"""Generate a standalone HTML report from category,amount CSV input."""
import argparse
import csv
from decimal import Decimal, InvalidOperation
from html import escape
from pathlib import Path
def totals(source):
reader = csv.DictReader(source)
if not {"category", "amount"}.issubset(reader.fieldnames or []):
raise ValueError("CSV requires category and amount columns")
result = {}
for line, row in enumerate(reader, 2):
category = (row.get("category") or "").strip()
try:
amount = Decimal(row.get("amount") or "")
except InvalidOperation as error:
raise ValueError(f"Invalid amount on line {line}") from error
if not category or not amount.is_finite():
raise ValueError(f"Invalid category or amount on line {line}")
result[category] = result.get(category, Decimal(0)) + amount
return result
def render(values):
rows = "".join(f"
{escape(key)}
{value:,.2f}
" for key, value in sorted(values.items()))
return """Category report
Category report
Amounts grouped by category
Category
Amount
""" + rows + f"
Total
{sum(values.values(), Decimal(0)):,.2f}
"
if __name__ == "__main__":
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument("input", type=Path)
parser.add_argument("--output", type=Path, default=Path("report.html"))
args = parser.parse_args()
try:
with args.input.open(encoding="utf-8-sig", newline="") as source:
html = render(totals(source))
if args.input.resolve() == args.output.resolve():
parser.error("Output must not overwrite the input CSV")
args.output.write_text(html, encoding="utf-8")
except (ValueError, OSError) as error:
parser.error(str(error))
print(f"Created {args.output}")