# Adapt from https://github.com/vllm-project/vllm/blob/main/vllm/v1/worker/gpu/model_runner.py
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
# Copyright (c) 2025 Huawei Technologies Co., Ltd. All Rights Reserved.
#
# 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.
# This file is a part of the vllm-ascend project.
#

import numpy as np
import torch
from vllm.config import VllmConfig
from vllm.config.compilation import CUDAGraphMode
from vllm.v1.core.sched.output import SchedulerOutput
from vllm.v1.worker.gpu.buffer_utils import async_copy_to_gpu
from vllm.v1.worker.gpu.cudagraph_utils import BatchExecutionDescriptor
from vllm.v1.worker.gpu.input_batch import (
    combine_sampled_and_draft_tokens,
    expand_idx_mapping,
    prepare_pos_seq_lens,
    prepare_prefill_inputs,
)
from vllm.v1.worker.gpu.model_runner import GPUModelRunner

from vllm_ascend.ascend_config import get_ascend_config
from vllm_ascend.utils import set_weight_prefetch_method
from vllm_ascend.worker.v2.aclgraph_utils import ModelAclGraphManager
from vllm_ascend.worker.v2.attn_utils import build_attn_state
from vllm_ascend.worker.v2.input_batch import AscendInputBatch, AscendInputBuffers
from vllm_ascend.worker.v2.sample.sampler import AscendSampler
from vllm_ascend.worker.v2.spec_decode import init_speculator
from vllm_ascend.worker.v2.spec_decode.eagle import AscendEagleSpeculator
from vllm_ascend.worker.v2.states import AscendRequestState
from vllm_ascend.worker.v2.utils import torch_cuda_wrapper


class NPUModelRunner(GPUModelRunner):
    """Model runner for Ascend NPUs."""

    def __init__(self, vllm_config: VllmConfig, device: torch.device):
        with torch_cuda_wrapper():
            super().__init__(vllm_config, device)

        # because we will override these attribute, delete these attribute to
        # make sure it's collected by python gc immediately.
        del self.cudagraph_manager
        del self.req_states
        del self.input_buffers
        del self.sampler
        del self.speculator

        # NPU specific initializations can be added below.
        self.cudagraph_manager: ModelAclGraphManager = ModelAclGraphManager(
            self.vllm_config,
            self.device,
            self.compilation_config.cudagraph_mode,
            decode_query_len=self.decode_query_len,
            model_runner=self,
        )

        # we define AscendEagleSpeculator in vllm_ascend.worker.v2.spec_decode.eagle
        # init_speculator will return AscendEagleSpeculator when eagle is used.
        # so here we just call init_speculator to reinitialize speculator.
        self.speculator: AscendEagleSpeculator | None = None
        if self.speculative_config is not None:
            self.speculator = init_speculator(self.vllm_config, self.device)

        # AscendRequestState has extra `num_computed_tokens_cpu` attribute.
        # so reinitialize req_states here.
        self.req_states: AscendRequestState = AscendRequestState(
            max_num_reqs=self.max_num_reqs,
            max_model_len=self.max_model_len,
            max_num_batched_tokens=self.max_num_tokens,
            num_speculative_steps=self.num_speculative_steps,
            vocab_size=self.vocab_size,
            device=self.device,
        )
        # AscendInputBuffers has extra `seq_lens_cpu` attribute.
        # so reinitialize input_buffers here.
        self.input_buffers: AscendInputBuffers = AscendInputBuffers(
            max_num_reqs=self.max_num_reqs,
            max_num_tokens=self.max_num_tokens,
            device=self.device,
        )
        # we need to adjust triton operators in sampler,
        # so reinitialize sampler here.
        self.sampler: AscendSampler = AscendSampler(
            max_num_reqs=self.max_num_reqs,
            vocab_size=self.vocab_size,
            device=self.device,
            req_states=self.req_states,
            logprobs_mode=self.model_config.logprobs_mode,
            num_speculative_tokens=self.num_speculative_steps + 1,
        )

