app.py

import torch
import torch.nn as nn
from torchvision import transforms
from PIL import Image
import gradio as gr
import requests
from io import BytesIO

# ✅ Define model
class SimpleCNN(nn.Module):
    def __init__(self):
        super().__init__()
        self.conv = nn.Sequential(
            nn.Conv2d(3, 16, 3, padding=1), nn.ReLU(), nn.MaxPool2d(2),
            nn.Conv2d(16, 32, 3, padding=1), nn.ReLU(), nn.MaxPool2d(2),
            nn.Conv2d(32, 64, 3, padding=1), nn.ReLU(), nn.MaxPool2d(2),
        )
        self.fc = nn.Sequential(
            nn.Flatten(),
            nn.Linear(64 * 32 * 32, 128),
            nn.ReLU(),
            nn.Linear(128, 3)
        )

    def forward(self, x):
        x = self.conv(x)
        x = self.fc(x)
        return x

# ✅ Load model
device = "cuda" if torch.cuda.is_available() else "cpu"
model = SimpleCNN().to(device)
model.load_state_dict(torch.load("sid_cnn_model.pt", map_location=device))
model.eval()

# ✅ Labels & Transform
LABELS = {0: "🟩 Real", 1: "🤖 AI-generated", 2: "🧩 Tampered"}
transform = transforms.Compose([transforms.Resize((256, 256)), transforms.ToTensor()])

# ✅ Prediction function
def predict_image(image_url=None, uploaded_image=None):
    try:
        if image_url:
            response = requests.get(image_url, timeout=10)
            image = Image.open(BytesIO(response.content)).convert("RGB")
        elif uploaded_image is not None:
            image = uploaded_image.convert("RGB")
        else:
            return "⚠️ Please provide an image URL or upload an image."

        img_tensor = transform(image).unsqueeze(0).to(device)
        with torch.no_grad():
            outputs = model(img_tensor)
            pred = outputs.argmax(1).item()
            label = LABELS[pred]
        return f"🧠 Prediction: {label}"

    except Exception as e:
        return f"❌ Error: {str(e)}"

# ✅ Gradio app with API route
with gr.Blocks() as app:
    gr.Markdown("## 🧠 AI Image Detector")
    url_input = gr.Textbox(label="Image URL")
    upload_input = gr.Image(label="Upload Image", type="pil")
    output = gr.Textbox(label="Result")
    detect_btn = gr.Button("Detect")
    detect_btn.click(predict_image, [url_input, upload_input], output)

    # ✅ Expose public API route
    gr.Interface(fn=predict_image,
                 inputs=[gr.Textbox(), gr.Image(type="pil")],
                 outputs="text").api_name = "predict"

# ✅ Launch
app.launch(server_name="0.0.0.0", server_port=7860, share=True)