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

import torch

import vllm.model_executor.layers.fused_moe.modular_kernel as mk
from vllm.model_executor.layers.fused_moe.config import FusedMoEQuantConfig
from vllm.model_executor.layers.fused_moe.deep_gemm_moe import (
    DeepGemmExperts,
    _valid_deep_gemm,
    _valid_deep_gemm_shape,
)
from vllm.model_executor.layers.fused_moe.fallback import FallbackExperts
from vllm.model_executor.layers.fused_moe.fused_moe import TritonExperts
from vllm.utils.deep_gemm import (
    is_deep_gemm_e8m0_used,
)


class TritonOrDeepGemmExperts(FallbackExperts):
    """DeepGemm with fallback to Triton for low latency shapes."""

    def __init__(self, quant_config: FusedMoEQuantConfig):
        super().__init__(
            experts=DeepGemmExperts(quant_config),
            fallback_experts=TritonExperts(quant_config),
        )

    def workspace_shapes(
        self,
        M: int,
        N: int,
        K: int,
        topk: int,
        global_num_experts: int,
        local_num_experts: int,
        expert_tokens_meta: mk.ExpertTokensMetadata | None,
    ) -> tuple[tuple[int, ...], tuple[int, ...], tuple[int, ...]]:
        # Note: the deep gemm workspaces are strictly larger than the triton
        # workspaces so we can be pessimistic here and allocate for DeepGemm
        # even if we fall back to triton later, e.g. if expert maps are set.
        if is_deep_gemm_e8m0_used() or _valid_deep_gemm_shape(M, N, K):
            return self.experts.workspace_shapes(
                M,
                N,
                K,
                topk,
                global_num_experts,
                local_num_experts,
                expert_tokens_meta,
            )
        else:
            return self.fallback_experts.workspace_shapes(
                M,
                N,
                K,
                topk,
                global_num_experts,
                local_num_experts,
                expert_tokens_meta,
            )

    def _select_experts_impl(
        self,
        hidden_states: torch.Tensor,
        w1: torch.Tensor,
        w2: torch.Tensor,
    ) -> mk.FusedMoEPermuteExpertsUnpermute:
        if is_deep_gemm_e8m0_used() or _valid_deep_gemm(hidden_states, w1, w2):
            return self.experts
        else:
            return self.fallback_experts
