import logging
from typing import Callable, List, Optional, Tuple

import einops
import torch
from sgl_kernel import silu_and_mul
from torch.nn import Module

from sglang.srt.custom_op import CustomOp
from sglang.srt.distributed import (
    get_tensor_model_parallel_rank,
    get_tensor_model_parallel_world_size,
)
from sglang.srt.layers.moe.ep_moe.kernels import (
    ep_gather,
    ep_scatter,
    gelu_and_mul_triton_kernel,
    grouped_gemm_triton,
    post_reorder_triton_kernel,
    pre_reorder_triton_kernel,
    run_moe_ep_preproess,
    silu_and_mul_masked_post_quant_fwd,
    silu_and_mul_triton_kernel,
    tma_align_input_scale,
)
from sglang.srt.layers.moe.fused_moe_triton import FusedMoeWeightScaleSupported
from sglang.srt.layers.moe.fused_moe_triton.layer import FusedMoE, FusedMoEMethodBase
from sglang.srt.layers.moe.topk import select_experts
from sglang.srt.layers.quantization import deep_gemm_wrapper
from sglang.srt.layers.quantization.base_config import (
    QuantizationConfig,
    QuantizeMethodBase,
)
from sglang.srt.layers.quantization.fp8 import Fp8Config, Fp8MoEMethod
from sglang.srt.layers.quantization.fp8_kernel import (
    scaled_fp8_quant,
    sglang_per_token_group_quant_fp8,
    sglang_per_token_quant_fp8,
)
from sglang.srt.managers.expert_location import get_global_expert_location_metadata
from sglang.srt.managers.expert_location_dispatch import ExpertLocationDispatchInfo
from sglang.srt.managers.schedule_batch import global_server_args_dict
from sglang.srt.model_executor.forward_batch_info import ForwardMode
from sglang.srt.utils import (
    DeepEPMode,
    dispose_tensor,
    get_bool_env_var,
    is_hip,
    set_weight_attrs,
)

_is_hip = is_hip()

if _is_hip:
    from vllm._custom_ops import scaled_fp8_quant

logger = logging.getLogger(__name__)


class GroupedGemmRunner(torch.nn.Module):
    flashinfer_gemm_warpper = None

    def __init__(
        self,
        device,
        use_flashinfer: bool = False,
        use_per_token_if_dynamic: bool = True,
    ):
        super().__init__()
        self.device = device
        self.use_flashinfer = use_flashinfer
        self.use_per_token_if_dynamic = use_per_token_if_dynamic
        if self.use_flashinfer and GroupedGemmRunner.flashinfer_gemm_warpper is None:
            GroupedGemmRunner._init_flashinfer_wrapper(device)

    @classmethod
    def _init_flashinfer_wrapper(cls, device):
        from flashinfer import SegmentGEMMWrapper

        workspace_buffer = torch.empty(
            128 * 1024 * 1024, dtype=torch.int8, device=device
        )
        cls.flashinfer_gemm_warpper = SegmentGEMMWrapper(workspace_buffer)

    # c = a * b
    def forward(
        self,
        a: torch.Tensor,
        b: torch.Tensor,
        c: torch.Tensor,
        batch_size: int,
        weight_column_major: bool,
        seg_indptr: Optional[torch.Tensor] = None,
        weight_indices: Optional[torch.Tensor] = None,
        use_fp8_w8a8: bool = False,
        scale_a: torch.Tensor = None,
        scale_b: torch.Tensor = None,
        block_shape: Optional[List[int]] = None,
        c_dtype=None,
    ):
        if self.use_flashinfer:
            # TODO: flashinfer
            assert False
            assert GroupedGemmRunner.flashinfer_gemm_warpper is not None
            c = GroupedGemmRunner.flashinfer_gemm_warpper.run(
                x=a,
                weights=b,
                batch_size=batch_size,
                weight_column_major=weight_column_major,
                seg_indptr=seg_indptr,
                weight_indices=weight_indices,
            )
        else:
            assert weight_column_major == True
            c = grouped_gemm_triton(
                a,
                b,
                c,
                batch_size,
                weight_column_major,
                seg_indptr,
                weight_indices,
                use_fp8_w8a8,
                scale_a,
                scale_b,
                block_shape=block_shape,
                c_dtype=c_dtype,
                use_per_token_if_dynamic=self.use_per_token_if_dynamic,
            )
        return c


class EPMoE(torch.nn.Module):
    """
    MoE Expert Parallel Impl


    """

    def __init__(
        self,
        num_experts: int,
        top_k: int,
        hidden_size: int,
        intermediate_size: int,
        layer_id: int,
        params_dtype: Optional[torch.dtype] = None,
        renormalize: bool = True,
        use_grouped_topk: bool = False,
        num_expert_group: Optional[int] = None,
        num_fused_shared_experts: int = 0,
        topk_group: Optional[int] = None,
        quant_config: Optional[QuantizationConfig] = None,
        tp_size: Optional[int] = None,
        prefix: str = "",
        correction_bias: Optional[torch.Tensor] = None,
        custom_routing_function: Optional[Callable] = None,
        activation: str = "silu",
        routed_scaling_factor: Optional[float] = None,
        use_per_token_if_dynamic: bool = True,
    ):
        super().__init__()

