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

from typing import Optional

import pytest
import torch

from tests.kernels.utils import torch_experts
from vllm import _custom_ops as ops
from vllm.config import VllmConfig, set_current_vllm_config
from vllm.model_executor.layers.fused_moe.config import fp8_w8a8_moe_quant_config
from vllm.model_executor.layers.fused_moe.cutlass_moe import CutlassBatchedExpertsFp8
from vllm.model_executor.layers.fused_moe.fused_moe import fused_topk
from vllm.model_executor.layers.fused_moe.modular_kernel import FusedMoEModularKernel
from vllm.platforms import current_platform
from vllm.utils import cdiv

from ...utils import multi_gpu_test
from .parallel_utils import ProcessGroupInfo, parallel_launch

try:
    from pplx_kernels import AllToAll
    from pplx_kernels.nvshmem import (
        nvshmem_alloc_empty_unique_id,
        nvshmem_finalize,
        nvshmem_get_unique_id,
        nvshmem_init,
    )

    has_pplx = True
except ImportError:
    has_pplx = False

requires_pplx = pytest.mark.skipif(
    not has_pplx,
    reason="Requires PPLX kernels",
)

NUM_EXPERTS = [40, 64]
TOP_KS = [6, 8]


def rank_chunk(num, r, w):
    rem = num % w
    return (num // w) + (1 if r < rem else 0)


def chunk_by_rank(t, r, w):
    num = t.shape[0]
    chunk = rank_chunk(num, r, w)
    rem = num % w
    if rem == 0 or r < rem:
        return t[(r * chunk) : (r + 1) * chunk].contiguous()
    else:
        long_chunks = (num // w + 1) * rem
        short_chunks = (r - rem) * chunk
        start = long_chunks + short_chunks
        return t[start : start + chunk].contiguous()


def pplx_cutlass_moe(
    pgi: ProcessGroupInfo,
    dp_size: int,
    a: torch.Tensor,
    w1: torch.Tensor,
    w2: torch.Tensor,
    w1_scale: torch.Tensor,
    w2_scale: torch.Tensor,
    topk_weights: torch.Tensor,
    topk_ids: torch.Tensor,
    a1_scale: torch.Tensor,
    out_dtype,
    per_act_token: bool,
    per_out_ch: bool,
    group_name: Optional[str],
):
    from vllm.model_executor.layers.fused_moe.pplx_prepare_finalize import (
        PplxPrepareAndFinalize,
    )

    assert torch.cuda.current_device() == pgi.local_rank

    num_tokens, hidden_dim = a.shape
    intermediate_dim = w2.shape[2]
    num_experts = w1.shape[0]
    block_size = hidden_dim  # TODO support more cases
    device = pgi.device
    rank = pgi.rank
    world_size = pgi.world_size
    rank_num_tokens = rank_chunk(num_tokens, rank, world_size)
    max_num_tokens = rank_chunk(num_tokens, 0, world_size)
    topk = topk_ids.shape[1]

    if block_size == hidden_dim:
        scale_elems = 4  # hack to circumvent pplx data format requirements
    else:
        scale_elems = (hidden_dim + block_size - 1) // block_size

    args = dict(
        max_num_tokens=max_num_tokens,
        num_experts=num_experts,
        experts_per_token=topk,
        rank=rank,
        world_size=world_size,
        dp_size=dp_size,
        hidden_dim=hidden_dim,
        hidden_dim_bytes=hidden_dim,  # because a.dtype.itemsize == 1
        hidden_dim_scale_bytes=scale_elems * torch.float32.itemsize,
    )

    if group_name is None:
        ata = AllToAll.internode(**args)
    else:
        args["group_name"] = group_name
        ata = AllToAll.intranode(**args)

    w1 = w1.to(device)
    w2 = w2.to(device)
    w1_scale = w1_scale.to(device)
    w2_scale = w2_scale.to(device)
    a1_scale = a1_scale.to(device)

