# coding=utf-8
# Adapted from
# https://github.com/huggingface/transformers/blob/v4.28.0/src/transformers/models/llama/modeling_llama.py
# Copyright 2023 The PygmalionAI team.
# Copyright 2023 The vLLM team.
# Copyright 2023 DeepSeek-AI and the HuggingFace Inc. team. All rights reserved.
#
# This code is based on EleutherAI's GPT-NeoX library and the GPT-NeoX
# and OPT implementations in this library. It has been modified from its
# original forms to accommodate minor architectural differences compared
# to GPT-NeoX and OPT used by the Meta AI team that trained the model.
#
# 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 model."""
from typing import Any, Dict, List, Optional

import numpy as np
import torch
from torch import nn
from transformers import PretrainedConfig

from aphrodite.attention import Attention, AttentionMetadata
from aphrodite.modeling.layers.activation import SiluAndMul
from aphrodite.modeling.layers.fused_moe import fused_topk
from aphrodite.modeling.layers.layernorm import RMSNorm
from aphrodite.modeling.layers.linear import (
    LinearMethodBase, MergedColumnParallelLinear, QKVParallelLinear,
    ReplicatedLinear, RowParallelLinear, UnquantizedLinearMethod)
from aphrodite.modeling.layers.logits_processor import LogitsProcessor
from aphrodite.modeling.layers.rotary_embedding import get_rope
from aphrodite.modeling.layers.sampler import Sampler
from aphrodite.modeling.layers.vocab_parallel_embedding import (
    ParallelLMHead, VocabParallelEmbedding)
from aphrodite.distributed import (get_tensor_model_parallel_rank,
                                   get_tensor_model_parallel_world_size,
                                   tensor_model_parallel_all_reduce)
from aphrodite.modeling.sampling_metadata import SamplingMetadata
from aphrodite.modeling.hf_downloader import (default_weight_loader,
                                              hf_model_weights_iterator)
from aphrodite.common.sequence import SamplerOutput


class DeepseekMLP(nn.Module):

    def __init__(
        self,
        hidden_size: int,
        intermediate_size: int,
        hidden_act: str,
        linear_method: Optional[LinearMethodBase] = None,
        reduce_results: bool = True,
    ) -> None:
        super().__init__()
        self.gate_up_proj = MergedColumnParallelLinear(
            hidden_size, [intermediate_size] * 2,
            bias=False,
            linear_method=linear_method)
        self.down_proj = RowParallelLinear(intermediate_size,
                                           hidden_size,
                                           bias=False,
                                           linear_method=linear_method,
                                           reduce_results=reduce_results)
        if hidden_act != "silu":
            raise ValueError(f"Unsupported activation: {hidden_act}. "
                             "Only silu is supported for now.")
        self.act_fn = SiluAndMul()

    def forward(self, x):
        gate_up, _ = self.gate_up_proj(x)
        x = self.act_fn(gate_up)
        x, _ = self.down_proj(x)
        return x


class DeepseekExpertMLP(nn.Module):

    def __init__(
        self,
        hidden_size: int,
        intermediate_size: int,
        hidden_act: str,
        linear_method: Optional[LinearMethodBase] = None,
    ) -> None:
        super().__init__()
        self.gate_proj = ReplicatedLinear(hidden_size,
                                          intermediate_size,
                                          bias=False,
                                          linear_method=linear_method)
        self.up_proj = ReplicatedLinear(hidden_size,
                                        intermediate_size,
                                        bias=False,
                                        linear_method=linear_method)
        self.down_proj = ReplicatedLinear(intermediate_size,
                                          hidden_size,
                                          bias=False,
                                          linear_method=linear_method)
        self.act_fn = nn.SiLU()

    def forward(self, hidden_states):
        gate_out, _ = self.gate_proj(hidden_states)
        gate_out = self.act_fn(gate_out)
        up_out, _ = self.up_proj(hidden_states)
        current_hidden_states = gate_out * up_out
        current_hidden_states, _ = self.down_proj(current_hidden_states)
        return current_hidden_states


class DeepseekMoE(nn.Module):

    def __init__(
        self,
        config: PretrainedConfig,
        linear_method: Optional[LinearMethodBase] = None,
    ):
        super().__init__()
        self.config = config
        self.rank = get_tensor_model_parallel_rank()
        self.tp_size = get_tensor_model_parallel_world_size()
        self.n_routed_experts = config.n_routed_experts
        self.top_k = config.num_experts_per_tok
        self.linear_method = linear_method
        if self.linear_method is None:
            self.linear_method = UnquantizedLinearMethod()

        if not isinstance(
                self.linear_method, UnquantizedLinearMethod
        ) and not self.linear_method.quant_config.support_fused_moe():
            if self.tp_size > self.n_routed_experts:
                raise ValueError(
                    f"Tensor parallel size {self.tp_size} is greater than "
                    f"the number of experts {self.n_routed_experts}.")
            # Split experts equally between ranks
            self.expert_indicies = np.array_split(range(
                self.n_routed_experts), self.tp_size)[self.rank].tolist()
            if not self.expert_indicies:
                raise ValueError(
                    f"Rank {self.rank} has no experts assigned to it.")