        if params_dtype is None:
            params_dtype = torch.get_default_dtype()

        self.tp_size = (
            tp_size if tp_size is not None else get_tensor_model_parallel_world_size()
        )
        self.tp_rank = get_tensor_model_parallel_rank()

        self.layer_id = layer_id
        self.num_experts = num_experts
        assert self.num_experts % self.tp_size == 0
        assert (
            num_fused_shared_experts == 0
        ), "num_fused_shared_experts is not supported in EP"
        self.num_experts_per_partition = self.num_experts // self.tp_size
        self.start_expert_id = self.tp_rank * self.num_experts_per_partition
        self.end_expert_id = self.start_expert_id + self.num_experts_per_partition - 1

        self.top_k = top_k
        self.intermediate_size = intermediate_size
        self.renormalize = renormalize
        self.use_grouped_topk = use_grouped_topk
        if self.use_grouped_topk:
            assert num_expert_group is not None and topk_group is not None
        self.num_expert_group = num_expert_group
        self.topk_group = topk_group
        self.correction_bias = correction_bias
        self.custom_routing_function = custom_routing_function
        self.activation = activation
        self.routed_scaling_factor = routed_scaling_factor
        self.use_per_token_if_dynamic = use_per_token_if_dynamic

        if quant_config is None:
            self.quant_method: Optional[QuantizeMethodBase] = UnquantizedEPMoEMethod()
            self.use_fp8_w8a8 = False
            self.use_block_quant = False
            self.block_shape = None
            self.activation_scheme = None
        else:
            self.quant_method: Optional[QuantizeMethodBase] = Fp8EPMoEMethod(
                quant_config
            )
            self.use_fp8_w8a8 = True
            self.use_block_quant = getattr(self.quant_method, "block_quant", False)
            self.block_shape = (
                self.quant_method.quant_config.weight_block_size
                if self.use_block_quant
                else None
            )
            self.fp8_dtype = torch.float8_e4m3fn
            self.activation_scheme = quant_config.activation_scheme

        self.quant_method.create_weights(
            layer=self,
            num_experts_per_partition=self.num_experts_per_partition,
            hidden_size=hidden_size,
            intermediate_size=self.intermediate_size,
            params_dtype=params_dtype,
            weight_loader=self.weight_loader,
        )

        self.grouped_gemm_runner = None

    def forward(self, hidden_states: torch.Tensor, router_logits: torch.Tensor):
        hidden_states_shape = hidden_states.shape
        hidden_states_dtype = hidden_states.dtype
        hidden_states_device = hidden_states.device

        assert self.quant_method is not None

        if self.grouped_gemm_runner is None:
            self.grouped_gemm_runner = GroupedGemmRunner(
                hidden_states.device,
                use_flashinfer=False,  # TODO: use flashinfer
                use_per_token_if_dynamic=self.use_per_token_if_dynamic,
            )

        topk_weights, topk_ids = select_experts(
            hidden_states=hidden_states,
            router_logits=router_logits,
            top_k=self.top_k,
            use_grouped_topk=self.use_grouped_topk,
            renormalize=self.renormalize,
            topk_group=self.topk_group,
            num_expert_group=self.num_expert_group,
            correction_bias=self.correction_bias,
            custom_routing_function=self.custom_routing_function,
            routed_scaling_factor=self.routed_scaling_factor,
            expert_location_dispatch_info=ExpertLocationDispatchInfo.init_new(
                layer_id=self.layer_id,
            ),
        )

        reorder_topk_ids, src2dst, seg_indptr = run_moe_ep_preproess(
            topk_ids, self.num_experts
        )

        gateup_input = torch.empty(
            (int(hidden_states.shape[0] * self.top_k), hidden_states.shape[1]),
            device=hidden_states.device,
            dtype=(
                self.fp8_dtype
                if (self.use_fp8_w8a8 and not self.use_block_quant)
                else hidden_states.dtype
            ),
        )
        if self.activation_scheme == "dynamic" and not self.use_block_quant:
            if self.use_per_token_if_dynamic:
                max_value = torch.max(hidden_states, dim=1).values.to(torch.float32)
                self.w13_input_scale = max_value / torch.finfo(self.fp8_dtype).max
            else:
                max_value = (
                    torch.max(hidden_states)
                    .repeat(self.num_experts_per_partition)
                    .to(torch.float32)
                )
                self.w13_input_scale = max_value / torch.finfo(self.fp8_dtype).max

        # PreReorder
        pre_reorder_triton_kernel[(hidden_states.shape[0],)](
            hidden_states,
            gateup_input,
            src2dst,
            topk_ids,
            self.w13_input_scale,
            self.start_expert_id,
            self.end_expert_id,
            self.top_k,
            hidden_states.shape[1],
            BLOCK_SIZE=512,
            use_per_token_if_dynamic=self.use_per_token_if_dynamic,
        )
        dispose_tensor(hidden_states)

        if (
            self.activation_scheme == "dynamic"
            and not self.use_block_quant
            and self.use_per_token_if_dynamic
        ):
            scale = torch.empty(
                hidden_states_shape[0] * self.top_k,
                device=hidden_states_device,
                dtype=torch.float32,
            )
            scale[src2dst] = (
                self.w13_input_scale.unsqueeze(1)
                .expand(hidden_states_shape[0], self.top_k)
                .reshape(-1)
            )
            self.w13_input_scale = scale

