import pandas as pd

orders = pd.DataFrame(
    {
        "order_id": [1005, 1001, 1004, 1002, 1006, 1003],
        "customer": ["Nia", "Ada", "Omar", "Lin", "Kai", "Maya"],
        "region": ["APAC", "EMEA", "EMEA", "APAC", "AMER", "AMER"],
        "order_date": pd.to_datetime(
            [
                "2026-02-03",
                "2026-02-01",
                "2026-02-04",
                "2026-02-02",
                "2026-02-05",
                "2026-02-01",
            ]
        ),
        "ship_date": pd.to_datetime(
            [
                None,
                "2026-02-03",
                "2026-02-06",
                "2026-02-04",
                "2026-02-08",
                "2026-02-05",
            ]
        ),
        "total_usd": [360.0, 150.0, 95.0, 240.0, 420.0, 875.0],
    }
).set_index("order_id", drop=False)

print(f"pandas {pd.__version__}")
print()

print("BASE")
print(
    orders[
        ["customer", "region", "order_date", "ship_date", "total_usd"]
    ].to_string()
)
print()

by_total = orders.sort_values("total_usd", ascending=False)
print("SORT_TOTAL_DESC")
print(by_total.loc[:, ["customer", "region", "total_usd"]].to_string())
print()

by_region_date = orders.sort_values(
    ["region", "order_date"],
    ascending=[True, False],
)
print("SORT_REGION_DATE")
print(by_region_date.loc[:, ["customer", "region", "order_date", "total_usd"]].to_string())
print()

missing_ship_first = orders.sort_values("ship_date", na_position="first")
print("SORT_MISSING_SHIP_FIRST")
print(missing_ship_first.loc[:, ["customer", "ship_date", "total_usd"]].to_string())
print()

ranked = orders.sort_values("total_usd", ascending=False, ignore_index=True)
print("SORT_RESET_INDEX")
print(ranked.loc[:, ["order_id", "customer", "total_usd"]].to_string())
print()

by_index = orders.sort_index()
print("SORT_INDEX")
print(by_index.loc[:, ["customer", "region", "total_usd"]].to_string())
print()

print("VERIFY")
print(f"highest total order_id: {by_total.iloc[0]['order_id']}")
print(f"region/date order_ids: {by_region_date['order_id'].tolist()}")
print(f"missing ship_date first: {missing_ship_first.iloc[0]['ship_date']}")
print(f"reset index labels: {ranked.index.tolist()}")
print(f"source index order unchanged: {orders.index.tolist()}")