#!/bin/bash

# Configuration
WIFI_INTERFACE="wlan0"
MODEM_INTERFACE="wwan0"
CHECK_INTERVAL=10  # Check every 60 seconds

# Function to check Wi-Fi connection
check_wifi() {
    if iwconfig "$WIFI_INTERFACE" | grep -q "ESSID:off/any"; then
        return 1  # Wi-Fi is not connected
    else
        return 0  # Wi-Fi is connected
    fi
}

# Function to enable 4G modem
enable_4g() {
    echo "Wi-Fi disconnected. Enabling 4G modem..."
    sudo ifconfig "$MODEM_INTERFACE" up
    sudo dhclient "$MODEM_INTERFACE"
}

# Function to disable 4G modem
disable_4g() {
    echo "Wi-Fi connected. Disabling 4G modem..."
    sudo ifconfig "$MODEM_INTERFACE" down
}

# Main loop
while true; do
    if check_wifi; then
        echo "Wi-Fi is connected."
        if ifconfig "$MODEM_INTERFACE" | grep -q "UP"; then
            disable_4g
        fi
    else
        echo "Wi-Fi is disconnected."
        if ! ifconfig "$MODEM_INTERFACE" | grep -q "UP"; then
            enable_4g
        fi
    fi
    sleep "$CHECK_INTERVAL"
done