"""Helper functions to use with handlers."""

import datetime
from functools import wraps
import json

from flask import request
import marshmallow
from oto import response
from oto.adaptors.flask import flaskify
from werkzeug.exceptions import BadRequest, UnsupportedMediaType

from conflict_manager.constants import error


def parse_and_validate_request_json(schema):
    """Use to decorate handler with request JSON data.

    Used to parse, deserialize, and validate JSON request data with.

    Args:
        schema: Marshallow Schema to validate request json data with.

    Returns:
        callable: the wrapped function.
    """
    def decorator(function):
        @wraps(function)
        def wrapper(*args, **kwargs):
            """Validate the request body against a validator.

            Returns:
                Response: error HTTP response, or continue to the calling
                function if successful.
            """
            try:
                json = request.get_json()
            except BadRequest as e:
                return flaskify(response.create_error_response(
                    error.ERROR_CODE_BAD_REQUEST, e.description))
            except UnsupportedMediaType as e:
                return flaskify(response.create_error_response(
                    error.ERROR_CODE_BAD_REQUEST, e.description))

            # Marshmallow doesn't return validation errors unless the passed
            # in data type is a dict.
            if not isinstance(json, dict):
                return flaskify(response.create_error_response(
                    error.ERROR_CODE_BAD_REQUEST,
                    'Request data must be a JSON object and include proper '
                    'Content-Type header parameter.'))

            try:
                kwargs['json_data'] = schema().load(json)
            except marshmallow.ValidationError as err:
                return flaskify(response.create_error_response(
                    code=error.ERROR_CODE_VALIDATION,
                    message=err.messages, status=400))
            return function(*args, **kwargs)

        return wrapper
    return decorator


class DateJSONEncoder(json.JSONEncoder):
    """Custom JSON encoder for handling datetime objects."""

    def default(self, obj):
        """Override the object seralizer."""
        if isinstance(obj, (datetime.datetime, datetime.date)):
            return obj.isoformat()
        return super().default(obj)