"""
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.
"""

from typing import Iterable, Optional, Tuple

import torch
from torch import nn
from transformers import PretrainedConfig

from sglang.srt.layers.pooler import EmbeddingPoolerOutput, Pooler, PoolingType
from sglang.srt.layers.quantization.base_config import QuantizationConfig
from sglang.srt.model_executor.forward_batch_info import ForwardBatch
from sglang.srt.models.internlm2 import InternLM2ForCausalLM, InternLM2Model


class InternLM2ForRewardModel(nn.Module):
    def __init__(
        self,
        config: PretrainedConfig,
        quant_config: Optional[QuantizationConfig] = None,
        cache_config=None,
    ) -> None:
        super().__init__()
        self.config = config
        self.quant_config = quant_config
        self.vocab_size = config.vocab_size
        self.model = InternLM2Model(config, quant_config)
        self.v_head = nn.Linear(config.hidden_size, 1, bias=False)
        self.pooler = Pooler(pooling_type=PoolingType.LAST, normalize=False)

    @torch.no_grad()
    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        forward_batch: ForwardBatch,
        input_embeds: torch.Tensor = None,
        get_embedding: bool = True,
    ) -> EmbeddingPoolerOutput:
        assert get_embedding, "InternLM2ForRewardModel is only used for embedding"
        hidden_states = self.model(input_ids, positions, forward_batch, input_embeds)
        last_token_hidden = self.pooler(hidden_states, forward_batch).embeddings
        scores = self.v_head(last_token_hidden)
        return EmbeddingPoolerOutput(scores)

    def load_weights(self, weights: Iterable[Tuple[str, torch.Tensor]]):
        return InternLM2ForCausalLM.load_weights(self, weights)


EntryClass = InternLM2ForRewardModel
