# Importing required libraries
from transformers import pipeline  # Hugging Face transformers for translation
import gradio as gr  # For building the web interface

# Defining available models with descriptive names
MODELS = {
    "T5-small (Fast)": "t5-small",  # Smaller, faster model
    "T5-base (Better Quality)": "t5-base"  # Larger, more accurate model
}

def translate_text(text, model_name, max_length=50):
    """
    Translates English text to French using the specified model.
    
    Args:
        text (str): Input English text
        model_name (str): Key from MODELS dictionary
        max_length (int): Maximum length of generated translation
        
    Returns:
        str: Translated French text
    """
    # Initializing the translation pipeline
    translator = pipeline(
        "translation_en_to_fr", 
        model=MODELS[model_name],  # Select model based on user choice
        truncation=True  # Ensure long texts are truncated properly
    )
    
    # Performing translation with length control
    result = translator(text, max_length=max_length)[0]["translation_text"]
    return result

# Creating Gradio interface using Blocks for advanced layout
with gr.Blocks(title="Advanced English→French Translator") as demo:
    # ===== HEADER SECTION =====
    gr.Markdown("## 🌍 English to French Translator")
    gr.Markdown("Powered by Hugging Face Transformers")
    
    # ===== MAIN LAYOUT (2 COLUMNS) =====
    with gr.Row():
        # === LEFT COLUMN (INPUTS) ===
        with gr.Column():
            # Text input box
            input_text = gr.Textbox(
                label="English Text",
                placeholder="Type something...",
                lines=3  # 3-line tall textbox
            )
            
            # Model selection dropdown
            model_choice = gr.Dropdown(
                choices=list(MODELS.keys()),  # Show model options
                value="T5-small (Fast)",  # Default selection
                label="Model"
            )
            
            # Translation length slider
            max_length = gr.Slider(
                minimum=10,  # Min character length
                maximum=200,  # Max character length
                value=50,  # Default value
                label="Max Translation Length"
            )
            
            # Submit button
            submit_btn = gr.Button("Translate", variant="primary")
        
        # === RIGHT COLUMN (OUTPUT) ===
        with gr.Column():
            # Output text box (non-editable)
            output_text = gr.Textbox(
                label="French Translation",
                interactive=False,  # Users can't edit output
                lines=5  # 5-line tall textbox
            )
    
    # ===== EXAMPLE SECTION =====
    gr.Examples(
        examples=[
            ["She walks in beauty, like the night Of cloudless climes and starry skies.", "T5-small (Fast)", 100],
            ["And all that’s best of dark and bright Meet in her aspect and her eyes.", "T5-base (Better Quality)", 110]
        ],
        inputs=[input_text, model_choice, max_length],  # Auto-fill these inputs
        label="Try these examples!"  # Section header
    )
    
    # ===== EVENT HANDLING =====
    submit_btn.click(
        fn=translate_text,  # Function to call
        inputs=[input_text, model_choice, max_length],  # Input components
        outputs=output_text,  # Output component
        api_name="translate"  # For API endpoint naming
    )

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