import streamlit as st
import matplotlib.pyplot as plt

st.set_page_config(page_title="BMI Calculator", page_icon="⚖️")
st.title("⚖️ BMI Calculator")

# Gender/age group selector
category = st.selectbox("Select Category", ["Male", "Female", "Child"])

# Age input
age = st.number_input("Enter your age (in years)", min_value=1, max_value=120, step=1)

# Approximate average height/weight based on age and gender
def get_avg_hw(age, group):
    if group == "Child":
        if age <= 2:
            return (85, 12)
        elif age <= 5:
            return (105, 17)
        elif age <= 10:
            return (130, 25)
        elif age <= 15:
            return (155, 45)
        else:
            return (160, 50)
    elif group == "Male":
        if age < 20:
            return (170, 60)
        else:
            return (175, 70)
    elif group == "Female":
        if age < 20:
            return (160, 55)
        else:
            return (162, 60)

avg_height, avg_weight = get_avg_hw(age, category)
st.info(f"📊 Average for {category}, Age {age}: Height ≈ {avg_height} cm | Weight ≈ {avg_weight} kg")

# Height input unit toggle
height_unit = st.radio("Choose height input unit", ["Centimeters (cm)", "Feet & Inches"])

# Get height based on unit
if height_unit == "Centimeters (cm)":
    height_cm = st.number_input("Enter your height (in cm)", min_value=50.0, max_value=250.0, step=1.0)
    height_m = height_cm / 100
else:
    feet = st.number_input("Feet", min_value=1, max_value=8, step=1)
    inches = st.number_input("Inches", min_value=0, max_value=11, step=1)
    total_inches = (feet * 12) + inches
    height_m = total_inches * 0.0254  # convert inches to meters

# Weight input
weight_kg = st.number_input("Enter your weight (in kg)", min_value=10.0, max_value=300.0, step=0.5)

# Calculate BMI
if height_m > 0 and weight_kg > 0:
    bmi = round(weight_kg / (height_m ** 2), 2)

    # Determine category
    def bmi_category(bmi_val, cat):
        if cat == "Child":
            if bmi_val < 14:
                return "Underweight"
            elif bmi_val < 18:
                return "Healthy"
            elif bmi_val < 20:
                return "Overweight"
            else:
                return "Obese"
        else:
            if bmi_val < 18.5:
                return "Underweight"
            elif bmi_val < 24.9:
                return "Healthy"
            elif bmi_val < 29.9:
                return "Overweight"
            else:
                return "Obese"

    category_label = bmi_category(bmi, category)

    # Display result
    st.success(f"Your BMI is **{bmi}** ({category_label})")

    # Graphical representation
    st.subheader("📊 BMI Category Ranges")

    fig, ax = plt.subplots(figsize=(8, 2))

    if category == "Child":
        thresholds = [14, 18, 20]
        labels = ["Underweight", "Healthy", "Overweight", "Obese"]
    else:
        thresholds = [18.5, 24.9, 29.9]
        labels = ["Underweight", "Healthy", "Overweight", "Obese"]

    colors = ['lightblue', 'lightgreen', 'orange', 'red']
    ranges = [0] + thresholds + [40]

    for i in range(len(labels)):
        ax.barh(0, ranges[i+1] - ranges[i], left=ranges[i], color=colors[i], edgecolor='black', label=labels[i])

    ax.axvline(bmi, color='black', linestyle='--', label=f"Your BMI: {bmi}")
    ax.set_xlim(0, 40)
    ax.set_yticks([])
    ax.set_xlabel("BMI")
    ax.legend(loc="upper center", bbox_to_anchor=(0.5, 1.25), ncol=4)
    st.pyplot(fig)