form = cls.get_form(root, info, **input)

        if form.is_valid():
            return cls.perform_mutate(form, info)
        else:
            errors = [
                ErrorType(field=key, messages=value)
                for key, value in form.errors.items()
            ]

            return cls(errors=errors)

    @classmethod
    def get_form(cls, root, info, **input):
        form_kwargs = cls.get_form_kwargs(root, info, **input)
        return cls._meta.form_class(**form_kwargs)

    @classmethod
    def get_form_kwargs(cls, root, info, **input):
        kwargs = {'data': input}

        pk = input.pop('id', None)
        if pk:
            instance = cls._meta.model._default_manager.get(pk=pk)
            kwargs['instance'] = instance

        return kwargs


class DjangoFormMutationOptions(MutationOptions):
    form_class = None


class DjangoFormMutation(BaseDjangoFormMutation):
    class Meta:
        abstract = True

    errors = graphene.List(ErrorType)

    @classmethod
    def __init_subclass_with_meta__(cls, form_class=None,
                                    only_fields=(), exclude_fields=(), **options):

        if not form_class:
            raise Exception('form_class is required for FormMutation')

        form = form_class()
        input_fields = fields_for_form(form, only_fields, exclude_fields)
        output_fields = fields_for_form(form, only_fields, exclude_fields)

        _meta = DjangoFormMutationOptions(cls)
        _meta.form_class = form_class
        _meta.fields = yank_fields_from_attrs(
            output_fields,
            _as=Field,
        )

        input_fields = yank_fields_from_attrs(
            input_fields,
            _as=InputField,
        )
        super(DjangoFormMutation, cls).__init_subclass_with_meta__(_meta=_meta, input_fields=input_fields, **options)

    @classmethod
    def perform_mutate(cls, form, info):
        form.save()
        return cls(errors=[])


class DjangoModelDjangoFormMutationOptions(DjangoFormMutationOptions):
    model = None
    return_field_name = None


class DjangoModelFormMutation(BaseDjangoFormMutation):
    class Meta:
        abstract = True

    errors = graphene.List(ErrorType)

    @classmethod
    def __init_subclass_with_meta__(cls, form_class=None, model=None, return_field_name=None,
                                    only_fields=(), exclude_fields=(), **options):

        if not form_class:
            raise Exception('form_class is required for DjangoModelFormMutation')

        if not model:
            model = form_class._meta.model

        if not model:
            raise Exception('model is required for DjangoModelFormMutation')

        form = form_class()
        input_fields = fields_for_form(form, only_fields, exclude_fields)

        registry = get_global_registry()
        model_type = registry.get_type_for_model(model)
        return_field_name = return_field_name or model._meta.model_name
        output_fields = OrderedDict()
        output_fields[return_field_name] = graphene.Field(model_type)

        _meta = DjangoModelDjangoFormMutationOptions(cls)
        _meta.form_class = form_class
        _meta.model = model
        _meta.return_field_name = return_field_name
        _meta.fields = yank_fields_from_attrs(
            output_fields,
            _as=Field,
        )

        input_fields = yank_fields_from_attrs(
            input_fields,
            _as=InputField,
        )
        super(DjangoModelFormMutation, cls).__init_subclass_with_meta__(_meta=_meta, input_fields=input_fields, **options)

    @classmethod
    def perform_mutate(cls, form, info):
        obj = form.save()
        kwargs = {cls._meta.return_field_name: obj}
        return cls(errors=[], **kwargs)