# SPDX-License-Identifier: Apache-2.0

from __future__ import annotations

import logging
from typing import TYPE_CHECKING, Any, Callable, Optional

import torch
from aiter import ActivationType, QuantType, biased_grouped_topk
from aiter.fused_moe import fused_moe
from aiter.utility.fp4_utils import e8m0_shuffle

from sglang.srt.layers.moe import MoeRunnerConfig
from sglang.srt.layers.quantization.base_config import FusedMoEMethodBase
from sglang.srt.utils import get_bool_env_var, mxfp_supported, set_weight_attrs

if TYPE_CHECKING:
    from sglang.srt.layers.moe.token_dispatcher import (
        CombineInput,
        StandardDispatchOutput,
    )
    from sglang.srt.layers.quantization.quark.quark import QuarkConfig

logger = logging.getLogger(__name__)

__all__ = ["QuarkMoEMethod", "QuarkW4A4MXFp4MoEMethod"]

OCP_MX_BLOCK_SIZE = 32

if TYPE_CHECKING:
    from sglang.srt.layers.quantization import QuarkConfig


class QuarkMoEMethod(FusedMoEMethodBase):

    def __init__(self, quant_config: QuarkConfig):
        self.quant_config = quant_config

    @staticmethod
    def get_moe_method(
        quant_config: QuarkConfig,  # type: ignore # noqa E501 # noqa F821
        module: torch.nn.Module,
        layer_name: str,
    ) -> "QuarkMoEMethod":
        layer_quant_config = quant_config._find_matched_config(layer_name, module)

        if layer_quant_config.get("output_tensors") or layer_quant_config.get("bias"):
            raise NotImplementedError(
                "Currently, Quark models with "
                "output_tensors and bias "
                "quantized are not supported"
            )
        weight_config = layer_quant_config.get("weight")
        input_config = layer_quant_config.get("input_tensors")

        if quant_config._is_mx_fp4(weight_config, input_config):
            return QuarkW4A4MXFp4MoEMethod(weight_config, input_config)
        else:
            raise RuntimeError("Unsupported FusedMoe scheme")


class QuarkW4A4MXFp4MoEMethod(QuarkMoEMethod):

    def __init__(self, weight_config: dict[str, Any], input_config: dict[str, Any]):
        self.weight_quant = weight_config
        self.input_quant = input_config

        weight_qscheme = self.weight_quant.get("qscheme")
        input_qscheme = self.input_quant.get("qscheme")
        if not (weight_qscheme == "per_group" and input_qscheme == "per_group"):
            raise ValueError(
                "For MX(FP4) Fused MoE layers, only per-group scales "
                "for weights and activations are supported. Found "
                f"{weight_qscheme}, {input_qscheme}"
            )  # noqa E501

        self.static_input_scales = not self.input_quant.get("is_dynamic")
        self.with_bias = False

    def create_weights(
        self,
        layer: torch.nn.Module,
        num_experts: int,
        hidden_size: int,
        intermediate_size_per_partition: int,
        params_dtype: torch.dtype,
        **extra_weight_attrs,
    ):

        from sglang.srt.layers.moe.fused_moe_triton import FusedMoeWeightScaleSupported

        # 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}
        )

        params_dtype = torch.uint8

        # WEIGHTS
        w13_weight = torch.nn.Parameter(
            torch.empty(
                num_experts,
                2 * intermediate_size_per_partition,
                hidden_size // 2,
                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,
                hidden_size,
                intermediate_size_per_partition // 2,
                dtype=params_dtype,
            ),
            requires_grad=False,
        )
        layer.register_parameter("w2_weight", w2_weight)

        set_weight_attrs(w2_weight, extra_weight_attrs)

        # WEIGHT_SCALES
        w13_weight_scale = torch.nn.Parameter(
            torch.ones(
                num_experts,
                2 * intermediate_size_per_partition,
                hidden_size // OCP_MX_BLOCK_SIZE,
                dtype=params_dtype,
            ),
            requires_grad=False,
        )
        w2_weight_scale = torch.nn.Parameter(
            torch.ones(
                num_experts,
                hidden_size,
                intermediate_size_per_partition // OCP_MX_BLOCK_SIZE,
                dtype=params_dtype,
            ),
            requires_grad=False,
        )
        set_weight_attrs(w2_weight_scale, extra_weight_attrs)
        set_weight_attrs(w13_weight_scale, extra_weight_attrs)

        layer.register_parameter("w13_weight_scale", w13_weight_scale)
        layer.register_parameter("w2_weight_scale", w2_weight_scale)

    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
        float_dtype = torch.get_default_dtype()

        # Pre-shuffle weight scales
        s0, s1, _ = layer.w13_weight_scale.shape
        w13_weight_scale = layer.w13_weight_scale.view(s0 * s1, -1)
        w13_weight_scale = e8m0_shuffle(w13_weight_scale)
        # layer.w13_weight_scale = torch.nn.Parameter(w13_weight_scale, requires_grad=False)
        layer.w13_weight_scale.data = w13_weight_scale.view(s0, s1, -1)

        s0, s1, _ = layer.w2_weight_scale.shape
        w2_weight_scale = layer.w2_weight_scale.view(s0 * s1, -1)
        w2_weight_scale = e8m0_shuffle(w2_weight_scale)
        # layer.w2_weight_scale = torch.nn.Parameter(w2_weight_scale, requires_grad=False)
        layer.w2_weight_scale.data = w2_weight_scale.view(s0, s1, -1)

    def create_moe_runner(
        self, layer: torch.nn.Module, moe_runner_config: MoeRunnerConfig
    ):
        self.moe_runner_config = moe_runner_config

    def apply(
        self,
        layer: torch.nn.Module,
        dispatch_output: StandardDispatchOutput,
    ) -> CombineInput:

        from sglang.srt.layers.moe.token_dispatcher import StandardCombineInput

        x = dispatch_output.hidden_states
        topk_output = dispatch_output.topk_output
        moe_runner_config = self.moe_runner_config
        topk_weights, topk_ids, _ = topk_output

        if hasattr(torch, "float4_e2m1fn_x2"):
            w13_weight = layer.w13_weight.view(torch.float4_e2m1fn_x2)
            w2_weight = layer.w2_weight.view(torch.float4_e2m1fn_x2)
        else:
            w13_weight = layer.w13_weight
            w2_weight = layer.w2_weight

        output = fused_moe(
            x,
            w13_weight,
            w2_weight,
            topk_weights,
            topk_ids,
            quant_type=QuantType.per_1x32,
            w1_scale=layer.w13_weight_scale,
            w2_scale=layer.w2_weight_scale,
            activation=(
                ActivationType.Silu
                if moe_runner_config.activation == "silu"
                else ActivationType.Gelu
            ),
            doweight_stage1=False,
        )
        return StandardCombineInput(hidden_states=output)