        seg_indptr_cur_rank = seg_indptr[self.start_expert_id : self.end_expert_id + 2]
        weight_indices_cur_rank = torch.arange(
            0,
            self.num_experts_per_partition,
            device=hidden_states_device,
            dtype=torch.int64,
        )
        # GroupGemm-0
        gateup_output = self.grouped_gemm_runner(
            a=gateup_input,
            b=self.w13_weight,
            c=None,
            c_dtype=hidden_states_dtype,
            batch_size=self.num_experts_per_partition,
            weight_column_major=True,
            seg_indptr=seg_indptr_cur_rank,
            weight_indices=weight_indices_cur_rank,
            use_fp8_w8a8=self.use_fp8_w8a8,
            scale_a=self.w13_input_scale,
            scale_b=(
                self.w13_weight_scale_inv
                if self.use_block_quant
                else self.w13_weight_scale
            ),
            block_shape=self.block_shape,
        )
        del gateup_input

        # Act
        if self.activation_scheme == "dynamic" and not self.use_block_quant:
            self.w2_input_scale = None
            down_input = torch.empty(
                gateup_output.shape[0],
                gateup_output.shape[1] // 2,
                device=gateup_output.device,
                dtype=hidden_states_dtype,
            )
        else:
            down_input = torch.empty(
                gateup_output.shape[0],
                gateup_output.shape[1] // 2,
                device=gateup_output.device,
                dtype=(
                    self.fp8_dtype
                    if (self.use_fp8_w8a8 and not self.use_block_quant)
                    else hidden_states_dtype
                ),
            )

        if self.activation == "silu":
            silu_and_mul_triton_kernel[(gateup_output.shape[0],)](
                gateup_output,
                down_input,
                gateup_output.shape[1],
                reorder_topk_ids,
                self.w2_input_scale,
                self.start_expert_id,
                self.end_expert_id,
                BLOCK_SIZE=512,
            )
        elif self.activation == "gelu":
            gelu_and_mul_triton_kernel[(gateup_output.shape[0],)](
                gateup_output,
                down_input,
                gateup_output.shape[1],
                reorder_topk_ids,
                self.w2_input_scale,
                self.start_expert_id,
                self.end_expert_id,
                BLOCK_SIZE=512,
            )
        else:
            raise ValueError(f"Unsupported activation: {self.activation=}")
        del gateup_output

        if self.activation_scheme == "dynamic" and not self.use_block_quant:
            if self.use_per_token_if_dynamic:
                down_input, self.w2_input_scale = sglang_per_token_quant_fp8(down_input)
            else:
                self.w2_input_scale = torch.ones(
                    self.num_experts_per_partition,
                    dtype=torch.float32,
                    device=hidden_states_device,
                )

        # GroupGemm-1
        down_output = torch.empty(
            down_input.shape[0],
            self.w2_weight.shape[1],
            device=hidden_states_device,
            dtype=hidden_states_dtype,
        )
        down_output = self.grouped_gemm_runner(
            a=down_input,
            b=self.w2_weight,
            c=down_output,
            batch_size=self.num_experts_per_partition,
            weight_column_major=True,
            seg_indptr=seg_indptr_cur_rank,
            weight_indices=weight_indices_cur_rank,
            use_fp8_w8a8=self.use_fp8_w8a8,
            scale_a=self.w2_input_scale,
            scale_b=(
                self.w2_weight_scale_inv
                if self.use_block_quant
                else self.w2_weight_scale
            ),
            block_shape=self.block_shape,
        )
        del down_input

        # PostReorder
        output = torch.empty(
            hidden_states_shape, dtype=hidden_states_dtype, device=hidden_states_device
        )
        post_reorder_triton_kernel[(hidden_states_shape[0],)](
            down_output,
            output,
            src2dst,
            topk_ids,
            topk_weights,
            self.start_expert_id,
            self.end_expert_id,
            self.top_k,
            hidden_states_shape[1],
            BLOCK_SIZE=512,
        )
        return output

    @classmethod
    def make_expert_params_mapping(
        cls,
        ckpt_gate_proj_name: str,
        ckpt_down_proj_name: str,
        ckpt_up_proj_name: str,
        num_experts: int,
    ) -> List[Tuple[str, str, int, str]]:
        return [
            # (param_name, weight_name, expert_id, shard_id)
            (
                (
                    "experts.w13_"
                    if weight_name in [ckpt_gate_proj_name, ckpt_up_proj_name]
                    else "experts.w2_"
                ),
                f"experts.{expert_id}.{weight_name}.",
                expert_id,
                shard_id,
            )
            for expert_id in range(num_experts)
            for shard_id, weight_name in [
                ("w1", ckpt_gate_proj_name),
                ("w2", ckpt_down_proj_name),
                ("w3", ckpt_up_proj_name),
            ]
        ]

    def weight_loader(
        self,
        param: torch.nn.Parameter,
        loaded_weight: torch.Tensor,
        weight_name: str,
        shard_id: str,
        expert_id: int,
    ) -> None:
        physical_expert_ids = (
            get_global_expert_location_metadata().logical_to_all_physical(
                self.layer_id, expert_id
            )
        )
        for physical_expert_id in physical_expert_ids:
            self._weight_loader_physical(
                param=param,
                loaded_weight=loaded_weight,
                weight_name=weight_name,
                shard_id=shard_id,
                expert_id=physical_expert_id,
            )

    def _weight_loader_physical(
        self,
        param: torch.nn.Parameter,
        loaded_weight: torch.Tensor,
        weight_name: str,
        shard_id: str,
        expert_id: int,
    ) -> None:
        if expert_id < self.start_expert_id or expert_id > self.end_expert_id:
            return
        expert_id = expert_id - self.start_expert_id

        if shard_id not in ("w1", "w2", "w3"):
            raise ValueError(
                f"shard_id must be ['w1','w2','w3'] but " f"got {shard_id}."
            )

