app.py

"""
Production-ready Flask backend for deployment
Optimized for Hugging Face Spaces / Railway / Render
"""

from flask import Flask, request, jsonify
import io
from PIL import Image
from flask_cors import CORS
import logging
import os

app = Flask(__name__)
CORS(app, resources={r"/predict_pet": {"origins": "*"}})

# Logging configuration
logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
)
logger = logging.getLogger(__name__)

# Model global variables
model = None
image_processor = None

def load_model():
    """Load model on first request"""
    global model, image_processor
    
    if model is not None:
        return
    
    try:
        import torch
        from transformers import AutoImageProcessor, AutoModelForImageClassification
        
        logger.info("Loading ConvNextV2-large-DogBreed model...")
        
        model_name = "Pavarissy/ConvNextV2-large-DogBreed"
        
        # Detect device
        device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
        logger.info(f"Using device: {device}")
        
        # Load model
        image_processor = AutoImageProcessor.from_pretrained(model_name)
        model = AutoModelForImageClassification.from_pretrained(model_name)
        model = model.to(device)
        model.eval()
        
        logger.info(f"✓ Model loaded successfully on {device}")
        
    except Exception as e:
        logger.error(f"Failed to load model: {e}")
        raise

@app.route('/', methods=['GET'])
def health_check():
    """Health check endpoint"""
    return jsonify({
        'status': 'healthy',
        'service': 'Dog Breed Prediction API',
        'model': 'ConvNextV2-large-DogBreed',
        'accuracy': '91.39%',
        'version': '1.0.0'
    })

@app.route('/predict_pet', methods=['POST'])
def predict_pet():
    """Predict dog breed from uploaded image"""
    
    try:
        # Load model if not loaded
        load_model()
        
        # Validate request
        if 'image' not in request.files:
            return jsonify({'error': 'No image file provided'}), 400
            
        file = request.files['image']
        
        # Read and validate image
        image_bytes = file.read()
        pil_image = Image.open(io.BytesIO(image_bytes))
        
        if pil_image.mode != 'RGB':
            pil_image = pil_image.convert('RGB')
        
        # Make prediction
        import torch
        inputs = image_processor(pil_image, return_tensors="pt")
        
        device = next(model.parameters()).device
        inputs = {k: v.to(device) for k, v in inputs.items()}
        
        with torch.no_grad():
            outputs = model(**inputs)
            logits = outputs.logits
            
        probs = torch.nn.functional.softmax(logits, dim=-1)[0].cpu()
        top_5_probs, top_5_indices = torch.topk(probs, 5)
        
        # Format results
        top_5_breeds = []
        for prob, idx in zip(top_5_probs, top_5_indices):
            top_5_breeds.append({
                'breed': model.config.id2label[idx.item()],
                'confidence': float(prob.item())
            })
        
        logger.info(f"Prediction: {top_5_breeds[0]['breed']} ({top_5_breeds[0]['confidence']:.2%})")
        
        return jsonify({
            'breed': top_5_breeds[0]['breed'],
            'confidence': top_5_breeds[0]['confidence'],
            'top_5': top_5_breeds,
            'model': 'ConvNextV2-large-DogBreed',
            'accuracy': '91.39%'
        })
        
    except Exception as e:
        logger.error(f"Error: {str(e)}", exc_info=True)
        return jsonify({'error': str(e)}), 500

if __name__ == '__main__':
    port = int(os.environ.get('PORT', 7860))
    app.run(host='0.0.0.0', port=port, debug=False)