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


import torch

from vllm import _custom_ops as ops
from vllm._aiter_ops import (
    rocm_aiter_ops,
)
from vllm.logger import init_logger
from vllm.model_executor.layers.quantization.utils.quant_utils import (
    GroupShape,
)
from vllm.model_executor.utils import replace_parameter
from vllm.platforms import current_platform

from .BlockScaledMMLinearKernel import (
    Fp8BlockScaledMMLinearKernel,
)
from .cutlass import CutlassInt8ScaledMMLinearKernel
from .ScaledMMLinearKernel import (
    FP8ScaledMMLinearKernel,
    FP8ScaledMMLinearLayerConfig,
    Int8ScaledMMLinearLayerConfig,
)

logger = init_logger(__name__)


class AiterInt8ScaledMMLinearKernel(CutlassInt8ScaledMMLinearKernel):
    @classmethod
    def is_supported(
        cls, compute_capability: int | None = None
    ) -> tuple[bool, str | None]:
        if not current_platform.is_rocm():
            return False, "Requires ROCm."

        if compute_capability is not None and compute_capability < 90:
            return False, "requires compute capability 90 and above."

        try:
            import aiter  # noqa: F401 # deliberately attempt to import aiter
        except Exception:
            return False, "requires `aiter` to be installed."

        if not rocm_aiter_ops.is_linear_enabled():
            return (
                False,
                "requires setting `VLLM_ROCM_USE_AITER=1` "
                "and `VLLM_ROCM_USE_AITER_LINEAR=1`. "
                "`VLLM_ROCM_USE_AITER_LINEAR` default is True.",
            )
        return True, None

    @classmethod
    def can_implement(cls, c: Int8ScaledMMLinearLayerConfig) -> tuple[bool, str | None]:
        if not c.input_symmetric:
            return False, "supports symmetric quantization only."
        return True, None

    def apply_weights(
        self,
        layer: torch.nn.Module,
        x: torch.Tensor,
        bias: torch.Tensor | None = None,
    ) -> torch.Tensor:
        """
        `AiterInt8ScaledMMLinearKernel` implements a fused version of
            `output = torch.mm((scale_a * a), (scale_b * b)).to(out_dtype)`
        where scale_a * a and scale_b * b are implemented using numpy-style
        broadcasting.
        Currently only support per-tensor-per-tensor GEMM
        and per-token-per-channel GEMM through AITER
        w8a8 scaled gemm. `AiterInt8ScaledMMLinearKernel` also does not support
        ATIER block scaled GEMM and mix-precision GEMM.
        """
        w_q, w_s, i_s, i_zp, azp_adj = self._get_layer_params(layer)

        # ops.scaled_int8_quant supports both dynamic and static quant:
        # * dynamic, i_s is None and x_s computed from x.
        # * static, i_s is scalar and x_s is i_s.
        symmetric = azp_adj is None
        assert symmetric, (
            "AiterInt8ScaledMMLinearKernel only supports symmetric quantization."
        )
        x_q, x_s, x_zp = ops.scaled_int8_quant(x, i_s, i_zp, symmetric=symmetric)

        assert x_zp is None, (
            "AiterInt8ScaledMMLinearKernel only supports symmetric quantization."
        )
        out_dtype = x.dtype

        assert w_q.shape[0] % 16 == 0 and w_q.shape[1] % 16 == 0
        assert out_dtype is torch.bfloat16 or out_dtype is torch.float16
        assert bias is None or bias.shape[0] == w_q.shape[1] and bias.dtype == out_dtype

        m = x_q.shape[0]  # a
        n = w_q.shape[1]  # b

        per_tensor_scale_a = x_s.numel() == 1
        per_tensor_scale_b = w_s.numel() == 1
        per_token_scale_a = x_s.numel() == m
        per_channel_scale_b = w_s.numel() == n

        # @TODO:
        # Maybe broadcast the per-tensor-scale into per-channel-scale
        # if one of the scale is a per-channel-scale.
        # For now, it only supports:
        # - per-tensor-per-tensor a8w8 scaled GEMM, and
        # - per-token-per-channel a8w8 scaled GEMM
        assert (per_tensor_scale_a and per_tensor_scale_b) or (
            per_token_scale_a and per_channel_scale_b
        ), (
            "Currently only support per-tensor-per-tensor GEMM "
            " and per-token-per-channel GEMM through AITER"
            " w8a8 scaled gemm. `AiterInt8ScaledMMLinearKernel` "
            "does not support AITER block scaled GEMM."
        )

        # gemm_a8w8_CK(a, b, scale_a, scale_b, bias) expects
        # a to be [M, K]
        # b to be [N, K]
        # CutlassInt8ScaledMMLinearKernel prepare weight `w_q` in [K, N] format
        return rocm_aiter_ops.w8a8_gemm(x_q, w_q.t(), x_s, w_s, bias, out_dtype)


class AiterPreshuffledPerTokenFp8ScaledMMLinearKernel(FP8ScaledMMLinearKernel):
    @classmethod
    def is_supported(
        cls, compute_capability: int | None = None
    ) -> tuple[bool, str | None]:
        if not current_platform.is_rocm():
            return False, "requires ROCm."
        if not rocm_aiter_ops.is_linear_fp8_enabled():
            return (
                False,
                "requires setting `VLLM_ROCM_USE_AITER=1` "
                "and `VLLM_ROCM_USE_AITER_LINEAR=1`. "
                "`VLLM_ROCM_USE_AITER_LINEAR` default is True.",
            )
        try:
            import aiter  # noqa: F401
        except Exception:
            return False, "requires aiter library to be installed."
        return True, None

