"""Tests for empty model fallback — when provider is configured but model is missing."""

from unittest.mock import patch








class TestGatewayEmptyModelFallback:
    """Test that _resolve_session_agent_runtime fills in empty model from provider catalog."""

    def test_empty_model_filled_from_provider(self):
        """When config has no model but provider is openai-codex, use first codex model."""
        from gateway.run import GatewayRunner

        runner = object.__new__(GatewayRunner)
        runner._session_model_overrides = {}

        # Mock _resolve_gateway_model to return empty string
        # Mock _resolve_runtime_agent_kwargs to return openai-codex provider
        with patch("gateway.run._resolve_gateway_model", return_value=""), \
             patch("gateway.run._resolve_runtime_agent_kwargs", return_value={
                 "provider": "openai-codex",
                 "api_key": "test-key",
                 "base_url": "https://chatgpt.com/backend-api/codex",
                 "api_mode": "codex_responses",
             }):
            model, kwargs = runner._resolve_session_agent_runtime()

        # Model should have been filled in from provider catalog
        assert model, "Model should not be empty when provider is known"
        assert isinstance(model, str)
        assert kwargs["provider"] == "openai-codex"

    def test_nonempty_model_not_overridden(self):
        """When config has a model set, don't override it."""
        from gateway.run import GatewayRunner

        runner = object.__new__(GatewayRunner)
        runner._session_model_overrides = {}

        with patch("gateway.run._resolve_gateway_model", return_value="gpt-5.4"), \
             patch("gateway.run._resolve_runtime_agent_kwargs", return_value={
                 "provider": "openai-codex",
                 "api_key": "test-key",
                 "base_url": "https://chatgpt.com/backend-api/codex",
                 "api_mode": "codex_responses",
             }):
            model, kwargs = runner._resolve_session_agent_runtime()

        assert model == "gpt-5.4", "Explicit model should not be overridden"

    def test_empty_model_no_provider_stays_empty(self):
        """When both model and provider are empty, model stays empty."""
        from gateway.run import GatewayRunner

        runner = object.__new__(GatewayRunner)
        runner._session_model_overrides = {}

        with patch("gateway.run._resolve_gateway_model", return_value=""), \
             patch("gateway.run._resolve_runtime_agent_kwargs", return_value={
                 "provider": "",
                 "api_key": "test-key",
                 "base_url": "https://example.com",
                 "api_mode": "chat_completions",
             }):
            model, kwargs = runner._resolve_session_agent_runtime()

        # Can't fill in a default without knowing the provider
        assert model == ""


class TestResolveGatewayModel:
    """Test _resolve_gateway_model reads model from config correctly."""

    def test_returns_default_key(self):
        from gateway.run import _resolve_gateway_model
        assert _resolve_gateway_model({"model": {"default": "gpt-5.4"}}) == "gpt-5.4"

    def test_returns_model_key_fallback(self):
        from gateway.run import _resolve_gateway_model
        assert _resolve_gateway_model({"model": {"model": "gpt-5.4"}}) == "gpt-5.4"

    def test_returns_empty_when_missing(self):
        from gateway.run import _resolve_gateway_model
        assert _resolve_gateway_model({"model": {}}) == ""

    def test_returns_empty_when_no_model_section(self):
        from gateway.run import _resolve_gateway_model
        assert _resolve_gateway_model({}) == ""

    def test_string_model_config(self):
        from gateway.run import _resolve_gateway_model
        assert _resolve_gateway_model({"model": "my-model"}) == "my-model"