app.py

import gradio as gr
import torch
import torch.nn as nn
import torchvision.transforms as T
import torchvision.models as models
from PIL import Image
import os

# -----------------------------
# Safe model loading
# -----------------------------
possible_paths = [
    "model/model.pth",
    "model.pth",
    "/app/model/model.pth",
    "/app/model.pth"
]

model_path = None
for p in possible_paths:
    if os.path.exists(p):
        model_path = p
        break

if model_path is None:
    raise FileNotFoundError(
        "❌ model.pth not found. Upload it to /model/model.pth or root folder."
    )

checkpoint = torch.load(model_path, map_location="cpu")
class_names = checkpoint["class_names"]

# -----------------------------
# Load Model
# -----------------------------
model = models.resnet50(pretrained=False)
model.fc = nn.Linear(model.fc.in_features, len(class_names))
model.load_state_dict(checkpoint["model_state_dict"], strict=True)
model.eval()

# -----------------------------
# Image Preprocessing
# -----------------------------
transform = T.Compose([
    T.Resize((224,224)),
    T.ToTensor(),
    T.Normalize([0.485, 0.456, 0.406],
                [0.229, 0.224, 0.225])
])

# -----------------------------
# Prediction Function
# -----------------------------
def predict(img):
    img = transform(img).unsqueeze(0)
    with torch.no_grad():
        outputs = model(img)
        probs = torch.softmax(outputs[0], dim=0)

    top3_probs, top3_idxs = torch.topk(probs, 3)
    result = {class_names[i]: float(top3_probs[idx]) 
              for idx, i in enumerate(top3_idxs)}

    return result

# -----------------------------
# Gradio Interface
# -----------------------------
title = "🐾 Animal Classifier — ResNet50 Fine-Tuned"
description = """
Upload an image of an animal and the model will predict what species it is.
"""

iface = gr.Interface(
    fn=predict,
    inputs=gr.Image(type="pil"),
    outputs=gr.Label(num_top_classes=3),
    title=title,
    description=description,
)

iface.launch()