#!/usr/bin/env python3
"""Shared, dependency-free helpers for v25 evaluation tools."""

from __future__ import annotations

import json
import math
from pathlib import Path
from typing import Any, Iterable


NOT_MEASURED = "not measured"


def read_json(path: Path) -> Any:
    with path.open(encoding="utf-8") as handle:
        return json.load(handle)


def read_jsonl(path: Path) -> list[dict[str, Any]]:
    rows = []
    with path.open(encoding="utf-8") as handle:
        for line_number, line in enumerate(handle, 1):
            if not line.strip():
                continue
            value = json.loads(line)
            if not isinstance(value, dict):
                raise ValueError(f"{path}:{line_number}: expected a JSON object")
            rows.append(value)
    return rows


def write_json(path: Path, value: Any) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    temporary = path.with_suffix(path.suffix + ".tmp")
    temporary.write_text(json.dumps(value, indent=2, sort_keys=True) + "\n", encoding="utf-8")
    temporary.replace(path)


def finite_number(value: Any) -> float | None:
    if isinstance(value, bool) or not isinstance(value, (int, float)):
        return None
    number = float(value)
    return number if math.isfinite(number) else None


def mean(values: Iterable[float]) -> float | None:
    items = list(values)
    return sum(items) / len(items) if items else None


def percentile(values: Iterable[float], fraction: float) -> float | None:
    items = sorted(values)
    if not items:
        return None
    index = (len(items) - 1) * fraction
    low = int(index)
    high = min(low + 1, len(items) - 1)
    return items[low] + (items[high] - items[low]) * (index - low)