app.py

import streamlit as st
from gtts import gTTS
from urllib.parse import urlparse, parse_qs
from youtube_transcript_api import YouTubeTranscriptApi, TranscriptUnavailable, NoTranscriptFound
import unicodedata
from deepmultilingualpunctuation import PunctuationModel
from transformers import pipeline
import io
import re

# =============================================================================
# CACHE MODELS - Agar tidak reload setiap kali form disubmit
# =============================================================================
@st.cache_resource
def load_punctuation_model():
    """Load punctuation model once and cache it"""
    return PunctuationModel("oliverguhr/fullstop-punctuation-multilingual--large")

@st.cache_resource
def load_summarization_pipeline():
    """Load summarization pipeline once and cache it"""
    return pipeline(
        "summarization",
        model="t5-base",
        tokenizer="t5-base",
        device=0 if st.runtime.get_option("server.headless") == False and hasattr(st, 'runtime') else -1  # CPU fallback
    )

# =============================================================================
# HELPER FUNCTIONS
# =============================================================================
def extract_video_id(url):
    """Extract video ID from various YouTube URL formats"""
    # Handle short URLs: youtu.be/VIDEO_ID
    if "youtu.be" in url:
        parsed = urlparse(url)
        return parsed.path.lstrip('/')
    
    # Handle standard URLs: youtube.com/watch?v=VIDEO_ID
    if "watch" in url:
        parsed = urlparse(url)
        params = parse_qs(parsed.query)
        return params.get('v', [None])[0]
    
    # Handle embed URLs: youtube.com/embed/VIDEO_ID
    if "embed" in url:
        parsed = urlparse(url)
        return parsed.path.split('/')[-1]
    
    # Handle short URLs without protocol
    if re.match(r'^[a-zA-Z0-9_-]{11}$', url.strip()):
        return url.strip()
    
    return None

def get_transcript_text(video_id, language='en'):
    """Fetch and combine transcript text from YouTube"""
    try:
        # Try to get transcript in preferred language, fallback to any available
        transcript_list = YouTubeTranscriptApi.list_transcripts(video_id)
        transcript = transcript_list.find_transcript([language])
    except (TranscriptUnavailable, NoTranscriptFound):
        # Fallback: get any available transcript
        transcript = YouTubeTranscriptApi.list_transcripts(video_id).find_generated_transcript(['en'])
    
    transcript_data = transcript.fetch()
    # Combine all text segments
    text_segments = [item["text"] for item in transcript_data]
    return " ".join(text_segments)

def chunk_text(text, max_chars=4000):
    """Split text into chunks respecting sentence boundaries"""
    chunks = []
    current_chunk = ""
    
    # Split by sentences (basic approach)
    sentences = re.split(r'(?<=[.!?])\s+', text)
    
    for sentence in sentences:
        if len(current_chunk) + len(sentence) <= max_chars:
            current_chunk += sentence + " "
        else:
            if current_chunk:
                chunks.append(current_chunk.strip())
            current_chunk = sentence + " "
    
    if current_chunk:
        chunks.append(current_chunk.strip())
    
    return chunks if chunks else [text]  # Fallback if no sentences found

def normalize_text(text):
    """Normalize unicode characters in text"""
    return unicodedata.normalize('NFKD', text)

# =============================================================================
# MAIN SUMMARIZATION FUNCTION
# =============================================================================
def summarize_video(url, language='en'):
    """Main function to summarize YouTube video"""
    
    # Extract video ID
    video_id = extract_video_id(url)
    if not video_id:
        raise ValueError("Invalid YouTube URL. Please check the link and try again.")
    
    # Get transcript
    with st.spinner("📝 Mengambil transkrip video..."):
        video_transcript = get_transcript_text(video_id, language)
    
    if not video_transcript or len(video_transcript.strip()) < 50:
        raise ValueError("Transkrip tidak ditemukan atau terlalu pendek. Video mungkin tidak memiliki subtitle.")
    
