import gradio as gr

# --- Conversion Functions ---
def kg_to_g(value): return value * 1000
def g_to_kg(value): return value / 1000
def m_to_cm(value): return value * 100
def cm_to_m(value): return value / 100
def m_to_ft(value): return value * 3.28084
def ft_to_m(value): return value / 3.28084
def c_to_f(value): return (value * 9/5) + 32
def f_to_c(value): return (value - 32) * 5/9

# --- Conversion Dispatcher ---
def convert_value(category, from_unit, to_unit, input_value):
    try:
        x = float(input_value)
    except:
        return "⚠️ Please enter a valid number."

    if category == "Mass":
        if from_unit == "kg" and to_unit == "g": result = kg_to_g(x)
        elif from_unit == "g" and to_unit == "kg": result = g_to_kg(x)
        elif from_unit == to_unit: result = x
        else: return "Conversion not supported in Mass category."

    elif category == "Length":
        if from_unit == "m" and to_unit == "cm": result = m_to_cm(x)
        elif from_unit == "cm" and to_unit == "m": result = cm_to_m(x)
        elif from_unit == "m" and to_unit == "ft": result = m_to_ft(x)
        elif from_unit == "ft" and to_unit == "m": result = ft_to_m(x)
        elif from_unit == to_unit: result = x
        else: return "Conversion not supported in Length category."

    elif category == "Temperature":
        if from_unit == "°C" and to_unit == "°F": result = c_to_f(x)
        elif from_unit == "°F" and to_unit == "°C": result = f_to_c(x)
        elif from_unit == to_unit: result = x
        else: return "Conversion not supported in Temperature category."

    else:
        return "Unknown category."

    return f"{x} {from_unit} = {round(result, 4)} {to_unit}"

# --- Gradio Interface ---
categories = ["Mass", "Length", "Temperature"]
units_map = {
    "Mass": ["kg", "g"],
    "Length": ["m", "cm", "ft"],
    "Temperature": ["°C", "°F"]
}

def update_units(cat):
    return (
        gr.update(choices=units_map[cat], value=units_map[cat][0]),
        gr.update(choices=units_map[cat], value=units_map[cat][1]),
    )

with gr.Blocks() as demo:
    gr.Markdown("# 🧮 Unit Converter App\nConvert mass, length, and temperature easily!")
    with gr.Row():
        category = gr.Dropdown(label="Category", choices=categories, value="Mass")
        from_unit = gr.Dropdown(label="From unit", choices=units_map["Mass"], value="kg")
        to_unit = gr.Dropdown(label="To unit", choices=units_map["Mass"], value="g")
    value = gr.Textbox(label="Value to convert", placeholder="e.g., 12.5")
    convert_btn = gr.Button("Convert")
    output = gr.Textbox(label="Result", interactive=False)
    
    category.change(fn=update_units, inputs=category, outputs=[from_unit, to_unit])
    convert_btn.click(fn=convert_value, inputs=[category, from_unit, to_unit, value], outputs=output)

demo.launch()