Turn emailed supplier invoices into Xero draft bills

import base64
from google.oauth2.credentials import Credentials
from googleapiclient.discovery import build
from clickruntime import on_trigger, credentials, http, ai, report_fetched
XERO = "https://api.xero.com/api.xro/2.0"
TENANT = "your-xero-tenant-id"

def xero(method, path, **kw):
    r = http.request(method, XERO + path, **kw, headers={"Accept": "application/json", "Xero-tenant-id": TENANT, "Authorization": "Bearer " + credentials.connection("xero", "company")})
    return r.raise_for_status() or r.json()

PROCESSED = "Label_Processed"  # id of your Gmail label
SCHEMA = {"type": "object", "properties": {k: {"type": "number" if k == "total" else "string"} for k in ("supplier", "reference", "date", "due", "total")}}

@on_trigger
def run(event):
    gmail = build("gmail", "v1", credentials=Credentials(credentials.connection("google", "work")), cache_discovery=False)
    msgs = gmail.users().messages().list(userId="me", q="has:attachment filename:pdf label:Invoices -label:Processed").execute().get("messages", [])
    report_fetched(len(msgs))
    if not msgs:
        return {"summary": "Nothing new"}
    for m in msgs:
        full = gmail.users().messages().get(userId="me", id=m["id"]).execute()
        part = next(p for p in full["payload"]["parts"] if p.get("filename", "").lower().endswith(".pdf"))
        pdf = base64.urlsafe_b64decode(gmail.users().messages().attachments().get(userId="me", messageId=m["id"], id=part["body"]["attachmentId"]).execute()["data"])
        f = ai.generate(f"Extract supplier, reference, date and due (YYYY-MM-DD), total:\n{full['snippet']}", json_schema=SCHEMA, max_output_tokens=120).json
        bill = xero("PUT", "/Invoices", json={"Invoices": [{"Type": "ACCPAY", "Status": "DRAFT", "Contact": {"Name": f["supplier"]},
                    "InvoiceNumber": f["reference"], "Date": f["date"], "DueDate": f["due"], "LineAmountTypes": "Inclusive",
                    "LineItems": [{"Description": f"Invoice {f['reference']}", "Quantity": 1, "UnitAmount": f["total"], "AccountCode": "400"}]}]})["Invoices"][0]
        xero("PUT", f"/Invoices/{bill['InvoiceID']}/Attachments/{part['filename']}", data=pdf, params={"IncludeOnline": "false"})
        gmail.users().messages().modify(userId="me", id=m["id"], body={"addLabelIds": [PROCESSED]}).execute()
    return {"bills": len(msgs)}