    # Normalize text
    normalized_text = normalize_text(video_transcript)
    
    # Add punctuation
    with st.spinner("✏️ Menambahkan tanda baca..."):
        punctuation_model = load_punctuation_model()
        punctuated_text = punctuation_model.restore_punctuation(normalized_text)
    
    # Summarization
    with st.spinner("🤖 Meringkas konten..."):
        summarizer = load_summarization_pipeline()
        
        # T5-base max input: ~512 tokens (~2000-3000 chars safe limit)
        chunks = chunk_text(punctuated_text, max_chars=3000)
        summaries = []
        
        for i, chunk in enumerate(chunks):
            # T5 expects prefix "summarize: " for some versions
            input_text = f"summarize: {chunk}" if "t5" in "t5-base" else chunk
            
            summary_result = summarizer(
                input_text,
                max_length=150,
                min_length=30,
                do_sample=False,
                truncation=True
            )
            summaries.append(summary_result[0]['summary_text'])
            st.progress(min((i + 1) / len(chunks), 1.0))
        
        final_summary = " ".join(summaries)
    
    return final_summary

# =============================================================================
# STREAMLIT APP
# =============================================================================
def main():
    st.set_page_config(page_title="YouTube Summarizer", page_icon="🎬", layout="centered")
    
    st.title("🎬 YouTube Video Summarizer")
    st.markdown("""
        Masukkan URL video YouTube untuk mendapatkan ringkasan otomatis berbasis AI.
        Mendukung video dengan subtitle/closed caption.
    """)
    
    # Input form
    with st.form(key="summarizer_form"):
        video_url = st.text_input(
            "🔗 URL Video YouTube",
            placeholder="https://www.youtube.com/watch?v=..."
        )
        language = st.selectbox(
            "🌐 Bahasa Transkrip (opsional)",
            options=['en', 'id', 'es', 'fr', 'de', 'pt', 'auto'],
            index=0,
            help="Pilih bahasa transkrip. 'auto' akan mencoba mendeteksi otomatis."
        )
        col1, col2 = st.columns([1, 3])
        with col1:
            submit_button = st.form_submit_button("🚀 Ringkas", use_container_width=True)
    
    # Process submission
    if submit_button:
        if not video_url.strip():
            st.error("⚠️ Harap masukkan URL video YouTube yang valid.")
            return
        
        try:
            # Generate summary
            summary = summarize_video(video_url, language if language != 'auto' else 'en')
            
            # Display results
            st.success("✅ Ringkasan berhasil dibuat!")
            st.subheader("📄 Hasil Ringkasan")
            st.markdown(f"> {summary}")
            
            # Text-to-Speech
            with st.spinner("🔊 Membuat audio..."):
                # Detect language for gTTS (simplified: default to 'en')
                tts_lang = 'id' if any(kata in summary.lower() for kata in ['dan', 'yang', 'di', 'ke']) else 'en'
                tts = gTTS(text=summary, lang=tts_lang, slow=False)
                
                # Convert to bytes for download (no file I/O)
                audio_buffer = io.BytesIO()
                tts.write_to_fp(audio_buffer)
                audio_buffer.seek(0)
            
            # Download button
            st.download_button(
                label="📥 Download Ringkasan Audio (MP3)",
                data=audio_buffer,
                file_name="youtube_summary.mp3",
                mime="audio/mpeg",
                use_container_width=True
            )
            
            # Copy summary to clipboard hint
            st.code(summary, language="text")
            st.caption("💡 Tip: Klik teks di atas untuk menyalin ringkasan.")
            
        except Exception as e:
            st.error(f"❌ Terjadi kesalahan: {str(e)}")
            with st.expander("🔍 Detail Error (untuk debugging)"):
                st.exception(e)
    
    # Sidebar info
    with st.sidebar:
        st.header("ℹ️ Informasi")
        st.markdown("""
        **Fitur:**
        - ✅ Ekstrak transkrip otomatis
        - ✅ Penambahan tanda baca AI
        - ✅ Ringkasan multi-bahasa
        - ✅ Export ke audio MP3
        
        **Batasan:**
        - Video harus memiliki subtitle/closed caption
        - Durasi video sangat panjang mungkin diproses per bagian
        - Model T5-base optimal untuk teks bahasa Inggris
        
        **Tips:**
        - Gunakan video dengan subtitle resmi untuk hasil terbaik
        - Untuk video bahasa Indonesia, pastikan subtitle tersedia
        """)
        
        st.markdown("---")
        st.caption("Dibuat dengan ❤️ menggunakan Streamlit & Hugging Face")

if __name__ == "__main__":
    main()