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

from copy import deepcopy
import datetime
from functools import wraps
import json

from flask import request
from marshmallow import ValidationError
from oto import response
from oto.adaptors.flask import flaskify

from ows_product_physical.constant 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.
            """
            json_data = request.get_json(force=True, silent=True) or dict()
            # Marshmallow doesn't return validation errors unless the passed
            # in data type is a dict.
            if not isinstance(json_data, dict):
                return flaskify(response.create_error_response(
                    error.BAD_REQUEST_ERROR,
                    'Request data must be a JSON object and include proper '
                    'Content-Type header parameter.'))

            params = request.args or dict()  # from url params
            data = deepcopy(json_data)
            data.update(kwargs)
            data.update(params)

            try:
                result = schema().load(data)
                kwargs['json_data'] = result
                return function(*args, **kwargs)
            except ValidationError as e:
                return flaskify(response.create_error_response(
                    code=error.VALIDATION_ERROR,
                    message=e.messages, status=400))

        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)