"""Benchmark set.intersection_update for gh-142659.

Measures the performance of intersection_update across different set sizes
and usage patterns. Each benchmark recreates the set on every iteration
to measure the full intersection_update path including set_replace_body.
"""
import statistics
import sys
import timeit

ROUNDS = 50

BENCHMARKS = {
    "small (5 & 5)": {
        "setup": "",
        "stmt": "set(range(5)).intersection_update({3, 4, 5, 6, 7})",
        "number": 2_000_000,
    },
    "medium (100 & 100)": {
        "setup": "b = set(range(50, 150))",
        "stmt": "set(range(100)).intersection_update(b)",
        "number": 500_000,
    },
    "large (10k & 10k)": {
        "setup": "b = set(range(5000, 15000))",
        "stmt": "set(range(10000)).intersection_update(b)",
        "number": 2_000,
    },
    "multi-arg (100 & 100 & 50)": {
        "setup": "b = set(range(50, 150)); c = set(range(75, 125))",
        "stmt": "set(range(100)).intersection_update(b, c)",
        "number": 500_000,
    },
    "empty result (100 & 0 overlap)": {
        "setup": "b = set(range(200, 300))",
        "stmt": "set(range(100)).intersection_update(b)",
        "number": 500_000,
    },
}


def main():
    print(f"Python {sys.version}")
    print(f"Rounds: {ROUNDS}")
    print()
    print(f"{'Benchmark':<32} {'Mean (ns)':>10} {'Stdev':>10} {'Min':>10} {'Max':>10}")
    print("-" * 78)

    for name, bench in BENCHMARKS.items():
        times = timeit.repeat(
            bench["stmt"],
            setup=bench["setup"],
            number=bench["number"],
            repeat=ROUNDS,
        )
        per_iter = [t / bench["number"] * 1e9 for t in times]
        mean = statistics.mean(per_iter)
        stdev = statistics.stdev(per_iter)
        print(
            f"{name:<32} {mean:>10.1f} {stdev:>9.1f} {min(per_iter):>10.1f} {max(per_iter):>10.1f}"
        )


if __name__ == "__main__":
    main()