        # Special case for fp8 scales.
        if "scale" in weight_name:
            self._load_fp8_scale(
                param.data,
                loaded_weight,
                weight_name,
                shard_id,
                expert_id,
            )
            return

        if shard_id == "w2":
            param.data[expert_id] = loaded_weight
        elif shard_id == "w1":
            param.data[expert_id][: self.intermediate_size, :] = loaded_weight
        elif shard_id == "w3":
            param.data[expert_id][self.intermediate_size :, :] = loaded_weight
        else:
            raise ValueError(f"Expected shard_id w1,w2 or w3 but got {shard_id}")

    def _load_fp8_scale(
        self,
        param: torch.nn.Parameter,
        loaded_weight: torch.Tensor,
        weight_name: str,
        shard_id: str,
        expert_id: int,
    ) -> None:
        param_data = param.data

        # Input scales can be loaded directly and should be equal.
        if "input_scale" in weight_name:
            if (
                (shard_id == "w1" or shard_id == "w3")
                and param_data[expert_id] != 1
                and (param_data[expert_id] - loaded_weight).abs() > 1e-5
            ):
                raise ValueError(
                    "input_scales of w1 and w3 of a layer "
                    f"must be equal. But got {param_data[expert_id]} "
                    f"vs. {loaded_weight}"
                )
            param_data[expert_id] = loaded_weight
        # Weight scales
        elif "weight_scale" in weight_name:
            if self.use_block_quant:
                block_n, block_k = self.block_shape[0], self.block_shape[1]
                if shard_id == "w1":
                    param_data[expert_id][
                        : (self.intermediate_size + block_n - 1) // block_n, :
                    ] = loaded_weight
                elif shard_id == "w3":
                    param_data[expert_id][
                        (self.intermediate_size + block_n - 1) // block_n :, :
                    ] = loaded_weight
                else:  # w2
                    param_data[expert_id] = loaded_weight
            # If we are in merged column case (gate_up_proj)
            else:
                if shard_id in ("w1", "w3"):
                    # We have to keep the weight scales of w1 and w3 because
                    # we need to re-quantize w1/w3 weights after weight loading.
                    idx = 0 if shard_id == "w1" else 1
                    param_data[expert_id][idx] = loaded_weight

                # If we are in the row parallel case (down_proj)
                else:
                    param_data[expert_id] = loaded_weight


class UnquantizedEPMoEMethod(FusedMoEMethodBase, CustomOp):

    def create_weights(
        self,
        layer: torch.nn.Module,
        num_experts_per_partition: int,
        hidden_size: int,
        intermediate_size: int,
        params_dtype: torch.dtype,
        **extra_weight_attrs,
    ):
        # Fused gate_up_proj (column parallel)
        w13_weight = torch.nn.Parameter(
            torch.empty(
                num_experts_per_partition,
                2 * intermediate_size,
                hidden_size,
                dtype=params_dtype,
            ),
            requires_grad=False,
        )
        layer.register_parameter("w13_weight", w13_weight)
        set_weight_attrs(w13_weight, extra_weight_attrs)

        # down_proj (row parallel)
        w2_weight = torch.nn.Parameter(
            torch.empty(
                num_experts_per_partition,
                hidden_size,
                intermediate_size,
                dtype=params_dtype,
            ),
            requires_grad=False,
        )
        layer.register_parameter("w2_weight", w2_weight)
        set_weight_attrs(w2_weight, extra_weight_attrs)

        # scale
        layer.register_parameter("w13_input_scale", None)
        layer.register_parameter("w13_weight_scale", None)

        ones_tensor = torch.ones(num_experts_per_partition, dtype=torch.float32)

        w2_input_scale = torch.nn.Parameter(
            ones_tensor,
            requires_grad=False,
        )
        layer.register_parameter("w2_input_scale", w2_input_scale)
        set_weight_attrs(w2_input_scale, extra_weight_attrs)

        w2_weight_scale = torch.nn.Parameter(
            ones_tensor,
            requires_grad=False,
        )
        layer.register_parameter("w2_weight_scale", w2_weight_scale)
        set_weight_attrs(w2_weight_scale, extra_weight_attrs)

    def apply(
        self,
        layer: torch.nn.Module,
        x: torch.Tensor,
        router_logits: torch.Tensor,
        top_k: int,
        renormalize: bool,
        use_grouped_topk: bool,
        topk_group: Optional[int] = None,
        num_expert_group: Optional[int] = None,
        custom_routing_function: Optional[Callable] = None,
    ) -> torch.Tensor:
        raise NotImplementedError


class Fp8EPMoEMethod(Fp8MoEMethod):
    """MoE method for FP8.
    Supports loading FP8 checkpoints with static weight scale and
    dynamic/static activation scale.

