Automatically Email a Weekly Report from a CSV with Python

Weekly sales report 2026-09-28 to 2026-10-04 Revenue: $175.98 (+114.6% vs the week before) Sales: 7 (average $25.14) Best day: Tuesday 2026-09-29 ($90.00) Top products 1. Desk lamp: $90.00 2. Pen set: $49.98 3. Blue notebook: $36.00 Notes - 1 of 11 rows were skipped because the date or amount couldn't be read. 

date,product,amount 2026-09-23,Blue notebook,12.00 2026-09-24,Desk lamp,45.00 2026-09-26,Pen set,24.99 2026-09-28,Blue notebook,12.00 2026-09-29,Desk lamp,45.00 2026-09-29,Desk lamp,45.00 2026-09-30,Pen set,24.99 2026-10-01,Blue notebook,12.00 2026-10-02,Desk lamp,N/A 2026-10-03,Pen set,24.99 2026-10-04,Blue notebook,12.00 

import csv import html import io import json import os import re import smtplib import ssl import sys import urllib.request from collections import defaultdict from datetime import datetime, timedelta, timezone from email.message import EmailMessage CSV_URL = os.environ.get("CSV_URL", "") CSV_PATH = os.environ.get("CSV_PATH") or "sales.csv" CURRENCY = os.environ.get("CURRENCY") or "$" TITLE = os.environ.get("REPORT_TITLE") or "Weekly sales report" # The report covers the 7 days up to yesterday, compared with the 7 days before that today = (datetime.fromisoformat(os.environ["REPORT_DATE"]) if os.environ.get("REPORT_DATE") else datetime.now(timezone.utc)).date() end = today - timedelta(days=1) start = end - timedelta(days=6) prev_start, prev_end = start - timedelta(days=7), start - timedelta(days=1) # Plain numbers like 1299.50 or 1,299.50. Anything else (like 12,50) is skipped, not guessed. AMOUNT = re.compile(r"^-?(\d{1,3}(,\d{3})+|\d+)(\.\d+)?$") def read_rows(): if CSV_URL: with urllib.request.urlopen(CSV_URL, timeout=30) as response: text = response.read().decode("utf-8-sig") else: with open(CSV_PATH, encoding="utf-8-sig") as file: text = file.read() return list(csv.DictReader(io.StringIO(text))) def parse(rows): """Turn rows into (date, product, amount). Rows we can't read are counted, not hidden.""" sales, skipped = [], 0 for row in rows: try: day = datetime.strptime(row["date"].strip(), "%Y-%m-%d").date() amount = row["amount"].strip().lstrip("$€£").strip() if not AMOUNT.match(amount): raise ValueError(amount) sales.append((day, row["product"].strip() or "Unknown", float(amount.replace(",", "")))) except (KeyError, ValueError, AttributeError): skipped += 1 return sales, skipped def money(value): return f"{CURRENCY}{value:,.2f}" def build_report(sales, skipped, row_count): this_week = [s for s in sales if start <= s[0] <= end] last_week = [s for s in sales if prev_start <= s[0] <= prev_end] total = sum(s[2] for s in this_week) before = sum(s[2] for s in last_week) if before: change = f"{(total - before) / before * 100:+.1f}% vs the week before" else: change = "no sales the week before to compare with" by_product, by_day = defaultdict(float), defaultdict(float) for day, product, amount in this_week: by_product[product] += amount by_day[day] += amount top = sorted(by_product.items(), key=lambda item: item[1], reverse=True)[:5] notes = [] if skipped: notes.append(f"{skipped} of {row_count} rows were skipped because the date or amount couldn't be read.") newest = max(s[0] for s in sales) if (end - newest).days > 2: notes.append(f"The newest row is dated {newest}, so the data may be out of date.") facts = [("Revenue", f"{money(total)} ({change})"), ("Sales", f"{len(this_week)}" + (f" (average {money(total / len(this_week))})" if this_week else ""))] if by_day: best = max(by_day, key=by_day.get) facts.append(("Best day", f"{best:%A} {best} ({money(by_day[best])})")) return {"period": f"{start} to {end}", "facts": facts, "top": top, "notes": notes} def as_text(report): lines = [TITLE, report["period"], ""] lines += [f"{label}: {value}" for label, value in report["facts"]] if report["top"]: lines += ["", "Top products"] lines += [f"{i}. {name}: {money(amount)}" for i, (name, amount) in enumerate(report["top"], 1)] if report["notes"]: lines += ["", "Notes"] + [f"- {note}" for note in report["notes"]] return "\n".join(lines) def as_html(report): esc = html.escape cell = "padding:6px 12px;border-bottom:1px solid #ddd;" facts = "".join(f"<tr><td style='{cell}'><b>{esc(label)}</b></td><td style='{cell}'>{esc(value)}</td></tr>" for label, value in report["facts"]) top = "".join(f"<tr><td style='{cell}'>{esc(name)}</td><td style='{cell}text-align:right'>{esc(money(amount))}</td></tr>" for name, amount in report["top"]) notes = "".join(f"<li>{esc(note)}</li>" for note in report["notes"]) return (f"<html><body style='font-family:Arial,sans-serif;color:#222'>" f"<h2>{esc(TITLE)}</h2><p>{esc(report['period'])}</p>" f"<table style='border-collapse:collapse'>{facts}</table>" + (f"<h3>Top products</h3><table style='border-collapse:collapse'>{top}</table>" if top else "") + (f"<h3>Notes</h3><ul>{notes}</ul>" if notes else "") + "</body></html>") def send_discord(text): body = json.dumps({"content": text[:1900]}).encode() request = urllib.request.Request(os.environ["DISCORD_WEBHOOK"], data=body, headers={ "Content-Type": "application/json", "User-Agent": "weekly-report/1.0"}) urllib.request.urlopen(request, timeout=15).close() def send_email(subject, text, html_body): host, port = os.environ["SMTP_HOST"], int(os.environ.get("SMTP_PORT") or "587") user, password = os.environ["SMTP_USER"], os.environ["SMTP_PASSWORD"] message = EmailMessage() message["Subject"] = subject message["From"] = os.environ.get("MAIL_FROM") or user message["To"] = os.environ["MAIL_TO"] message.set_content(text) # plain version, for email apps that don't show HTML  message.add_alternative(html_body, subtype="html") context = ssl.create_default_context() if port == 465: server = smtplib.SMTP_SSL(host, port, context=context, timeout=30) else: server = smtplib.SMTP(host, port, timeout=30) server.starttls(context=context) with server: server.login(user, password) server.send_message(message) rows = read_rows() sales, skipped = parse(rows) if not sales: sys.exit("No readable rows. Check that the file has the columns: date, product, amount") report = build_report(sales, skipped, len(rows)) text, page = as_text(report), as_html(report) with open("report.txt", "w") as file: file.write(text) with open("report.html", "w") as file: file.write(page) print(text) if os.environ.get("GITHUB_STEP_SUMMARY"): # shows the report on the run page  with open(os.environ["GITHUB_STEP_SUMMARY"], "a") as file: fence = "`" * 3 file.write(f"{fence}\n{text}\n{fence}\n") errors = [] for name, enabled, send in [ ("Discord", os.environ.get("DISCORD_WEBHOOK"), lambda: send_discord(text)), ("Email", os.environ.get("SMTP_HOST"), lambda: send_email(f"{TITLE}: {report['period']}", text, page)), ]: if enabled: try: send() except Exception as error: errors.Source：https://dev.to/procwire/automatically-email-a-weekly-report-from-a-csv-with-python-32m5
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