src/app.py

import io
from pathlib import Path
import streamlit as st
from fastai.vision.all import load_learner, PILImage


# ✅ Correct absolute path for Hugging Face Spaces
MODEL_PATH = Path("models/pokemon_gen9_classifier_resnet101_after_cleaning.pkl") 


@st.cache_resource
def load_model():
    """Load and cache the FastAI learner. Returns None if model missing or incompatible."""
    if not MODEL_PATH.exists():
        st.error(f"❌ Model not found at {MODEL_PATH}")
        return None
    try:
        learner = load_learner(MODEL_PATH)
        return learner
    except Exception as e:
        st.error(f"⚠️ Error loading model:\n\n{e}")
        return None


def predict(learner, img_bytes: bytes):
    """Make a prediction on uploaded image bytes."""
    img = PILImage.create(io.BytesIO(img_bytes))
    pred, pred_idx, probs = learner.predict(img)
    return pred, probs


def main():
    st.title("🎯 FastAI Image Classifier")
    st.write("Upload an image and the model will predict its class.")

    learner = load_model()
    if learner is None:
        st.warning(
            "Model not loaded. Please ensure the `.pkl` file is correctly placed under `models/` and committed with Git LFS."
        )
        st.stop()

    uploaded_file = st.file_uploader("📤 Choose an image...", type=["png", "jpg", "jpeg"])
    if uploaded_file is not None:
        st.image(uploaded_file, caption="Uploaded Image", use_column_width=True)

        with st.spinner("Predicting..."):
            try:
                pred, probs = predict(learner, uploaded_file.read())
                st.success(f"✅ Predicted: **{pred}**")
                # Show top-5 predictions
                vocab = learner.dls.vocab
                probs_list = sorted(zip(vocab, probs), key=lambda x: x[1], reverse=True)
                st.write("### Top Predictions:")
                for label, p in probs_list[:5]:
                    st.write(f"- {label}: {p:.4f}")
            except Exception as e:
                st.error(f"Error during prediction: {e}")


if __name__ == "__main__":
    main()