# 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.
# ==============================================================================

# Adapted from
# https://github.com/vllm-project/vllm/blob/c7f2cf2b7f67bce5842fedfdba508440fe257375/vllm/model_executor/models/mixtral.py#L1
"""Inference-only Grok1 model."""

from typing import Iterable, List, Optional, Tuple

import torch
import torch.nn.functional as F
from torch import nn
from transformers import PretrainedConfig

from sglang.srt.distributed import (
    get_tensor_model_parallel_rank,
    get_tensor_model_parallel_world_size,
)
from sglang.srt.layers.activation import GeluAndMul
from sglang.srt.layers.layernorm import RMSNorm
from sglang.srt.layers.linear import (
    MergedColumnParallelLinear,
    QKVParallelLinear,
    ReplicatedLinear,
    RowParallelLinear,
)
from sglang.srt.layers.logits_processor import LogitsProcessor
from sglang.srt.layers.moe.fused_moe_triton import FusedMoE
from sglang.srt.layers.quantization.base_config import QuantizationConfig
from sglang.srt.layers.radix_attention import RadixAttention
from sglang.srt.layers.rotary_embedding import get_rope
from sglang.srt.layers.vocab_parallel_embedding import (
    ParallelLMHead,
    VocabParallelEmbedding,
)
from sglang.srt.model_executor.forward_batch_info import ForwardBatch
from sglang.srt.model_loader.loader import DefaultModelLoader
from sglang.srt.model_loader.weight_utils import default_weight_loader


class Grok1MLP(nn.Module):
    def __init__(
        self,
        hidden_size: int,
        intermediate_size: int,
        quant_config: Optional[QuantizationConfig] = None,
        prefix: str = "",
        reduce_results=True,
        use_presharded_weights: bool = False,
    ) -> None:
        super().__init__()
        self.gate_up_proj = MergedColumnParallelLinear(
            hidden_size,
            [intermediate_size] * 2,
            bias=False,
            quant_config=quant_config,
            prefix=f"{prefix}.gate_up_proj",
            use_presharded_weights=use_presharded_weights,
        )
        self.down_proj = RowParallelLinear(
            intermediate_size,
            hidden_size,
            bias=False,
            quant_config=quant_config,
            prefix=f"{prefix}.down_proj",
            reduce_results=reduce_results,
            use_presharded_weights=use_presharded_weights,
        )
        self.act_fn = GeluAndMul(approximate="tanh")

    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 Grok1MoE(nn.Module):
    """A tensor-parallel MoE implementation for Grok1 that shards each expert
    across all ranks.

    Each expert's weights are sharded across all ranks and a fused MoE
    kernel is used for the forward pass, and finally we reduce the outputs
    across ranks.
    """

    def __init__(
        self,
        config: PretrainedConfig,
        num_experts: int,
        top_k: int,
        hidden_size: int,
        intermediate_size: int,
        params_dtype: Optional[torch.dtype] = None,
        quant_config: Optional[QuantizationConfig] = None,
        tp_size: Optional[int] = None,
        reduce_results=True,
        use_presharded_weights: bool = False,
    ):
        super().__init__()
        self.hidden_size = hidden_size

        # Gate always runs at half / full precision for now.
        self.gate = ReplicatedLinear(
            hidden_size,
            num_experts,
            bias=False,
            params_dtype=params_dtype,
            quant_config=None,
        )

        self.router_logit_softcapping = getattr(
            config, "router_logit_softcapping", 30.0
        )
        self.experts = FusedMoE(
            num_experts=num_experts,
            top_k=top_k,
            hidden_size=hidden_size,
            intermediate_size=intermediate_size,
            params_dtype=params_dtype,
            reduce_results=reduce_results,
            renormalize=False,
            quant_config=quant_config,
            tp_size=tp_size,
            activation="gelu",
            use_presharded_weights=use_presharded_weights,
        )

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        # NOTE: hidden_states can have either 1D or 2D shape.
        orig_shape = hidden_states.shape
        hidden_states = hidden_states.view(-1, self.hidden_size)

        # router_logits: (num_tokens, n_experts)
        router_logits, _ = self.gate(hidden_states)
        router_logits = 30.0 * F.tanh(router_logits / 30.0)