    Args:
        quant_config: The quantization config.
    """

    def __init__(self, quant_config: Fp8Config):
        self.quant_config = quant_config
        self.block_quant = self.quant_config.weight_block_size is not None

    def create_weights(
        self,
        layer: Module,
        num_experts_per_partition: int,
        hidden_size: int,
        intermediate_size: int,
        params_dtype: torch.dtype,
        **extra_weight_attrs,
    ):
        if self.quant_config.is_checkpoint_fp8_serialized:
            params_dtype = torch.float8_e4m3fn

        tp_size = get_tensor_model_parallel_world_size()
        if self.block_quant:
            block_n, block_k = (
                self.quant_config.weight_block_size[0],
                self.quant_config.weight_block_size[1],
            )
            # NOTE(HandH1998): To ensure proper alignment of the block-wise quantization scales, the output_size of the weights for both the gate and up layers must be divisible by block_n.
            # Required by column parallel or enabling merged weights
            if intermediate_size % block_n != 0:
                raise ValueError(
                    f"The output_size of gate's and up's weight = "
                    f"{intermediate_size} is not divisible by "
                    f"weight quantization block_n = {block_n}."
                )
            if tp_size > 1:
                # Required by row parallel
                if intermediate_size % block_k != 0:
                    raise ValueError(
                        f"The input_size of down's weight = "
                        f"{intermediate_size} is not divisible by "
                        f"weight quantization block_k = {block_k}."
                    )

        # WEIGHTS
        w13_weight = torch.nn.Parameter(
            torch.empty(
                num_experts_per_partition,
                2 * intermediate_size,
                hidden_size,
                dtype=params_dtype,
            ),
            requires_grad=False,
        )
        layer.register_parameter("w13_weight", w13_weight)
        set_weight_attrs(w13_weight, extra_weight_attrs)

        w2_weight = torch.nn.Parameter(
            torch.empty(
                num_experts_per_partition,
                hidden_size,
                intermediate_size,
                dtype=params_dtype,
            ),
            requires_grad=False,
        )
        layer.register_parameter("w2_weight", w2_weight)
        set_weight_attrs(w2_weight, extra_weight_attrs)

        # WEIGHT_SCALES
        if self.block_quant:
            w13_weight_scale = torch.nn.Parameter(
                torch.ones(
                    num_experts_per_partition,
                    2 * ((intermediate_size + block_n - 1) // block_n),
                    (hidden_size + block_k - 1) // block_k,
                    dtype=torch.float32,
                ),
                requires_grad=False,
            )
            w2_weight_scale = torch.nn.Parameter(
                torch.ones(
                    num_experts_per_partition,
                    (hidden_size + block_n - 1) // block_n,
                    (intermediate_size + block_k - 1) // block_k,
                    dtype=torch.float32,
                ),
                requires_grad=False,
            )
            layer.register_parameter("w13_weight_scale_inv", w13_weight_scale)
            layer.register_parameter("w2_weight_scale_inv", w2_weight_scale)
            assert self.quant_config.activation_scheme == "dynamic"
        else:
            # WEIGHT_SCALES
            # Allocate 2 scales for w1 and w3 respectively.
            w13_weight_scale = torch.nn.Parameter(
                torch.ones(num_experts_per_partition, 2, dtype=torch.float32),
                requires_grad=False,
            )
            layer.register_parameter("w13_weight_scale", w13_weight_scale)

            w2_weight_scale = torch.nn.Parameter(
                torch.ones(num_experts_per_partition, dtype=torch.float32),
                requires_grad=False,
            )
            layer.register_parameter("w2_weight_scale", w2_weight_scale)
        # Add the quantization method used (per tensor/grouped/channel)
        # to ensure the weight scales are loaded in properly
        extra_weight_attrs.update(
            {"quant_method": FusedMoeWeightScaleSupported.BLOCK.value}
            if self.block_quant
            else {"quant_method": FusedMoeWeightScaleSupported.TENSOR.value}
        )
        # If loading fp8 checkpoint, pass the weight loaders.
        # If loading an fp16 checkpoint, do not (we will quantize in
        #   process_weights_after_loading()
        if self.quant_config.is_checkpoint_fp8_serialized:
            set_weight_attrs(w13_weight_scale, extra_weight_attrs)
            set_weight_attrs(w2_weight_scale, extra_weight_attrs)

        # INPUT_SCALES
        if self.quant_config.activation_scheme == "static":
            if not self.quant_config.is_checkpoint_fp8_serialized:
                raise ValueError(
                    "Found static activation scheme for checkpoint that "
                    "was not serialized fp8."
                )

            w13_input_scale = torch.nn.Parameter(
                torch.ones(num_experts_per_partition, dtype=torch.float32),
                requires_grad=False,
            )
            layer.register_parameter("w13_input_scale", w13_input_scale)
            set_weight_attrs(w13_input_scale, extra_weight_attrs)

            w2_input_scale = torch.nn.Parameter(
                torch.ones(num_experts_per_partition, dtype=torch.float32),
                requires_grad=False,
            )
            layer.register_parameter("w2_input_scale", w2_input_scale)
            set_weight_attrs(w2_input_scale, extra_weight_attrs)

        else:
            layer.w13_input_scale = None
            layer.w2_input_scale = None

    def process_weights_after_loading(self, layer: Module) -> None:

