"""Unit tests for RuntimeConfig.apply_session_update / _apply_update.

Verifies the merge semantics: only explicitly-set fields (model_fields_set)
are written, nested BaseModels recurse without clobbering siblings, and
explicit None clears a previously-set value.
"""

from openai.types.realtime import RealtimeSessionCreateRequest
from openai.types.realtime.session_update_event import SessionUpdateEvent

from speech_to_speech.api.openai_realtime.runtime_config import RuntimeConfig


def _parse_session(**session_fields) -> RealtimeSessionCreateRequest:
    """Parse a session dict the same way the SDK does (tracks model_fields_set)."""
    session_fields.setdefault("type", "realtime")
    evt = SessionUpdateEvent.model_validate(
        {
            "type": "session.update",
            "session": session_fields,
        }
    )
    return evt.session  # type: ignore[return-value]


class TestApplySessionUpdate:
    def test_partial_update_preserves_untouched_fields(self):
        cfg = RuntimeConfig()
        cfg.apply_session_update(
            _parse_session(
                instructions="Be a pirate",
                audio={"output": {"voice": "coral"}},
                tool_choice="auto",
            )
        )
        assert cfg.session.instructions == "Be a pirate"
        assert cfg.session.audio.output.voice == "coral"
        assert cfg.session.tool_choice == "auto"

        cfg.apply_session_update(_parse_session(instructions="Be an astronaut"))
        assert cfg.session.instructions == "Be an astronaut"
        assert cfg.session.audio.output.voice == "coral"
        assert cfg.session.tool_choice == "auto"

    def test_explicit_none_clears_field(self):
        """Sending ``"turn_detection": null`` clears a previously-set value."""
        cfg = RuntimeConfig()
        cfg.apply_session_update(
            _parse_session(
                audio={"input": {"turn_detection": {"type": "server_vad"}}},
            )
        )
        assert cfg.session.audio.input.turn_detection is not None
        assert cfg.session.audio.input.turn_detection.type == "server_vad"

        cfg.apply_session_update(
            _parse_session(
                audio={"input": {"turn_detection": None}},
            )
        )
        assert cfg.session.audio.input.turn_detection is None

    def test_nested_sibling_preserved(self):
        """Updating audio.output.voice must not touch audio.input.turn_detection."""
        cfg = RuntimeConfig()
        cfg.apply_session_update(
            _parse_session(
                audio={
                    "input": {"turn_detection": {"type": "server_vad", "threshold": 0.6}},
                    "output": {"voice": "echo"},
                },
            )
        )
        assert cfg.session.audio.output.voice == "echo"
        assert cfg.session.audio.input.turn_detection.threshold == 0.6

        cfg.apply_session_update(
            _parse_session(
                audio={"output": {"voice": "shimmer"}},
            )
        )
        assert cfg.session.audio.output.voice == "shimmer"
        assert cfg.session.audio.input.turn_detection.type == "server_vad"
        assert cfg.session.audio.input.turn_detection.threshold == 0.6

    def test_sequential_updates_accumulate(self):
        cfg = RuntimeConfig()
        cfg.apply_session_update(_parse_session(instructions="Step 1"))
        cfg.apply_session_update(_parse_session(audio={"output": {"voice": "alloy"}}))
        cfg.apply_session_update(_parse_session(tool_choice="required"))

        assert cfg.session.instructions == "Step 1"
        assert cfg.session.audio.output.voice == "alloy"
        assert cfg.session.tool_choice == "required"

    def test_deep_nested_leaf_update(self):
        """Changing only turn_detection.threshold preserves the rest."""
        cfg = RuntimeConfig()
        cfg.apply_session_update(
            _parse_session(
                audio={
                    "input": {
                        "turn_detection": {
                            "type": "server_vad",
                            "threshold": 0.5,
                            "silence_duration_ms": 800,
                        },
                    },
                },
            )
        )
        assert cfg.session.audio.input.turn_detection.threshold == 0.5
        assert cfg.session.audio.input.turn_detection.silence_duration_ms == 800

        cfg.apply_session_update(
            _parse_session(
                audio={"input": {"turn_detection": {"type": "server_vad", "threshold": 0.8}}},
            )
        )
        assert cfg.session.audio.input.turn_detection.threshold == 0.8
        assert cfg.session.audio.input.turn_detection.silence_duration_ms == 800

    def test_tools_replaced_wholesale(self):
        """Tools is a list, not a BaseModel — the whole list is replaced."""
        cfg = RuntimeConfig()
        cfg.apply_session_update(
            _parse_session(
                tools=[{"type": "function", "name": "get_weather"}],
            )
        )
        assert len(cfg.session.tools) == 1

        cfg.apply_session_update(
            _parse_session(
                tools=[
                    {"type": "function", "name": "get_weather"},
                    {"type": "function", "name": "get_time"},
                ],
            )
        )
        assert len(cfg.session.tools) == 2

    def test_update_after_fresh_init(self):
        """apply_session_update works on a freshly-constructed RuntimeConfig."""
        cfg = RuntimeConfig()
        cfg.apply_session_update(
            _parse_session(
                instructions="Hello",
                audio={"output": {"voice": "sage"}},
            )
        )
        assert cfg.session.instructions == "Hello"
        assert cfg.session.audio.output.voice == "sage"

    def test_validator_ensures_audio_structure_on_init(self):
        """Default construction guarantees audio.input and audio.output are not None."""
        cfg = RuntimeConfig()
        assert cfg.session.audio is not None
        assert cfg.session.audio.input is not None
        assert cfg.session.audio.output is not None