from app.bm25 import BM25Index
from app.chunking import chunk_text
from app.query import extract_pages, match_docs


def test_chunks_respect_size_and_overlap():
    text = " ".join(f"This is sentence number {i} about topic {i % 5}." for i in range(80))
    chunks = chunk_text(text, size=300, overlap=80)
    assert len(chunks) > 5
    assert all(len(c) <= 300 + 80 for c in chunks)
    # overlap: the end of one chunk reappears at the start of the next
    assert chunks[0].split(". ")[-1] in chunks[1]


def test_chunk_handles_giant_unbroken_text():
    chunks = chunk_text("word " * 2000, size=500, overlap=50)
    assert chunks and all(len(c) <= 560 for c in chunks)


def test_extract_pages_variants():
    assert extract_pages("what is written on page 20?") == [20]
    assert extract_pages("page no. 7 pe kya hai") == [7]
    assert extract_pages("20 no ke page pe kya likha hai") == [20]
    assert extract_pages("20th page summary") == [20]
    assert extract_pages("explain pages 20-23") == [20, 21, 22, 23]
    assert extract_pages("page 5 to 7") == [5, 6, 7]
    assert extract_pages("20 se 22 pages") == [20, 21, 22]
    assert extract_pages("page 3, 9 and 12") == [3, 9, 12]
    assert extract_pages("what is the refund policy?") == []
    assert extract_pages("who was born in 1990?") == []


def test_match_docs_by_filename():
    docs = [
        {"doc_id": "a", "filename": "HR_Policy.pdf"},
        {"doc_id": "b", "filename": "annual-report-2024.pdf"},
    ]
    assert match_docs("what does the hr policy say about leave", docs) == ["a"]
    assert match_docs("summary of annual report 2024", docs) == ["b"]
    assert match_docs("what about leave", docs) == []


def test_bm25_scopes_by_doc_and_page():
    idx = BM25Index()
    idx.build(
        [
            {"id": "1", "doc_id": "A", "page": 1, "text": "zebra migration across the plains"},
            {"id": "2", "doc_id": "B", "page": 2, "text": "zebra stripes and lions"},
            {"id": "3", "doc_id": "B", "page": 3, "text": "completely unrelated tax filing"},
        ]
    )
    idx._dirty = False
    assert {h["id"] for h in idx.search("zebra", limit=5)} == {"1", "2"}
    assert [h["id"] for h in idx.search("zebra", doc_ids=["B"])] == ["2"]
    assert idx.search("zebra", pages=[1])[0]["id"] == "1"