        # If checkpoint is fp16, quantize in place.
        if not self.quant_config.is_checkpoint_fp8_serialized:
            # If rocm, use float8_e4m3fnuz as dtype
            fp8_dtype = torch.float8_e4m3fnuz if _is_hip else torch.float8_e4m3fn
            w13_weight = torch.empty_like(layer.w13_weight.data, dtype=fp8_dtype)
            w2_weight = torch.empty_like(layer.w2_weight.data, dtype=fp8_dtype)

            layer.w13_weight_scale = torch.nn.Parameter(
                torch.ones(
                    layer.num_experts_per_partition,
                    dtype=torch.float32,
                    device=w13_weight.device,
                ),
                requires_grad=False,
            )

            for expert in range(layer.num_experts_per_partition):
                w13_weight[expert, :, :], layer.w13_weight_scale[expert] = (
                    scaled_fp8_quant(layer.w13_weight.data[expert, :, :])
                )
                w2_weight[expert, :, :], layer.w2_weight_scale[expert] = (
                    scaled_fp8_quant(layer.w2_weight.data[expert, :, :])
                )
            layer.w13_weight = torch.nn.Parameter(w13_weight, requires_grad=False)
            layer.w2_weight = torch.nn.Parameter(w2_weight, requires_grad=False)
            return

        # If checkpoint is fp8, we need to handle that the
        # MoE kernels require single activation scale and single weight
        # scale for w13 per expert.
        else:
            if self.quant_config.activation_scheme == "static":
                if layer.w13_input_scale is None or layer.w2_input_scale is None:
                    raise ValueError(
                        "QuantConfig has static quantization, but found "
                        "activation scales are None."
                    )
                layer.w13_weight_scale = torch.nn.Parameter(
                    torch.max(layer.w13_weight_scale, dim=1).values,
                    requires_grad=False,
                )
            return

    def apply(
        self,
        layer: torch.nn.Module,
        x: torch.Tensor,
        router_logits: torch.Tensor,
        top_k: int,
        renormalize: bool,
        use_grouped_topk: bool,
        topk_group: Optional[int] = None,
        num_expert_group: Optional[int] = None,
        custom_routing_function: Optional[Callable] = None,
    ) -> torch.Tensor:
        raise NotImplementedError


class DeepEPMoE(EPMoE):
    """
    MoE Expert Parallel Impl based on DeepEP (https://github.com/deepseek-ai/DeepEP/tree/main)
    """

    _has_printed = False

    def __init__(
        self,
        num_experts: int,
        top_k: int,
        hidden_size: int,
        intermediate_size: int,
        layer_id: int,
        params_dtype: Optional[torch.dtype] = None,
        renormalize: bool = True,
        use_grouped_topk: bool = False,
        num_expert_group: Optional[int] = None,
        num_fused_shared_experts: int = 0,
        topk_group: Optional[int] = None,
        quant_config: Optional[QuantizationConfig] = None,
        tp_size: Optional[int] = None,
        prefix: str = "",
        correction_bias: Optional[torch.Tensor] = None,
        custom_routing_function: Optional[Callable] = None,
        activation: str = "silu",
        routed_scaling_factor: Optional[float] = None,
        deepep_mode: DeepEPMode = DeepEPMode.auto,
    ):
        super().__init__(
            num_experts=num_experts,
            top_k=top_k,
            hidden_size=hidden_size,
            intermediate_size=intermediate_size,
            layer_id=layer_id,
            params_dtype=params_dtype,
            renormalize=renormalize,
            use_grouped_topk=use_grouped_topk,
            num_expert_group=num_expert_group,
            num_fused_shared_experts=num_fused_shared_experts,
            topk_group=topk_group,
            quant_config=quant_config,
            tp_size=tp_size,
            prefix=prefix,
            correction_bias=correction_bias,
            custom_routing_function=custom_routing_function,
            activation=activation,
            routed_scaling_factor=routed_scaling_factor,
        )
        self.deepep_mode = deepep_mode
        if self.deepep_mode.enable_low_latency():
            assert (
                deep_gemm_wrapper.ENABLE_JIT_DEEPGEMM
            ), f"DeepEP {self.deepep_mode} mode requires deep_gemm"
        self.w13_weight_fp8 = (
            self.w13_weight,
            (
                self.w13_weight_scale_inv
                if self.use_block_quant
                else self.w13_weight_scale
            ),
        )
        self.w2_weight_fp8 = (
            self.w2_weight,
            self.w2_weight_scale_inv if self.use_block_quant else self.w2_weight_scale,
        )

    def forward(
        self,
        hidden_states: torch.Tensor,
        topk_idx: torch.Tensor,
        topk_weights: torch.Tensor,
        reorder_topk_ids: torch.Tensor,
        seg_indptr: torch.Tensor,
        masked_m: torch.Tensor,
        expected_m: int,
        num_recv_tokens_per_expert: List[int],
        forward_mode: ForwardMode,
    ):
        resolved_deepep_mode = self.deepep_mode.resolve(forward_mode)
        if resolved_deepep_mode == DeepEPMode.normal:
            if deep_gemm_wrapper.ENABLE_JIT_DEEPGEMM:
                return self.forward_deepgemm_contiguous(
                    hidden_states, topk_idx, topk_weights, num_recv_tokens_per_expert
                )
            else:
                return self.forward_normal(hidden_states, reorder_topk_ids, seg_indptr)
        elif resolved_deepep_mode == DeepEPMode.low_latency:
            return self.forward_deepgemm_masked(hidden_states, masked_m, expected_m)
        else:
            raise ValueError(f"Invalid deepep_mode: {self.deepep_mode}")

