import dataclasses
import os
from datetime import datetime
from typing import (
    List, Tuple, ClassVar, Type, TypeVar, Dict, Any, Optional
)

from dbt.clients.system import write_json, read_json
from dbt.exceptions import (
    InternalException,
    RuntimeException,
)
from dbt.version import __version__
from dbt.tracking import get_invocation_id
from dbt.dataclass_schema import dbtClassMixin

SourceKey = Tuple[str, str]


def list_str() -> List[str]:
    """Mypy gets upset about stuff like:

    from dataclasses import dataclass, field
    from typing import Optional, List

    @dataclass
    class Foo:
        x: Optional[List[str]] = field(default_factory=list)


    Because `list` could be any kind of list, I guess
    """
    return []


class Replaceable:
    def replace(self, **kwargs):
        return dataclasses.replace(self, **kwargs)


class Mergeable(Replaceable):
    def merged(self, *args):
        """Perform a shallow merge, where the last non-None write wins. This is
        intended to merge dataclasses that are a collection of optional values.
        """
        replacements = {}
        cls = type(self)
        for arg in args:
            for field in dataclasses.fields(cls):
                value = getattr(arg, field.name)
                if value is not None:
                    replacements[field.name] = value

        return self.replace(**replacements)


class Writable:
    def write(self, path: str):
        write_json(
            path, self.to_dict(omit_none=False)  # type: ignore
        )


class AdditionalPropertiesMixin:
    """Make this class an extensible property.

    The underlying class definition must include a type definition for a field
    named '_extra' that is of type `Dict[str, Any]`.
    """
    ADDITIONAL_PROPERTIES = True

    # This takes attributes in the dictionary that are
    # not in the class definitions and puts them in an
    # _extra dict in the class
    @classmethod
    def __pre_deserialize__(cls, data):
        # dir() did not work because fields with
        # metadata settings are not found
        # The original version of this would create the
        # object first and then update extra with the
        # extra keys, but that won't work here, so
        # we're copying the dict so we don't insert the
        # _extra in the original data. This also requires
        # that Mashumaro actually build the '_extra' field
        cls_keys = cls._get_field_names()
        new_dict = {}
        for key, value in data.items():
            if key not in cls_keys and key != '_extra':
                if '_extra' not in new_dict:
                    new_dict['_extra'] = {}
                new_dict['_extra'][key] = value
            else:
                new_dict[key] = value
        data = new_dict
        data = super().__pre_deserialize__(data)
        return data

    def __post_serialize__(self, dct):
        data = super().__post_serialize__(dct)
        data.update(self.extra)
        if '_extra' in data:
            del data['_extra']
        return data

    def replace(self, **kwargs):
        dct = self.to_dict(omit_none=False)
        dct.update(kwargs)
        return self.from_dict(dct)

    @property
    def extra(self):
        return self._extra


class Readable:
    @classmethod
    def read(cls, path: str):
        try:
            data = read_json(path)
        except (EnvironmentError, ValueError) as exc:
            raise RuntimeException(
                f'Could not read {cls.__name__} at "{path}" as JSON: {exc}'
            ) from exc

        return cls.from_dict(data)  # type: ignore


BASE_SCHEMAS_URL = 'https://schemas.getdbt.com/'
SCHEMA_PATH = 'dbt/{name}/v{version}.json'


@dataclasses.dataclass
class SchemaVersion:
    name: str
    version: int

    @property
    def path(self) -> str:
        return SCHEMA_PATH.format(
            name=self.name,
            version=self.version
        )

    def __str__(self) -> str:
        return BASE_SCHEMAS_URL + self.path


SCHEMA_VERSION_KEY = 'dbt_schema_version'


METADATA_ENV_PREFIX = 'DBT_ENV_CUSTOM_ENV_'


def get_metadata_env() -> Dict[str, str]:
    return {
        k[len(METADATA_ENV_PREFIX):]: v for k, v in os.environ.items()
        if k.startswith(METADATA_ENV_PREFIX)
    }


@dataclasses.dataclass
class BaseArtifactMetadata(dbtClassMixin):
    dbt_schema_version: str
    dbt_version: str = __version__
    generated_at: datetime = dataclasses.field(
        default_factory=datetime.utcnow
    )
    invocation_id: Optional[str] = dataclasses.field(
        default_factory=get_invocation_id
    )
    env: Dict[str, str] = dataclasses.field(default_factory=get_metadata_env)


def schema_version(name: str, version: int):
    def inner(cls: Type[VersionedSchema]):
        cls.dbt_schema_version = SchemaVersion(
            name=name,
            version=version,
        )
        return cls
    return inner


@dataclasses.dataclass
class VersionedSchema(dbtClassMixin):
    dbt_schema_version: ClassVar[SchemaVersion]

    @classmethod
    def json_schema(cls, embeddable: bool = False) -> Dict[str, Any]:
        result = super().json_schema(embeddable=embeddable)
        if not embeddable:
            result['$id'] = str(cls.dbt_schema_version)
        return result


T = TypeVar('T', bound='ArtifactMixin')


# metadata should really be a Generic[T_M] where T_M is a TypeVar bound to
# BaseArtifactMetadata. Unfortunately this isn't possible due to a mypy issue:
# https://github.com/python/mypy/issues/7520
@dataclasses.dataclass(init=False)
class ArtifactMixin(VersionedSchema, Writable, Readable):
    metadata: BaseArtifactMetadata

    @classmethod
    def validate(cls, data):
        super().validate(data)
        if cls.dbt_schema_version is None:
            raise InternalException(
                'Cannot call from_dict with no schema version!'
            )