Post a summary of each invoice uploaded to S3 to Slack

import boto3
from clickruntime import on_trigger, credentials, http, state, notify, ai, report_fetched
REGION, BUCKET = "us-east-1", "northwind-files"

def aws(service):
    return boto3.client(service, region_name=REGION, aws_access_key_id=credentials.secret("AWS_ACCESS_KEY_ID"),
                        aws_secret_access_key=credentials.secret("AWS_SECRET_ACCESS_KEY"))

@on_trigger
def run(event):
    s3, since = aws("s3"), state.get("since") or ""
    objs = [o for o in s3.list_objects_v2(Bucket=BUCKET, Prefix="invoices/").get("Contents", []) if o["LastModified"].isoformat() > since]
    report_fetched(len(objs))
    if not objs:
        return {"summary": "Nothing new"}
    tx = aws("textract")
    for o in objs:
        doc = tx.analyze_expense(Document={"S3Object": {"Bucket": BUCKET, "Name": o["Key"]}})["ExpenseDocuments"][0]
        f = {x["Type"]["Text"]: x.get("ValueDetection", {}).get("Text", "") for x in doc["SummaryFields"]}
        items = ", ".join(i["ValueDetection"]["Text"] for g in doc.get("LineItemGroups", []) for li in g["LineItems"] for i in li["LineItemExpenseFields"] if i["Type"]["Text"] == "ITEM")
        text = f"🧾 {f.get('VENDOR_NAME', '?')}: {f.get('TOTAL', '?')}, due {f.get('DUE_DATE', 'not stated')} ({o['Key']})"
        try:
            text += "\n" + ai.generate(f"In under 15 words, what is this invoice for? {items[:1000]}", max_output_tokens=40).text
        except ai.AIError:
            pass
        notify.slack(text, channel="#finance")
    state.set("since", max(o["LastModified"].isoformat() for o in objs))
    return {"posted": len(objs)}