# Copyright 2023-2024 SGLang Team
# 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.
# ==============================================================================

"""Inference-only DeepSeek NextN Speculative Decoding."""
import logging
from typing import Iterable, Optional, Tuple

import torch
from torch import nn
from transformers import PretrainedConfig

from sglang.srt.distributed import get_tensor_model_parallel_world_size
from sglang.srt.layers.layernorm import RMSNorm
from sglang.srt.layers.linear import ReplicatedLinear
from sglang.srt.layers.logits_processor import LogitsProcessor
from sglang.srt.layers.moe.ep_moe.layer import EPMoE
from sglang.srt.layers.moe.fused_moe_triton import FusedMoE
from sglang.srt.layers.quantization.base_config import QuantizationConfig
from sglang.srt.layers.quantization.fp8_utils import (
    block_quant_to_tensor_quant,
    normalize_e4m3fn_to_e4m3fnuz,
)
from sglang.srt.layers.quantization.int8_utils import (
    block_dequant as int8_block_dequant,
)
from sglang.srt.layers.vocab_parallel_embedding import (
    ParallelLMHead,
    VocabParallelEmbedding,
)
from sglang.srt.managers.schedule_batch import global_server_args_dict
from sglang.srt.model_executor.forward_batch_info import ForwardBatch
from sglang.srt.model_loader.weight_utils import default_weight_loader
from sglang.srt.models.deepseek_v2 import DeepseekV2DecoderLayer, DeepseekV3ForCausalLM
from sglang.srt.utils import BumpAllocator, add_prefix, is_cuda, is_hip

_is_hip = is_hip()
_is_cuda = is_cuda()

if _is_cuda:
    from sgl_kernel import awq_dequantize
else:
    from vllm._custom_ops import awq_dequantize


logger = logging.getLogger(__name__)


class DeepseekModelNextN(nn.Module):
    def __init__(
        self,
        config: PretrainedConfig,
        quant_config: Optional[QuantizationConfig] = None,
        prefix: str = "",
    ) -> None:
        super().__init__()
        self.vocab_size = config.vocab_size

        self.embed_tokens = VocabParallelEmbedding(
            config.vocab_size,
            config.hidden_size,
            enable_tp=not global_server_args_dict["enable_dp_attention"],
            prefix=add_prefix("embed_tokens", prefix),
        )

        self.enorm = RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
        self.hnorm = RMSNorm(config.hidden_size, eps=config.rms_norm_eps)

        self.eh_proj = nn.Linear(2 * config.hidden_size, config.hidden_size, bias=False)

        self.decoder = DeepseekV2DecoderLayer(
            config,
            0,
            quant_config=quant_config,
            is_nextn=True,
            prefix=add_prefix("decoder", prefix),
        )

        self.shared_head = nn.Module()
        self.shared_head.norm = RMSNorm(config.hidden_size, eps=config.rms_norm_eps)

    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        forward_batch: ForwardBatch,
        input_embeds: torch.Tensor = None,
    ) -> torch.Tensor:
        zero_allocator = BumpAllocator(
            buffer_size=2,
            dtype=torch.float32,
            device=(
                input_embeds.device if input_embeds is not None else input_ids.device
            ),
        )

        if input_embeds is None:
            hidden_states = self.embed_tokens(input_ids)
        else:
            hidden_states = input_embeds

        hidden_states = self.eh_proj(
            torch.cat(
                (
                    self.enorm(hidden_states),
                    self.hnorm(forward_batch.spec_info.hidden_states),
                ),
                dim=-1,
            )
        )

        residual = None
        hidden_states, residual = self.decoder(
            positions, hidden_states, forward_batch, residual, zero_allocator
        )

        if not forward_batch.forward_mode.is_idle():
            hidden_states, _ = self.shared_head.norm(hidden_states, residual)
        return hidden_states


class DeepseekV3ForCausalLMNextN(DeepseekV3ForCausalLM):

    def __init__(
        self,
        config: PretrainedConfig,
        quant_config: Optional[QuantizationConfig] = None,
        prefix: str = "",
    ) -> None:
        nn.Module.__init__(self)
        self.config = config
        self.tp_size = get_tensor_model_parallel_world_size()
        self.quant_config = quant_config
        self.determine_n_share_experts_fusion("DeepseekV3ForCausalLMNextN")

        self.model = DeepseekModelNextN(
            config, quant_config, prefix=add_prefix("model", prefix)
        )

        if global_server_args_dict["enable_dp_attention"]:
            self.lm_head = ReplicatedLinear(
                config.hidden_size,
                config.vocab_size,
                bias=False,
                prefix=add_prefix("model.shared_head.head", prefix),
            )
            self.logits_processor = LogitsProcessor(config, skip_all_gather=True)
        else:
            self.lm_head = ParallelLMHead(
                config.vocab_size,
                config.hidden_size,
                quant_config=quant_config,
                prefix=add_prefix("model.shared_head.head", prefix),
            )
            self.logits_processor = LogitsProcessor(config)