        # need to assert self.gate.quant_method is unquantized
        final_hidden_states = self.experts(hidden_states, router_logits)
        return final_hidden_states.view(orig_shape)


class Grok1Attention(nn.Module):
    def __init__(
        self,
        config: PretrainedConfig,
        hidden_size: int,
        num_heads: int,
        num_kv_heads: int,
        layer_id: int = 0,
        max_position: int = 4096 * 32,
        rope_theta: float = 10000,
        quant_config: Optional[QuantizationConfig] = None,
        reduce_results: bool = True,
    ) -> None:
        super().__init__()
        self.config = config
        self.layer_id = layer_id
        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 = getattr(config, "head_dim", 128)
        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.qkv_proj = QKVParallelLinear(
            hidden_size,
            self.head_dim,
            self.total_num_heads,
            self.total_num_kv_heads,
            bias=False,
            quant_config=quant_config,
        )
        self.o_proj = RowParallelLinear(
            self.total_num_heads * self.head_dim,
            hidden_size,
            bias=False,
            quant_config=quant_config,
            reduce_results=reduce_results,
        )
        self.rotary_emb = get_rope(
            self.head_dim,
            rotary_dim=self.head_dim,
            max_position=max_position,
            base=int(self.rope_theta),
            is_neox_style=True,
        )

        logit_cap = max(getattr(config, "attn_logit_softcapping", 30.0), 0.0)

        self.attn = RadixAttention(
            self.num_heads,
            self.head_dim,
            self.scaling,
            num_kv_heads=self.num_kv_heads,
            layer_id=layer_id,
            logit_cap=logit_cap,
        )

    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
        forward_batch: ForwardBatch,
    ) -> 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, forward_batch)
        output, _ = self.o_proj(attn_output)
        return output


class Grok1DecoderLayer(nn.Module):
    def __init__(
        self,
        config: PretrainedConfig,
        layer_id: int = 0,
        quant_config: Optional[QuantizationConfig] = None,
        use_presharded_weights: bool = False,
    ) -> None:
        super().__init__()
        self.num_experts = config.num_local_experts
        self.hidden_size = config.hidden_size
        self.layer_id = layer_id

        rope_theta = getattr(config, "rope_theta", 10000)
        self.self_attn = Grok1Attention(
            config=config,
            hidden_size=self.hidden_size,
            num_heads=config.num_attention_heads,
            max_position=config.max_position_embeddings,
            num_kv_heads=config.num_key_value_heads,
            layer_id=layer_id,
            rope_theta=rope_theta,
            quant_config=quant_config,
        )
        self.block_sparse_moe = Grok1MoE(
            config=config,
            num_experts=config.num_local_experts,
            top_k=config.num_experts_per_tok,
            hidden_size=config.hidden_size,
            intermediate_size=getattr(
                config,
                "moe_intermediate_size",
                getattr(config, "intermediate_size", None),
            ),
            quant_config=quant_config,
            reduce_results=True,
            use_presharded_weights=use_presharded_weights,
        )
        self.pre_attn_norm = RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
        self.post_attn_norm = RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
        self.pre_moe_norm = RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
        self.post_moe_norm = RMSNorm(config.hidden_size, eps=config.rms_norm_eps)

    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
        forward_batch: ForwardBatch,
    ) -> torch.Tensor:
        # Self Attention
        hidden_states = (
            self.post_attn_norm(
                self.self_attn(
                    positions=positions,
                    hidden_states=self.pre_attn_norm(hidden_states),
                    forward_batch=forward_batch,
                )
            )
            + hidden_states
        )

        # Fully Connected
        hidden_states = (
            self.post_moe_norm(self.block_sparse_moe(self.pre_moe_norm(hidden_states)))
            + hidden_states
        )
        return hidden_states


class Grok1Model(nn.Module):
    def __init__(
        self,
        config: PretrainedConfig,
        quant_config: Optional[QuantizationConfig] = None,
        use_presharded_weights: bool = False,
    ) -> None:
        super().__init__()
        self.config = config
        self.padding_idx = config.pad_token_id
        self.vocab_size = config.vocab_size

        self.embed_tokens = VocabParallelEmbedding(
            config.vocab_size,
            config.hidden_size,
        )
        self.layers = nn.ModuleList(
            [
                Grok1DecoderLayer(
                    config,
                    i,
                    quant_config=quant_config,
                    use_presharded_weights=use_presharded_weights,
                )
                for i 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,
        forward_batch: ForwardBatch,
        input_embeds: torch.Tensor = None,
    ) -> torch.Tensor:
        if input_embeds is None:
            hidden_states = self.embed_tokens(input_ids)
            hidden_states.mul_(self.config.embedding_multiplier_scale)
        else:
            hidden_states = input_embeds

