import os
import io
import logging
from flask import Flask, request, jsonify
from werkzeug.utils import secure_filename
from PyPDF2 import PdfReader
from docx import Document
from pptx import Presentation
from transformers import T5Tokenizer, T5ForConditionalGeneration

# Configure logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# Initialize Flask app
app = Flask(__name__)

# Set Hugging Face cache directory
os.environ["HF_HOME"] = "/app/hf_cache"

# Load T5 model and tokenizer
logger.info("Loading T5-Base model...")
try:
    tokenizer = T5Tokenizer.from_pretrained("t5-base")
    model = T5ForConditionalGeneration.from_pretrained("t5-base")
    logger.info("T5-Base model loaded successfully.")
except Exception as e:
    logger.error(f"Failed to load T5-Base: {str(e)}")
    raise

ALLOWED_EXTENSIONS = {"pdf", "docx", "pptx", "txt"}

def allowed_file(filename):
    """Check if the uploaded file has an allowed extension."""
    return "." in filename and filename.rsplit(".", 1)[1].lower() in ALLOWED_EXTENSIONS

def summarize_text(text, max_length=150, min_length=30):
    """Summarize text using T5-Base."""
    try:
        if not text.strip():
            return "No text found in the document to summarize."

        input_text = "summarize: " + text
        inputs = tokenizer(input_text, return_tensors="pt", max_length=512, truncation=True)
        summary_ids = model.generate(
            inputs["input_ids"],
            max_length=max_length,
            min_length=min_length,
            length_penalty=2.0,
            num_beams=4,
            early_stopping=True
        )
        summary = tokenizer.decode(summary_ids[0], skip_special_tokens=True)
        return summary
    except Exception as e:
        logger.error(f"Error in T5 summarization: {str(e)}")
        return "Error summarizing text."

@app.route("/", methods=["GET"])
def index():
    """Root endpoint."""
    logger.info("Root endpoint accessed.")
    return "Document Summarizer API with T5-Base is running! Use /summarize endpoint for POST requests."

@app.route("/summarize", methods=["POST"])
def summarize():
    """Handle file uploads and summarization."""
    logger.info("Summarize endpoint called.")
    
    if "file" not in request.files:
        logger.error("No file uploaded.")
        return jsonify({"error": "No file uploaded"}), 400
    
    file = request.files["file"]
    if file.filename == "":
        logger.error("No file selected.")
        return jsonify({"error": "No selected file"}), 400
    
    if not allowed_file(file.filename):
        logger.error(f"Unsupported file format: {file.filename}")
        return jsonify({"error": "Unsupported file format"}), 400

    filename = secure_filename(file.filename)
    file_content = file.read()
    file_ext = filename.rsplit(".", 1)[1].lower()
    
    try:
        if file_ext == "pdf":
            text = summarize_pdf(file_content)
        elif file_ext == "docx":
            text = summarize_docx(file_content)
        elif file_ext == "pptx":
            text = summarize_pptx(file_content)
        elif file_ext == "txt":
            text = summarize_txt(file_content)
        else:
            return jsonify({"error": "Unsupported file format"}), 400

        if not text.strip():
            return jsonify({"error": "No extractable text found in the document"}), 400

        summary = summarize_text(text)
        logger.info(f"File {filename} summarized successfully.")
        return jsonify({"filename": filename, "summary": summary})
    
    except Exception as e:
        logger.error(f"Error processing file {filename}: {str(e)}")
        return jsonify({"error": f"Error processing file: {str(e)}"}), 500

def summarize_pdf(file_content):
    """Extract text from PDF."""
    reader = PdfReader(io.BytesIO(file_content))
    text = "\n".join([page.extract_text() or "" for page in reader.pages])
    return text.strip()

def summarize_docx(file_content):
    """Extract text from DOCX."""
    doc = Document(io.BytesIO(file_content))
    text = "\n".join([para.text for para in doc.paragraphs if para.text.strip()])
    return text.strip()

def summarize_pptx(file_content):
    """Extract text from PPTX."""
    ppt = Presentation(io.BytesIO(file_content))
    text = []
    for slide in ppt.slides:
        for shape in slide.shapes:
            if hasattr(shape, "text") and shape.text.strip():
                text.append(shape.text.strip())
    return "\n".join(text).strip()

def summarize_txt(file_content):
    """Extract text from TXT file."""
    return file_content.decode("utf-8").strip()

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=7860, debug=True)