import gradio as gr
from transformers import AutoModelForCausalLM, AutoTokenizer, StoppingCriteria, StoppingCriteriaList, TextIteratorStreamer
import torch
from threading import Thread

model_name = "fzmnm/TinyStoriesAdv_v2_92M"

tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModelForCausalLM.from_pretrained(model_name)
model.eval()

model.generation_config.pad_token_id = tokenizer.eos_token_id

max_tokens = 512

def build_input_str(message: str, history: 'list[list[str]]'):
    history_str = ""
    for entity in history:
        if entity['role'] == 'user':
            history_str += f"问：{entity['content']}\n\n"
        elif entity['role'] == 'assistant':
            history_str += f"答：{entity['content']}\n\n"
    return history_str + f"问：{message}\n\n"

def stop_criteria(input_str):
    return input_str.endswith("\n") and len(input_str.strip()) > 0

class StopOnTokens(StoppingCriteria):
    def __call__(self, input_ids: torch.LongTensor, scores: torch.FloatTensor, **kwargs) -> bool:
        input_str = tokenizer.decode(input_ids[0], skip_special_tokens=True)
        return stop_criteria(input_str)
    
def chat(message, history):
    input_str = build_input_str(message, history)
    input_ids = tokenizer.encode(input_str, return_tensors="pt")
    input_ids = input_ids[:, -max_tokens:]
    streamer = TextIteratorStreamer(
        tokenizer, 
        timeout=10, 
        skip_prompt=True, 
        skip_special_tokens=True)
    stopping_criteria = StoppingCriteriaList([StopOnTokens()])
    generate_kwargs = dict(
        input_ids=input_ids,
        streamer=streamer,
        stopping_criteria=stopping_criteria,
        max_new_tokens=512,
        top_p=0.9,
        do_sample=True,
        temperature=0.7
    )
    t = Thread(target=model.generate, kwargs=generate_kwargs)
    t.start()

    output_str = ""
    for new_str in streamer:
        output_str += new_str
        yield output_str

app = gr.ChatInterface(
    fn=chat, 
    type='messages',
    examples=['什么是鹦鹉？', '什么是大象？', '谁是李白？', '什么是黑洞？'],
    title='聊天机器人',
)

app.launch()