#!/bin/sh
# k3os-config.sh
# A configuration utility for k3os environments (BusyBox/Alpine compatible)

# --- Global Variables and Constants ---

CONNMAN_CONFIG="/var/lib/connman/default.config"
HOSTNAME_FILE="/var/lib/rancher/k3os/hostname"
SSHD_CONFIG="/etc/ssh/sshd_config"

# Get current user's home directory for Kubeconfig
USER_HOME=$(getent passwd "$(whoami)" | cut -d: -f6)
KUBECONFIG_PATH="$USER_HOME/.kube/config"

# --- ANSI Color Definitions (Portable across BusyBox) ---
# Use %b in printf to interpret these backslash escapes
RED='\033[31m'
GREEN='\033[32m'
YELLOW='\033[33m'
BLUE='\033[34m'
MAGENTA='\033[35m'
CYAN='\033[36m'
BOLD='\033[1m'
BG_BLUE='\033[44;1m'
NC='\033[0m' # No Color

# --- Utility Functions ---

# Function to display system status indicators
show_status() {
    printf '\n'
    printf '%b\n' "${BG_BLUE}--- K3OS Node Status ---${NC}"

    # 1. Hostname
    CURRENT_HOSTNAME=$(hostname)

    # 2. SSHD Password Auth Status
    SSHD_STATUS="${RED}Error (Need Sudo)${NC}"
    if sudo test -f "$SSHD_CONFIG"; then
        if sudo grep -q '^PasswordAuthentication yes' "$SSHD_CONFIG"; then
            SSHD_STATUS="${GREEN}Enabled${NC}"
        else
            SSHD_STATUS="${YELLOW}Disabled${NC}"
        fi
    fi

    # 3. Static IP Configuration Check (from Connman config)
    STATIC_IP=""
    CONFIG_IFACE=""
    if sudo test -f "$CONNMAN_CONFIG"; then
        CONNMAN_CONTENT=$(sudo cat "$CONNMAN_CONFIG" 2>/dev/null)
        CONFIG_IFACE=$(echo "$CONNMAN_CONTENT" | grep '^\[service_' | head -n 1 | sed -e 's/^\[service_\(.*\)\].*$/\1/' | tr -d '[]')
        STATIC_IP=$(echo "$CONNMAN_CONTENT" | grep -oE 'IPv4 = ([0-9]{1,3}\.){3}[0-9]{1,3}' 2>/dev/null | head -n 1 | awk '{print $3}' | cut -d'/' -f1)
    fi

    # 4. Current/Active IP and DHCP status - Use the default route interface
    ACTIVE_IFACE=$(ip route get 1.1.1.1 2>/dev/null | grep -o 'dev [^ ]*' | awk '{print $2}' | head -n 1)
    if [ -z "$ACTIVE_IFACE" ]; then
        ACTIVE_IFACE="eth0"
    fi
    
    CURRENT_IP=$(ip addr show "$ACTIVE_IFACE" 2>/dev/null | grep 'inet ' | awk '{print $2}' | cut -d/ -f1 | head -n 1)

    DHCP_STATUS="${RED}N/A${NC}"
    IP_ADDRESS_STATUS="${RED}No Active Link${NC}"

    if [ -n "$CURRENT_IP" ]; then
        IP_ADDRESS_STATUS="$CURRENT_IP (${CYAN}$ACTIVE_IFACE${NC})"
        if [ -n "$STATIC_IP" ] && [ "$STATIC_IP" = "$CURRENT_IP" ]; then
            DHCP_STATUS="${YELLOW}No${NC} (${CYAN}Static Configured${NC}: $CONFIG_IFACE)"
        else
            DHCP_STATUS="${GREEN}Yes${NC} (or Link-Local)"
        fi
    elif [ -n "$STATIC_IP" ]; then
        IP_ADDRESS_STATUS="${YELLOW}Static Configured${NC}: $STATIC_IP (Inactive)"
        DHCP_STATUS="${YELLOW}No${NC} (Check Link)"
    fi

    # Display results using printf for aligned columns
    printf '%b%-30s%b: %s\n' "$BOLD" "Hostname" "$NC" "$CURRENT_HOSTNAME"
    printf '%b%-30s%b: %s\n' "$BOLD" "Active IP Address (Interface)" "$NC" "$IP_ADDRESS_STATUS"
    printf '%b%-30s%b: %s\n' "$BOLD" "DHCP Assigned" "$NC" "$DHCP_STATUS"
    printf '%b%-30s%b: %s\n' "$BOLD" "SSHD Password Authentication" "$NC" "$SSHD_STATUS"
    printf '\n'
}

# Function to notify user about reboot
notify_reboot() {
    printf '\n%b*** Configuration Applied ***%b\n' "${YELLOW}${BOLD}" "${NC}"
    printf 'For the new settings (Hostname, IP) to take full effect, you must reboot.\n'
    printf '%b(Note: SSH changes are active, but a reboot is safer).%b\n' "$CYAN" "$NC"
}

