example of OOP python main

import logging
import os
import sys
from dataclasses import dataclass
from typing import List
from uuid import uuid4

import structlog
from bson.objectid import ObjectId
from dotenv import load_dotenv
from pymongo import uri_parser
from pymongo.collection import Collection
from pymongo.mongo_client import MongoClient

from etl import model
from etl.anonymization import AccessorsAnonymizer, Tokenizer
from etl.bigquery import Bigquery, CommandTableFacade
from etl.processing import Processor
from etl.util import fatal

FALLBACK_MONGO_URI = "mongodb://localhost:27017/we"
execution_id = str(uuid4())


def main():
    cfg = get_config()

    if cfg.is_deployment:
        configure_logging()
    log = structlog.stdlib.get_logger().bind(execution_id=cfg.execution_id, environment=cfg.environment)

    log.info(f"Discovered configuration: {cfg}")

    cfg.deployment_config_sanity_check(log)

    # MongoCatalog, Tokenizer, AccessorsAnonymizer, Bigquery and CommandTableFacade are "library" classes. Notices that these classes are instantiated only once.

    mongo = MongoCatalog(cfg.mongo_rs_core_uri, cfg.mongo_rs_accessors_uri)
    tokenizer = Tokenizer(cfg.tokenizer_url, cfg.tokenizer_user, cfg.tokenizer_pw)
    filter_accessors_for_users = user_filter_factory(mongo.get_collection("user"))
    accessors_anonymizer = AccessorsAnonymizer(tokenizer, filter_accessors_for_users)
    bq = Bigquery(log, cfg.dataset_id, cfg.full_scan, cfg.execution_id, cfg.environment)

    def with_prefix(base_name: str):
        return f"{cfg.table_prefix}_{base_name}"

    cmd_table = CommandTableFacade(log, bq, with_prefix("exec_commands"))
    cmd_table.create()

    processors = [
        Processor(
            log,
            bq,
            cmd_table,
            mongo.get_collection("installation"),
            model.Table(
                with_prefix("exported_installations"),
                "",
                model.installation_table_definition(accessors_anonymizer),
            ),
            "installation",
            mongo_cursor_batch_size=300,
        ),
        Processor(
            log,
            bq,
            cmd_table,
            mongo.get_collection("branch"),
            model.Table(
                with_prefix("exported_branches"),
                "",
                model.branch_table_definition(),
            ),
            "branch",
            mongo_cursor_batch_size=3000,
        ),
        Processor(
            log,
            bq,
            cmd_table,
            mongo.get_collection("space"),
            model.Table(
                with_prefix("exported_spaces"),
                "",
                model.space_table_definition(accessors_anonymizer),
            ),
            "space",
            mongo_cursor_batch_size=300,
        ),
        Processor(
            log,
            bq,
            cmd_table,
            mongo.get_collection("user"),
            model.Table(
                with_prefix("exported_users"),
                "",
                model.user_table_definition(tokenizer),
            ),
            "user",
            mongo_cursor_batch_size=1000,
        ),
    ]

    for p in processors:
        p.setup()

    for p in processors:
        p.export()

    log.info("Done")