from jsonmodels import models, fields
from mongoengine.base import BaseDocument

from apimodels import DictField


class MongoengineFieldsDict(DictField):
    """
    DictField representing mongoengine field names/value mapping.
    Used to convert mongoengine-style field/subfield notation to user-presentable syntax, including handling update
        operators.
    """

    mongoengine_update_operators = (
        'inc',
        'dec',
        'push',
        'push_all',
        'pop',
        'pull',
        'pull_all',
        'add_to_set',
    )

    @staticmethod
    def _normalize_mongo_value(value):
        if isinstance(value, BaseDocument):
            return value.to_mongo()
        return value

    @classmethod
    def _normalize_mongo_field_path(cls, path, value):
        parts = path.split('__')
        if len(parts) > 1:
            if parts[0] == 'set':
                parts = parts[1:]
            elif parts[0] == 'unset':
                parts = parts[1:]
                value = None
            elif parts[0] in cls.mongoengine_update_operators:
                return None, None
        return '.'.join(parts), cls._normalize_mongo_value(value)

    def parse_value(self, value):
        value = super(MongoengineFieldsDict, self).parse_value(value)
        return {
            k: v
            for k, v in (self._normalize_mongo_field_path(*p) for p in value.items())
            if k is not None
        }


class UpdateResponse(models.Base):
    updated = fields.IntField(required=True)
    fields = MongoengineFieldsDict()


class PagedRequest(models.Base):
    page = fields.IntField()
    page_size = fields.IntField()