#!/bin/bash
# Toggle Pi-hole DNS on/off for active network connection

set -e

# Pi-hole DNS servers
PIHOLE_DNS="192.168.1.120 192.168.1.121 192.168.1.122 192.168.1.1"

# Colors for output
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
RED='\033[0;31m'
NC='\033[0m' # No Color

# Get active connection name (excluding loopback)
get_active_connection() {
    nmcli -t -f NAME,DEVICE connection show --active | grep -v ':lo$' | head -1 | cut -d: -f1
}

# Check if Pi-hole DNS is currently enabled
is_pihole_enabled() {
    local connection="$1"
    local ignore_auto_dns=$(nmcli -t -f ipv4.ignore-auto-dns connection show "$connection" | cut -d: -f2)
    [[ "$ignore_auto_dns" == "yes" ]]
}

# Enable Pi-hole DNS
enable_pihole() {
    local connection="$1"
    echo -e "${YELLOW}Enabling Pi-hole DNS for connection: $connection${NC}"
    nmcli con mod "$connection" ipv4.dns "$PIHOLE_DNS"
    nmcli con mod "$connection" ipv4.ignore-auto-dns yes
    nmcli con up "$connection" > /dev/null 2>&1
    echo -e "${GREEN}✓ Pi-hole DNS enabled${NC}"
    echo "DNS servers: $PIHOLE_DNS"
}

# Disable Pi-hole DNS (use DHCP-provided DNS)
disable_pihole() {
    local connection="$1"
    echo -e "${YELLOW}Disabling Pi-hole DNS for connection: $connection${NC}"
    nmcli con mod "$connection" ipv4.dns ""
    nmcli con mod "$connection" ipv4.ignore-auto-dns no
    nmcli con up "$connection" > /dev/null 2>&1
    echo -e "${GREEN}✓ Pi-hole DNS disabled (using DHCP DNS)${NC}"
}

# Show current DNS status
show_status() {
    local connection="$1"
    echo -e "\n${YELLOW}Current DNS configuration:${NC}"
    nmcli dev show | grep "IP4.DNS" | head -4
}

# Check if running on Fedora
check_os() {
    if [[ ! -f /etc/fedora-release ]]; then
        echo -e "${RED}Error: This script is designed for Fedora Linux only${NC}"
        if [[ -f /etc/os-release ]]; then
            source /etc/os-release
            echo "Detected OS: $NAME"
        fi
        exit 1
    fi
}

# Main logic
main() {
    # Check OS compatibility
    check_os

    # Check if running as root
    if [[ $EUID -eq 0 ]]; then
        echo -e "${RED}Error: Do not run this script as root${NC}"
        exit 1
    fi

    # Get active connection
    CONNECTION=$(get_active_connection)
    
    if [[ -z "$CONNECTION" ]]; then
        echo -e "${RED}Error: No active network connection found${NC}"
        exit 1
    fi

    echo "Active connection: $CONNECTION"

    # Handle command-line arguments
    case "${1:-toggle}" in
        on|enable)
            enable_pihole "$CONNECTION"
            show_status "$CONNECTION"
            ;;
        off|disable)
            disable_pihole "$CONNECTION"
            show_status "$CONNECTION"
            ;;
        status)
            if is_pihole_enabled "$CONNECTION"; then
                echo -e "${GREEN}Pi-hole DNS is currently ENABLED${NC}"
            else
                echo -e "${YELLOW}Pi-hole DNS is currently DISABLED${NC}"
            fi
            show_status "$CONNECTION"
            ;;
        toggle|*)
            if is_pihole_enabled "$CONNECTION"; then
                disable_pihole "$CONNECTION"
            else
                enable_pihole "$CONNECTION"
            fi
            show_status "$CONNECTION"
            ;;
    esac
}

main "$@"