"""Utilities to simplify reading and writing data from and to files."""

from __future__ import annotations

import json
from collections.abc import Mapping
from pathlib import Path
from typing import TypeVar, cast

T = TypeVar("T", bound=Mapping)


def save_and_return_json(data: T, dst: str | Path | None) -> T:
    """Save and return a JSON-serializable data structure."""
    if dst is None:
        return data

    if isinstance(dst, str):
        dst = Path(dst)

    dst.write_text(json.dumps(data, indent=4))

    return data


def read_data_json(val: str | Path | T) -> T:
    """Read JSON data from a file if a path is passed, or return the argument itself."""
    if isinstance(val, str):
        val = Path(val)

    if isinstance(val, Path):
        val = cast("T", json.loads(val.read_text()))

    return val