from __future__ import annotations

import json
import os
from collections.abc import Iterable
from pathlib import Path
from typing import Any


def read_jsonl(path: str | os.PathLike) -> list[dict[str, Any]]:
    rows: list[dict[str, Any]] = []
    with open(path) as f:
        for line in f:
            line = line.strip()
            if line:
                rows.append(json.loads(line))
    return rows


def write_jsonl(path: str | os.PathLike, rows: Iterable[dict[str, Any]]) -> int:
    os.makedirs(os.path.dirname(os.path.abspath(path)), exist_ok=True)
    count = 0
    with open(path, "w") as f:
        for row in rows:
            f.write(json.dumps(row, ensure_ascii=False) + "\n")
            count += 1
    return count


def require_file(path: Path, hint: str) -> Path:
    """Raise an actionable error when the data file is missing (this directory ships no datasets)."""
    if not path.is_file():
        raise FileNotFoundError(
            f"data file not found: {path}\n"
            "The evaluation scripts do not download datasets. Obtain it and place it at this path, "
            f"or set DATA_FILE / --data-file.\n{hint}"
        )
    return path