"""Regression: langfuse_client surface + span context manager behaviour.

Bugs captured:
1. AttributeError: module 'api.langfuse_client' has no attribute 'span'
   — the module was at the old observability.py shape with `langfuse_span`.
2. RuntimeError: generator didn't stop after throw()
   — the @contextmanager wrapped the user's `with` body in `try/except`
   and yielded a second value on exception, which @contextmanager rejects.
"""

import pytest

from api import langfuse_client as lf


def test_public_surface():
    assert callable(lf.span)
    assert callable(lf.flush)
    assert callable(lf.get_client)


def test_span_returns_nullspan_without_keys(monkeypatch):
    # Ensure no keys → no client → null span.
    from api.config import get_settings
    get_settings.cache_clear()
    monkeypatch.setenv("LANGFUSE_PUBLIC_KEY", "")
    monkeypatch.setenv("LANGFUSE_SECRET_KEY", "")
    # Reset cached client too
    lf._client = None
    with lf.span("t") as s:
        assert isinstance(s, lf._NullSpan)
        s.update(output={"x": 1})  # no-op should not raise
    get_settings.cache_clear()


def test_span_body_exception_propagates():
    """The body's exception MUST propagate — wrapping it inside @contextmanager
    causes 'generator didn't stop after throw()' if the except clause yields."""
    with pytest.raises(ValueError, match="kaboom"):
        with lf.span("t"):
            raise ValueError("kaboom")