"""Tests for app.services.bm25_index."""

from __future__ import annotations

import pytest

from app.services.bm25_index import BM25Index, BM25Result


def _seeded_index() -> BM25Index:
    idx = BM25Index()
    idx._load_chunks(
        [
            {
                "id": "c1",
                "doc_id": "book-a",
                "page_number": 1,
                "text": "Fireball deals 8d6 fire damage on a failed Dexterity saving throw.",
            },
            {
                "id": "c2",
                "doc_id": "book-a",
                "page_number": 2,
                "text": "A wizard can cast one spell per turn unless they have Action Surge.",
            },
            {
                "id": "c3",
                "doc_id": "book-b",
                "page_number": 5,
                "text": "Grapple rules apply when the attacker uses the Attack action to grab a target.",
            },
        ]
    )
    return idx


def test_query_returns_relevant_result():
    idx = _seeded_index()
    results = idx.query("fireball fire damage")
    assert len(results) >= 1
    assert results[0].chunk_id == "c1"
    assert results[0].score > 0


def test_query_respects_top_k():
    # "action" matches all three chunks; top_k=2 must hard-cap the result list
    idx = _seeded_index()
    results = idx.query("action", top_k=2)
    assert len(results) == 2


def test_query_filters_by_doc_id():
    idx = _seeded_index()
    results = idx.query("rules", doc_ids=["book-b"])
    assert all(r.doc_id == "book-b" for r in results)


def test_query_empty_corpus_returns_empty():
    idx = BM25Index()
    idx._load_chunks([])
    results = idx.query("anything")
    assert results == []


def test_mark_dirty_triggers_rebuild(tmp_path):
    import sqlite3

    db_path = str(tmp_path / "test.db")
    conn = sqlite3.connect(db_path)
    conn.execute(
        "CREATE TABLE page_chunks(id TEXT, doc_id TEXT, page_number INT, text TEXT)"
    )
    conn.execute(
        "INSERT INTO page_chunks VALUES ('x1','doc-1',1,'Ranger favored enemy favored terrain terrain bonuses bonuses action attack')"
    )
    conn.execute(
        "INSERT INTO page_chunks VALUES ('x2','doc-1',2,'Wizard can cast spells and perform actions')"
    )
    conn.execute(
        "INSERT INTO page_chunks VALUES ('x3','doc-1',3,'Fighter attacks and deals damage with weapon')"
    )
    conn.commit()
    conn.close()

    idx = BM25Index()
    idx.mark_dirty()
    idx.ensure_fresh(db_path)
    results = idx.query("ranger terrain")
    assert len(results) >= 1
    assert results[0].chunk_id == "x1"


def test_bm25_result_is_frozen():
    r = BM25Result(chunk_id="x", doc_id="d", page_number=1, text="hello", score=0.5)
    with pytest.raises(Exception):
        r.score = 1.0  # type: ignore[misc]