"""Summarize retained raw samples; nearest-rank p95, no gate claims."""
import json
import math
import sys


def percentile(values, probability):
    if not values or not 0 < probability <= 1:
        raise ValueError("nonempty samples and probability in (0, 1] required")
    if any(not math.isfinite(value) or value < 0 for value in values):
        raise ValueError("samples must be finite nonnegative milliseconds")
    ordered = sorted(values)
    return ordered[math.ceil(len(ordered) * probability) - 1]


def summarize(report):
    if report.get("kind") != "synthetic_lexical_index_only":
        raise ValueError("unsupported report")
    rows = []
    for case in report["cases"]:
        if len(case["basic"]) != len(case["debug"]) or not case["basic"]:
            raise ValueError("paired basic/debug samples required")
        row = {"case": case["case"], "samples_per_mode": len(case["basic"])}
        for mode in ("basic", "debug"):
            values = [sample["wall_ms"] for sample in case[mode]]
            row[mode] = {
                "p50_ms": percentile(values, 0.5),
                "p95_ms": percentile(values, 0.95),
                "maximum_ms": max(values),
                "engine_p95_ms": percentile(
                    [sample["metrics"]["total_ms"] for sample in case[mode]], 0.95
                ),
            }
        # Pair order follows the same deterministic request IDs in both arrays.
        row["mean_paired_debug_minus_basic_ms"] = sum(
            debug["wall_ms"] - basic["wall_ms"]
            for basic, debug in zip(case["basic"], case["debug"])
        ) / len(case["basic"])
        rows.append(row)
    return {"kind": report["kind"], "production_gate_pass": None, "cases": rows}


if __name__ == "__main__":
    with open(sys.argv[1], encoding="utf-8") as source:
        print(json.dumps(summarize(json.load(source)), indent=2))