#! /usr/bin/python3

from argparse import ArgumentParser
from email.message import EmailMessage
import io
import json
from smtplib import SMTP
import statistics

import requests
import toml


def fetch_data():
    # Fetch new case counts for Cambridgeshire.
    data = requests.get(
        "https://api.coronavirus.data.gov.uk/v1/data",
        params={
            "filters": "areaType=utla;areaName=Cambridgeshire",
            "structure": json.dumps(
                ["date", "newCasesBySpecimenDate"], separators=(",", ":")
            ),
        },
    ).json()["data"]

    # Skip the first three days of the response.  This seems to be what the
    # website does, presumably because recent dates don't have reliable
    # enough numbers yet.
    data = data[3:]

    last_week = data[:7]
    mean = statistics.mean([new_cases for _, new_cases in last_week])
    return last_week, mean


def main():
    parser = ArgumentParser()
    parser.add_argument(
        "--config", type=toml.load, default={},
        help="Configuration file (TOML format)")
    parser.add_argument("--email", action="store_true")
    args = parser.parse_args()

    last_week, mean = fetch_data()
    formatted = io.StringIO()
    print(
        "Most recent week's worth of new cases in Cambridgeshire, "
        "by specimen date:",
        file=formatted)
    print(file=formatted)
    print(f"Mean: {mean:.1f}", file=formatted)
    for date, new_cases in last_week:
        print(f"{date}: {new_cases}", file=formatted)
    if args.email and "email" in args.config:
        new_cases_message = EmailMessage()
        new_cases_message["From"] = args.config["email"]["from"]
        new_cases_message["To"] = ", ".join(args.config["email"]["to_always"])
        new_cases_message["Subject"] = f"Cambridgeshire case count: {mean:.1f}"
        new_cases_message.set_content(formatted.getvalue())
        with SMTP("localhost") as smtp:
            smtp.send_message(new_cases_message)
    else:
        print(formatted.getvalue(), end="")


if __name__ == "__main__":
    main()