import os
import time
from pathlib import Path

import pytest

from main import find_latest_file_in_folder, should_copy_file, compute_file_checksum, verify_copy



def _touch(path: Path, mtime: float) -> None:
    path.write_text('data', encoding='utf-8')
    os.utime(path, (mtime, mtime))



def test_find_latest_file_returns_none_for_missing_folder(tmp_path):
    missing = tmp_path / 'missing'
    assert find_latest_file_in_folder(str(missing)) is None



def test_find_latest_file_picks_newest(tmp_path):
    folder = tmp_path / 'src'
    folder.mkdir()

    now = time.time()
    older = folder / 'older.bak'
    newer = folder / 'newer.bak'
    other = folder / 'other.sql'

    _touch(older, now - 10)
    _touch(newer, now - 5)
    _touch(other, now - 1)

    latest = find_latest_file_in_folder(str(folder))
    assert latest is not None
    assert latest.name == 'other.sql'



def test_should_copy_file_when_target_missing(tmp_path):
    src = tmp_path / 'src.bak'
    src.write_text('x', encoding='utf-8')
    dst = tmp_path / 'dst.bak'

    assert should_copy_file(src, dst) is True



def test_should_copy_file_when_source_newer(tmp_path):
    now = time.time()
    src = tmp_path / 'src.bak'
    dst = tmp_path / 'dst.bak'

    _touch(dst, now - 10)
    _touch(src, now)

    assert should_copy_file(src, dst) is True



def test_should_copy_file_when_target_newer_or_equal(tmp_path):
    now = time.time()
    src = tmp_path / 'src.bak'
    dst = tmp_path / 'dst.bak'

    _touch(src, now)
    _touch(dst, now)

    assert should_copy_file(src, dst) is False


def test_compute_file_checksum_stable(tmp_path):
    src = tmp_path / 'a.bak'
    src.write_text('hello', encoding='utf-8')
    c1 = compute_file_checksum(src)
    c2 = compute_file_checksum(src)
    assert c1 == c2


def test_verify_copy_true_for_equal_files(tmp_path):
    src = tmp_path / 'src.bak'
    dst = tmp_path / 'dst.bak'
    src.write_text('data', encoding='utf-8')
    dst.write_text('data', encoding='utf-8')
    assert verify_copy(src, dst) is True


def test_verify_copy_false_for_different_files(tmp_path):
    src = tmp_path / 'src.bak'
    dst = tmp_path / 'dst.bak'
    src.write_text('data1', encoding='utf-8')
    dst.write_text('data2', encoding='utf-8')
    assert verify_copy(src, dst) is False