"""Unit tests for the librarian DOI search - specifically that it always
terminates.

The producer/consumer search used to hang whenever the number of chunk files it
was told to read (MAXTHREADS) did not exactly match the files on disk: too few
and it silently skipped trailing chunks, too many and a producer pointed at a
missing file crashed before emitting its sentinel, starving the consumers'
termination count forever. These tests pin down the fix: chunk files are
auto-discovered, the sentinel threshold equals the number of producers actually
started, and every producer emits its sentinel even on error.
"""
import logging
import threading

import search_bot

_LOG = logging.getLogger("test-search-bot")
_LOG.addHandler(logging.NullHandler())


def _write_chunks(directory, count, target=None, target_index=None):
    """Create <n>_chunk.txt files; optionally drop `target` into one of them."""
    for n in range(count):
        lines = [f"10.0000/decoy-{n}-a\n", f"10.0000/decoy-{n}-b\n"]
        if target is not None and n == target_index:
            lines.append(target + "\n")
        (directory / f"{n}_chunk.txt").write_text("".join(lines), encoding="utf-8")


def _run_bounded(dois, timeout=20):
    """Run search_for_doi in a thread; return (finished_in_time, result)."""
    box = {}
    live = []
    worker = threading.Thread(
        target=lambda: box.update(result=search_bot.search_for_doi(dois, live, _LOG)),
        daemon=True,
    )
    worker.start()
    worker.join(timeout)
    return (not worker.is_alive()), box.get("result")


def test_finds_doi_in_trailing_chunk(tmp_path, monkeypatch):
    # Target lives in the LAST chunk - the one the old MAXTHREADS=N-too-low would
    # never have read. Auto-discovery must read every chunk present.
    monkeypatch.setattr(search_bot, "DATABASE_PATH", str(tmp_path) + "/")
    target = "10.1234/target.in.trailing.chunk"
    _write_chunks(tmp_path, count=6, target=target, target_index=5)

    finished, result = _run_bounded([(target, "DATA"), ("10.9999/absent", "DATA")])

    assert finished, "search hung instead of terminating"
    hit = [r for r in result if r["DOI"] == target and r["exists"]]
    assert hit, "DOI in the trailing chunk was not found"


def test_terminates_when_a_chunk_is_unreadable(tmp_path, monkeypatch):
    # A chunk that exists at discovery time but cannot be opened (here: it is a
    # directory) makes its producer raise. The finally-sentinel must still fire
    # so the consumers' count completes and the search does not deadlock.
    monkeypatch.setattr(search_bot, "DATABASE_PATH", str(tmp_path) + "/")
    _write_chunks(tmp_path, count=3)
    (tmp_path / "9_chunk.txt").mkdir()  # discovered as a chunk, un-openable

    finished, _ = _run_bounded([("10.0000/decoy-0-a", "DATA")])

    assert finished, "an unreadable chunk deadlocked the search"


def test_no_chunks_returns_immediately(tmp_path, monkeypatch):
    # Empty database dir: return an (all-not-found) result at once, never hang.
    monkeypatch.setattr(search_bot, "DATABASE_PATH", str(tmp_path) + "/")

    finished, result = _run_bounded([("10.0/x", "DATA")], timeout=10)

    assert finished
    assert result == [{"DOI": "10.0/x", "exists": False, "data": "DATA"}]


def test_survives_invalid_utf8_byte_and_still_finds_later_doi(tmp_path, monkeypatch):
    # A chunk with a stray non-UTF-8 byte (0x96, the one from the field report)
    # must not crash the producer or abort the file mid-read: DOIs AFTER the bad
    # byte still have to be found.
    monkeypatch.setattr(search_bot, "DATABASE_PATH", str(tmp_path) + "/")
    target = "10.1234/after.the.bad.byte"
    (tmp_path / "0_chunk.txt").write_bytes(
        b"10.0000/before\n" + b"\x96 broken \x96 line \x96\n" + target.encode() + b"\n"
    )

    finished, result = _run_bounded([(target, "DATA")])

    assert finished, "an invalid UTF-8 byte hung or crashed the search"
    hit = [r for r in result if r["DOI"] == target and r["exists"]]
    assert hit, "DOI after the bad byte was not found - the file was aborted mid-read"


def test_doi_match_is_exact_not_substring(tmp_path, monkeypatch):
    # A DB line "10.1/12" must NOT satisfy a search for "10.1/1" (the old
    # `doi in line` substring test did). The exact DOI must still be found.
    monkeypatch.setattr(search_bot, "DATABASE_PATH", str(tmp_path) + "/")
    (tmp_path / "0_chunk.txt").write_text(
        "10.1/12\n10.1/1\n10.2/999\n", encoding="utf-8"
    )

    finished, result = _run_bounded([("10.1/1", "DATA"), ("10.9/absent", "DATA")])

    assert finished
    by_doi = {r["DOI"]: r["exists"] for r in result}
    assert by_doi["10.1/1"] is True  # exact line present -> found
    assert by_doi["10.9/absent"] is False


def test_doi_match_handles_line_with_trailing_metadata(tmp_path, monkeypatch):
    # Lines of the form "<DOI>\t<metadata>" still match on the first token.
    monkeypatch.setattr(search_bot, "DATABASE_PATH", str(tmp_path) + "/")
    (tmp_path / "0_chunk.txt").write_text("10.5/abc\tsome title here\n", encoding="utf-8")

    finished, result = _run_bounded([("10.5/abc", "DATA")])

    assert finished
    assert result[0]["exists"] is True


def test_discover_chunk_files_sorted_numerically(tmp_path, monkeypatch):
    monkeypatch.setattr(search_bot, "DATABASE_PATH", str(tmp_path) + "/")
    for n in (0, 2, 10, 1):
        (tmp_path / f"{n}_chunk.txt").write_text("x\n", encoding="utf-8")
    (tmp_path / "notes.txt").write_text("ignore me\n", encoding="utf-8")

    found = search_bot.discover_chunk_files(_LOG)

    # Numeric order (10 after 2, not lexicographic), and non-chunk files ignored.
    assert found == ["0_chunk.txt", "1_chunk.txt", "2_chunk.txt", "10_chunk.txt"]