Compare eBay listing traffic week on week

from datetime import date, timedelta
from clickruntime import on_trigger, credentials, http, state, notify

METRICS = ["LISTING_IMPRESSION_TOTAL", "LISTING_VIEWS_TOTAL", "TRANSACTION"]

@on_trigger
def run(event):
    end = date.today() - timedelta(days=1)
    start = end - timedelta(days=6)
    resp = http.get("https://api.ebay.com/sell/analytics/v1/traffic_report",
                    headers={"Authorization": f"Bearer {credentials.connection('ebay', 'seller')}"},
                    params={"dimension": "DAY", "metric": ",".join(METRICS),
                            "filter": f"marketplace_ids:{{EBAY_US}},date_range:[{start:%Y%m%d}..{end:%Y%m%d}]"})
    resp.raise_for_status()
    body = resp.json()
    order = [m["key"] for m in body["header"]["metrics"]]
    totals = dict.fromkeys(order, 0)
    for rec in body.get("records", []):
        for key, mv in zip(order, rec["metricValues"]):
            totals[key] += mv.get("value") or 0
    totals["CONVERSION"] = totals["TRANSACTION"] / totals["LISTING_VIEWS_TOTAL"] if totals["LISTING_VIEWS_TOTAL"] else 0
    prev = state.get("last_week") or {}
    def line(label, key, fmt="{:,.0f}"):
        diff = f" ({totals[key] - prev[key]:+,.0f})" if key in prev and key != "CONVERSION" else ""
        return f"{label}: {fmt.format(totals[key])}{diff}"
    body_text = "\n".join([line("Impressions", "LISTING_IMPRESSION_TOTAL"), line("Page views", "LISTING_VIEWS_TOTAL"),
                           line("Conversion rate", "CONVERSION", "{:.2%}")])
    notify.email_me(f"eBay traffic {start} to {end}", body_text)
    state.set("last_week", totals)
    return totals