        # we need to copy num_computed_tokens back to cpu to help
        # update actual seq_lens_cpu. gpu attention backend doesn't need these
        # attributes, cause their attention backends doesn't use seq_lens_cpu.
        # and seq_lens_cpu is deprecated in gpu_model_runner_v2.
        self.num_computed_tokens_event = torch.npu.Event()
        self.num_computed_tokens_stream = torch.npu.Stream()
        self.num_computed_tokens_cpu = torch.empty(
            self.max_num_reqs,
            dtype=torch.int32,
            device="cpu",
            pin_memory=True,
        )

        # Ascend-specific configurations
        self.ascend_config = get_ascend_config()
        # set this just the same as model runner v1, or it will raise error.
        set_weight_prefetch_method(self.ascend_config.weight_prefetch_config)

        # we need to update full graph params in run_fullgraph,
        # so create a stream to update full graph params.
        if self.compilation_config.cudagraph_mode.has_full_cudagraphs():
            self.update_stream: torch.npu.Stream = torch.npu.Stream()

        # we need to use return value of `get_cudagraph_and_dp_padding`
        # to set forward_context in `run_fullgraph`.
        # so we can inherit `execute_model` method.
        self.cudagraph_and_dp_padding: tuple[int, torch.Tensor | None, int] | None = None

        # we need to use input_batch to set forward_context in run_fullgraph.
        # so we can inherit `execute_model` method.
        self.input_batch: AscendInputBatch | None = None

    def prepare_inputs(
        self,
        scheduler_output: SchedulerOutput,
        batch_desc: BatchExecutionDescriptor,
    ) -> AscendInputBatch:
        """Override GPUModelRunner.prepare_inputs for Ascend NPUs.
        npu attention backends need seq_lens_cpu to work.
        so we need to prepare seq_lens_cpu here.
        """
        num_tokens = scheduler_output.total_num_scheduled_tokens
        num_tokens_after_padding = batch_desc.num_tokens
        assert num_tokens > 0
        num_tokens_per_req = scheduler_output.num_scheduled_tokens
        num_reqs = len(num_tokens_per_req)

        # Decode first, then prefill.
        # batch_idx -> req_id
        req_ids = sorted(num_tokens_per_req, key=num_tokens_per_req.get)  # type: ignore

        self._update_seq_lens_cpu(scheduler_output, req_ids)

        numtoks_iter = map(num_tokens_per_req.get, req_ids)
        num_scheduled_tokens = np.fromiter(numtoks_iter, dtype=np.int32, count=num_reqs)
        num_valid_tokens = num_scheduled_tokens
        if scheduler_output.scheduled_spec_decode_tokens:
            num_valid_tokens = np.array(
                [
                    num_tokens - len(scheduler_output.scheduled_spec_decode_tokens.get(i, []))
                    for num_tokens, i in zip(num_scheduled_tokens, req_ids)
                ],
                dtype=np.int32,
            )
        attn_state = build_attn_state(
            self.vllm_config,
            self.input_buffers.seq_lens_np,
            num_reqs,
            num_scheduled_tokens,
            num_valid_tokens,
        )
        idx_mapping_iter = map(self.req_states.req_id_to_index.get, req_ids)
        idx_mapping_np = np.fromiter(idx_mapping_iter, dtype=np.int32, count=num_reqs)
        idx_mapping_cpu = torch.from_numpy(idx_mapping_np)
        idx_mapping = async_copy_to_gpu(idx_mapping_cpu, device=self.device)

        # Get the number of draft tokens for each request.
        draft_tokens = scheduler_output.scheduled_spec_decode_tokens
        if not draft_tokens:
            # No draft token scheduled (common case).
            total_num_draft_tokens = 0
            total_num_logits = num_reqs
            cu_num_logits_np = np.arange(num_reqs + 1, dtype=np.int32)
            cu_num_logits = torch.arange(num_reqs + 1, device=self.device, dtype=torch.int32)
            expanded_idx_mapping = idx_mapping
            expanded_local_pos = torch.zeros(num_reqs, dtype=torch.int32, device=self.device)
        else:
            num_draft_tokens = np.array(
                [len(draft_tokens.get(req_id, ())) for req_id in req_ids],
                dtype=np.int32,
            )
            total_num_draft_tokens = int(num_draft_tokens.sum())
            total_num_logits = num_reqs + total_num_draft_tokens

            num_logits = num_draft_tokens + 1
            cu_num_logits_np = np.empty(num_reqs + 1, dtype=np.int32)
            cu_num_logits_np[0] = 0
            np.cumsum(num_logits, out=cu_num_logits_np[1:])
            cu_num_logits = async_copy_to_gpu(cu_num_logits_np, device=self.device)

            max_expand_len = self.num_speculative_steps + 1
            expanded_idx_mapping, expanded_local_pos = expand_idx_mapping(
                idx_mapping, total_num_logits, cu_num_logits, max_expand_len
            )

