# Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
#
#     http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file is
# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
# ANY KIND, either express or implied. See the License for the specific
# language governing permissions and limitations under the License.

import base64
import io
import json

import requests


def input_handler(data, context):
    """Pre-process request input before it is sent to TensorFlow Serving REST API

    Args:
        data (obj): the request data stream
        context (Context): an object containing request and configuration details

    Returns:
        (dict): a JSON-serializable dict that contains request body and headers
    """

    if context.request_content_type == "application/x-image":
        payload = data.read()
        encoded_image = base64.b64encode(payload).decode("utf-8")
        instance = [{"b64": encoded_image}]
        return json.dumps({"instances": instance})
    else:
        _return_error(
            415, 'Unsupported content type "{}"'.format(context.request_content_type or "Unknown")
        )


def output_handler(response, context):
    """Post-process TensorFlow Serving output before it is returned to the client.

    Args:
        response (obj): the TensorFlow serving response
        context (Context): an object containing request and configuration details

    Returns:
        (bytes, string): data to return to client, response content type
    """
    if response.status_code != 200:
        _return_error(response.status_code, response.content.decode("utf-8"))
    response_content_type = context.accept_header
    prediction = response.content
    return prediction, response_content_type


def _return_error(code, message):
    raise ValueError("Error: {}, {}".format(str(code), message))