from abc import ABC, abstractmethod

import aiohttp
import orjson
from glom import glom
from pydantic.error_wrappers import ValidationError

from core.lib import schemas
from core.util import logs

# Return error if the schema for the message type is not found
STRICT_VALIDATION = False

# Raise exception if the conversion schema is not found
STRICT_CONVERSION = False

# TODO: Set them to True when all message types are implemented

log = logs.get_logger("clients")


class NoSchema(Exception):
    """
    Raised when:
    - The schema for the message type is not found
    - The conversion schema is not found
    - There is no schema library for the client
    """

    pass


class NoSuchMethod(Exception):
    """
    Client library has no such method.
    """

    pass


class GenericAPIError(Exception):
    """
    Generic API error.
    """

    pass


def is_camel_case(s):
    return s != s.lower() and s != s.upper() and "_" not in s


def snake_to_camel(word):
    if is_camel_case(word):
        return word
    return "".join(x.capitalize() or "_" for x in word.split("_"))


DEFAULT_HEADERS = {
    "accept": "application/json",
    "Content-Type": "application/json",
}


class BaseClient(ABC):
    token = None

    async def __new__(cls, *a, **kw):
        instance = super().__new__(cls)
        await instance.__init__(*a, **kw)
        return instance

    async def __init__(self, instance):
        """
        Initialise the client.
        :param instance: the database object, e.g. Aggregator
        """
        name = self.__class__.__name__
        self.name = name.replace("Client", "").lower()
        self.instance = instance
        self.client = None

        await self.connect()

    @abstractmethod
    async def connect(self):
        pass

    @property
    def schema(self):
        """
        Get the schema library for the client.
        """
        # Does the schemas library have a library for this client name?
        if hasattr(schemas, f"{self.name}_s"):
            schema_instance = getattr(schemas, f"{self.name}_s")
        else:
            log.error(f"No schema library for {self.name}")
            raise Exception(f"No schema library for client {self.name}")

        return schema_instance

    def get_schema(self, method, convert=False):
        if isinstance(method, str):
            to_camel = snake_to_camel(method)
        else:
            to_camel = snake_to_camel(method.__class__.__name__)
        if convert:
            to_camel = f"{to_camel}Schema"

        # if hasattr(self.schema, method):
        #     schema = getattr(self.schema, method)
        if hasattr(self.schema, to_camel):
            schema = getattr(self.schema, to_camel)
        else:
            raise NoSchema(f"Could not get schema: {to_camel}")
        return schema

    async def call_method(self, method, *args, **kwargs):
        """
        Call a method with aiohttp.
        """
        if kwargs.get("append_slash", True):
            path = f"{self.url}/{method}/"
        else:
            path = f"{self.url}/{method}"

        http_method = kwargs.get("http_method", "get")

        cast = {
            "headers": DEFAULT_HEADERS,
        }

        # Use the token if it's set
        if self.token is not None:
            cast["headers"]["Authorization"] = f"Bearer {self.token}"

        if "data" in kwargs:
            cast["data"] = orjson.dumps(kwargs["data"])

        # Use the method to send a HTTP request
        async with aiohttp.ClientSession() as session:
            session_method = getattr(session, http_method)
            async with session_method(path, **cast) as response:
                response_json = await response.json()
                return response_json

    def convert_spec(self, response, method):
        """
        Convert an API response to the requested spec.
        :raises NoSchema: If the conversion schema is not found
        """
        schema = self.get_schema(method, convert=True)

        # Use glom to convert the response to the schema
        converted = glom(response, schema)
        return converted

    def validate_response(self, response, method):
        schema = self.get_schema(method)
        # Return a dict of the validated response
        try:
            response_valid = schema(**response).dict()
        except ValidationError as e:
            log.error(f"Error validating {method} response: {response}")
            log.error(f"Errors: {e}")
            raise GenericAPIError("Error validating response")
        return response_valid

    def method_filter(self, method):
        """
        Return a new method.
        """
        return method

    async def call(self, method, *args, **kwargs):
        """
        Call the exchange API and validate the response
        :raises NoSchema: If the method is not in the schema mapping
        :raises ValidationError: If the response cannot be validated
        """
        # try:
        response = await self.call_method(method, *args, **kwargs)
        # except (APIError, V20Error) as e:
        #    log.error(f"Error calling method {method}: {e}")
        #    raise GenericAPIError(e)

        if "schema" in kwargs:
            method = kwargs["schema"]
        else:
            method = self.method_filter(method)
        try:
            response_valid = self.validate_response(response, method)
        except NoSchema as e:
            log.error(f"{e} - {response}")
            response_valid = response
        # Convert the response to a format that we can use
        try:
            response_converted = self.convert_spec(response_valid, method)
        except NoSchema as e:
            log.error(f"{e} - {response}")
            response_converted = response_valid

        # return (True, response_converted)
        return response_converted