# coding=utf-8
# Adapted from
# https://huggingface.co/Qwen/Qwen-7B/blob/main/modeling_qwen.py
# Copyright (c) Alibaba Cloud.
# LICENSE: https://huggingface.co/Qwen/Qwen-7B/blob/main/LICENSE
"""Inference-only QWen model compatible with HuggingFace weights.

The input of the model is flattened to a 1D tensor of tokens. The model uses
InputMetadata to extract the original 2D shape of the input.
"""
from typing import List, Optional, Tuple

import torch
from torch import nn

from vllm.model_executor.input_metadata import InputMetadata
from vllm.model_executor.layers.activation import SiluAndMul
from vllm.model_executor.layers.layernorm import RMSNorm
from vllm.model_executor.layers.attention import PagedAttentionWithRoPE
from vllm.model_executor.layers.sampler import Sampler
from vllm.model_executor.weight_utils import (
    convert_pyslice_to_tensor,
    hf_model_weights_iterator,
    load_padded_tensor_parallel_vocab,
    load_tensor_parallel_weights,
)
from vllm.model_executor.parallel_utils.parallel_state import (
    get_tensor_model_parallel_rank,
    get_tensor_model_parallel_world_size,
)
from vllm.model_executor.parallel_utils.tensor_parallel import (
    VocabParallelEmbedding,
    ColumnParallelLinear,
    RowParallelLinear,
)
from vllm.sequence import SamplerOutput
from vllm.transformers_utils.configs.qwen import QWenConfig

KVCache = Tuple[torch.Tensor, torch.Tensor]


class QWenMLP(nn.Module):

    def __init__(
        self,
        hidden_size: int,
        intermediate_size: int,
        hidden_act: str = "silu",
    ):
        super().__init__()
        self.gate_up_proj = ColumnParallelLinear(
            hidden_size,
            2 * intermediate_size,
            bias=False,
            gather_output=False,
            perform_initialization=False,
        )
        self.c_proj = RowParallelLinear(
            intermediate_size,
            hidden_size,
            bias=False,
            input_is_parallel=True,
            perform_initialization=False,
        )
        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.c_proj(x)
        return x


class QWenAttention(nn.Module):

    def __init__(self, hidden_size: int, num_heads: int,
                 max_position_embeddings: int):
        super().__init__()
        self.hidden_size = hidden_size
        tensor_model_parallel_world_size = get_tensor_model_parallel_world_size(
        )
        self.total_num_heads = num_heads
        assert self.total_num_heads % tensor_model_parallel_world_size == 0
        self.num_heads = (self.total_num_heads //
                          tensor_model_parallel_world_size)
        self.head_dim = hidden_size // self.total_num_heads

        # pylint: disable=invalid-name
        self.c_attn = ColumnParallelLinear(
            hidden_size,
            3 * hidden_size,
            bias=True,
            gather_output=False,
            perform_initialization=False,
        )
        self.c_proj = RowParallelLinear(
            self.total_num_heads * self.head_dim,
            hidden_size,
            bias=False,
            input_is_parallel=True,
            perform_initialization=False,
        )
        self.scaling = self.head_dim**-0.5
        self.attn = PagedAttentionWithRoPE(
            self.num_heads,
            self.head_dim,
            self.scaling,
            rotary_dim=self.head_dim,
            max_position=max_position_embeddings,
        )

    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
        kv_cache: KVCache,
        input_metadata: InputMetadata,
        cache_event: Optional[torch.cuda.Event],
    ) -> torch.Tensor:
        qkv, _ = self.c_attn(hidden_states)
        q, k, v = qkv.chunk(chunks=3, dim=-1)

        k_cache, v_cache = kv_cache
        attn_output = self.attn(positions, q, k, v, k_cache, v_cache,
                                input_metadata, cache_event)

        output, _ = self.c_proj(attn_output)
        return output


class QWenBlock(nn.Module):

    def __init__(self, config: QWenConfig):
        super().__init__()
        self.ln_1 = RMSNorm(config.n_embd, eps=config.layer_norm_epsilon)

        self.attn = QWenAttention(config.n_embd, config.num_attention_heads,
                                  config.max_position_embeddings)

        self.ln_2 = RMSNorm(config.n_embd, eps=config.layer_norm_epsilon)

        self.mlp = QWenMLP(config.n_embd, config.ffn_hidden_size // 2)

    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
        kv_cache: KVCache,
        input_metadata: InputMetadata,
        cache_event: Optional[torch.cuda.Event],
    ) -> torch.Tensor:
        # Self Attention
        residual = hidden_states
        hidden_states = self.ln_1(hidden_states)
        hidden_states = self.attn(
            positions=positions,
            hidden_states=hidden_states,
            kv_cache=kv_cache,
            input_metadata=input_metadata,
            cache_event=cache_event,
        )
        hidden_states = residual + hidden_states

