import os
from flask import Flask, render_template, request, jsonify
from transformers import AutoTokenizer, AutoModelForSeq2SeqLM

app = Flask(__name__)

MODEL_NAME = "facebook/bart-large-cnn"

tokenizer = AutoTokenizer.from_pretrained(MODEL_NAME)
model = AutoModelForSeq2SeqLM.from_pretrained(MODEL_NAME)

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/summarize', methods=['POST'])
def summarize():
    try:
        data = request.get_json()
        text = data.get('text', '').strip()

        if not text or len(text.split()) < 15:
            return jsonify({'error': 'Text too short.'}), 400

        inputs = tokenizer(text, return_tensors="pt", max_length=1024, truncation=True)

        summary_ids = model.generate(
            inputs["input_ids"], 
            max_length=300,        
            min_length=150,        
            length_penalty=2.5,    
            num_beams=5,           
            no_repeat_ngram_size=3,
            early_stopping=False   
        )

        summary = tokenizer.decode(summary_ids[0], skip_special_tokens=True)

        # --- SAFE CLEANING LOGIC ---
        # 1. Fix punctuation spacing
        summary = summary.replace(" .", ".").replace(" ,", ",").replace(" !", "!").replace(" ?", "?")
        
        # 2. Capitalize ONLY the first letter of each sentence
        # This prevents "James Webb" from becoming "James webb"
        parts = summary.split(". ")
        cleaned_sentences = []
        for p in parts:
            p = p.strip()
            if p:
                # Upcase only index 0, keep everything else exactly as the AI wrote it
                sentence = p[0].upper() + p[1:]
                cleaned_sentences.append(sentence)
        
        summary = ". ".join(cleaned_sentences)
        
        if summary and not summary.endswith('.'): 
            summary += '.'

        return jsonify({'summary': summary})

    except Exception as e:
        return jsonify({'error': str(e)}), 500

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=7860)