import pandas as pd

sales = pd.DataFrame(
    {
        "sold_at": [
            "2026-06-17 08:15",
            "2026-06-17 11:40",
            "2026-06-18 09:05",
            "2026-06-18 13:10",
            "2026-06-18 18:30",
            "2026-06-19 10:20",
        ],
        "region": ["east", "east", "east", "west", "west", "west"],
        "revenue": [120, 95, 180, 245, 400, 160],
    }
)

sales["sold_at"] = pd.to_datetime(sales["sold_at"])

daily = (
    sales.resample("D", on="sold_at", label="left", closed="left")
    .agg(revenue=("revenue", "sum"), orders=("revenue", "size"))
)
daily.index.name = "sales_day"

print("Daily revenue buckets")
print(daily.to_string())
print()
print("index name:", daily.index.name)
print("index frequency:", daily.index.freqstr)
print("2026-06-18 revenue:", int(daily.loc["2026-06-18", "revenue"]))
print("2026-06-18 orders:", int(daily.loc["2026-06-18", "orders"]))
print("source revenue:", int(sales["revenue"].sum()))
print("resampled revenue:", int(daily["revenue"].sum()))

assert daily.index.freqstr == "D"
assert int(daily.loc["2026-06-18", "revenue"]) == 825
assert int(daily.loc["2026-06-18", "orders"]) == 3
assert int(daily["revenue"].sum()) == int(sales["revenue"].sum())

print("verification: daily buckets match source revenue totals")