            self.experts = nn.ModuleList([
                DeepseekExpertMLP(
                    hidden_size=config.hidden_size,
                    intermediate_size=config.moe_intermediate_size,
                    hidden_act=config.hidden_act,
                    linear_method=linear_method,
                ) if idx in self.expert_indicies else None
                for idx in range(self.n_routed_experts)
            ])
        else:
            self.w1 = MergedColumnParallelLinear(
                config.hidden_size, [config.moe_intermediate_size] * 2,
                bias=False,
                linear_method=linear_method,
                num_experts=self.n_routed_experts)
            self.w2 = RowParallelLinear(config.moe_intermediate_size,
                                        config.hidden_size,
                                        bias=False,
                                        linear_method=linear_method,
                                        num_experts=self.n_routed_experts)

        self.gate = ReplicatedLinear(config.hidden_size,
                                     self.n_routed_experts,
                                     bias=False,
                                     linear_method=None)

        if config.n_shared_experts is not None:
            intermediate_size = (config.moe_intermediate_size *
                                 config.n_shared_experts)
            self.shared_experts = DeepseekMLP(
                hidden_size=config.hidden_size,
                intermediate_size=intermediate_size,
                hidden_act=config.hidden_act,
                linear_method=linear_method,
                reduce_results=False,
            )

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        num_tokens, hidden_dim = hidden_states.shape
        hidden_states = hidden_states.view(-1, hidden_dim)
        if self.config.n_shared_experts is not None:
            shared_output = self.shared_experts(hidden_states)
        # router_logits: (num_tokens, n_experts)
        router_logits, _ = self.gate(hidden_states)

        if not isinstance(
                self.linear_method, UnquantizedLinearMethod
        ) and not self.linear_method.quant_config.support_fused_moe():
            routing_weights, selected_experts = fused_topk(
                router_logits,
                self.top_k,
                renormalize=self.config.norm_topk_prob)
            final_hidden_states = None
            for expert_idx in self.expert_indicies:
                expert_layer = self.experts[expert_idx]
                expert_mask = (selected_experts == expert_idx)
                expert_weights = (routing_weights * expert_mask).sum(
                    dim=-1, keepdim=True)

                current_hidden_states = expert_layer(hidden_states).mul_(
                    expert_weights)
                if final_hidden_states is None:
                    final_hidden_states = current_hidden_states
                else:
                    final_hidden_states.add_(current_hidden_states)
        else:
            final_hidden_states = self.linear_method.apply_moe_weights(
                self.w1.linear_weights,
                self.w2.linear_weights,
                hidden_states,
                router_logits,
                self.top_k,
                renormalize=self.config.norm_topk_prob,
            )

        if self.config.n_shared_experts is not None:
            final_hidden_states = final_hidden_states + shared_output
        final_hidden_states = tensor_model_parallel_all_reduce(
            final_hidden_states)

        return final_hidden_states.view(num_tokens, hidden_dim)


class DeepseekAttention(nn.Module):

    def __init__(
        self,
        hidden_size: int,
        num_heads: int,
        num_kv_heads: int,
        rope_theta: float = 10000,
        rope_scaling: Optional[Dict[str, Any]] = None,
        max_position_embeddings: int = 8192,
        linear_method: Optional[LinearMethodBase] = None,
    ) -> None:
        super().__init__()
        self.hidden_size = hidden_size
        tp_size = get_tensor_model_parallel_world_size()
        self.total_num_heads = num_heads
        assert self.total_num_heads % tp_size == 0
        self.num_heads = self.total_num_heads // tp_size
        self.total_num_kv_heads = num_kv_heads
        if self.total_num_kv_heads >= tp_size:
            # Number of KV heads is greater than TP size, so we partition
            # the KV heads across multiple tensor parallel GPUs.
            assert self.total_num_kv_heads % tp_size == 0
        else:
            # Number of KV heads is less than TP size, so we replicate
            # the KV heads across multiple tensor parallel GPUs.
            assert tp_size % self.total_num_kv_heads == 0
        self.num_kv_heads = max(1, self.total_num_kv_heads // tp_size)
        self.head_dim = hidden_size // self.total_num_heads
        self.q_size = self.num_heads * self.head_dim
        self.kv_size = self.num_kv_heads * self.head_dim
        self.scaling = self.head_dim**-0.5
        self.rope_theta = rope_theta
        self.max_position_embeddings = max_position_embeddings

