# routes/pdf_routes.py - PDF Upload and Processing Routes

import json
from flask import Blueprint, request, jsonify

from db import get_db
from pdf_processor import process_pdf_to_markdown
from ai_processor import process_document_smartly
from thumbnail_generator import generate_pdf_thumbnail
from media_storage import save_pending_thumbnail
from auth import login_required

pdf_bp = Blueprint('pdf', __name__)


@pdf_bp.route('/api/upload-pdf', methods=['POST'])
@login_required
def upload_pdf():
    """Upload and process a PDF file."""
    if 'file' not in request.files:
        return jsonify({'error': 'No file provided'}), 400
    
    pdf_file = request.files['file']
    
    if not pdf_file or not pdf_file.filename:
        return jsonify({'error': 'Invalid file'}), 400
    
    if not pdf_file.filename.lower().endswith('.pdf'):
        return jsonify({'error': 'File must be a PDF'}), 400
    
    try:
        print(f"📄 Processing PDF: {pdf_file.filename}")
        
        pdf_bytes = pdf_file.read()
        result = process_pdf_to_markdown(pdf_bytes)
        
        # --- AI Powered Smart Reconstruction & Section Tagging ---
        smart_blocks = process_document_smartly(result['markdown_blocks'], result['metadata'])
        
        # --- v4.4: প্রথম পেজ থেকে অটো থাম্বনেইল জেনারেট ---
        pending_thumbnail = None
        pending_thumbnail_format = None
        try:
            thumb_bytes, thumb_fmt = generate_pdf_thumbnail(pdf_bytes)
            if thumb_bytes:
                token = save_pending_thumbnail(thumb_bytes, thumb_fmt)
                if token:
                    pending_thumbnail = token
                    pending_thumbnail_format = thumb_fmt
                    print(f"  🖼️ Auto-thumbnail generated: {token} ({len(thumb_bytes)} bytes)")
        except Exception as te:
            print(f"  ⚠️ Thumbnail step skipped: {te}")
        
        # Save PDF document record
        db = get_db()
        cursor = db.cursor()
        
        cursor.execute('''
            INSERT INTO pdf_documents (filename, page_count, metadata)
            VALUES (?, ?, ?)
        ''', (
            pdf_file.filename,
            result["page_count"],
            json.dumps(result["metadata"])
        ))
        db.commit()
        
        doc_id = cursor.lastrowid
        
        print(f"✅ PDF processed & reconstructed: {result['page_count']} pages, {len(smart_blocks)} blocks")
        
        return jsonify({
            'success': True,
            'document_id': doc_id,
            'filename': pdf_file.filename,
            'page_count': result['page_count'],
            'metadata': result['metadata'],
            'blocks': smart_blocks,
            'pending_thumbnail': pending_thumbnail,
            'pending_thumbnail_format': pending_thumbnail_format
        })
        
    except Exception as e:
        import traceback
        traceback.print_exc()
        return jsonify({'error': str(e)}), 500