        # Fully Connected
        residual = hidden_states
        hidden_states = self.ln_2(hidden_states)
        hidden_states = self.mlp(hidden_states)
        hidden_states = residual + hidden_states
        return hidden_states


class QWenModel(nn.Module):

    def __init__(self, config: QWenConfig):
        super().__init__()
        self.config = config
        self.vocab_size = config.vocab_size

        vocab_size = ((config.vocab_size + 63) // 64) * 64
        self.wte = VocabParallelEmbedding(vocab_size,
                                          config.n_embd,
                                          perform_initialization=False)
        self.h = nn.ModuleList(
            [QWenBlock(config) for _ in range(config.num_hidden_layers)])
        self.ln_f = RMSNorm(config.n_embd, eps=config.layer_norm_epsilon)

    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        kv_caches: List[KVCache],
        input_metadata: InputMetadata,
        cache_events: Optional[List[torch.cuda.Event]],
    ) -> torch.Tensor:
        hidden_states = self.wte(input_ids)
        for i in range(len(self.h)):
            if cache_events is None:
                cache_event = None
            else:
                cache_event = cache_events[i]
            layer = self.h[i]
            hidden_states = layer(
                positions,
                hidden_states,
                kv_caches[i],
                input_metadata,
                cache_event,
            )
        hidden_states = self.ln_f(hidden_states)
        return hidden_states


class QWenLMHeadModel(nn.Module):

    def __init__(self, config: QWenConfig):
        super().__init__()
        self.config = config
        self.transformer = QWenModel(config)
        vocab_size = ((config.vocab_size + 63) // 64) * 64
        self.lm_head = ColumnParallelLinear(
            config.n_embd,
            vocab_size,
            bias=False,
            gather_output=False,
            perform_initialization=False,
        )
        self.sampler = Sampler(config.vocab_size)

    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        kv_caches: List[KVCache],
        input_metadata: InputMetadata,
        cache_events: Optional[List[torch.cuda.Event]],
    ) -> SamplerOutput:
        hidden_states = self.transformer(input_ids, positions, kv_caches,
                                         input_metadata, cache_events)
        next_tokens = self.sampler(self.lm_head.weight, hidden_states,
                                   input_metadata)
        return next_tokens

    _column_parallel_weights = []
    _row_parallel_weights = ["c_proj.weight"]

    def load_weights(
        self,
        model_name_or_path: str,
        cache_dir: Optional[str] = None,
        load_format: str = "auto",
        revision: Optional[str] = None,
    ):
        tp_world_size = get_tensor_model_parallel_world_size()
        tp_rank = get_tensor_model_parallel_rank()
        state_dict = self.state_dict()

        for name, loaded_weight in hf_model_weights_iterator(
                model_name_or_path, cache_dir, load_format, revision):
            if "rotary_emb.inv_freq" in name:
                continue

            loaded_weight = convert_pyslice_to_tensor(loaded_weight)

            if "c_attn" in name:
                total_num_heads = self.config.num_attention_heads
                hidden_size = self.config.hidden_size
                head_size = hidden_size // total_num_heads
                num_heads = total_num_heads // tp_world_size
                head_start = tp_rank * num_heads
                head_end = (tp_rank + 1) * num_heads

                if "weight" in name:
                    loaded_weight = loaded_weight.view(3, total_num_heads,
                                                       head_size, hidden_size)
                    loaded_weight = loaded_weight[:, head_start:head_end, :, :]
                    loaded_weight = loaded_weight.reshape(-1, hidden_size)
                elif "bias" in name:
                    loaded_weight = loaded_weight.view(3, total_num_heads,
                                                       head_size)
                    loaded_weight = loaded_weight[:, head_start:head_end, :]
                    loaded_weight = loaded_weight.reshape(-1)

            is_gate_up_weight = False
            for stride_id, weight_name in enumerate(["w2", "w1"]):
                if weight_name not in name:
                    continue
                param = state_dict[name.replace(weight_name, "gate_up_proj")]
                shard_size = param.shape[0] // 2
                loaded_weight = loaded_weight[shard_size * tp_rank:shard_size *
                                              (tp_rank + 1)]
                param_slice = param.data[shard_size * stride_id:shard_size *
                                         (stride_id + 1)]
                assert param_slice.shape == loaded_weight.shape
                param_slice.copy_(loaded_weight)
                is_gate_up_weight = True
                break
            if is_gate_up_weight:
                continue

            param = state_dict[name]

            if "wte" in name or "lm_head" in name:
                load_padded_tensor_parallel_vocab(param, loaded_weight,
                                                  tp_rank)
                continue

            load_tensor_parallel_weights(
                param,
                loaded_weight,
                name,
                self._column_parallel_weights,
                self._row_parallel_weights,
                tp_rank,
            )
