#!/bin/bash
read -r CURRENT_IFA < $CURRENT_IFA_FILE
NOW=$(date --iso-8601=ns | sed s/,/./)

ping -I eth0 -c 1 google.com >> /dev/null

if [ $? -eq 0 ]; then
    if [[ $CURRENT_IFA != "eth0" ]]; then
        # If we're using another interface than ethernet,
        # switch back to ethernet
        echo "{"event": "switchifa", "to": "eth0", "msg": "Switch to ethernet", "datetime": "$NOW"}"
        sudo ifmetric eth0 50
        sudo ifmetric eth1 100 >> /dev/null
        echo "eth0" > $CURRENT_IFA_FILE
    fi
else
    if [[ $CURRENT_IFA != "eth1" ]]; then
        # If we're not on 4G, switch to it
        echo "{"event": "switchifa", "to": "eth1", "msg": "Switch to 4G", "datetime": "$NOW"}"
        sudo ifmetric eth1 50 >> /dev/null
        sudo ifmetric eth0 100
        echo "eth1" > $CURRENT_IFA_FILE
    fi
fi