Component Declaration Status Python Script Generator (BOM CSV vs Supplier Declarations)

import csv
from datetime import date, datetime

BOM_FILE = "bom_export.csv"
DECL_FILE = "declarations.csv"
OUT_FILE = "compliance_gaps.csv"
PART_COL = "part_number"
STATUS_COL = "status"
DATE_COL = "declaration_date"
GOOD_VALUE = "Compliant"
MAX_AGE_DAYS = 730


def load_declarations(path):
    result = {}
    with open(path, newline="", encoding="utf-8-sig") as handle:
        for row in csv.DictReader(handle):
            part = row[PART_COL].strip().upper()
            result[part] = row
    return result


def age_in_days(text):
    try:
        return (date.today() - datetime.strptime(text.strip(), "%Y-%m-%d").date()).days
    except ValueError:
        return None


def main():
    declarations = load_declarations(DECL_FILE)
    gaps = []
    with open(BOM_FILE, newline="", encoding="utf-8-sig") as handle:
        for row in csv.DictReader(handle):
            part = row[PART_COL].strip().upper()
            decl = declarations.get(part)
            if decl is None:
                gaps.append([part, "MISSING", ""])
            elif decl[STATUS_COL].strip() != GOOD_VALUE:
                gaps.append([part, "NOT COMPLIANT", decl[DATE_COL]])
            else:
                age = age_in_days(decl[DATE_COL])
                if age is None:
                    gaps.append([part, "BAD DATE", decl[DATE_COL]])
                elif age > MAX_AGE_DAYS:
                    gaps.append([part, "EXPIRED", decl[DATE_COL]])
    with open(OUT_FILE, "w", newline="", encoding="utf-8") as handle:
        writer = csv.writer(handle)
        writer.writerow(["part_number", "gap_reason", "declaration_date"])
        writer.writerows(gaps)
    print("Gaps found:", len(gaps), "written to", OUT_FILE)


if __name__ == "__main__":
    main()

# BOM CSV header:          part_number,description,qty
# Declarations CSV header: part_number,status,declaration_date
# Dates must be YYYY-MM-DD. Status text must match: Compliant