    def forward_normal(
        self,
        hidden_states: torch.Tensor,
        reorder_topk_ids: torch.Tensor,
        seg_indptr: torch.Tensor,
    ):
        hidden_states_dtype = hidden_states.dtype
        hidden_states_device = hidden_states.device

        assert self.quant_method is not None
        assert self.activation == "silu"
        if self.grouped_gemm_runner is None:
            self.grouped_gemm_runner = GroupedGemmRunner(
                hidden_states.device, use_flashinfer=False  # TODO: use flashinfer
            )

        if self.activation_scheme == "dynamic" and not self.use_block_quant:
            max_value = (
                torch.max(hidden_states)
                .repeat(self.num_experts_per_partition)
                .to(torch.float32)
            )
            self.w13_input_scale = max_value / torch.finfo(self.fp8_dtype).max
        weight_indices_cur_rank = torch.arange(
            0,
            self.num_experts_per_partition,
            device=hidden_states.device,
            dtype=torch.int64,
        )

        # GroupGemm-0
        if hidden_states.shape[0] > 0:
            gateup_output = self.grouped_gemm_runner(
                a=hidden_states,
                b=self.w13_weight,
                c=None,
                c_dtype=hidden_states.dtype,
                batch_size=self.num_experts_per_partition,
                weight_column_major=True,
                seg_indptr=seg_indptr,
                weight_indices=weight_indices_cur_rank,
                use_fp8_w8a8=self.use_fp8_w8a8,
                scale_a=self.w13_input_scale,
                scale_b=(
                    self.w13_weight_scale_inv
                    if self.use_block_quant
                    else self.w13_weight_scale
                ),
                block_shape=self.block_shape,
            )
        else:
            gateup_output = torch.empty(
                hidden_states.shape[0],
                self.w13_weight.shape[1],
                device=hidden_states.device,
                dtype=hidden_states.dtype,
            )

        # Act
        down_input = torch.empty(
            gateup_output.shape[0],
            gateup_output.shape[1] // 2,
            device=gateup_output.device,
            dtype=(
                self.fp8_dtype
                if (self.use_fp8_w8a8 and not self.use_block_quant)
                else hidden_states_dtype
            ),
        )
        if self.w2_input_scale is None and not self.use_block_quant:
            self.w2_input_scale = torch.ones(
                self.num_experts_per_partition,
                dtype=torch.float32,
                device=hidden_states_device,
            )

        if self.activation == "silu":
            silu_and_mul_triton_kernel[(gateup_output.shape[0],)](
                gateup_output,
                down_input,
                gateup_output.shape[1],
                reorder_topk_ids,
                self.w2_input_scale,
                0,
                self.num_experts_per_partition - 1,
                BLOCK_SIZE=512,
            )
        else:
            raise ValueError(f"Unsupported activation: {self.activation=}")

        del gateup_output

        # GroupGemm-1
        down_output = torch.empty(
            down_input.shape[0],
            self.w2_weight.shape[1],
            device=hidden_states_device,
            dtype=hidden_states_dtype,
        )
        if down_input.shape[0] > 0:
            down_output = self.grouped_gemm_runner(
                a=down_input,
                b=self.w2_weight,
                c=down_output,
                batch_size=self.num_experts_per_partition,
                weight_column_major=True,
                seg_indptr=seg_indptr,
                weight_indices=weight_indices_cur_rank,
                use_fp8_w8a8=self.use_fp8_w8a8,
                scale_a=self.w2_input_scale,
                scale_b=(
                    self.w2_weight_scale_inv
                    if self.use_block_quant
                    else self.w2_weight_scale
                ),
                block_shape=self.block_shape,
            )
        return down_output

    def forward_deepgemm_contiguous(
        self,
        hidden_states_fp8: Tuple[torch.Tensor, torch.Tensor],
        topk_idx,
        topk_weights,
        num_recv_tokens_per_expert: List[int],
    ):
        hidden_states_fp8, hidden_states_scale = hidden_states_fp8
        assert self.quant_method is not None
        assert self.activation == "silu"
        if num_recv_tokens_per_expert is None:
            return hidden_states_fp8.bfloat16()
        all_tokens = sum(num_recv_tokens_per_expert)
        if all_tokens <= 0:
            return hidden_states_fp8.bfloat16()
        M, K = hidden_states_fp8.size()
        N = self.w13_weight.size(1)
        scale_block_size = 128

        hidden_states_fp8_shape = hidden_states_fp8.shape
        hidden_states_fp8_device = hidden_states_fp8.device
        hidden_states_fp8_dtype = hidden_states_fp8.dtype

