import inspect
from abc import abstractmethod
from typing import List, Optional, Type, TypeVar, Generic, Dict, Any

from hologram import JsonSchemaMixin, ValidationError

from dbt.contracts.rpc import RPCParameters, RemoteResult, RemoteMethodFlags
from dbt.exceptions import NotImplementedException, InternalException

Parameters = TypeVar('Parameters', bound=RPCParameters)
Result = TypeVar('Result', bound=RemoteResult)


# If you call recursive_subclasses on a subclass of BaseRemoteMethod, it should
# only return subtypes of the given subclass.
T = TypeVar('T', bound='RemoteMethod')


class RemoteMethod(Generic[Parameters, Result]):
    METHOD_NAME: Optional[str] = None

    def __init__(self, args, config):
        self.args = args
        self.config = config

    @classmethod
    def get_parameters(cls) -> Type[Parameters]:
        argspec = inspect.getfullargspec(cls.set_args)
        annotations = argspec.annotations
        if 'params' not in annotations:
            raise InternalException(
                'set_args must have parameter named params with a valid '
                'RPCParameters type definition (no params annotation found)'
            )
        params_type = annotations['params']
        if not issubclass(params_type, RPCParameters):
            raise InternalException(
                'set_args must have parameter named params with a valid '
                'RPCParameters type definition (got {}, expected '
                'RPCParameters subclass)'.format(params_type)
            )
        if params_type is RPCParameters:
            raise InternalException(
                'set_args must have parameter named params with a valid '
                'RPCParameters type definition (got RPCParameters itself!)'
            )
        return params_type

    def get_flags(self) -> RemoteMethodFlags:
        return RemoteMethodFlags.Empty

    @classmethod
    def recursive_subclasses(
        cls: Type[T],
        named_only: bool = True,
    ) -> List[Type[T]]:
        classes = []
        current = [cls]
        while current:
            klass = current.pop()
            scls = klass.__subclasses__()
            classes.extend(scls)
            current.extend(scls)
        if named_only:
            classes = [c for c in classes if c.METHOD_NAME is not None]
        return classes

    @abstractmethod
    def set_args(self, params: Parameters):
        """set_args executes in the parent process for an RPC call"""
        raise NotImplementedException('set_args not implemented')

    @abstractmethod
    def handle_request(self) -> Result:
        """handle_request executes inside the child process for an RPC call"""
        raise NotImplementedException('handle_request not implemented')

    def cleanup(self, result: Optional[Result]):
        """cleanup is an optional method that executes inside the parent
        process for an RPC call.

        This will always be executed if set_args was.

        It's optional, and by default it does nothing.
        """

    def set_config(self, config):
        self.config = config


class RemoteManifestMethod(RemoteMethod[Parameters, Result]):
    def __init__(self, args, config, manifest):
        super().__init__(args, config)
        self.manifest = manifest


class RemoteBuiltinMethod(RemoteMethod[Parameters, Result]):
    def __init__(self, task_manager):
        self.task_manager = task_manager
        super().__init__(task_manager.args, task_manager.config)
        self.params: Optional[Parameters] = None

    def set_args(self, params: Parameters):
        self.params = params

    def run(self):
        raise InternalException(
            'the run() method on builtins should never be called'
        )

    def __call__(self, **kwargs: Dict[str, Any]) -> JsonSchemaMixin:
        try:
            params = self.get_parameters().from_dict(kwargs)
        except ValidationError as exc:
            raise TypeError(exc) from exc
        self.set_args(params)
        return self.handle_request()


class TaskTypes(Dict[str, Type[RemoteMethod]]):
    def __init__(
        self, tasks: Optional[List[Type[RemoteMethod]]] = None
    ) -> None:
        task_list: List[Type[RemoteMethod]]
        if tasks is None:
            task_list = RemoteMethod.recursive_subclasses(named_only=True)
        else:
            task_list = tasks
        super().__init__(
            (t.METHOD_NAME, t) for t in task_list
            if t.METHOD_NAME is not None
        )

    def manifest(self) -> Dict[str, Type[RemoteManifestMethod]]:
        return {
            k: t for k, t in self.items()
            if issubclass(t, RemoteManifestMethod)
        }

    def builtin(self) -> Dict[str, Type[RemoteBuiltinMethod]]:
        return {
            k: t for k, t in self.items()
            if issubclass(t, RemoteBuiltinMethod)
        }

    def non_manifest(self) -> Dict[str, Type[RemoteMethod]]:
        return {
            k: t for k, t in self.items()
            if (
                not issubclass(t, RemoteManifestMethod) and
                not issubclass(t, RemoteBuiltinMethod)
            )
        }