        for i in range(len(self.layers)):
            hidden_states = self.layers[i](positions, hidden_states, forward_batch)
        hidden_states = self.norm(hidden_states)
        hidden_states.mul_(self.config.output_multiplier_scale)
        return hidden_states


class Grok1ForCausalLM(nn.Module):
    def __init__(
        self,
        config: PretrainedConfig,
        quant_config: Optional[QuantizationConfig] = None,
    ) -> None:
        super().__init__()
        self.config = config
        self.quant_config = quant_config

        if (
            self.config.num_local_experts > 0
            and get_tensor_model_parallel_world_size() > 1
        ):
            self.use_presharded_weights = True
            setattr(DefaultModelLoader, "_prepare_weights", _prepare_presharded_weights)
        else:
            self.use_presharded_weights = False

        self.model = Grok1Model(
            config,
            quant_config=quant_config,
            use_presharded_weights=self.use_presharded_weights,
        )
        self.lm_head = ParallelLMHead(config.vocab_size, config.hidden_size)
        self.logits_processor = LogitsProcessor(config)

    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        forward_batch: ForwardBatch,
        input_embeds: torch.Tensor = None,
    ) -> torch.Tensor:
        hidden_states = self.model(input_ids, positions, forward_batch, input_embeds)
        return self.logits_processor(
            input_ids, hidden_states, self.lm_head, forward_batch
        )

    def load_weights(
        self,
        weights: Iterable[Tuple[str, torch.Tensor]],
    ):
        num_experts = self.config.num_local_experts

        stacked_params_mapping = [
            # (param_name, shard_name, shard_id)
            ("qkv_proj", "q_proj", "q"),
            ("qkv_proj", "k_proj", "k"),
            ("qkv_proj", "v_proj", "v"),
            ("gate_up_proj", "gate_proj", 0),
            ("gate_up_proj", "up_proj", 1),
        ]

        # Params for weights, fp8 weight scales, fp8 activation scales
        # (param_name, weight_name, expert_id, shard_id)
        expert_params_mapping = FusedMoE.make_expert_params_mapping(
            ckpt_gate_proj_name="w1",
            ckpt_down_proj_name="w2",
            ckpt_up_proj_name="w3",
            num_experts=num_experts,
        )

        params_dict = dict(self.named_parameters())
        all_names = set(params_dict.keys())
        hit_names = set()

        def load_weight_wrapper(name, loaded_weight, *args, **kwargs):
            if name not in params_dict:
                return

            param = params_dict[name]
            weight_loader = getattr(param, "weight_loader", default_weight_loader)
            weight_loader(param, loaded_weight, *args, **kwargs)

            hit_names.add(name)

        for name, loaded_weight in weights:
            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

                load_weight_wrapper(name, 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)

                    load_weight_wrapper(
                        name,
                        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
                    if name is None:
                        continue

                    load_weight_wrapper(name=name, loaded_weight=loaded_weight)


old_prepare_weights = getattr(DefaultModelLoader, "_prepare_weights")


def _prepare_presharded_weights(
    self, model_name_or_path: str, revision: Optional[str], fall_back_to_pt: bool
) -> Tuple[str, List[str], bool]:
    import glob
    import os

    if get_tensor_model_parallel_world_size() == 1:
        return old_prepare_weights(self, model_name_or_path, revision, fall_back_to_pt)

    if not os.path.isdir(model_name_or_path):
        from sglang.srt.model_loader.weight_utils import download_weights_from_hf

        allow_patterns = ["*.safetensors", "*.bin"]
        hf_folder = download_weights_from_hf(
            model_name_or_path,
            self.load_config.download_dir,
            allow_patterns,
            revision,
            ignore_patterns=self.load_config.ignore_patterns,
        )
    else:
        hf_folder = model_name_or_path

    tp_rank = get_tensor_model_parallel_rank()

    # The old format
    allow_patterns = [f"*-{tp_rank:03d}.bin"]

    # The new format
    allow_patterns += [f"*-TP-{tp_rank:03d}.safetensors", "*-TP-common.safetensors"]

    hf_weights_files: List[str] = []
    for pattern in allow_patterns:
        hf_weights_files += glob.glob(os.path.join(hf_folder, pattern))

    if hf_weights_files[0].endswith("safetensors"):
        use_safetensors = True
    else:
        use_safetensors = False

    return hf_folder, hf_weights_files, use_safetensors


class Grok1ModelForCausalLM(Grok1ForCausalLM):
    """An alias for backward-compatbility."""

    pass


EntryClass = [Grok1ForCausalLM, Grok1ModelForCausalLM]