        self.qkv_proj = QKVParallelLinear(
            hidden_size,
            self.head_dim,
            self.total_num_heads,
            self.total_num_kv_heads,
            bias=False,
            linear_method=linear_method,
        )

        self.o_proj = RowParallelLinear(
            self.total_num_heads * self.head_dim,
            hidden_size,
            bias=False,
            linear_method=linear_method,
        )

        self.rotary_emb = get_rope(
            self.head_dim,
            rotary_dim=self.head_dim,
            max_position=max_position_embeddings,
            base=rope_theta,
            rope_scaling=rope_scaling,
        )
        self.attn = Attention(self.num_heads,
                              self.head_dim,
                              self.scaling,
                              num_kv_heads=self.num_kv_heads)

    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
        kv_cache: torch.Tensor,
        attn_metadata: AttentionMetadata,
    ) -> torch.Tensor:
        qkv, _ = self.qkv_proj(hidden_states)
        q, k, v = qkv.split([self.q_size, self.kv_size, self.kv_size], dim=-1)
        q, k = self.rotary_emb(positions, q, k)
        attn_output = self.attn(q, k, v, kv_cache, attn_metadata)
        output, _ = self.o_proj(attn_output)
        return output


class DeepseekDecoderLayer(nn.Module):

    def __init__(
        self,
        config: PretrainedConfig,
        layer_idx: int,
        linear_method: Optional[LinearMethodBase] = None,
    ) -> None:
        super().__init__()
        self.hidden_size = config.hidden_size
        rope_theta = getattr(config, "rope_theta", 10000)
        rope_scaling = getattr(config, "rope_scaling", None)
        max_position_embeddings = getattr(config, "max_position_embeddings",
                                          8192)
        self.self_attn = DeepseekAttention(
            hidden_size=self.hidden_size,
            num_heads=config.num_attention_heads,
            num_kv_heads=config.num_key_value_heads,
            rope_theta=rope_theta,
            rope_scaling=rope_scaling,
            max_position_embeddings=max_position_embeddings,
            linear_method=linear_method,
        )
        if (config.n_routed_experts is not None
                and layer_idx >= config.first_k_dense_replace
                and layer_idx % config.moe_layer_freq == 0):
            self.mlp = DeepseekMoE(config=config, linear_method=linear_method)
        else:
            self.mlp = DeepseekMLP(
                hidden_size=config.hidden_size,
                intermediate_size=config.intermediate_size,
                hidden_act=config.hidden_act,
                linear_method=linear_method,
            )
        self.input_layernorm = RMSNorm(config.hidden_size,
                                       eps=config.rms_norm_eps)
        self.post_attention_layernorm = RMSNorm(config.hidden_size,
                                                eps=config.rms_norm_eps)

    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
        kv_cache: torch.Tensor,
        attn_metadata: AttentionMetadata,
        residual: Optional[torch.Tensor],
    ) -> torch.Tensor:
        # Self Attention
        if residual is None:
            residual = hidden_states
            hidden_states = self.input_layernorm(hidden_states)
        else:
            hidden_states, residual = self.input_layernorm(
                hidden_states, residual)
        hidden_states = self.self_attn(
            positions=positions,
            hidden_states=hidden_states,
            kv_cache=kv_cache,
            attn_metadata=attn_metadata,
        )

        # Fully Connected
        hidden_states, residual = self.post_attention_layernorm(
            hidden_states, residual)
        hidden_states = self.mlp(hidden_states)
        return hidden_states, residual


class DeepseekModel(nn.Module):

    def __init__(
        self,
        config: PretrainedConfig,
        linear_method: Optional[LinearMethodBase] = None,
    ) -> None:
        super().__init__()
        self.padding_idx = config.pad_token_id
        self.vocab_size = config.vocab_size

        self.embed_tokens = VocabParallelEmbedding(config.vocab_size,
                                                   config.hidden_size,
                                                   linear_method=linear_method)
        self.layers = nn.ModuleList([
            DeepseekDecoderLayer(config,
                                 layer_idx,
                                 linear_method=linear_method)
            for layer_idx in range(config.num_hidden_layers)
        ])
        self.norm = RMSNorm(config.hidden_size, eps=config.rms_norm_eps)