    assert num_experts % world_size == 0
    num_local_experts = cdiv(num_experts, world_size)
    num_dispatchers = pgi.world_size // dp_size

    prepare_finalize = PplxPrepareAndFinalize(
        ata,
        max_num_tokens=max_num_tokens,
        num_local_experts=num_local_experts,
        num_dispatchers=num_dispatchers,
    )

    ab_strides1 = torch.full(
        (num_local_experts,), hidden_dim, device="cuda", dtype=torch.int64
    )
    ab_strides2 = torch.full(
        (num_local_experts,), intermediate_dim, device="cuda", dtype=torch.int64
    )
    c_strides1 = torch.full(
        (num_local_experts,), 2 * intermediate_dim, device="cuda", dtype=torch.int64
    )
    c_strides2 = torch.full(
        (num_local_experts,), hidden_dim, device="cuda", dtype=torch.int64
    )

    experts = CutlassBatchedExpertsFp8(
        num_local_experts,
        num_dispatchers,
        out_dtype,
        ab_strides1,
        ab_strides2,
        c_strides1,
        c_strides2,
        fp8_w8a8_moe_quant_config(
            per_act_token_quant=per_act_token,
            per_out_ch_quant=per_out_ch,
            w1_scale=chunk_by_rank(w1_scale, rank, world_size),
            w2_scale=chunk_by_rank(w2_scale, rank, world_size),
            a1_scale=chunk_by_rank(a1_scale, rank, world_size)
            if per_act_token
            else a1_scale[rank],
        ),
    )

    fused_cutlass_experts = FusedMoEModularKernel(
        prepare_finalize,
        experts,
    )

    a_chunk = chunk_by_rank(a, rank, world_size).to(device)
    chunk_topk_weight = chunk_by_rank(topk_weights, rank, world_size).to(device)
    chunk_topk_ids = (
        chunk_by_rank(topk_ids, rank, world_size).to(torch.uint32).to(device)
    )

    out = fused_cutlass_experts(
        a_chunk,
        chunk_by_rank(w1, rank, world_size),
        chunk_by_rank(w2, rank, world_size),
        chunk_topk_weight,
        chunk_topk_ids,
        global_num_experts=num_experts,
        expert_map=None,  # TODO
    )

    torch.cuda.synchronize()

    ata.destroy()

    return out[:rank_num_tokens]


vllm_config = VllmConfig()
vllm_config.scheduler_config.max_num_seqs = 128
vllm_config.scheduler_config.max_model_len = 8192


def _pplx_moe(
    pgi: ProcessGroupInfo,
    dp_size: int,
    a: torch.Tensor,
    w1: torch.Tensor,
    w2: torch.Tensor,
    w1_scale: torch.Tensor,
    w2_scale: torch.Tensor,
    topk_weights: torch.Tensor,
    topk_ids: torch.Tensor,
    a1_scale: torch.Tensor,
    out_dtype,
    a_full: torch.Tensor,
    w1_full: torch.Tensor,
    w2_full: torch.Tensor,
    per_act_token: bool,
    per_out_ch: bool,
    use_internode: bool,
):
    try:
        if use_internode:
            uid = (
                nvshmem_get_unique_id()
                if pgi.rank == 0
                else nvshmem_alloc_empty_unique_id()
            )
            torch.distributed.broadcast(uid, src=0)
            nvshmem_init(uid, pgi.rank, pgi.world_size)
        else:
            group_ranks = list(range(pgi.world_size))
            cpu_group = torch.distributed.new_group(group_ranks, backend="gloo")
            group_name = cpu_group.group_name

        with set_current_vllm_config(vllm_config):
            torch_output = torch_experts(
                a_full, w1_full, w2_full, topk_weights, topk_ids
            )
            pplx_output = pplx_cutlass_moe(
                pgi,
                dp_size,
                a,
                w1,
                w2,
                w1_scale,
                w2_scale,
                topk_weights,
                topk_ids,
                a1_scale,
                out_dtype,
                per_act_token,
                per_out_ch,
                group_name,
            )

            torch_output = chunk_by_rank(torch_output, pgi.rank, pgi.world_size).to(
                pplx_output.device
            )

