#
# Copyright (c) 2025 Baidu, Inc. All Rights Reserved.
# Author: Li Wei, Pan Xiakai, You Zeyu
# Email: liwei157@baidu.com
# This file is a part of the vllm-kunlun project.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import torch

from typing import Optional
from vllm.model_executor.layers.quantization.awq import AWQLinearMethod


def repack_int4_for_kunlun(self, packed: torch.Tensor, num_bits: int = 4):
    """Convert AWQ-packed int4 weights to Kunlun XPU format.
    Input:  packed[N, K], dtype=int32, saved as AWQ order
    Output: packed_reordered[N, K], dtype=int32, saved as Kunlun order
    """
    N, K = packed.shape
    self.align_type = 1 if K % 8 == 0 else 0
    assert num_bits == 4, "Only int4 supported now"
    shifts = torch.arange(0, 32, num_bits, device=packed.device, dtype=torch.int32)

    if self.align_type == 0:  # NORMAL MODE
        # Unpack AWQ order:[0, 2, 4, 6, 1, 3, 5, 7]
        unpacked_awq = (packed.unsqueeze(-1) >> shifts) & 0xF  # [N, K, 8]

        # Reverse AWQ order and convert to KUNLUN order
        AWQ_TO_KUNLUN_ORDER_NORMAL = [4, 0, 5, 1, 6, 2, 7, 3]
        # [0,2,4,6,1,3,5,7] --> [1, 0, 3, 2, 5, 4, 7, 6]
        unpacked_kunlun = unpacked_awq[..., AWQ_TO_KUNLUN_ORDER_NORMAL]  # [N, K, 8]

        # Pack to int32, order[6, 7, 4, 5, 2, 3, 0, 1]
        packed_kunlun = (unpacked_kunlun << shifts).sum(
            dim=-1, dtype=torch.int32
        )  # [N, K]
    elif self.align_type == 1:  # FAST MODEL
        # Unpack AWQ order
        unpacked_awq = (
            packed.view(N, K // 8, 8).unsqueeze(-1) >> shifts
        ) & 0xF  # [N, K//8, 8, 8]

        # Reverse AWQ order and convert to KUNLUN order
        AWQ_TO_KUNLUN_ORDER_FAST = [
            32, 0, 36, 4, 33, 1, 37, 5,
            34, 2, 38, 6, 35, 3, 39, 7,
            40, 8, 44, 12, 41, 9, 45, 13,
            42, 10, 46, 14, 43, 11, 47, 15,
            48, 16, 52, 20, 49, 17, 53, 21,
            50, 18, 54, 22, 51, 19, 55, 23,
            56, 24, 60, 28, 57, 25, 61, 29,
            58, 26, 62, 30, 59, 27, 63, 31
        ]
        unpacked_awq = unpacked_awq.reshape(N, K // 8, 64)
        unpacked_kunlun = unpacked_awq[..., AWQ_TO_KUNLUN_ORDER_FAST]  # [N, K//8, 64]

        # Pack to int32
        unpacked_kunlun = unpacked_kunlun.reshape(N, K // 8, 8, 8)
        packed_kunlun = (
            (unpacked_kunlun << shifts).sum(dim=-1, dtype=torch.int32).reshape(N, K)
        )  # [N, K]
    else:
        raise NotImplementedError

    return packed_kunlun


def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
    layer.qweight = torch.nn.Parameter(
        (
            self.repack_int4_for_kunlun(layer.qweight.data)
            if layer.qweight.data.dtype == torch.int32
            else layer.qweight.data
        ),
        requires_grad=False,
    )
    layer.qzeros = torch.nn.Parameter(
        (
            self.repack_int4_for_kunlun(layer.qzeros.data)
            if layer.qzeros.data.dtype == torch.int32
            else layer.qzeros.data
        ),
        requires_grad=False,
    )
    layer.scales = torch.nn.Parameter(layer.scales.data, requires_grad=False)


def apply(
    self, layer: torch.nn.Module, x: torch.Tensor, bias: Optional[torch.Tensor] = None
) -> torch.Tensor:
    qweight = layer.qweight
    scales = layer.scales
    qzeros = layer.qzeros
    pack_factor = self.quant_config.pack_factor
    out_shape = x.shape[:-1] + (qweight.shape[-1] * pack_factor,)
    reshaped_x = x.reshape(-1, x.shape[-1])

    # num_tokens >= threshold
    FP16_MATMUL_HEURISTIC_CONDITION = x.shape[:-1].numel() >= 256

    if FP16_MATMUL_HEURISTIC_CONDITION:
        out = torch.ops._C.awq_dequantize(
            qweight, scales, qzeros, quant_type=0, align_type=self.align_type
        )
        out = torch.matmul(reshaped_x, out)
    else:
        out = torch.ops._C.awq_gemm(
            reshaped_x, qweight, scales, qzeros, align_type=self.align_type
        )
    if bias is not None:
        out.add_(bias)
    return out.reshape(out_shape)


AWQLinearMethod.repack_int4_for_kunlun = repack_int4_for_kunlun
AWQLinearMethod.process_weights_after_loading = process_weights_after_loading
AWQLinearMethod.apply = apply