"""
Tests for attn_implementation normalization, registry registration, and
backwards compatibility with legacy boolean attention flags.
"""

import pytest

from axolotl.utils.schemas.config import AxolotlInputConfig


class TestAttnImplementationNormalizer:
    """Test the normalize_attn_implementation validator."""

    @staticmethod
    def _normalize(data):
        return AxolotlInputConfig.normalize_attn_implementation(data)

    # --- Forward mapping: attn_implementation -> legacy flags ---

    @pytest.mark.parametrize(
        "impl,expected_flags",
        [
            ("eager", {"eager_attention": True}),
            ("flash", {"flash_attention": True}),
            ("sdpa", {"sdp_attention": True}),
            ("flex", {"flex_attention": True}),
            ("xformers", {"xformers_attention": True, "flash_attention": True}),
            ("sage", {"sage_attention": True, "flash_attention": True}),
            ("s2", {"s2_attention": True, "flash_attention": True}),
        ],
    )
    def test_attn_impl_sets_legacy_flags(self, impl, expected_flags):
        data = {"attn_implementation": impl}
        result = AxolotlInputConfig.normalize_attn_implementation(data)
        for flag, val in expected_flags.items():
            assert result.get(flag) == val, f"{impl}: expected {flag}={val}"

    def test_fp8_sets_no_legacy_flags(self):
        result = self._normalize({"attn_implementation": "fp8"})
        for flag in [
            "flash_attention",
            "sdp_attention",
            "eager_attention",
            "xformers_attention",
            "sage_attention",
            "flex_attention",
            "s2_attention",
        ]:
            assert not result.get(flag), f"fp8 should not set {flag}"

    # --- Reverse mapping: legacy flags -> attn_implementation ---

    @pytest.mark.parametrize(
        "flag,expected_impl",
        [
            ("flash_attention", "flash"),
            ("sdp_attention", "sdpa"),
            ("xformers_attention", "xformers"),
            ("flex_attention", "flex"),
            ("sage_attention", "sage"),
            ("eager_attention", "eager"),
            ("s2_attention", "s2"),
        ],
    )
    def test_legacy_flag_sets_attn_impl(self, flag, expected_impl):
        result = self._normalize({flag: True})
        assert result["attn_implementation"] == expected_impl

    # --- Priority: s2/sage should win over flash when both set ---

    def test_s2_plus_flash_maps_to_s2(self):
        """Legacy configs often have both s2_attention and flash_attention."""
        result = self._normalize({"s2_attention": True, "flash_attention": True})
        assert result["attn_implementation"] == "s2"

    def test_sage_plus_flash_maps_to_sage(self):
        """sage_attention should take priority over flash_attention."""
        result = self._normalize({"sage_attention": True, "flash_attention": True})
        assert result["attn_implementation"] == "sage"

    # --- Consistency: both set, matching ---

    def test_consistent_both_set_no_error(self):
        result = self._normalize(
            {"attn_implementation": "flash", "flash_attention": True}
        )
        assert result["attn_implementation"] == "flash"
        assert result["flash_attention"] is True

    def test_consistent_xformers_with_extra_flags(self):
        """xformers needs flash_attention=True, so both flags with attn_impl should be OK."""
        result = self._normalize(
            {
                "attn_implementation": "xformers",
                "xformers_attention": True,
                "flash_attention": True,
            }
        )
        assert result["attn_implementation"] == "xformers"

    def test_consistent_s2_with_flash(self):
        result = self._normalize(
            {
                "attn_implementation": "s2",
                "s2_attention": True,
                "flash_attention": True,
            }
        )
        assert result["attn_implementation"] == "s2"

    # --- Conflict detection ---

    def test_conflicting_impl_and_flag_raises(self):
        with pytest.raises(ValueError, match="conflicts with"):
            self._normalize({"attn_implementation": "flash", "sdp_attention": True})

    def test_conflicting_xformers_impl_with_sdp_flag(self):
        with pytest.raises(ValueError, match="conflicts with"):
            self._normalize({"attn_implementation": "xformers", "sdp_attention": True})

    # --- Hub kernel strings pass through ---

    def test_hub_kernel_passthrough(self):
        result = self._normalize(
            {"attn_implementation": "kernels-community/flash-attn3"}
        )
        assert result["attn_implementation"] == "kernels-community/flash-attn3"
        # Should not set any legacy flags
        for flag in [
            "flash_attention",
            "sdp_attention",
            "eager_attention",
            "xformers_attention",
        ]:
            assert not result.get(flag)

    def test_custom_string_passthrough(self):
        result = self._normalize({"attn_implementation": "my_custom_kernel"})
        assert result["attn_implementation"] == "my_custom_kernel"