        input_tensor = [
            torch.empty(
                (all_tokens, K),
                device=hidden_states_fp8.device,
                dtype=hidden_states_fp8.dtype,
            ),
            torch.empty(
                (all_tokens, K // 128),
                device=hidden_states_fp8.device,
                dtype=torch.float32,
            ),
        ]
        m_indices = torch.empty(
            all_tokens, device=hidden_states_fp8.device, dtype=torch.int32
        )
        output_index = torch.empty_like(topk_idx)

        num_recv_tokens_per_expert_gpu = torch.tensor(
            num_recv_tokens_per_expert,
            dtype=torch.int32,
            pin_memory=True,
            device="cpu",
        ).cuda(non_blocking=True)
        expert_start_loc = torch.empty_like(num_recv_tokens_per_expert_gpu)

        ep_scatter(
            hidden_states_fp8,
            hidden_states_scale,
            topk_idx,
            num_recv_tokens_per_expert_gpu,
            expert_start_loc,
            input_tensor[0],
            input_tensor[1],
            m_indices,
            output_index,
        )
        dispose_tensor(hidden_states_fp8)

        gateup_output = torch.empty(
            (all_tokens, N),
            device=hidden_states_fp8_device,
            dtype=torch.bfloat16,
        )
        input_tensor[1] = tma_align_input_scale(input_tensor[1])
        deep_gemm_wrapper.grouped_gemm_nt_f8f8bf16_contig(
            input_tensor, self.w13_weight_fp8, gateup_output, m_indices
        )
        del input_tensor
        down_input = torch.empty(
            (
                all_tokens,
                N // 2,
            ),
            device=gateup_output.device,
            dtype=torch.bfloat16,
        )
        silu_and_mul(gateup_output.view(-1, N), down_input)
        del gateup_output
        down_output = torch.empty(
            (all_tokens, K),
            device=hidden_states_fp8_device,
            dtype=torch.bfloat16,
        )
        down_input_fp8, down_input_scale = sglang_per_token_group_quant_fp8(
            down_input, scale_block_size
        )
        del down_input
        down_input_scale = tma_align_input_scale(down_input_scale)
        deep_gemm_wrapper.grouped_gemm_nt_f8f8bf16_contig(
            (down_input_fp8, down_input_scale),
            self.w2_weight_fp8,
            down_output,
            m_indices,
        )
        del down_input_fp8, down_input_scale

        gather_out = torch.empty(
            hidden_states_fp8_shape,
            device=hidden_states_fp8_device,
            dtype=torch.bfloat16,
        )
        ep_gather(down_output, topk_idx, topk_weights, output_index, gather_out)

        return gather_out

    def forward_deepgemm_masked(
        self,
        hidden_states_fp8: Tuple[torch.Tensor, torch.Tensor],
        masked_m: torch.Tensor,
        expected_m: int,
    ):
        assert self.quant_method is not None
        assert self.activation == "silu"

        # GroupGemm-0
        num_groups, m, k = hidden_states_fp8[0].size()
        n = self.w13_weight.size(1)
        expected_m = min(expected_m, m)
        gateup_output = torch.empty(
            (num_groups, m, n), device=hidden_states_fp8[0].device, dtype=torch.bfloat16
        )
        deep_gemm_wrapper.grouped_gemm_nt_f8f8bf16_masked(
            hidden_states_fp8,
            self.w13_weight_fp8,
            gateup_output,
            masked_m,
            expected_m,
            recipe=(1, 128, 128) if deep_gemm_wrapper.DEEPGEMM_V202506 else None,
        )
        dispose_tensor(hidden_states_fp8[0])

        # Act
        down_input = torch.empty(
            (
                gateup_output.shape[0],
                gateup_output.shape[1],
                gateup_output.shape[2] // 2,
            ),
            device=gateup_output.device,
            dtype=self.fp8_dtype,
        )
        scale_block_size = 128
        down_input_scale = torch.empty(
            (
                gateup_output.shape[0],
                gateup_output.shape[1],
                gateup_output.shape[2] // 2 // scale_block_size,
            ),
            device=gateup_output.device,
            dtype=torch.float32,
        )
        silu_and_mul_masked_post_quant_fwd(
            gateup_output,
            down_input,
            down_input_scale,
            scale_block_size,
            masked_m,
            scale_ue8m0=deep_gemm_wrapper.DEEPGEMM_SCALE_UE8M0,
        )
        del gateup_output

        # GroupGemm-1
        n = self.w2_weight.size(1)
        down_input_fp8 = (
            down_input,
            (
                down_input_scale
                if deep_gemm_wrapper.DEEPGEMM_SCALE_UE8M0
                else deep_gemm_wrapper.get_col_major_tma_aligned_tensor(
                    down_input_scale
                )
            ),
        )
        down_output = torch.empty(
            (num_groups, m, n), device=down_input.device, dtype=torch.bfloat16
        )
        deep_gemm_wrapper.grouped_gemm_nt_f8f8bf16_masked(
            down_input_fp8,
            self.w2_weight_fp8,
            down_output,
            masked_m,
            expected_m,
            recipe=(1, 128, 128) if deep_gemm_wrapper.DEEPGEMM_V202506 else None,
        )

        return down_output


def get_moe_impl_class():
    if global_server_args_dict["enable_deepep_moe"]:
        return DeepEPMoE
    if global_server_args_dict["enable_ep_moe"]:
        return EPMoE
    return FusedMoE
