app.py

# Import necessary libraries
import gradio as gr  # Gradio: Library for building web interfaces
import requests       # Library for sending API requests
from openai import OpenAI  # OpenAI-compatible client for using Upstage Solar LLM
from io import BytesIO      # Tool for handling image data in memory

def extract_text_from_image(image, api_key):
    """
    Function to extract text from an image (using Upstage Document OCR API)
    """
    # Upstage API Endpoint
    url = "https://api.upstage.ai/v1/document-digitization"  

    # Set up headers for API Key authentication
    headers = {'Authorization': f'Bearer {api_key}'}  

    # Save the image to a memory buffer (JPEG format)
    buffer = BytesIO()
    image.save(buffer, format="JPEG")
    buffer.seek(0)

    # Prepare files and data for the request
    files = {"document": ("image.jpg", buffer, "image/jpeg")}
    data = {"model": "ocr"}  # Model to use: OCR

    # Send POST request
    response = requests.post(url, headers=headers, files=files, data=data)

    # If request is successful, extract text
    if response.status_code == 200:
        text = response.json().get("text", "")  # Extract text from JSON response
        return text.strip()  # Remove leading/trailing whitespace and return
    else:
        # Return error message on failure
        return f"OCR Failed: {response.status_code} - {response.text}"



def translate_text_with_solar(korean_text, api_key):
    """
    Function to translate Korean text into English (using Upstage Solar Pro API)
    """
    # Initialize OpenAI client for calling Solar LLM
    client = OpenAI(
        api_key=api_key,
        base_url="https://api.upstage.ai/v1"
    )

    # Construct prompt for the model
    prompt = f"""
    Below is a handwritten letter in Korean.\n
    {korean_text} \n
    Please translate it into English.\n\n  
    Translated letter in English: 
    """

    # Call Solar LLM to perform translation
    response = client.chat.completions.create(
        model="solar-pro",  # Model to use
        messages=[{"role": "user", "content": prompt}],  # User message
        temperature=0.5,     # Creativity level (0.0~1.0)
        max_tokens=2048      # Max response length
    )

    # Return translated text
    return response.choices[0].message.content


# Gradio interface layout
with gr.Blocks() as demo:
    # Header description
    gr.Markdown("# 💌 Handwritten Letter Translator")
    gr.Markdown("Upload a letter image to extract Korean text using Upstage Document OCR.\nClick the 🌐 Translate button to translate it into English using Solar LLM!")
    gr.Markdown("The example images are AI-generated. Click the Files button to view or download them.")

    # ✅ API Key input
    api_key_input = gr.Textbox(label="🔑 Upstage API Key", type="password", placeholder="Paste your API key here")

    # Layout: 2-column format
    with gr.Row():
        # Left column: image upload
        with gr.Column(scale=1):
            image_input = gr.Image(type="pil", label=" 💌 Upload Letter Image")

        # Right column: extracted text and translation
        with gr.Column(scale=2):
            korean_box = gr.Textbox(label="📝 Extracted Korean Text", lines=10)
            translate_button = gr.Button("🌐 Translate")
            english_box = gr.Textbox(label="Translated English Text", lines=10)

    # Step 1: Run OCR when image is uploaded → display extracted text
    image_input.change(fn=extract_text_from_image, inputs=[image_input, api_key_input], outputs=korean_box)

    # Step 2: Run translation when button is clicked → display translated result
    translate_button.click(fn=translate_text_with_solar, inputs=[korean_box, api_key_input], outputs=english_box)

# Run app
if __name__ == "__main__":
    demo.launch()