app.py

import gradio as gr
import numpy as np
import tensorflow as tf
from tensorflow.keras.applications.efficientnet import preprocess_input
import base64
import io
from PIL import Image

# ── Load model ───────────────────────────────────────────────────────────────
print("Loading model...")
model = tf.keras.models.load_model("ViolenceDetector_EfficientNetB0.keras")
print("✅ Model loaded!")
IMG_SIZE = (224, 224)

# ── Helper ───────────────────────────────────────────────────────────────────
def preprocess_frame(img_pil):
    img = img_pil.convert("RGB").resize(IMG_SIZE)
    arr = np.expand_dims(np.array(img).astype(np.float32), axis=0)
    return preprocess_input(arr)

# ── Predict for Gradio UI ─────────────────────────────────────────────────────
def predict_image(img_pil):
    if img_pil is None:
        return {"Error": 1.0}
    inp = preprocess_frame(img_pil)
    prob = float(model.predict(inp, verbose=0)[0][0])
    label = "🔴 Violence" if prob >= 0.5 else "🟢 Safe"
    confidence = prob if prob >= 0.5 else 1 - prob
    return {label: float(round(confidence, 4))}

# ── API via Gradio's built-in endpoint ───────────────────────────────────────
def predict_base64(frame_b64: str):
    """Accepts base64 image string, returns JSON result"""
    try:
        img_bytes = base64.b64decode(frame_b64)
        img_pil = Image.open(io.BytesIO(img_bytes)).convert("RGB")
        inp = preprocess_frame(img_pil)
        prob = float(model.predict(inp, verbose=0)[0][0])
        return {
            "violence": prob >= 0.5,
            "probability": round(prob, 4),
            "label": "Violence" if prob >= 0.5 else "NonViolence",
            "confidence": round(prob if prob >= 0.5 else 1 - prob, 4),
        }
    except Exception as e:
        return {"error": str(e)}

# ── Gradio UI with API endpoints ──────────────────────────────────────────────
with gr.Blocks(title="Violence Detection API") as demo:
    gr.Markdown("# 🔍 Violence Detection API")
    gr.Markdown("Upload a video frame to detect violence. Also available as REST API.")

    with gr.Tab("🖼️ Test UI"):
        with gr.Row():
            img_input = gr.Image(type="pil", label="Upload Frame")
            result_out = gr.Label(label="Result")
        btn = gr.Button("Detect", variant="primary")
        btn.click(fn=predict_image, inputs=img_input, outputs=result_out)

    with gr.Tab("🔌 API - Base64"):
        gr.Markdown("### POST to `/predict_base64`")
        gr.Markdown("Send: `{frame: '<base64_image>'}` → Receive: `{violence, probability, label}`")
        b64_input = gr.Textbox(label="Base64 Image", placeholder="Paste base64 string here...")
        b64_result = gr.JSON(label="Result")
        b64_btn = gr.Button("Test API")
        b64_btn.click(fn=predict_base64, inputs=b64_input, outputs=b64_result)

demo.launch()