from __future__ import annotations

from app.change_detection.text_diff import bounded_text_diff


def test_identical_text_has_zero_diff_ratio():
    text = "Acme Corp builds electric trucks.\nWe are hiring engineers."
    result = bounded_text_diff(text, text)
    assert result.diff_ratio == 0.0
    assert result.is_identical is True


def test_changed_text_has_nonzero_diff_ratio_and_captures_lines():
    previous = "Acme Corp builds gasoline trucks.\nContact us for a quote."
    current = "Acme Corp builds electric trucks.\nContact us for a quote."
    result = bounded_text_diff(previous, current)
    assert result.diff_ratio > 0.0
    assert any("electric" in line for line in result.added_lines)
    assert any("gasoline" in line for line in result.removed_lines)


def test_noise_only_changes_do_not_register_as_a_diff():
    previous = "About us.\nUpdated: 2026-01-01 10:00\nWe build trucks."
    current = "About us.\nUpdated: 2026-06-15 14:30\nWe build trucks."
    result = bounded_text_diff(previous, current)
    assert result.diff_ratio == 0.0


def test_diff_is_bounded_in_size():
    previous = "\n".join(f"line {i} original" for i in range(200))
    current = "\n".join(f"line {i} changed" for i in range(200))
    result = bounded_text_diff(previous, current)
    assert len(result.added_lines) <= 40
    assert len(result.removed_lines) <= 40