import streamlit as st
from transformers import pipeline

available_models = [
    "facebook/t5-small",
    "facebook/t5-base",
    "facebook/t5-large",
    "google/pegasus-xsum",
    "google/pegasus-cnn_dailymail",
    "sshleifer/distilbart-cnn-12-6",
    "allenai/led-base-16384",
    "google/mt5-small",
    "google/mt5-base",
    # Add more models as needed
]

@st.cache_resource
def load_summarizer(model_name):
    """Loads the summarization pipeline for a given model from Hugging Face."""
    try:
        summarizer = pipeline("summarization", model=model_name)
        return summarizer
    except Exception as e:
        st.error(f"Error loading model {model_name}: {e}")
        return None

st.title("Hugging Face Text Summarization App")

text_to_summarize = st.text_area("Enter text to summarize:", height=300)

selected_model = st.selectbox("Choose a summarization model from Hugging Face:", available_models)

st.sidebar.header("Summarization Parameters")
max_length = st.sidebar.slider("Max Summary Length:", min_value=50, max_value=500, value=150)
min_length = st.sidebar.slider("Min Summary Length:", min_value=10, max_value=250, value=30)
temperature = st.sidebar.slider("Temperature (for sampling):", min_value=0.0, max_value=1.0, value=0.0, step=0.01, help="Higher values make the output more random.")
repetition_penalty = st.sidebar.slider("Repetition Penalty:", min_value=1.0, max_value=2.5, value=1.0, step=0.01, help="Penalizes repeated tokens to improve coherence.")
num_beams = st.sidebar.slider("Number of Beams (for beam search):", min_value=1, max_value=10, value=1, help="More beams improve quality but increase computation.")
do_sample = st.sidebar.checkbox("Enable Sampling?", value=False, help="Whether to use sampling; set to False for deterministic output.")

if st.button("Summarize"):
    if text_to_summarize:
        summarizer = load_summarizer(selected_model)
        if summarizer:
            with st.spinner(f"Summarizing using {selected_model}..."):
                try:
                    summary = summarizer(
                        text_to_summarize,
                        max_length=max_length,
                        min_length=min_length,
                        do_sample=do_sample,
                        temperature=temperature if do_sample else None,
                        repetition_penalty=repetition_penalty,
                        num_beams=num_beams if not do_sample else 1, # Beam search is usually not used with sampling
                        early_stopping=True,
                    )[0]['summary_text']
                    st.subheader("Summary:")
                    st.write(summary)
                except Exception as e:
                    st.error(f"Error during summarization: {e}")
        else:
            st.warning("Failed to load the selected model.")
    else:
        st.warning("Please enter some text to summarize.")

st.sidebar.header("About")
st.sidebar.info(
    "This app uses the `transformers` library from Hugging Face "
    "to perform text summarization. You can select from a variety of "
    "pre-trained models available on the Hugging Face Model Hub. "
    "Experiment with the parameters in the sidebar to control the "
    "summarization process."
)