    # --- No attention set ---

    def test_no_attention_set_is_noop(self):
        result = self._normalize({"some_other_config": True})
        assert result.get("attn_implementation") is None

    # --- Sample packing interactions ---

    def test_xformers_with_sample_packing_sets_flash(self):
        """xformers + sample_packing needs flash_attention=True for the patch chain."""
        result = self._normalize(
            {"attn_implementation": "xformers", "sample_packing": True}
        )
        assert result["xformers_attention"] is True
        assert result["flash_attention"] is True


class TestAttnImplToHFMapping:
    """Test that attn_implementation enum values map correctly to HF strings."""

    # This dict mirrors _ATTN_IMPL_TO_HF in model.py
    _ATTN_IMPL_TO_HF = {
        "eager": "eager",
        "flash": "flash_attention_2",
        "sdpa": "sdpa",
        "xformers": "xformers",
        "flex": "flex_attention",
        "sage": "sage",
        "s2": "flash_attention_2",
        "fp8": "sdpa",
    }

    @pytest.mark.parametrize(
        "impl,expected_hf",
        [
            ("eager", "eager"),
            ("flash", "flash_attention_2"),
            ("sdpa", "sdpa"),
            ("xformers", "xformers"),
            ("flex", "flex_attention"),
            ("sage", "sage"),
            ("s2", "flash_attention_2"),
            ("fp8", "sdpa"),
        ],
    )
    def test_known_impl_maps_correctly(self, impl, expected_hf):
        assert self._ATTN_IMPL_TO_HF[impl] == expected_hf

    def test_hub_kernel_falls_through(self):
        """Hub kernel strings should pass through .get() unchanged."""
        hub_str = "kernels-community/flash-attn3"
        result = self._ATTN_IMPL_TO_HF.get(hub_str, hub_str)
        assert result == hub_str


def _xformers_available():
    try:
        import xformers.ops  # noqa: F401

        return True
    except (ImportError, OSError):
        return False


class TestAttentionRegistration:
    """Test that attention backends register correctly in HF's registries."""

    @pytest.mark.skipif(not _xformers_available(), reason="xformers not available")
    def test_register_xformers(self):
        from transformers.masking_utils import ALL_MASK_ATTENTION_FUNCTIONS
        from transformers.modeling_utils import ALL_ATTENTION_FUNCTIONS

        from axolotl.monkeypatch.attention import register_xformers_attn

        register_xformers_attn()

        assert "xformers" in ALL_ATTENTION_FUNCTIONS
        assert "xformers" in ALL_MASK_ATTENTION_FUNCTIONS
        # xformers mask should be the same function as flash_attention_2's mask
        assert (
            ALL_MASK_ATTENTION_FUNCTIONS["xformers"]
            == ALL_MASK_ATTENTION_FUNCTIONS["flash_attention_2"]
        )

    def test_register_sage(self):
        from transformers.masking_utils import ALL_MASK_ATTENTION_FUNCTIONS
        from transformers.modeling_utils import ALL_ATTENTION_FUNCTIONS

        from axolotl.monkeypatch.attention import register_sage_attn

        register_sage_attn()

        assert "sage" in ALL_ATTENTION_FUNCTIONS
        assert "sage" in ALL_MASK_ATTENTION_FUNCTIONS
        assert (
            ALL_MASK_ATTENTION_FUNCTIONS["sage"]
            == ALL_MASK_ATTENTION_FUNCTIONS["flash_attention_2"]
        )

    @pytest.mark.skipif(not _xformers_available(), reason="xformers not available")
    def test_xformers_does_not_overwrite_fa2(self):
        """Registering xformers should not modify the flash_attention_2 slot."""
        from transformers.modeling_utils import ALL_ATTENTION_FUNCTIONS

        original_fa2 = ALL_ATTENTION_FUNCTIONS["flash_attention_2"]

        from axolotl.monkeypatch.attention import register_xformers_attn

        register_xformers_attn()

        assert ALL_ATTENTION_FUNCTIONS["flash_attention_2"] is original_fa2

    def test_sage_does_not_overwrite_fa2(self):
        """Registering sage should not modify the flash_attention_2 slot."""
        from transformers.modeling_utils import ALL_ATTENTION_FUNCTIONS

        original_fa2 = ALL_ATTENTION_FUNCTIONS["flash_attention_2"]

        from axolotl.monkeypatch.attention import register_sage_attn

        register_sage_attn()

        assert ALL_ATTENTION_FUNCTIONS["flash_attention_2"] is original_fa2