#!/bin/bash
# Domotz VLAN Configurator script for Linux
# What it does:
# - configures VLANs on a Linux host

ver="1.0"

# Check if the script is run as root
if [[ $EUID -ne 0 ]]; then
    echo "This script must be run as root"
    exit 1
fi

echo "+------------------------------------------------+"
echo "|  ___                             _             |"
echo "| (  _'\                          ( )_           |"
echo "| | | ) |   _     ___ ___     _   | ,_) ____     |"
echo "| | | | ) /'_'\ /' _ ' _ '\ /'_'\ | |  (_  ,)    |"
echo "| | |_) |( (_) )| ( ) ( ) |( (_) )| |_  /'/_     |"
echo "| (____/''\___/'(_) (_) (_)'\___/''\__)(____)    |"
echo "| ---------------------------------------------- |"
echo "| The IT Monitoring and Management Solution      |"
echo "+------------------------------------------------+"
echo ""
echo "VLAN Configurator for Ubuntu Linux ver ${ver}"
echo "========================"
echo "Before using this, make sure your system uses the"
echo "netplan file to configure its network properties"
echo "========================"

# Change this to your netplan file path
NETPLAN_FILE="/etc/netplan/00-installer-config.yaml"

# Function to check if the IP address is valid
validate_ip() {
    local ip_with_mask=$1
    local ip=${ip_with_mask%%/*}
    local mask=${ip_with_mask##*/}

    # Validate IP format
    if [[ $ip =~ ^([0-9]{1,3}\.){3}[0-9]{1,3}$ ]]; then
        IFS='.' read -r -a octets <<< "$ip"
        for octet in "${octets[@]}"; do
            if ((octet < 0 || octet > 255)); then
                return 1
            fi
        done
    else
        return 1
    fi

    # Validate subnet mask if present
    if [[ $ip_with_mask == */* ]]; then
        if ! [[ $mask =~ ^[0-9]{1,2}$ ]] || ((mask < 16 || mask > 32)); then
            return 1
        fi
    fi

    return 0
}

# Function to add /24 subnet mask if not provided
add_subnet_mask() {
    local ip=$1
    if [[ ! $ip =~ /[0-9]{1,2}$ ]]; then
        ip="${ip}/24"
    fi
    echo "$ip"
}

# Function to check if the input is a number
is_number() {
    local num=$1
    [[ $num =~ ^[0-9]+$ ]]
}

# Show the interfaces currently configured
echo "Current interfaces configuration:"
echo ""
ip -o link show | awk -F': ' '{print $2}' | grep -v lo
echo ""
echo "========================"

# Function to check if an interface exists
validate_interface() {
    local iface=$1
    ip -o link show | awk -F': ' '{print $2}' | grep -v lo | grep -wq "$iface"
}

# Function to get ordinal number in uppercase
get_ordinal() {
    local number=$1
    case $number in
        1) echo "FIRST";;
        2) echo "SECOND";;
        3) echo "THIRD";;
        4) echo "FOURTH";;
        5) echo "FIFTH";;
        6) echo "SIXTH";;
        7) echo "SEVENTH";;
        8) echo "EIGHTH";;
        9) echo "NINTH";;
        10) echo "TENTH";;
        *) echo "${number}TH";;
    esac
}

# Ask on which interface to configure the VLANs
while true; do
    read -p "Enter the interface name to configure VLANs: " IFACE
    if validate_interface "$IFACE"; then
        break
    else
        printf "Interface not found. Please enter a valid interface name.\n" >&2
    fi
done
echo "========================"

# Ask the number of VLANs to configure
while true; do
    read -p "Enter the number of VLANs you want to configure: " VLAN_COUNT
    if is_number "$VLAN_COUNT"; then
        break
    else
        printf "Invalid input. Please enter a numeric value.\n" >&2
    fi
done
echo "========================"

# Define a function to make backup with incrementing names
make_backup() {
    local file=$1
    local backup_dir; backup_dir=$(dirname "$file")
    local backup_name; backup_name=$(basename "$file")
    local i=1
    while [[ -f "$backup_dir/${backup_name}.bak$i" ]]; do
        let i++
    done
    cp "$file" "$backup_dir/${backup_name}.bak$i"
    echo "Backup made as ${backup_name}.bak$i"
}
echo "========================"

# Collect VLAN details
declare -A vlans
for (( i=1; i<=VLAN_COUNT; i++ )); do
    ordinal=$(get_ordinal $i)
    echo "Configuring the $ordinal VLAN of $VLAN_COUNT"
    
    while true; do
        read -p "Enter VLAN ID for the $ordinal VLAN: " vlan_id
        if is_number "$vlan_id"; then
            break
        else
            printf "Invalid input. Please enter a numeric value.\n" >&2
        fi
    done

    # Validate and get the IP address with subnet mask
    while true; do
        read -p "Enter IP (e.g., 192.168.1.1 or 192.168.1.1/24) for the $ordinal VLAN: " ip
        ip=$(add_subnet_mask "$ip")
        if validate_ip "$ip"; then
            break
        else
            printf "Invalid IP address or subnet mask wider than /16. Please enter a valid IP address.\n" >&2
        fi
    done

    vlans[$vlan_id]=$ip
    echo "VLAN ${IFACE}.${vlan_id} with IP $ip added"
    echo "========================"
done

# Recap
echo "Here's the summary of what you're about to apply:"
for id in "${!vlans[@]}"; do
    echo "Interface ${IFACE}.${id}, VLAN ID $id, IP ${vlans[$id]}"
done
echo "========================"

# Preview the netplan file with new configurations
echo "Preview of the netplan file with new configurations:"

# Read the existing netplan file, excluding any existing VLAN sections
if ! awk '
    /^  vlans:/ {delete_block=1}
    /^[^ ]/ {delete_block=0}
    !delete_block' "$NETPLAN_FILE" > "${NETPLAN_FILE}.tmp"; then
    printf "Error reading netplan file.\n" >&2
    exit 1
fi

# Append the new VLAN configurations
cat <<EOL >> "${NETPLAN_FILE}.tmp"
  vlans:
EOL

for id in "${!vlans[@]}"; do
    cat <<EOL >> "${NETPLAN_FILE}.tmp"
    ${IFACE}.${id}:
      id: ${id}
      link: ${IFACE}
      addresses:
        - ${vlans[$id]}
EOL
done

cat "${NETPLAN_FILE}.tmp"
echo "========================"

# Confirmation
read -p "Do you want to apply these settings? (yes/no): " confirm
if [[ $confirm == "yes" ]]; then
    make_backup "$NETPLAN_FILE"
    mv "${NETPLAN_FILE}.tmp" "$NETPLAN_FILE"
    echo "Configurations have been written to $NETPLAN_FILE. Please review and apply with 'netplan apply'."
else
    echo "Changes not applied."
    rm "${NETPLAN_FILE}.tmp"
    exit 0
fi
echo "========================"