import os

os.environ.setdefault("OPENAI_BASE_URL", "http://test/v1")

from src.memory.index import _chunk_text


class TestChunkText:
    def test_empty(self) -> None:
        assert _chunk_text("", 512, 64) == []

    def test_single_char(self) -> None:
        assert _chunk_text("x", 512, 64) == [("x", 0)]

    def test_exactly_size(self) -> None:
        text = "a" * 512
        assert _chunk_text(text, 512, 64) == [(text, 0)]

    def test_size_plus_one(self) -> None:
        text = "a" * 513
        chunks = _chunk_text(text, 512, 64)
        assert len(chunks) == 2
        assert chunks[0] == (text[:512], 0)
        assert chunks[1][1] == 512 - 64
        assert chunks[1][0] == text[448 : 448 + 512]

    def test_unicode_emoji(self) -> None:
        text = "😀" * 100
        chunks = _chunk_text(text, 10, 2)
        assert len(chunks) >= 2
        offsets = [off for _, off in chunks]
        assert offsets == sorted(offsets)
        assert offsets[0] == 0
        for chunk, _ in chunks:
            assert chunk in text

    def test_size_less_than_overlap(self) -> None:
        text = "a" * 100
        chunks = _chunk_text(text, 10, 20)
        assert len(chunks) == 1
        assert chunks[0] == (text, 0)

    def test_size_equals_overlap(self) -> None:
        text = "a" * 100
        chunks = _chunk_text(text, 10, 10)
        assert len(chunks) == 1
        assert chunks[0] == (text, 0)