from typing import Dict, List, Any
from transformers import AutoModelForCausalLM, AutoTokenizer, BitsAndBytesConfig
from peft import PeftModel, PeftConfig
import torch
import time

class EndpointHandler:
    def __init__(self, path="dangkhoa99/falcon-7b-finetuned-QA-MRC-4-bit"):
        # load the model
        config = PeftConfig.from_pretrained(path)

        bnb_config = BitsAndBytesConfig(
            load_in_4bit=True,
            bnb_4bit_use_double_quant=True,
            bnb_4bit_quant_type="nf4",
            bnb_4bit_compute_dtype=torch.float16,
        )      
        
        self.model = AutoModelForCausalLM.from_pretrained(
            config.base_model_name_or_path,
            return_dict=True,
            load_in_4bit=True,
            device_map={"":0},
            trust_remote_code=True,
            quantization_config=bnb_config,
        )
        
        self.tokenizer = AutoTokenizer.from_pretrained(config.base_model_name_or_path)
        self.tokenizer.pad_token = self.tokenizer.eos_token
        
        self.model = PeftModel.from_pretrained(self.model, path)

    def __call__(self, data: Any) -> Dict[str, Any]:
        """
        Args:
            inputs :obj:`list`:. The object should be like {"context": "some word", "question": "some word"} containing:
                - "context": 
                - "question": 
        Return:
            A :obj:`list`:. The object returned should be like {"answer": "some word", time: "..."} containing:
                - "answer": answer the question based on the context
                - "time": the time run predict
        """
        inputs = data.pop("inputs", data)
        context = inputs.pop("context", inputs)
        question = inputs.pop("question", inputs)

        prompt = f"""Answer the question based on the context below. If the question cannot be answered using the information provided answer with 'No answer'. Stop response if end.
>>TITLE<<: Flawless answer.
>>CONTEXT<<: {context}
>>QUESTION<<: {question}
>>ANSWER<<:
""".strip()

        batch = self.tokenizer(
            prompt,
            padding=True,
            truncation=True,
            return_tensors='pt'
        )
        batch = batch.to('cuda:0')
        
        generation_config = self.model.generation_config
        generation_config.top_p = 0.7
        generation_config.temperature = 0.7
        generation_config.max_new_tokens = 256
        generation_config.num_return_sequences = 1
        generation_config.pad_token_id = self.tokenizer.eos_token_id
        generation_config.eos_token_id = self.tokenizer.eos_token_id

        start = time.time()
        with torch.cuda.amp.autocast():
            output_tokens = self.model.generate(
                input_ids = batch.input_ids,
                generation_config=generation_config,
            )
        end = time.time()

        generated_text = self.tokenizer.decode(output_tokens[0])

        prediction = {'answer': generated_text.split('>>END<<')[0].split('>>ANSWER<<:')[1].strip(), 'time': f"{(end-start):.2f} s"} 

        return prediction