    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        kv_caches: List[torch.Tensor],
        attn_metadata: AttentionMetadata,
    ) -> torch.Tensor:
        hidden_states = self.embed_tokens(input_ids)
        residual = None
        for i in range(len(self.layers)):
            layer = self.layers[i]
            hidden_states, residual = layer(positions, hidden_states,
                                            kv_caches[i], attn_metadata,
                                            residual)
        hidden_states, _ = self.norm(hidden_states, residual)
        return hidden_states


class DeepseekForCausalLM(nn.Module):

    def __init__(
        self,
        config: PretrainedConfig,
        linear_method: Optional[LinearMethodBase] = None,
    ) -> None:
        super().__init__()
        self.config = config
        self.linear_method = linear_method
        self.model = DeepseekModel(config, linear_method)
        self.lm_head = ParallelLMHead(config.vocab_size, config.hidden_size)
        self.logits_processor = LogitsProcessor(config.vocab_size)
        self.sampler = Sampler()

    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        kv_caches: List[torch.Tensor],
        attn_metadata: AttentionMetadata,
    ) -> torch.Tensor:
        hidden_states = self.model(input_ids, positions, kv_caches,
                                   attn_metadata)
        return hidden_states

    def compute_logits(self, hidden_states: torch.Tensor,
                       sampling_metadata: SamplingMetadata) -> torch.Tensor:
        logits = self.logits_processor(self.lm_head, hidden_states,
                                       sampling_metadata)
        return logits

    def sample(
        self,
        logits: Optional[torch.Tensor],
        sampling_metadata: SamplingMetadata,
    ) -> Optional[SamplerOutput]:
        next_tokens = self.sampler(logits, sampling_metadata)
        return next_tokens

    def load_weights(self,
                     model_name_or_path: str,
                     cache_dir: Optional[str] = None,
                     load_format: str = "auto",
                     revision: Optional[str] = None):
        stacked_params_mapping = [
            # (param_name, shard_name, shard_id)
            ("qkv_proj", "q_proj", "q"),
            ("qkv_proj", "k_proj", "k"),
            ("qkv_proj", "v_proj", "v"),
            ("mlp.gate_up_proj", "mlp.gate_proj", 0),
            ("mlp.gate_up_proj", "mlp.up_proj", 1),
            ("shared_experts.gate_up_proj", "shared_experts.gate_proj", 0),
            ("shared_experts.gate_up_proj", "shared_experts.up_proj", 1),
        ]

        expert_params_mapping = [
            # (param_name, weight_name, shard_id, expert_id)
            ("w1" if weight_name in ["gate_proj", "up_proj"] else "w2",
             f"experts.{expert_id}.{weight_name}", shard_id, expert_id)
            for expert_id in range(self.config.n_routed_experts)
            for weight_name, shard_id in [("gate_proj",
                                           0), ("up_proj",
                                                1), ("down_proj", None)]
        ] if self.linear_method is None or (
            self.linear_method.quant_config.support_fused_moe()) else []

        params_dict = dict(self.named_parameters())
        for name, loaded_weight in hf_model_weights_iterator(
                model_name_or_path,
                cache_dir,
                load_format,
                revision,
                self.config,
                fall_back_to_pt=False):
            if "rotary_emb.inv_freq" in name:
                continue
            for (param_name, weight_name, shard_id) in stacked_params_mapping:
                if weight_name not in name:
                    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
                # Skip experts that are not assigned to this worker.
                if (("mlp.experts." in name or "mlp.shared_experts." in name)
                        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 (param_name, weight_name, shard_id,
                     expert_id) in expert_params_mapping:
                    if weight_name not in name:
                        continue
                    name = name.replace(weight_name, param_name)
                    if name.endswith(".bias") and name not in params_dict:
                        continue
                    param = params_dict[name]
                    weight_loader = param.weight_loader
                    if shard_id is None:
                        weight_loader(param,
                                      loaded_weight,
                                      expert_id=expert_id)
                    else:
                        weight_loader(param,
                                      loaded_weight,
                                      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
                    # Skip experts that are not assigned to this worker.
                    if (("mlp.experts." in name
                         or "mlp.shared_experts." in name)
                            and name not in params_dict):
                        continue
                    param = params_dict[name]
                    weight_loader = getattr(param, "weight_loader",
                                            default_weight_loader)
                    weight_loader(param, loaded_weight)