import logging
from typing import Optional
from unittest.mock import patch

import pytest
from pydantic import BaseModel, ValidationError

from litellm.proxy.common_utils.cache_pydantic_utils import CacheCodec


class _SampleModel(BaseModel):
    name: str
    count: Optional[int] = None


class _SampleSubModel(_SampleModel):
    pass


class TestCacheCodecSerialize:
    def test_without_model_type_base_model_dumped_json_safe(self):
        m = _SampleModel(name="a", count=1)
        out = CacheCodec.serialize(m)
        assert out == {"name": "a", "count": 1}

    def test_without_model_type_dict_unchanged(self):
        d = {"name": "x"}
        assert CacheCodec.serialize(d) is d

    def test_without_model_type_primitive_unchanged(self):
        assert CacheCodec.serialize(42) == 42

    def test_with_model_type_dict_validated_and_dumped(self):
        out = CacheCodec.serialize({"name": "b", "count": 2}, model_type=_SampleModel)
        assert out == {"name": "b", "count": 2}

    def test_with_model_type_base_model_validated_and_dumped(self):
        m = _SampleModel(name="c", count=None)
        out = CacheCodec.serialize(m, model_type=_SampleModel)
        assert out == {"name": "c"}

    def test_with_model_type_exclude_none_on_dump(self):
        out = CacheCodec.serialize({"name": "d"}, model_type=_SampleModel)
        assert out == {"name": "d"}
        assert "count" not in out

    def test_with_model_type_non_dict_non_model_passthrough(self):
        assert CacheCodec.serialize("raw", model_type=_SampleModel) == "raw"

    def test_with_model_type_invalid_dict_raises(self):
        with pytest.raises(ValidationError):
            CacheCodec.serialize({"count": 1}, model_type=_SampleModel)

    def test_with_model_type_already_correct_instance_skips_revalidation(self):
        """Fast-path: value is already model_type — model_validate must NOT be called."""
        m = _SampleModel(name="fast", count=7)
        with patch.object(_SampleModel, "model_validate", wraps=_SampleModel.model_validate) as mock_validate:
            out = CacheCodec.serialize(m, model_type=_SampleModel)
        assert out == {"name": "fast", "count": 7}
        mock_validate.assert_not_called()

    def test_with_model_type_subclass_instance_skips_revalidation(self):
        """Subclass is isinstance of base → should also take the fast path."""
        sub = _SampleSubModel(name="sub", count=2)
        with patch.object(_SampleModel, "model_validate", wraps=_SampleModel.model_validate) as mock_validate:
            out = CacheCodec.serialize(sub, model_type=_SampleModel)
        assert out == {"name": "sub", "count": 2}
        mock_validate.assert_not_called()

    def test_with_model_type_dict_input_goes_through_model_validate(self):
        """A dict value (not yet an instance) must still go through model_validate."""
        raw = {"name": "via-dict", "count": 5}
        with patch.object(
            _SampleModel, "model_validate", wraps=_SampleModel.model_validate
        ) as mock_validate:
            out = CacheCodec.serialize(raw, model_type=_SampleModel)
        assert out == {"name": "via-dict", "count": 5}
        mock_validate.assert_called_once()

    def test_with_model_type_incompatible_model_raises_validation_error(self):
        """Passing a BaseModel whose fields don't satisfy model_type's required fields raises.

        _IncompatibleModel only has `foo: int`, so when Pydantic v2 extracts its
        data and validates it against _SampleModel (which requires `name: str`),
        a ValidationError is raised.
        """

        class _IncompatibleModel(BaseModel):
            foo: int  # missing required 'name' field of _SampleModel

        with pytest.raises(ValidationError):
            CacheCodec.serialize(_IncompatibleModel(foo=1), model_type=_SampleModel)


class TestCacheCodecDeserialize:
    def test_none_returns_none(self):
        assert CacheCodec.deserialize(None, _SampleModel) is None

    def test_dict_validates_to_model(self):
        m = CacheCodec.deserialize({"name": "e", "count": 3}, _SampleModel)
        assert isinstance(m, _SampleModel)
        assert m.name == "e"
        assert m.count == 3

    def test_instance_same_type_returned_as_is(self):
        original = _SampleModel(name="f")
        m = CacheCodec.deserialize(original, _SampleModel)
        assert m is original

    def test_subclass_instance_accepted(self):
        sub = _SampleSubModel(name="g")
        m = CacheCodec.deserialize(sub, _SampleModel)
        assert m is sub

    def test_wrong_type_returns_none(self):
        assert CacheCodec.deserialize("not-a-dict", _SampleModel) is None

    def test_invalid_dict_returns_none_and_logs_warning(self, caplog):
        with caplog.at_level(logging.WARNING, logger="LiteLLM Proxy"):
            out = CacheCodec.deserialize({"count": 1}, _SampleModel)
        assert out is None
        assert any(
            "CacheCodec.deserialize" in r.message and "_SampleModel" in r.message
            for r in caplog.records
            if r.levelno >= logging.WARNING
        ), f"Expected deserialize validation warning. Records: {[r.message for r in caplog.records]}"