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

from typing import Any

import torch

from vllm.distributed import (
    get_ep_group,
)
from vllm.logger import init_logger
from vllm.model_executor.layers.fused_moe.config import (
    FusedMoEConfig,
    FusedMoEParallelConfig,
    FusedMoEQuantConfig,
)
from vllm.model_executor.layers.fused_moe.flashinfer_a2a_prepare_finalize import (
    FlashInferA2APrepareAndFinalize,
)
from vllm.model_executor.layers.fused_moe.modular_kernel import (
    FusedMoEPrepareAndFinalize,
)
from vllm.model_executor.layers.fused_moe.prepare_finalize import (
    make_moe_prepare_and_finalize_naive_dp_ep,
    make_moe_prepare_and_finalize_no_dp_ep,
)
from vllm.platforms import current_platform
from vllm.utils.import_utils import has_deep_ep, has_mori

logger = init_logger(__name__)

if current_platform.is_cuda_alike():
    if has_deep_ep():
        from .deepep_ht_prepare_finalize import DeepEPHTPrepareAndFinalize
        from .deepep_ll_prepare_finalize import (
            DEEPEP_QUANT_BLOCK_SHAPE,
            DeepEPLLPrepareAndFinalize,
        )
    if has_mori():
        from .mori_prepare_finalize import MoriPrepareAndFinalize


def maybe_roundup_layer_hidden_size(
    hidden_size: int,
    act_dtype: torch.dtype,
    moe_parallel_config: FusedMoEParallelConfig,
) -> int:
    """
    Given layer hidden size and MoE configurations, round up hidden_size
    if necessary.

    Args:
        hidden_size: Layer hidden-size
        act_dtype: Data type of the layer activations.
        moe_parallel_config: Fused MoE parallelization strategy configuration.

    Return:
        Rounded up hidden_size if rounding up is required based on the configs
        and all2all backend.
        Original hidden size otherwise.
    """
    if moe_parallel_config.use_deepep_ht_kernels:
        hidden_size = DeepEPHTPrepareAndFinalize.maybe_roundup_layer_hidden_size(
            hidden_size, act_dtype
        )

    if moe_parallel_config.use_deepep_ll_kernels:
        hidden_size = DeepEPLLPrepareAndFinalize.maybe_roundup_layer_hidden_size(
            hidden_size
        )

    return hidden_size


def maybe_make_prepare_finalize(
    moe: FusedMoEConfig,
    quant_config: FusedMoEQuantConfig | None,
    routing_tables: tuple[torch.Tensor, torch.Tensor, torch.Tensor] | None = None,
    allow_new_interface: bool = False,
    use_monolithic: bool = False,
) -> FusedMoEPrepareAndFinalize | None:
    # NOTE(rob): we are migrating each quant_method to hold the MK
    # in all cases. The allow_new_interface=False flag allow us to fall
    # back to the old method for methods that have not yet been migrated.
    #
    # In old method:
    #   * maybe_init_modular_kernel() calls this function. If we are
    #     using no Dp/Ep or naive all2all, we return None this function
    #     returns None and no ModularKernelMethod is created. If non-naive
    #     all2all is used, this returns a PrepareAndFinalize object and
    #     a ModularKernelMethod is created.
    # In new method:
    #   * maybe_make_prepare_finalize() is called from the oracle. We
    #     always return a PrepareAndFinalize object and the quant method
    #     holds the ModularKernel.
    if not moe.moe_parallel_config.use_all2all_kernels:
        if not allow_new_interface:
            return None

