from __future__ import annotations

import pytest

from app.rag.chunk import chunk_text


def test_chunk_windows_and_overlap():
    chunks = chunk_text("a" * 2500, size=1000, overlap=200)
    assert all(len(c) <= 1000 for c in chunks)
    assert len(chunks) == 4  # step=800 over 2500 chars
    # consecutive chunks overlap by `overlap` chars
    assert chunks[0][-200:] == chunks[1][:200]


def test_chunk_empty_returns_nothing():
    assert chunk_text("   \n\t ") == []
    assert chunk_text("") == []


def test_chunk_short_text_single_chunk():
    assert chunk_text("hola mundo", size=1000, overlap=200) == ["hola mundo"]


def test_chunk_invalid_overlap():
    with pytest.raises(ValueError):
        chunk_text("abc", size=100, overlap=100)