#!/bin/bash

# ===== CONFIG =====
COMMUNITY="PathCore"
LOCATION="Server Room"
CONTACT="sysadmin@pathcore.internal"
ALLOWED_IP="0.0.0.0/0"   # CHANGE THIS for security
# ==================

set -e

if [[ $EUID -ne 0 ]]; then
  echo "Please run as root"
  exit 1
fi

echo "Detecting OS..."

if [ -f /etc/os-release ]; then
  . /etc/os-release
  OS_FAMILY=$ID
else
  echo "Cannot detect OS"
  exit 1
fi

install_snmp_debian() {
  apt update -y
  apt install -y snmp snmpd
}

install_snmp_rhel() {
  dnf install -y net-snmp net-snmp-utils
}

case "$OS_FAMILY" in
  ubuntu|debian)
    echo "Detected Debian-based OS"
    install_snmp_debian
    ;;
  rhel|centos|rocky|almalinux|fedora)
    echo "Detected RHEL-based OS"
    install_snmp_rhel
    ;;
  *)
    echo "Unsupported OS: $OS_FAMILY"
    exit 1
    ;;
esac

echo "Backing up SNMP config..."
SNMP_CONF="/etc/snmp/snmpd.conf"
cp $SNMP_CONF ${SNMP_CONF}.bak.$(date +%F-%T)

echo "Configuring SNMP..."
cat <<EOF > $SNMP_CONF
agentAddress udp:161
rocommunity $COMMUNITY $ALLOWED_IP

sysLocation    $LOCATION
sysContact     $CONTACT

# Basic monitoring
extend uptime /usr/bin/uptime
extend df /bin/df -h
EOF

echo "Starting and enabling SNMP..."
systemctl restart snmpd
systemctl enable snmpd

echo
echo "SNMP setup complete ✅"
echo "Test with:"
echo "snmpwalk -v2c -c $COMMUNITY localhost system"