        # For DP/TP case, fall back to naive P/F.
        if moe.moe_parallel_config.dp_size > 1:
            logger.info_once(
                "Detected DP deployment with no --enable-expert-parallel. "
                "Falling back to AllGather+ReduceScatter dispatch/combine."
            )
            return make_moe_prepare_and_finalize_naive_dp_ep(
                is_sequence_parallel=moe.moe_parallel_config.is_sequence_parallel,
                num_dispatchers=(
                    get_ep_group().device_communicator.all2all_manager.world_size
                ),
                use_monolithic=use_monolithic,
            )
        else:
            return make_moe_prepare_and_finalize_no_dp_ep(use_monolithic)

    all2all_manager = get_ep_group().device_communicator.all2all_manager
    assert all2all_manager is not None

    prepare_finalize: FusedMoEPrepareAndFinalize | None = None

    if moe.use_deepep_ht_kernels:
        assert moe.dp_size == all2all_manager.dp_world_size

        all_to_all_args: dict[str, Any] = dict()
        handle = all2all_manager.get_handle(all_to_all_args)
        prepare_finalize = DeepEPHTPrepareAndFinalize(
            handle,
            num_dispatchers=all2all_manager.world_size,
            dp_size=all2all_manager.dp_world_size,
            rank_expert_offset=all2all_manager.rank * moe.num_local_experts,
        )

    elif moe.use_deepep_ll_kernels:
        assert quant_config is not None
        global_to_physical = physical_to_global = local_expert_global_ids = None
        if routing_tables is not None:
            (
                global_to_physical,
                physical_to_global,
                local_expert_global_ids,
            ) = routing_tables
        all_to_all_args = dict(
            max_num_tokens_per_dp_rank=moe.max_num_tokens,
            token_hidden_size=moe.hidden_dim,
            num_ep_ranks=all2all_manager.world_size,
            num_global_experts=moe.num_experts,
            num_local_experts=moe.num_experts // all2all_manager.world_size,
        )
        handle = all2all_manager.get_handle(all_to_all_args)

        # Note: We may want to use FP8 dispatch just to reduce
        # data movement.
        use_fp8_dispatch = (
            quant_config.quant_dtype == current_platform.fp8_dtype()
            and quant_config.block_shape == DEEPEP_QUANT_BLOCK_SHAPE
        )

        prepare_finalize = DeepEPLLPrepareAndFinalize(
            handle,
            max_tokens_per_rank=moe.max_num_tokens,
            num_dispatchers=all2all_manager.world_size,
            use_fp8_dispatch=use_fp8_dispatch,
            global_to_physical=global_to_physical,
            physical_to_global=physical_to_global,
            local_expert_global_ids=local_expert_global_ids,
        )
    elif moe.use_mori_kernels:
        assert quant_config is not None

        # Note: We may want to use FP8 dispatch just to reduce
        # data movement.
        use_fp8_dispatch = (
            quant_config.is_per_act_token or quant_config.is_block_quantized
        )
        # For PTPC (per token per channel) quant, the scale dim for each token is 1
        # For 1x128 quant, the scale dim for each token is hidden_dim // 128
        scale_dim = 1 if quant_config.is_per_act_token else moe.hidden_dim // 128
        all_to_all_args = dict(
            rank=all2all_manager.rank,
            num_ep_ranks=all2all_manager.world_size,
            quant_dtype=quant_config.quant_dtype,
            token_hidden_size=moe.hidden_dim,
            scale_dim=scale_dim,
            scale_type_size=torch.float32.itemsize,
            max_num_tokens_per_dp_rank=moe.max_num_tokens,
            input_dtype=moe.in_dtype,
            num_local_experts=moe.num_experts // all2all_manager.world_size,
            num_experts_per_token=moe.experts_per_token,
        )
        handle = all2all_manager.get_handle(all_to_all_args)

        prepare_finalize = MoriPrepareAndFinalize(
            handle,
            max_tokens_per_rank=moe.max_num_tokens,
            num_dispatchers=all2all_manager.world_size,
            use_fp8_dispatch=use_fp8_dispatch,
        )

    elif moe.use_fi_all2allv_kernels:
        assert quant_config is not None
        prepare_finalize = FlashInferA2APrepareAndFinalize(
            num_dispatchers=all2all_manager.world_size,
        )

    elif moe.use_naive_all2all_kernels and allow_new_interface:
        prepare_finalize = make_moe_prepare_and_finalize_naive_dp_ep(
            use_monolithic=use_monolithic,
            is_sequence_parallel=moe.moe_parallel_config.is_sequence_parallel,
            num_dispatchers=all2all_manager.world_size,
        )

    return prepare_finalize
