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 * 3.280839895013123
def ft_to_m(value): return value / 3.280839895013123

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 numeric value."

    if category == "Mass":
        if from_unit == "kg" and to_unit == "g":
            return f"{x} kg = {kg_to_g(x)} g"
        elif from_unit == "g" and to_unit == "kg":
            return f"{x} g = {g_to_kg(x)} kg"
        elif from_unit == to_unit:
            return f"{x} {from_unit} = {x} {to_unit}"
        else:
            return "Conversion not supported for Mass."

    elif category == "Length":
        if from_unit == "m" and to_unit == "cm":
            return f"{x} m = {m_to_cm(x)} cm"
        elif from_unit == "cm" and to_unit == "m":
            return f"{x} cm = {cm_to_m(x)} m"
        elif from_unit == "m" and to_unit == "ft":
            return f"{x} m = {round(m_to_ft(x), 4)} ft"
        elif from_unit == "ft" and to_unit == "m":
            return f"{x} ft = {round(ft_to_m(x), 4)} m"
        elif from_unit == to_unit:
            return f"{x} {from_unit} = {x} {to_unit}"
        else:
            return "Conversion not supported for Length."

    elif category == "Temperature":
        if from_unit == "°C" and to_unit == "°F":
            return f"{x} °C = {round(c_to_f(x), 2)} °F"
        elif from_unit == "°F" and to_unit == "°C":
            return f"{x} °F = {round(f_to_c(x), 2)} °C"
        elif from_unit == to_unit:
            return f"{x} {from_unit} = {x} {to_unit}"
        else:
            return "Conversion not supported for Temperature."

    else:
        return "Unknown category."

# -------------------------------
# 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(title="Unit Converter") as demo:
    gr.Markdown("# 🧮 Unit Converter\n### Convert mass, length, and temperature easily!\nBuilt with **Python + Gradio** (no APIs).")
    
    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="Enter a number like 10")
    convert_btn = gr.Button("Convert")
    output = gr.Textbox(label="Result")

    category.change(update_units, inputs=category, outputs=[from_unit, to_unit])
    convert_btn.click(convert_value, inputs=[category, from_unit, to_unit, value], outputs=output)

demo.launch()