    @classmethod
    def can_implement(cls, c: FP8ScaledMMLinearLayerConfig) -> tuple[bool, str | None]:
        is_ptpc = (
            c.activation_quant_key.scale.group_shape.is_per_token()
            and c.weight_quant_key.scale.group_shape.is_per_channel()
        )
        if c.weight_shape is None:
            return False, "weight_shape is required for Aiter kernels"
        N, K = c.weight_shape
        fp8_dtype = current_platform.fp8_dtype()

        if c.out_dtype is not torch.bfloat16:
            return False, "requires bfloat16 output dtype."

        if not is_ptpc:
            return (
                False,
                "requires per token activation scales and per channel weight scales.",
            )

        if not (N % 16 == 0 and K % 16 == 0):
            return (
                False,
                f"requires N and K dimensions divisible by 16, received "
                f"N={N} and K={K}.",
            )

        # Aiter's shuffled per-token Gemm performs better than torch only when its
        # tuned.
        if not rocm_aiter_ops.is_shuffled_per_token_w8a8_gemm_tuned(N, K, fp8_dtype):
            return (
                False,
                f"requires a tuned configuration for N: {N} and K: {K} "
                f"and fp8 dtype {fp8_dtype}.",
            )

        return True, None

    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
        w_name, *_ = self.layer_param_names
        w, *_ = self._get_layer_params(layer)

        replace_parameter(
            layer,
            w_name,
            torch.nn.Parameter(
                rocm_aiter_ops.shuffle_weight(w.t().contiguous()).data,
                requires_grad=False,
            ),
        )

    def apply_scaled_mm(
        self,
        *,
        A: torch.Tensor,
        B: torch.Tensor,
        out_dtype: torch.dtype,
        As: torch.Tensor,
        Bs: torch.Tensor,
        bias: torch.Tensor | None,
        output_shape: list,
    ) -> torch.Tensor:
        return rocm_aiter_ops.preshuffled_per_token_w8a8_gemm(
            A, B, As, Bs, bias, out_dtype
        )


class AiterPerTokenFp8ScaledMMLinearKernel(FP8ScaledMMLinearKernel):
    @classmethod
    def is_supported(
        cls, compute_capability: int | None = None
    ) -> tuple[bool, str | None]:
        return AiterPreshuffledPerTokenFp8ScaledMMLinearKernel.is_supported(
            compute_capability
        )

    @classmethod
    def can_implement(cls, c: FP8ScaledMMLinearLayerConfig) -> tuple[bool, str | None]:
        is_ptpc = (
            c.activation_quant_key.scale.group_shape.is_per_token()
            and c.weight_quant_key.scale.group_shape.is_per_channel()
        )
        if c.weight_shape is None:
            return False, "weight_shape is required for Aiter kernels"
        N, K = c.weight_shape
        fp8_dtype = current_platform.fp8_dtype()

        if not is_ptpc:
            return (
                False,
                "requires per token activation scales and per channel weight scales.",
            )

        # Aiter's per-token Gemm performs better than torch oonly when its
        # tuned.
        if not rocm_aiter_ops.is_per_token_w8a8_gemm_tuned(N, K, fp8_dtype):
            return (
                False,
                f"requires a tuned configuration for N: {N} and K: {K} "
                f"and fp8 dtype {fp8_dtype}.",
            )
        return True, None

    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
        w_name, *_ = self.layer_param_names
        w, *_ = self._get_layer_params(layer)

        replace_parameter(
            layer,
            w_name,
            torch.nn.Parameter(w.t(), requires_grad=False),
        )

    def apply_scaled_mm(
        self,
        *,
        A: torch.Tensor,
        B: torch.Tensor,
        out_dtype: torch.dtype,
        As: torch.Tensor,
        Bs: torch.Tensor,
        bias: torch.Tensor | None,
        output_shape: list,
    ) -> torch.Tensor:
        return rocm_aiter_ops.w8a8_gemm(A, B, As, Bs, bias, out_dtype)


class AiterFp8BlockScaledMMKernel(Fp8BlockScaledMMLinearKernel):
    def __init__(self, config: FP8ScaledMMLinearLayerConfig):
        super().__init__(config)
        n, k = config.weight_shape

        self.use_triton = (
            not current_platform.is_fp8_fnuz()
            and rocm_aiter_ops.is_triton_gemm_w8a8_tuned(n, k)
        )

    @classmethod
    def is_supported(cls, compute_capability=None):
        return (
            rocm_aiter_ops.is_linear_enabled(),
            "Only supported on ROCm platform \
                with aiter package installed.",
        )

    @classmethod
    def can_implement(cls, config: FP8ScaledMMLinearLayerConfig):
        can_implement_base, reason = super().can_implement(config)
        if not can_implement_base:
            return can_implement_base, reason

        act_quant_desc = config.activation_quant_key.scale
        if act_quant_desc.group_shape != GroupShape(1, 128):
            return (
                False,
                "Supports only dynamic per token group activation "
                "quantization with group_shape=(1,128).",
            )
        return True, None

    def apply_block_scaled_mm(
        self,
        A: torch.Tensor,
        B: torch.Tensor,
        As: torch.Tensor,
        Bs: torch.Tensor,
    ) -> torch.Tensor:
        out_dtype = self.config.out_dtype
        if self.use_triton:
            gemm_a8w8_blockscale_op = rocm_aiter_ops.triton_gemm_a8w8_blockscale
        else:
            gemm_a8w8_blockscale_op = rocm_aiter_ops.gemm_a8w8_blockscale

        return gemm_a8w8_blockscale_op(
            A, B, As, Bs, list(self.weight_group_shape), output_dtype=out_dtype
        )
