import concurrent.futures
import json
import logging
import requests

# AWS pricing API Endpoint
URL = "https://a0.p.awsstatic.com/pricing/1.0/ec2/region/{region}/reserved-instance/linux/index.json"


class AWSService:
    # Retrieving EC2 instance prices from AWS EC2 Pricing API
    @classmethod
    def get_ec2_prices(cls, **kwargs):

        prices_list = []
        try:
            response = requests.get(URL.format(region=kwargs["region"]))

            try:
                pricing_data = response.json()
                prices = pricing_data["prices"]

                for price in prices:
                    if cls.is_valid_input(price["attributes"], **kwargs):
                        prices_list.append(price)
            except Exception as exc:
                cls.exception_handler(exc)

        except Exception as exc:
            cls.exception_handler(exc)

        return prices_list

    @staticmethod
    def is_valid_input(base_argument, **kwargs):

        original_values = {
            "term_offering_class": base_argument["aws:offerTermOfferingClass"],
            "term_length": base_argument["aws:offerTermLeaseLength"],
            "payment_option": base_argument["aws:offerTermPurchaseOption"],
            "operating_system": base_argument["aws:ec2:operatingSystem"],
            "tenancy": base_argument["aws:ec2:tenancy"],
        }

        user_values = {
            "term_offering_class": kwargs["term_offering_class"],
            "term_length": kwargs["term_length"],
            "payment_option": kwargs["payment_option"],
            "operating_system": kwargs["operating_system"],
            "tenancy": kwargs["tenancy"],
        }

        for key in original_values.keys():
            if original_values.get(key) != user_values.get(key):
                return False

        return True

    @classmethod
    def save_prices_in_file(cls, prices_list, file_id):
        prices = json.dumps(prices_list)
        try:
            with open(f"./prices/ec2_price_{file_id}.json", "w") as prices_file:
                prices_file.write(prices)
        except Exception as exc:
            cls.exception_handler(exc)

    @staticmethod
    def exception_handler(exception):
        # Store possible exceptions in a map of key as exception class and value as a message
        exception_map = {
            json.decoder.JSONDecodeError: "JSON Decode Error",
            KeyError: "Key not found in JSON response",
            requests.exceptions.InvalidSchema: "Invalid URL. No connection adapters found",
            requests.exceptions.HTTPError: "HTTP error",
            requests.exceptions.ConnectionError: "Failed to establish a new connection",
            requests.exceptions.RequestException: "Request Exception",
            FileNotFoundError: "The prices directory is not present",
        }

        message = exception_map.get(exception.__class__)

        if message is None:
            message = exception

        logging.exception(message, exc_info=False)

    # Running get_ec2_prices and save_prices_in_file function using this function
    # This will enable us to run both functions in a single thread as both functions are dependent on each other
    # This will create new file for every input using file_id
    @staticmethod
    def get_and_save_ec2_prices(*args):
        list_of_args = list(args)

        file_id = list_of_args[0]
        reg = list_of_args[1]
        term_offer_cls = list_of_args[2]
        term_len = list_of_args[3]
        payment_opt = list_of_args[4]

        prices_list = AWSService.get_ec2_prices(
            region=reg,
            term_offering_class=term_offer_cls,
            term_length=term_len,
            payment_option=payment_opt,
            operating_system="Linux",
            tenancy="Shared",
        )
        # If prices_list is not empty then save the prices_list data into the file
        if len(prices_list) != 0:
            AWSService.save_prices_in_file(prices_list, file_id)


# List of inputs
# list_of_input[i] = ["id", "region", "term_offering_class", "term_length", "payment_option", "operating_system", "tenancy"]
list_of_input = [
    ["0", "ap-south-1", "standard", "1yr", "No Upfront", "Linux", "Shared"],
    ["1", "us-east-1", "convertible", "1yr", "No Upfront", "Linux", "Shared"],
]

# Get prices for all inputs in parallel
with concurrent.futures.ThreadPoolExecutor() as executor:
    for list_of_arguments in list_of_input:
        executor.submit(AWSService.get_and_save_ec2_prices, *list_of_arguments)