import streamlit as st

def chunk_text(text, chunk_size, overlap):
    chunks = []
    start = 0
    while start < len(text):
        end = start + chunk_size
        chunks.append(text[start:end])
        start += (chunk_size - overlap)
    return chunks

def main():
    st.set_page_config(page_title="Text Chunker", page_icon="✂️", layout="centered")
    
    # Custom CSS for styling
    st.markdown("""
    <style>
        .header {
            color: #2F4F4F;
            border-bottom: 2px solid #2F4F4F;
            padding-bottom: 10px;
        }
        .chunk-box {
            padding: 20px;
            margin: 10px 0;
            border-radius: 10px;
            background-color: #F0F2F6;
            box-shadow: 0 2px 4px rgba(0,0,0,0.1);
        }
    </style>
    """, unsafe_allow_html=True)

    st.markdown('<h1 class="header">✂️ Text Chunker</h1>', unsafe_allow_html=True)
    
    # Example text
    example_text = """Natural language processing (NLP) is a subfield of linguistics, computer science, 
    and artificial intelligence concerned with the interactions between computers and human language. 
    It focuses on how to program computers to process and analyze large amounts of natural language data. 
    The result is a computer capable of understanding natural language in a way that is both meaningful 
    and useful to humans."""
    
    # Inputs
    input_text = st.text_area("Input Text", value=example_text, height=200)
    col1, col2 = st.columns(2)
    with col1:
        chunk_size = st.slider("Chunk Size (characters)", 50, 200, 100, 10)
    with col2:
        overlap = st.slider("Overlap (characters)", 0, 50, 20, 5)
    
    if overlap >= chunk_size:
        st.error("Overlap must be smaller than chunk size!")
        return
    
    # Processing
    if st.button("Chunk It!", type="primary"):
        chunks = chunk_text(input_text, chunk_size, overlap)
        
        st.markdown(f"**🔖 {len(chunks)} Chunks Created**")
        for i, chunk in enumerate(chunks, 1):
            with st.container():
                st.markdown(f"""
                <div class="chunk-box">
                    <h4>Chunk #{i} (Length: {len(chunk)})</h4>
                    <hr style="border:1px solid #2F4F4F">
                    <p>{chunk}</p>
                </div>
                """, unsafe_allow_html=True)
                
        st.success("✅ Chunking completed! Scroll to see all chunks.")

if __name__ == "__main__":
    main()