"""Regression: truncate_messages must not set message_count above the real
number of messages when keep_count exceeds the message total.

The AI tool layer (src/ai_interaction.py manage_session action='truncate')
defaults keep_count=10, so a short session (say 3 messages) gets truncated
with keep_count=10. The DB has only 3 rows left, but truncate_messages used to
write db_session.message_count = keep_count (=10), leaving the persisted count
inconsistent with the actual rows. get_session relies on message_count>0 to
decide whether to lazily hydrate from the DB, so an inflated count is a latent
correctness hazard.
"""
import os
import tempfile


def _make_manager():
    db_fd, db_path = tempfile.mkstemp(suffix=".db")
    os.close(db_fd)
    os.environ["DATABASE_URL"] = f"sqlite:///{db_path}"

    # Import after DATABASE_URL is set so the engine binds to the temp DB.
    import importlib
    import core.database as database
    importlib.reload(database)
    database.Base.metadata.create_all(bind=database.engine)

    import core.session_manager as sm_mod
    importlib.reload(sm_mod)
    return sm_mod.SessionManager(), database, sm_mod


def test_truncate_keep_count_exceeds_total_does_not_inflate_count():
    from core.models import ChatMessage

    sm, database, sm_mod = _make_manager()
    sid = "short-session"
    sm.create_session(session_id=sid, name="t", endpoint_url="x",
                      model="m", rag=False, owner="u")
    for i in range(3):
        sm.add_message(sid, ChatMessage("user", f"msg{i}"))

    # AI default keep_count is 10 — larger than the 3 real messages.
    assert sm.truncate_messages(sid, 10) is True

    db = database.SessionLocal()
    try:
        DbSession = database.Session
        DbChatMessage = database.ChatMessage
        rows = db.query(DbChatMessage).filter(
            DbChatMessage.session_id == sid).count()
        db_session = db.query(DbSession).filter(DbSession.id == sid).first()
        # Nothing should have been deleted (only 3 messages exist).
        assert rows == 3
        # message_count must reflect the real number of rows, not keep_count.
        assert db_session.message_count == 3, (
            f"message_count={db_session.message_count} but only {rows} rows exist"
        )
    finally:
        db.close()


def test_truncate_keeps_history_alias_for_context_messages():
    from core.models import ChatMessage

    sm, database, sm_mod = _make_manager()
    sid = "alias-after-truncate"
    sm.create_session(session_id=sid, name="t", endpoint_url="x",
                      model="m", rag=False, owner="u")
    for i in range(3):
        sm.add_message(sid, ChatMessage("user", f"msg{i}"))

    assert sm.truncate_messages(sid, 2) is True

    session = sm.sessions[sid]
    assert session.history is session._history

    session.history.append(ChatMessage("user", "after direct mutation"))
    assert session.get_context_messages()[-1]["content"] == "after direct mutation"