Wells Fargo CSV output --> YNAB importable CSV

wells_fargo_to_ynab_import.py

#!/usr/bin/env python3
"""Convert given Wells Fargo exported CSV to YNAB import-compatible CSV format.

Usage:`python3 wells_fargo_to_ynab_import.py <input.csv> [output.csv]`
# outputs: input_ynab.csv

Or specify a custom output path:
python3 wells_fargo_to_ynab_import.py "CreditCard.csv" my_output.csv
# outputs: my_output.csv

The script maps: Date → Date (already MM/DD/YYYY), Description → Payee, Amount (negative = outflow) → Amount, and leaves Memo blank.                      
""" 

import csv
import sys
from pathlib import Path


def convert(input_path: str, output_path: str | None = None) -> None:
    input_file = Path(input_path)
    if output_path is None:
        output_path = str(input_file.parent / (input_file.stem + "_ynab.csv"))
    
    rows_written = 0
    with open(input_file, newline="", encoding="utf-8-sig") as infile, \
         open(output_path, "w", newline="", encoding="utf-8") as outfile:
    
        reader = csv.reader(infile)
        writer = csv.writer(outfile)
        writer.writerow(["Date", "Payee", "Memo", "Amount"])

        for row in reader:
            if not row or len(row) < 5:
                continue
            date       = row[0].strip()
            amount     = row[1].strip()
            payee      = row[4].strip()
            writer.writerow([date, payee, "", amount])
            rows_written += 1

    print(f"Wrote {rows_written} transactions → {Path(output_path).name}")


if __name__ == "__main__":
  if len(sys.argv) < 2:
      print("Usage: python3 wells_fargo_to_ynab_import.py <input.csv> [output.csv]")
      sys.exit(1)
  convert(sys.argv[1], sys.argv[2] if len(sys.argv) > 2 else None)