parsing and printing guarantees

main.py

#!/usr/bin/env python3
import csv
import sys
from collections import namedtuple
from datetime import datetime

Guarantee = namedtuple("Guarantee", "end_date address")

DEFAULT_CALCULATION_DATE = datetime(2020, 5, 2)
DEFULAT_FILE_NAME = "./guarantees_end.csv"


def print_expired_guarantees(guarantees_days_left, pre="\t"):
    for guarantee, days_left in guarantees_days_left:
        if days_left < 0:
            print(f"{pre}{guarantee.address}")


def print_expiry_details(guarantees_days_left, pre="\t"):
    for guarantee, days_left in guarantees_days_left:
        report_entry = None
        if days_left < 0:
            report_entry = f"has expired {-days_left} ago"
        elif days_left == 0:
            report_entry = f"will expire today"
        else:
            report_entry = f"will expire in {days_left} days"
        print(f"{pre}{guarantee.address} {report_entry}")


def days_left(gurantee, from_date):
    return (gurantee.end_date - from_date).days


def date_from_str(date_str):
    date_parts = map(int, date_str.split("-"))
    return datetime(*date_parts)


def parse_file_to_gurantees(csvfile):
    guarantees = []
    with open(csvfile) as csvfile:
        guarantees = [
            Guarantee(date_from_str(end_date), address)
            for [end_date, address] in csv.reader(csvfile)
        ]
    return guarantees


def main(file_name, calculation_date):
    guarantees = parse_file_to_gurantees(file_name)
    guarantees_days_left = [(g, days_left(g, calculation_date)) for g in guarantees]
    print(f"\n1. Guarantee has ended for following addresses on: {calculation_date}")
    print_expired_guarantees(guarantees_days_left)
    print(f"\n2. Expiration report for {file_name} for date {calculation_date}")
    print_expiry_details(guarantees_days_left)


"""
    main.py (author: manu.datta@gmail.com)
    usage: ./main.py <csv file> <date of calculation>
    output:
        1. report of already expired guarantees
        2. report of each guarantee with days remaining
    notes:
        1. No error handling on input (csv or date format)
        2. config parser can be used to make command line
           parameter handling more robust and standard
"""
if __name__ == "__main__":
    file_name, calculation_date = None, None
    try:
        file_name = sys.argv[1]
        calculation_date = date_from_str(sys.argv[2])
    except IndexError:
        file_name = file_name if file_name is not None else DEFULAT_FILE_NAME
        calculation_date = (
            calculation_date
            if calculation_date is not None
            else DEFAULT_CALCULATION_DATE
        )
    main(file_name, calculation_date)