"""Tests for atomic file writes."""

from pathlib import Path

import pytest

from src.fileutil import atomic_write_text


def test_writes_content(tmp_path: Path) -> None:
    target = tmp_path / "out.json"
    atomic_write_text(target, '{"a": 1}')
    assert target.read_text(encoding="utf-8") == '{"a": 1}'


def test_creates_parent_dirs(tmp_path: Path) -> None:
    target = tmp_path / "nested" / "deep" / "out.txt"
    atomic_write_text(target, "hi")
    assert target.read_text(encoding="utf-8") == "hi"


def test_overwrites_existing(tmp_path: Path) -> None:
    target = tmp_path / "out.txt"
    target.write_text("old", encoding="utf-8")
    atomic_write_text(target, "new")
    assert target.read_text(encoding="utf-8") == "new"


def test_leaves_no_temp_files_on_success(tmp_path: Path) -> None:
    target = tmp_path / "out.txt"
    atomic_write_text(target, "data")
    assert [p.name for p in tmp_path.iterdir()] == ["out.txt"]


def test_original_intact_when_write_fails(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
    target = tmp_path / "out.txt"
    target.write_text("original", encoding="utf-8")

    def boom(*args: object, **kwargs: object) -> None:
        raise OSError("disk full")

    monkeypatch.setattr("os.replace", boom)
    with pytest.raises(OSError):
        atomic_write_text(target, "new")

    # Original file is untouched and no temp file is left behind.
    assert target.read_text(encoding="utf-8") == "original"
    assert sorted(p.name for p in tmp_path.iterdir()) == ["out.txt"]