wichteln.py

from typing import Sequence, List, NamedTuple, Optional
from pprint import pprint
from os import getenv
import json
import random
import requests
import sys

class Person(NamedTuple):
    name: str
    email: str

class Message(NamedTuple):
    giver: Person
    subject: str
    message: str

class Pair(NamedTuple):
    receiver: Person
    giver: Person

def get_env_config(name: str, default: Optional[str] = None):
    value = getenv(name)
    if value is not None:
        return value
    if default is not None:
        return default
    raise ValueError("Environment variable config {} must be set".format(name))

def load_people(filename: str) -> List[Person]:
    people = []
    for line in open(filename):
        line = line.strip()
        if len(line) == 0:
            continue
        name, mail = line.split(':', 2)
        if len(name.strip()) == 0:
            raise ValueError("No name provided in line '{}'. Line format: '<name>: <mail>'".format(line))
        if mail is None or len(mail.strip()) == 0:
            raise ValueError("No email provided in line '{}'. Line format: '<name>: <mail>'".format(line))
        people.append(Person(
            name = name.strip(),
            email = mail.strip(),
        ))
    return people

def send_mails(messages: Sequence[Message], dry: bool = False):
    endpoint = "https://api.mailjet.com/v3.1/send"
    account = get_env_config("MAILJET_ACCOUNT")
    key = get_env_config("MAILJET_KEY")
    if account is None or key is None:
        raise ValueError("Can't send mails without MAILJET_ACCOUNT or MAILJET_KEY being set")
    mailjet_messages = [
        {
            "From": {
                "Name": get_env_config("SENDER_NAME", "n/a"),
                "Email": get_env_config("SENDER_MAIL", "n@a"),
            },
            "To": [
                {
                    "Name": message.giver.name,
                    "Email": message.giver.email,
                }
            ],
            "Subject": message.subject,
            "TextPart": message.message,
            "CustomID": get_env_config("MAILJET_CUSTOM_ID", "SecretSanta")
        } for message in messages
    ]
    if dry:
        pprint(mailjet_messages)
        return

    response = requests.post(
        endpoint,
        auth = (account, key),
        json = {"Messages": mailjet_messages}
    )
    # Does not print message text, so no pair leakage
    pprint(json.loads(response.text))

def generate_pairs(people: Sequence[Person]) -> List[Pair]:
    generate_candidate = lambda: list(zip(people, random.sample(people, len(people))))

    while True:
        candidate = generate_candidate()
        has_self_ref = any([pair[0] == pair[1] for pair in candidate])
        if has_self_ref:
            continue
        return [Pair(receiver = pair[0], giver = pair[1]) for pair in candidate]


def generate_messages(pairs: Sequence[Pair]) -> List[Message]:
    template = """Servus {giver}!

Dein Wichtel ist {receiver}, viel Spaß!

Liebe Grüße,
das Wichtel-Komitee"""
    messages = [
        Message(
            giver = pair.giver,
            subject = "Dein Wichtel",
            message = template.format(
                giver = pair.giver.name,
                receiver = pair.receiver.name,
            )
        ) for pair in pairs
    ]
    return messages

def main(args):
    if len(args) == 1:
        print('usage: MAILJET_ACCOUNT=... MAILJET_KEY=... santa.py people-file')
        return 1
    people_file = args[1]
    people = load_people(people_file)
    pairs = generate_pairs(people)
    messages = generate_messages(pairs)
    send_mails(messages)
    return 0

def test():
    test_people = [
        Person(name = "a", email = "amail"),
        Person(name = "b", email = "bmail"),
        Person(name = "c", email = "cmail"),
        Person(name = "d", email = "dmail"),
        Person(name = "e", email = "email"),
        Person(name = "f", email = "fmail"),
    ]
    pprint(generate_messages(generate_pairs(test_people)))

sys.exit(main(sys.argv))