# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import pytest
import torch

from tests.kernels.moe.utils import make_test_quant_config
from tests.kernels.quantization.nvfp4_utils import (
    FLOAT4_E2M1_MAX,
    FLOAT8_E4M3_MAX,
    dequantize_nvfp4_to_dtype,
)
from tests.kernels.utils import torch_moe
from vllm import _custom_ops as ops
from vllm.config import ParallelConfig, VllmConfig, set_current_vllm_config
from vllm.model_executor.layers.fused_moe.flashinfer_cutlass_moe import (
    FlashInferExperts,
    is_valid_flashinfer_cutlass_fused_moe,
)
from vllm.model_executor.layers.fused_moe.fused_moe import fused_topk
from vllm.model_executor.layers.fused_moe.modular_kernel import FusedMoEModularKernel
from vllm.model_executor.layers.fused_moe.prepare_finalize import (
    MoEPrepareAndFinalizeNoEP,
)
from vllm.platforms import current_platform
from vllm.utils.flashinfer import has_flashinfer_cutlass_fused_moe

if not has_flashinfer_cutlass_fused_moe() or not current_platform.has_device_capability(
    100
):
    pytest.skip(
        "Requires flashinfer_cutlass_fused_moe and nvfp4 support",
        allow_module_level=True,
    )

MNK_FACTORS = [
    (2, 1024, 1024),
    (2, 3072, 1024),
    (2, 3072, 1536),
    (64, 1024, 1536),
    (64, 3072, 1024),
    (64, 2048, 1536),
    (224, 1024, 1024),
    (224, 1024, 1536),
]


@pytest.mark.parametrize("m,n,k", MNK_FACTORS)
@pytest.mark.parametrize("e", [40, 64, 256])
@pytest.mark.parametrize("topk", [1, 6, 8])
@pytest.mark.parametrize("dtype", [torch.bfloat16])
@torch.inference_mode()
def test_flashinfer_fp4_moe_no_graph(
    m: int, n: int, k: int, e: int, topk: int, dtype: torch.dtype
):
    current_platform.seed_everything(7)
    with set_current_vllm_config(
        VllmConfig(parallel_config=ParallelConfig(pipeline_parallel_size=1))
    ):
        a = torch.randn((m, k), device="cuda", dtype=dtype) / 10

        quant_blocksize = 16

        w1_q, w2_q, quant_config = make_test_quant_config(
            e,
            n,
            k,
            in_dtype=dtype,
            quant_dtype="nvfp4",
            block_shape=None,
            per_act_token_quant=False,
        )

        score = torch.randn((m, e), device="cuda", dtype=dtype)
        topk_weights, topk_ids, _ = fused_topk(a, score, topk, renormalize=False)

        assert is_valid_flashinfer_cutlass_fused_moe(a, w1_q, w2_q)

        flashinfer_experts = FusedMoEModularKernel(
            MoEPrepareAndFinalizeNoEP(),
            FlashInferExperts(out_dtype=dtype, quant_config=quant_config),
        )

        flashinfer_output = flashinfer_experts(
            hidden_states=a,
            w1=w1_q,
            w2=w2_q,
            topk_weights=topk_weights,
            topk_ids=topk_ids,
        )

        # Reference check:
        a_global_scale = (
            (FLOAT8_E4M3_MAX * FLOAT4_E2M1_MAX) / torch.amax(a.flatten(), dim=-1)
        ).to(torch.float32)
        a_fp4, a_scale_interleaved = ops.scaled_fp4_quant(a, a_global_scale)
        _, m_k = a_fp4.shape
        a_in_dtype = dequantize_nvfp4_to_dtype(
            a_fp4,
            a_scale_interleaved,
            a_global_scale,
            dtype=a.dtype,
            device=a.device,
            block_size=quant_blocksize,
        )

        w1_d = torch.empty((e, 2 * n, k), device="cuda", dtype=dtype)
        w2_d = torch.empty((e, k, n), device="cuda", dtype=dtype)

        for idx in range(0, e):
            w1_d[idx] = dequantize_nvfp4_to_dtype(
                w1_q[idx],
                quant_config.w1_scale[idx],
                (1 / quant_config.g1_alphas[idx]),
                dtype=dtype,
                device=w1_q.device,
                block_size=quant_blocksize,
            )
            w2_d[idx] = dequantize_nvfp4_to_dtype(
                w2_q[idx],
                quant_config.w2_scale[idx],
                (1 / quant_config.g2_alphas[idx]),
                dtype=dtype,
                device=w2_q.device,
                block_size=quant_blocksize,
            )

        torch_output = torch_moe(a_in_dtype, w1_d, w2_d, score, topk)

        torch.testing.assert_close(
            torch_output, flashinfer_output, atol=1e-1, rtol=1e-1
        )


if __name__ == "__main__":
    test_flashinfer_fp4_moe_no_graph((2, 1024, 1024), 40, 1, torch.half)