    @torch.no_grad()
    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        forward_batch: ForwardBatch,
    ) -> torch.Tensor:
        hidden_states = self.model(input_ids, positions, forward_batch)
        return self.logits_processor(
            input_ids, hidden_states, self.lm_head, forward_batch
        )

    def load_weights(self, weights: Iterable[Tuple[str, torch.Tensor]]):
        if hasattr(self.config, "num_nextn_predict_layers"):
            num_nextn_layers = self.config.num_nextn_predict_layers
            assert num_nextn_layers == 1, "Only 1 nextn layer is supportted"
            assert num_nextn_layers == self.config.num_hidden_layers
        else:
            raise ValueError("num_nextn_predict_layers is not in the config")

        stacked_params_mapping = [
            # (param_name, shard_name, shard_id)
            ("gate_up_proj", "gate_proj", 0),
            ("gate_up_proj", "up_proj", 1),
        ]
        if self.n_share_experts_fusion > 0:
            logger.info(
                f"Cloning {self.n_share_experts_fusion} "
                "replicas of the shared expert into MoE for DeepseekV3ForCausalLMNextN"
            )
            weights_list = list(weights)
            weights_dict = dict(weights_list)
            if self.quant_config is None or self.quant_config.get_name() == "w8a8_int8":
                suffix_list = [
                    "down_proj.weight",
                    "down_proj.weight_scale",
                    "gate_proj.weight",
                    "gate_proj.weight_scale",
                    "up_proj.weight",
                    "up_proj.weight_scale",
                ]
            else:
                suffix_list = [
                    "down_proj.weight",
                    "down_proj.weight_scale_inv",
                    "gate_proj.weight",
                    "gate_proj.weight_scale_inv",
                    "up_proj.weight",
                    "up_proj.weight_scale_inv",
                ]
            names_to_remove = []
            for num_repeat in range(self.n_share_experts_fusion):
                for suffix in suffix_list:
                    shared_expert_weight_name = (
                        f"model.layers.0.mlp.shared_experts.{suffix}"
                    )
                    weights_list.append(
                        (
                            f"model.layers.0."
                            f"mlp.experts."
                            f"{self.config.n_routed_experts + num_repeat}"
                            f".{suffix}",
                            weights_dict[shared_expert_weight_name],
                        )
                    )
                    names_to_remove += [shared_expert_weight_name]
            weights = [w for w in weights_list if w[0] not in names_to_remove]

        # Params for weights, fp8 weight scales, fp8 activation scales
        # (param_name, weight_name, expert_id, shard_id)
        MoEImpl = EPMoE if global_server_args_dict["enable_ep_moe"] else FusedMoE
        expert_params_mapping = MoEImpl.make_expert_params_mapping(
            ckpt_gate_proj_name="gate_proj",
            ckpt_down_proj_name="down_proj",
            ckpt_up_proj_name="up_proj",
            num_experts=self.config.n_routed_experts + self.n_share_experts_fusion,
        )

        # Fuse q_a_proj and kv_a_proj_with_mqa along output dimension when q_lora_rank is not None
        fuse_qkv_a_proj = hasattr(self.config, "q_lora_rank") and (
            self.config.q_lora_rank is not None
        )
        cached_a_proj = {} if fuse_qkv_a_proj else None

        nextn_layer_prefix = "model.layers.0"
        nextn_spec_weight_names = [
            "shared_head.norm",
            "eh_proj",
            "enorm",
            "hnorm",
        ]

        params_dict = dict(self.named_parameters())
        for name, loaded_weight in weights:
            if not name.startswith(nextn_layer_prefix):
                continue

            # Use shared head and embed weights from target model
            if "shared_head.head" in name or "embed_tokens" in name:
                continue

            is_decoder = True
            # For nextn specific weights
            for weight_name in nextn_spec_weight_names:
                if weight_name in name:
                    name = name.replace(nextn_layer_prefix, "model")
                    is_decoder = False
                    break
            # For decoder layer weights
            if is_decoder:
                name = name.replace(nextn_layer_prefix, "model.decoder")

            if "rotary_emb.inv_freq" in name:
                continue
            for param_name, weight_name, shard_id in stacked_params_mapping:
                # Skip non-stacked layers and experts (experts handled below).
                if weight_name not in name:
                    continue
                # We have mlp.experts[0].gate_proj in the checkpoint.
                # Since we handle the experts below in expert_params_mapping,
                # we need to skip here BEFORE we update the name, otherwise
                # name will be updated to mlp.experts[0].gate_up_proj, which
                # will then be updated below in expert_params_mapping
                # for mlp.experts[0].gate_gate_up_proj, which breaks load.
                if ("mlp.experts." in name) and name not in params_dict:
                    continue
                name = name.replace(weight_name, param_name)
                # Skip loading extra bias for GPTQ models.
                if name.endswith(".bias") and name not in params_dict:
                    continue
                param = params_dict[name]
                weight_loader = param.weight_loader
                weight_loader(param, loaded_weight, shard_id)
                break
            else:
                for mapping in expert_params_mapping:
                    param_name, weight_name, expert_id, shard_id = mapping
                    if weight_name not in name:
                        continue
                    name = name.replace(weight_name, param_name)
                    param = params_dict[name]
                    weight_loader = param.weight_loader
                    weight_loader(
                        param,
                        loaded_weight,
                        name,
                        shard_id=shard_id,
                        expert_id=expert_id,
                    )
                    break
                else:
                    # Skip loading extra bias for GPTQ models.
                    if name.endswith(".bias") and name not in params_dict:
                        continue

