import torch
import torch.nn as nn
from transformers import AutoTokenizer, AutoModel, T5Tokenizer, T5EncoderModel
from transformers.modeling_outputs import BaseModelOutput

try:
    import torch_npu
    from torch_npu.contrib import transfer_to_npu
    DEVICE_TYPE = "npu"
except ModuleNotFoundError:
    DEVICE_TYPE = "cuda"


class TransformersTextEncoderBase(nn.Module):
    def __init__(self, model_name: str, embed_dim: int):
        super().__init__()
        self.tokenizer = AutoTokenizer.from_pretrained(model_name)
        self.model = AutoModel.from_pretrained(model_name)
        self.proj = nn.Linear(self.model.config.hidden_size, embed_dim)

    def forward(
        self,
        text: list[str],
    ):
        output, mask = self.encode(text)
        output = self.projection(output)
        return {"output": output, "mask": mask}

    def encode(self, text: list[str]):
        device = self.model.device
        batch = self.tokenizer(
            text,
            max_length=self.tokenizer.model_max_length,
            padding=True,
            truncation=True,
            return_tensors="pt",
        )
        input_ids = batch.input_ids.to(device)
        attention_mask = batch.attention_mask.to(device)
        output: BaseModelOutput = self.model(
            input_ids=input_ids, attention_mask=attention_mask
        )
        output = output.last_hidden_state
        mask = (attention_mask == 1).to(device)
        return output, mask

    def projection(self, x):
        return self.proj(x)


class T5TextEncoder(TransformersTextEncoderBase):
    def __init__(
        self, embed_dim: int, model_name: str = "google/flan-t5-large"
    ):
        nn.Module.__init__(self)
        self.tokenizer = T5Tokenizer.from_pretrained(model_name)
        self.model = T5EncoderModel.from_pretrained(model_name)
        for param in self.model.parameters():
            param.requires_grad = False
        self.model.eval()
        self.proj = nn.Linear(self.model.config.hidden_size, embed_dim)

    def encode(
        self,
        text: list[str],
    ):
        with torch.no_grad(), torch.amp.autocast(
            device_type=DEVICE_TYPE, enabled=False
        ):
            return super().encode(text)


if __name__ == "__main__":
    text_encoder = T5TextEncoder(embed_dim=512)
    text = ["a man is speaking", "a woman is singing while a dog is barking"]

    output = text_encoder(text)