        # Uncomment if more debugging is needed
        # print("PPLX OUT:", pplx_output)
        # print("TORCH OUT:", torch_output)

        torch.testing.assert_close(pplx_output, torch_output, atol=0.05, rtol=0)
    finally:
        if use_internode:
            nvshmem_finalize()


@pytest.mark.parametrize("m", [2, 224])
@pytest.mark.parametrize("n", [3072])
@pytest.mark.parametrize("k", [1536])
@pytest.mark.parametrize("e", NUM_EXPERTS)
@pytest.mark.parametrize("topk", TOP_KS)
@pytest.mark.parametrize("per_act_token", [True, False])
@pytest.mark.parametrize("per_out_ch", [True, False])
@pytest.mark.parametrize("world_dp_size", [[2, 1]])  # , [4, 2]])
@pytest.mark.parametrize("use_internode", [False])
@multi_gpu_test(num_gpus=2)
@pytest.mark.skipif(
    (lambda x: x is None or not ops.cutlass_group_gemm_supported(x.to_int()))(
        current_platform.get_device_capability()
    ),
    reason="Grouped gemm is not supported on this GPU type.",
)
@requires_pplx
def test_cutlass_moe_pplx(
    m: int,
    n: int,
    k: int,
    e: int,
    topk: int,
    per_act_token: bool,
    per_out_ch: bool,
    world_dp_size: tuple[int, int],
    use_internode: bool,
):
    current_platform.seed_everything(7)

    with set_current_vllm_config(vllm_config):
        dtype = torch.half

        a = torch.randn((m, k), device="cuda", dtype=dtype) / 10.0
        w1 = torch.randn((e, 2 * n, k), device="cuda", dtype=dtype) / 10.0
        w2 = torch.randn((e, k, n), device="cuda", dtype=dtype) / 10.0

        n_b_scales = 2 * n if per_out_ch else 1
        k_b_scales = k if per_out_ch else 1

        w1_q = torch.empty((e, 2 * n, k), device="cuda", dtype=torch.float8_e4m3fn)
        w2_q = torch.empty((e, k, n), device="cuda", dtype=torch.float8_e4m3fn)
        w1_scale = torch.empty((e, n_b_scales, 1), device="cuda", dtype=torch.float32)
        w2_scale = torch.empty((e, k_b_scales, 1), device="cuda", dtype=torch.float32)

        for expert in range(e):
            w1_q[expert], w1_scale[expert] = ops.scaled_fp8_quant(
                w1[expert], use_per_token_if_dynamic=per_out_ch
            )
            w2_q[expert], w2_scale[expert] = ops.scaled_fp8_quant(
                w2[expert], use_per_token_if_dynamic=per_out_ch
            )

        w1_d = torch.empty_like(w1)
        w2_d = torch.empty_like(w2)
        for expert in range(e):
            w1_d[expert] = (w1_q[expert].float() * w1_scale[expert]).half()
            w2_d[expert] = (w2_q[expert].float() * w2_scale[expert]).half()

        score = torch.randn((m, e), device="cuda", dtype=dtype)
        topk_weights, topk_ids, _ = fused_topk(a, score, topk, renormalize=False)

        world_size, dp_size = world_dp_size
        a_scale1 = (
            torch.randn(
                (m if per_act_token else 1, 1), device="cuda", dtype=torch.float32
            )
            / 10.0
        )
        if not per_act_token:
            a_scale1 = a_scale1.repeat(world_size, 1)

        parallel_launch(
            world_size,
            _pplx_moe,
            dp_size,
            a,
            w1_q,
            w2_q,
            w1_scale,
            w2_scale,
            topk_weights,
            topk_ids,
            a_scale1,
            dtype,
            a,
            w1_d,
            w2_d,
            per_act_token,
            per_out_ch,
            use_internode,
        )
