import streamlit as st
import pytorch
import transformers

@st.cache(suppress_st_warning=True)
def load_model():
    from transformers import AutoTokenizer, AutoModelForSequenceClassification
    model_name = 'distilbert-base-cased'
    tokenizer = AutoTokenizer.from_pretrained(model_name)
    model = AutoModelForSequenceClassification.from_pretrained(model_name, num_labels=8)
    model.load_state_dict(torch.load('model_weights.pt', map_location=torch.device('cpu')))
    model.eval()
    return tokenizer, model
    
@st.cache(suppress_st_warning=True)  
def predict(title, summary, tokenizer, model):
    text = title + "\n" + summary
    tokens = tokenizer.encode(text)
    with torch.no_grad():
        logits = model(torch.as_tensor([tokens], device=device))[0]
        probs = torch.softmax(logits[-1, :], dim=-1).data.cpu().numpy()
    
    classes = np.flip(np.argsort(probs))
    sum_probs = 0
    ind = 0
    prediction = []
    prediction_probs = []
    while sum_probs < 0.95:
        prediction.append(label_to_theme[classes[ind]])
        prediction_probs.append(probs[classes[ind]])
        sum_probs += probs[classes[ind]]
        ind += 1
    
    return prediction, prediction_probs
   
@st.cache(suppress_st_warning=True) 
def get_results(prediction, prediction_probs):
    ans = "Topic:\t\tConfidence:\n"
    for (class, prob) in zip(prediction, prediction_probs):
        ans += class + "\t\t" + str(prob) + "\n"
    return ans

st.title("Arxiv articles classification")
st.markdown("This is an interface that can determine the article's topic based on its title and summary. Though it can work with title only, it is recommended that you provide summary if possible - this will result in a better prediction quality.")

tokenizer, model = load_model()

title = st.text_area(label='Title', height=100)
summary = st.text_area(label='Summary (optional)', height=250)

prediction, prediction_probs = predict(title, summary, tokenizer, model)
ans = get_results(prediction, prediction_probs)
st.markdown(text)