Process csv file exported from ASN Bank to set account name

asn-csv-process.py

#!/usr/bin/env python3
"""
ASN Bank CSV export doesn't contain any opposing account name for contactless
payments but contains the merchant name in the description field along with a
lot of other information.

We can split this description on the '>' chracter and extract the merchant
that way.

Idea adapted from: https://github.com/DanielsWrath/YNABGoingDutch/blob/3dcde360906bc87dc43efb62b0698f3f20d34519/js/bankMapper.js#L101-L111

Relevant CSV field descriptions from document "Bestandsbeschrijving export
bestand ASN Online Bankieren"
[3]: Naam tegenrekening
[17]: Omschrijving
"""
import csv
import sys

if len(sys.argv) != 2:
    print(f"Usage: {sys.argv[0]} FILE.csv")
    sys.exit(1)

with open(sys.argv[1], newline='') as csvfile:
    reader = csv.reader(csvfile, delimiter=',', quotechar='\'')
    writer = csv.writer(sys.stdout, delimiter=',', quotechar='\'')

    for row in reader:
        # Check if oppposing account name is empty
        if not row[3]:
            # Split description on '>' character
            parts = row[17].split('>')
            if len(parts) == 2:
                # Get account name from first part - set as opposing account name
                row[3] = parts[0].strip()
            else:
                print(f"Expected two parts from string, ignoring. Got: {parts}", file=sys.stderr)

        # Write new row to new csv
        writer.writerow(row)