                    # Handle fused_qkv_a_proj
                    if fuse_qkv_a_proj and (
                        "q_a_proj" in name or "kv_a_proj_with_mqa" in name
                    ):
                        cached_a_proj[name] = loaded_weight
                        q_a_proj_name = (
                            name
                            if "q_a_proj" in name
                            else name.replace("kv_a_proj_with_mqa", "q_a_proj")
                        )
                        kv_a_proj_name = (
                            name
                            if "kv_a_proj_with_mqa" in name
                            else name.replace("q_a_proj", "kv_a_proj_with_mqa")
                        )

                        # When both q_a_proj and kv_a_proj_with_mqa has been cached, load the fused weight to parameter
                        if (
                            q_a_proj_name in cached_a_proj
                            and kv_a_proj_name in cached_a_proj
                        ):

                            q_a_proj_weight = cached_a_proj[q_a_proj_name]
                            kv_a_proj_weight = cached_a_proj[kv_a_proj_name]
                            fused_weight = torch.cat(
                                [q_a_proj_weight, kv_a_proj_weight], dim=0
                            )

                            param_name = name.replace(
                                "q_a_proj", "fused_qkv_a_proj_with_mqa"
                            )
                            param = params_dict[param_name]

                            weight_loader = getattr(
                                param, "weight_loader", default_weight_loader
                            )
                            weight_loader(param, fused_weight)
                            cached_a_proj.pop(q_a_proj_name)
                            cached_a_proj.pop(kv_a_proj_name)
                    else:
                        param = params_dict[name]
                        weight_loader = getattr(
                            param, "weight_loader", default_weight_loader
                        )
                        weight_loader(param, loaded_weight)

        self_attn = self.model.decoder.self_attn
        if hasattr(self_attn.kv_b_proj, "qweight"):
            # AWQ compatible
            if _is_cuda:
                w = awq_dequantize(
                    self_attn.kv_b_proj.qweight,
                    self_attn.kv_b_proj.scales,
                    self_attn.kv_b_proj.qzeros,
                ).T
            else:
                w = awq_dequantize(
                    self_attn.kv_b_proj.qweight,
                    self_attn.kv_b_proj.scales,
                    self_attn.kv_b_proj.qzeros,
                    0,
                    0,
                    0,
                ).T
        else:
            w = self_attn.kv_b_proj.weight
        # NOTE(HandH1998): Since `bmm_fp8` only supports per-tensor scale, we have to requantize `self_attn.kv_b_proj`.
        # This may affect the accuracy of fp8 model.
        if hasattr(self.quant_config, "weight_block_size") and w.dtype in (
            torch.float8_e4m3fn,
            torch.float8_e4m3fnuz,
        ):
            weight_block_size = self.quant_config.weight_block_size
            if weight_block_size is not None:
                assert hasattr(self_attn.kv_b_proj, "weight_scale_inv")
                if _is_hip:
                    weight, weight_scale, _ = normalize_e4m3fn_to_e4m3fnuz(
                        weight=w,
                        weight_scale=self_attn.kv_b_proj.weight_scale_inv,
                        input_scale=None,
                    )
                else:
                    weight = w
                    weight_scale = self_attn.kv_b_proj.weight_scale_inv

                w, scale = block_quant_to_tensor_quant(
                    weight, weight_scale, weight_block_size
                )
                self_attn.w_scale = scale
        if w.dtype == torch.int8:
            if hasattr(self.quant_config, "weight_block_size"):
                # block-wise int8 need it
                weight_block_size = self.quant_config.weight_block_size
                if weight_block_size is not None:
                    assert hasattr(self_attn.kv_b_proj, "weight_scale_inv")
                    weight = w
                    weight_scale = self_attn.kv_b_proj.weight_scale_inv
                    w = int8_block_dequant(weight, weight_scale, weight_block_size).to(
                        torch.bfloat16
                    )
            else:
                # channel-wise int8 need it
                assert hasattr(self_attn.kv_b_proj, "weight_scale")
                w = w.to(torch.bfloat16) * self_attn.kv_b_proj.weight_scale.to(
                    torch.bfloat16
                )
        w_kc, w_vc = w.unflatten(
            0, (-1, self_attn.qk_nope_head_dim + self_attn.v_head_dim)
        ).split([self_attn.qk_nope_head_dim, self_attn.v_head_dim], dim=1)
        self_attn.w_kc = w_kc.transpose(1, 2).contiguous().transpose(1, 2)
        self_attn.w_vc = w_vc.contiguous().transpose(1, 2)
        if hasattr(self_attn.kv_b_proj, "weight_scale") and self_attn.w_scale is None:
            self_attn.w_scale = self_attn.kv_b_proj.weight_scale
            if _is_hip:
                self_attn.w_scale *= 2.0


EntryClass = [DeepseekV3ForCausalLMNextN]