        # Get query_start_loc.
        # NOTE: For FULL mode we change +1 to +2 to reserve extra space for padding.
        # See _pad_query_start_loc_for_fia.
        num_reqs_padded = batch_desc.num_reqs or num_reqs
        query_start_loc_np = np.empty(self.max_num_reqs + 2, dtype=np.int32)
        query_start_loc_np[0] = 0
        np.cumsum(num_scheduled_tokens, out=query_start_loc_np[1 : num_reqs + 1])
        # Pad for full CUDA graph mode.
        # Some attention backends like FA3 require query_start_loc to be non-decreasing.
        query_start_loc_np[num_reqs + 1 :] = num_tokens

        # This is only required for vllm-ascend.
        query_start_loc_np, num_reqs_padded = self._pad_query_start_loc_for_fia(
            num_tokens_after_padding,
            num_reqs_padded,
            num_reqs,
            query_start_loc_np,
            batch_desc.cg_mode,
            batch_desc.num_reqs,
        )
        async_copy_to_gpu(query_start_loc_np, out=self.input_buffers.query_start_loc)

        query_start_loc_np = query_start_loc_np[: num_reqs_padded + 1]
        query_start_loc = self.input_buffers.query_start_loc[: num_reqs + 1]

        # Get prefill tokens if any.
        if self.req_states.any_prefills(idx_mapping_np):
            prepare_prefill_inputs(
                self.input_buffers.input_ids,
                self.req_states.next_prefill_tokens,
                idx_mapping,
                query_start_loc,
                self.req_states.all_token_ids.gpu,
                self.req_states.prefill_len.gpu,
                self.req_states.num_computed_tokens.gpu,
            )

        # Prepare positions and seq_lens.
        prepare_pos_seq_lens(
            idx_mapping,
            query_start_loc,
            self.req_states.num_computed_tokens.gpu,
            self.input_buffers.positions,
            self.input_buffers.seq_lens,
        )
        seq_lens = self.input_buffers.seq_lens[:num_reqs]

        # Pad for full CUDA graph mode.
        self.input_buffers.seq_lens_np[num_reqs_padded:] = 0

        # Some input token ids are directly read from the last sampled tokens
        # and draft tokens. Also, get the logits indices to sample tokens from.
        logits_indices = combine_sampled_and_draft_tokens(
            self.input_buffers.input_ids,
            idx_mapping,
            self.req_states.last_sampled_tokens,
            query_start_loc,
            seq_lens,
            self.req_states.prefill_len.gpu,
            self.req_states.draft_tokens,
            cu_num_logits,
            total_num_logits,
        )

        input_ids = self.input_buffers.input_ids[:num_tokens_after_padding]
        positions = self.input_buffers.positions[:num_tokens_after_padding]

        self.input_batch = AscendInputBatch(
            req_ids=req_ids,
            num_reqs=num_reqs,
            num_reqs_after_padding=num_reqs_padded,
            idx_mapping=idx_mapping,
            idx_mapping_np=idx_mapping_np,
            expanded_idx_mapping=expanded_idx_mapping,
            expanded_local_pos=expanded_local_pos,
            num_scheduled_tokens=num_scheduled_tokens,
            num_tokens=num_tokens,
            num_tokens_after_padding=num_tokens_after_padding,
            num_draft_tokens=total_num_draft_tokens,
            query_start_loc=query_start_loc,
            query_start_loc_np=query_start_loc_np,
            seq_lens=seq_lens,
            dcp_local_seq_lens=None,  # TODO(Ronald1995): support cp.
            input_ids=input_ids,
            positions=positions,
            logits_indices=logits_indices,
            cu_num_logits=cu_num_logits,
            cu_num_logits_np=cu_num_logits_np,
            has_structured_output_reqs=scheduler_output.has_structured_output_requests,
            # extra attributes for ascend npus.
            seq_lens_np=self.input_buffers.seq_lens_np,
            attn_state=attn_state,
        )
        return self.input_batch

