app.py

# app.py
"""
Streamlit Frontend App: Uploads a flowchart image, sends it to FastAPI backend,
and displays the structured JSON and English summary. Supports multiple OCR engines.
"""

import streamlit as st
from PIL import Image
import requests
import base64
import io
import os

# Set up Streamlit UI layout
st.set_page_config(page_title="Flowchart to English", layout="wide")
st.title("📄 Flowchart to Plain English")

# Enable debug mode toggle
debug_mode = st.toggle("🔧 Show Debug Info", value=False)

# OCR engine selection dropdown
ocr_engine = st.selectbox("Select OCR Engine", ["easyocr", "doctr"], index=0,
                          help="Choose between EasyOCR (lightweight) and Doctr (transformer-based)")

# Flowchart image uploader
uploaded_file = st.file_uploader("Upload a flowchart image", type=["png", "jpg", "jpeg"])

# Backend API URL (defaults to localhost for dev)
API_URL = os.getenv("API_URL", "http://localhost:7860/process-image")

if uploaded_file:
    # Load and resize uploaded image for preview
    image = Image.open(uploaded_file).convert("RGB")
    max_width = 600
    ratio = max_width / float(image.size[0])
    resized_image = image.resize((max_width, int(image.size[1] * ratio)))
    st.image(resized_image, caption="📤 Uploaded Image", use_container_width=False)

    if st.button("🔍 Analyze Flowchart"):
        progress = st.progress(0, text="Sending image to backend...")

        try:
            # Send request to FastAPI backend
            response = requests.post(
                API_URL,
                files={"file": uploaded_file.getvalue()},
                data={
                    "debug": str(debug_mode).lower(),
                    "ocr_engine": ocr_engine
                }
            )

            progress.progress(40, text="Processing detection and OCR...")

            if response.status_code == 200:
                result = response.json()

                # Show debug info if enabled
                if debug_mode:
                    st.markdown("### 🧪 Debug Info")
                    st.code(result.get("debug", ""), language="markdown")

                # Show YOLO visual if available
                if debug_mode and result.get("yolo_vis"):
                    st.markdown("### 🖼️ YOLO Detected Bounding Boxes")
                    yolo_bytes = base64.b64decode(result["yolo_vis"])
                    yolo_img = Image.open(io.BytesIO(yolo_bytes))
                    st.image(yolo_img, caption="YOLO Boxes", use_container_width=True)

                progress.progress(80, text="Finalizing output...")

                # Show flowchart JSON and generated English summary
                col1, col2 = st.columns(2)
                with col1:
                    st.subheader("🧠 Flowchart JSON")
                    st.json(result["flowchart"])
                with col2:
                    st.subheader("📝 English Summary")
                    st.markdown(result["summary"])

                progress.progress(100, text="Done!")

            else:
                st.error(f"❌ Backend Error: {response.status_code} - {response.text}")

        except Exception as e:
            st.error(f"⚠️ Request Failed: {e}")
else:
    st.info("Upload a flowchart image to begin.")