from typing import (
    Type, ClassVar, cast,
)
import re
from dataclasses import fields
from enum import Enum
from datetime import datetime
from dateutil.parser import parse

from hologram import JsonSchemaMixin, FieldEncoder, ValidationError

# type: ignore
from mashumaro import DataClassDictMixin
from mashumaro.config import (
    TO_DICT_ADD_OMIT_NONE_FLAG, BaseConfig as MashBaseConfig
)
from mashumaro.types import SerializableType, SerializationStrategy


class DateTimeSerialization(SerializationStrategy):
    def serialize(self, value):
        out = value.isoformat()
        # Assume UTC if timezone is missing
        if value.tzinfo is None:
            out = out + "Z"
        return out

    def deserialize(self, value):
        return (
            value if isinstance(value, datetime) else parse(cast(str, value))
        )


# This class pulls in both JsonSchemaMixin from Hologram and
# DataClassDictMixin from our fork of Mashumaro. The 'to_dict'
# and 'from_dict' methods come from Mashumaro. Building
# jsonschemas for every class and the 'validate' method
# come from Hologram.
class dbtClassMixin(DataClassDictMixin, JsonSchemaMixin):
    """Mixin which adds methods to generate a JSON schema and
       convert to and from JSON encodable dicts with validation
       against the schema
    """

    class Config(MashBaseConfig):
        code_generation_options = [
            TO_DICT_ADD_OMIT_NONE_FLAG,
        ]
        serialization_strategy = {
            datetime: DateTimeSerialization(),
        }

    _hyphenated: ClassVar[bool] = False
    ADDITIONAL_PROPERTIES: ClassVar[bool] = False

    # This is called by the mashumaro to_dict in order to handle
    # nested classes.
    # Munges the dict that's returned.
    def __post_serialize__(self, dct):
        if self._hyphenated:
            new_dict = {}
            for key in dct:
                if '_' in key:
                    new_key = key.replace('_', '-')
                    new_dict[new_key] = dct[key]
                else:
                    new_dict[key] = dct[key]
            dct = new_dict

        return dct

    # This is called by the mashumaro _from_dict method, before
    # performing the conversion to a dict
    @classmethod
    def __pre_deserialize__(cls, data):
        # `data` might not be a dict, e.g. for `query_comment`, which accepts
        # a dict or a string; only snake-case for dict values.
        if cls._hyphenated and isinstance(data, dict):
            new_dict = {}
            for key in data:
                if '-' in key:
                    new_key = key.replace('-', '_')
                    new_dict[new_key] = data[key]
                else:
                    new_dict[key] = data[key]
            data = new_dict
        return data

    # This is used in the hologram._encode_field method, which calls
    # a 'to_dict' method which does not have the same parameters in
    # hologram and in mashumaro.
    def _local_to_dict(self, **kwargs):
        args = {}
        if 'omit_none' in kwargs:
            args['omit_none'] = kwargs['omit_none']
        return self.to_dict(**args)


class ValidatedStringMixin(str, SerializableType):
    ValidationRegex = ''

    @classmethod
    def _deserialize(cls, value: str) -> 'ValidatedStringMixin':
        cls.validate(value)
        return ValidatedStringMixin(value)

    def _serialize(self) -> str:
        return str(self)

    @classmethod
    def validate(cls, value):
        res = re.match(cls.ValidationRegex, value)

        if res is None:
            raise ValidationError(f"Invalid value: {value}")  # TODO


# These classes must be in this order or it doesn't work
class StrEnum(str, SerializableType, Enum):
    def __str__(self):
        return self.value

    # https://docs.python.org/3.6/library/enum.html#using-automatic-values
    def _generate_next_value_(name, *_):
        return name

    def _serialize(self) -> str:
        return self.value

    @classmethod
    def _deserialize(cls, value: str):
        return cls(value)


class HyphenatedDbtClassMixin(dbtClassMixin):
    # used by from_dict/to_dict
    _hyphenated: ClassVar[bool] = True

    # used by jsonschema validation, _get_fields
    @classmethod
    def field_mapping(cls):
        result = {}
        for field in fields(cls):
            skip = field.metadata.get("preserve_underscore")
            if skip:
                continue

            if "_" in field.name:
                result[field.name] = field.name.replace("_", "-")
        return result


class ExtensibleDbtClassMixin(dbtClassMixin):
    ADDITIONAL_PROPERTIES = True


# This is used by Hologram in jsonschema validation
def register_pattern(base_type: Type, pattern: str) -> None:
    """base_type should be a typing.NewType that should always have the given
    regex pattern. That means that its underlying type ('__supertype__') had
    better be a str!
    """

    class PatternEncoder(FieldEncoder):
        @property
        def json_schema(self):
            return {"type": "string", "pattern": pattern}

    dbtClassMixin.register_field_encoders({base_type: PatternEncoder()})