    def postprocess(
        self,
        input_batch,
        sampled_tokens,
        num_sampled,
        num_rejected,
    ):
        """Override GPUModelRunner.postprocess for Ascend NPUs.
        npu attention backends need seq_lens_cpu to work.
        so we need to copy num_computed_tokens back to cpu here.
        """
        super().postprocess(
            input_batch,
            sampled_tokens,
            num_sampled,
            num_rejected,
        )
        # npu attention backend still need to use seq_lens_cpu,
        # we need to copy num_computed_tokens back to cpu.
        default_stream = torch.cuda.current_stream()
        assert self.num_computed_tokens_stream is not None
        assert self.num_computed_tokens_cpu is not None
        with torch.npu.stream(self.num_computed_tokens_stream):
            self.num_computed_tokens_stream.wait_stream(default_stream)
            self.num_computed_tokens_cpu.copy_(
                self.req_states.num_computed_tokens.gpu,
                non_blocking=True,
            )
            self.num_computed_tokens_event.record()

    def _update_seq_lens_cpu(
        self,
        scheduler_output: SchedulerOutput,
        req_ids: list[str],
    ):
        num_scheduled_tokens = scheduler_output.num_scheduled_tokens
        # wait for num_computed_tokens copy to cpu stream to finish.
        self.num_computed_tokens_event.synchronize()
        for req_id in scheduler_output.scheduled_cached_reqs.req_ids:
            req_index = self.req_states.req_id_to_index[req_id]
            # num_computed_tokens_cpu has reverted by num_rejected_tokens already.
            # in super postprocess method.
            self.req_states.num_computed_tokens_cpu[req_index] = self.num_computed_tokens_cpu[req_index]

        # update seq_lens_cpu
        for i, req_id in enumerate(req_ids):  # type: ignore
            req_index = self.req_states.req_id_to_index[req_id]
            num_computed_tokens = self.req_states.num_computed_tokens_cpu[req_index]
            self.input_buffers.seq_lens_cpu[i] = num_computed_tokens + num_scheduled_tokens[req_id]

    def eplb_warmup(self):
        # TODO(Ronald1995): just define the method in case calling error in
        # worker, implement it in the future.
        pass

    def _pad_query_start_loc_for_fia(
        self,
        num_tokens_padded: int,
        num_reqs_padded: int,
        num_reqs: int,
        query_start_loc_np: np.ndarray,
        cudagraph_runtime_mode: CUDAGraphMode | None = None,
        batch_desc_num_reqs: int | None = None,
    ) -> tuple[np.ndarray, int]:
        """
        This function is only designed to satisfied the constraint that when the layout is TND,
        the first dimension of `hidden_states` must equal the last element of `actual_seq_lengths_q`.
        """
        # TODO: need refactor later, related to vllm PR #34043 this pr delete func
        # relax_for_mixed_batch_cudagraphs, num_reqs no longer equals the actual number of requests.
        if cudagraph_runtime_mode == CUDAGraphMode.FULL:
            num_reqs_padded = num_reqs
        else:
            num_reqs_padded = batch_desc_num_reqs if batch_desc_num_reqs is not None else num_reqs

        if num_tokens_padded == num_reqs_padded * self.decode_query_len:
            # Uniform-batch case: num_reqs must be no greater than num_reqs_padded
            assert num_reqs <= num_reqs_padded

            last_loc = query_start_loc_np[num_reqs]
            query_start_loc_np[num_reqs + 1 : num_reqs_padded + 1] = (
                np.arange(1, num_reqs_padded + 1 - num_reqs) * self.decode_query_len + last_loc
            )
        else:
            # Mixed-batch case: num_reqs must equal num_reqs_padded
            assert num_reqs == num_reqs_padded

            # Insert a dummy request instead of setting query_start_loc[num_reqs] = num_tokens_padded directly
            query_start_loc_np[num_reqs_padded + 1] = num_tokens_padded
            num_reqs_padded = num_reqs_padded + 1

        return query_start_loc_np, num_reqs_padded