# Helper to run a command that modifies a root-owned file
run_privileged() {
    printf '\n%b[ACTION REQUIRING SUDO]%b\n' "${BLUE}${BOLD}" "${NC}"
    # Use sudo sh -c to execute the command as root
    if sudo sh -c "$1"; then
        return 0
    else
        printf '\n%bError: Sudo command failed. Check password or permissions.%b\n' "${RED}" "${NC}"
        return 1
    fi
}

# --- Menu Option Functions (1, 2, 3 require sudo via run_privileged) ---

# a. Update hostname
update_hostname() {
    printf "\n--- Update Hostname ---\n"
    printf "The current hostname is: %b%s%b\n" "$CYAN" "$(hostname)" "$NC"
    printf "Enter new hostname: "
    read NEW_HOSTNAME

    if [ -z "$NEW_HOSTNAME" ]; then
        printf '%b\n' "${RED}Hostname cannot be empty. Aborting.${NC}"
        return
    fi
    
    # Use run_privileged for writing to the root-owned file
    if run_privileged "echo '$NEW_HOSTNAME' > $HOSTNAME_FILE"; then
        # This updates the *runtime* hostname, not just the file
        hostname "$NEW_HOSTNAME"
        printf '\n%bSuccessfully updated hostname to: %s%b\n' "$GREEN" "$NEW_HOSTNAME" "$NC"
        notify_reboot
    fi
}

# b. Configure IP address (Static)
configure_ip() {
    printf "\n--- Configure Static IP Address (Connman) ---\n"
    
    # 1. Detect Interface
    IFACE=$(ip route get 1.1.1.1 2>/dev/null | grep -o 'dev [^ ]*' | awk '{print $2}' | head -n 1)
    
    if [ -z "$IFACE" ]; then
        printf '%b\n' "${RED}Could not detect a default network interface. Aborting.${NC}"
        return
    fi
    printf "Detected primary network interface: %b%s%b\n" "$CYAN" "$IFACE" "$NC"

    printf "Enter static IP address (e.g., 192.168.1.10): "
    read IP_ADDR

    printf "Enter netmask prefix (e.g., 24 for 255.255.255.0): "
    read MASK_PREFIX

    printf "Enter gateway address (e.g., 192.168.1.1): "
    read GATEWAY

    printf "Enter nameserver IP (e.g., 8.8.8.8): "
    read NAMESERVER

    if [ -z "$IP_ADDR" ] || [ -z "$MASK_PREFIX" ] || [ -z "$GATEWAY" ] || [ -z "$NAMESERVER" ]; then
        printf '%b\n' "${RED}All fields are required. Aborting.${NC}"
        return
    fi
    
    # Generate Connman config content in a shell variable
    CONFIG_CONTENT="# Automatically generated by k3os-config.sh\n"
    CONFIG_CONTENT="${CONFIG_CONTENT}[service_$IFACE]\n"
    CONFIG_CONTENT="${CONFIG_CONTENT}Type = ethernet\n"
    CONFIG_CONTENT="${CONFIG_CONTENT}Nameservers = $NAMESERVER\n"
    CONFIG_CONTENT="${CONFIG_CONTENT}IPv4 = $IP_ADDR/$MASK_PREFIX/$GATEWAY\n"
    
    # Use run_privileged to write the configuration content
    printf "Writing static configuration to %s...\n" "$CONNMAN_CONFIG"
    
    # Use tee to safely overwrite the file as root.
    # Note: We use single quotes around $CONNMAN_CONFIG for safety, but double quotes around $CONFIG_CONTENT to allow variable expansion.
    PRIV_CMD="printf \"\%b\" \"$CONFIG_CONTENT\" | tee \"$CONNMAN_CONFIG\" >/dev/null"

    if run_privileged "$PRIV_CMD"; then
        printf '\n%bStatic IP configuration saved for interface %s.%b\n' "$GREEN" "$IFACE" "$NC"
        printf "IP: %s/%s, Gateway: %s, Nameserver: %s\n" "$IP_ADDR" "$MASK_PREFIX" "$GATEWAY" "$NAMESERVER"
        notify_reboot
    fi
}

# c. Toggle sshd password authentication
toggle_ssh_auth() {
    printf "\n--- Toggle SSHD Password Authentication ---\n"
    
    # Check current status by reading the root-owned file
    if sudo grep -q '^PasswordAuthentication yes' "$SSHD_CONFIG" 2>/dev/null; then
        CURRENT_SETTING="yes"
        NEW_SETTING="no"
    else
        CURRENT_SETTING="no"
        NEW_SETTING="yes"
    fi
    
    printf "Current setting: %b%s%b\n" "$CYAN" "$CURRENT_SETTING" "$NC"
    
    # 1. Check if line exists (commented or not) and replace it
    # 2. If it doesn't exist, append it
    
    # We use a combined, double-quoted command for run_privileged
    PRIV_CMD="if grep -q '^#*PasswordAuthentication' $SSHD_CONFIG; then
        sed -i 's/^#*PasswordAuthentication .*/PasswordAuthentication $NEW_SETTING/g' $SSHD_CONFIG
    else
        echo 'PasswordAuthentication $NEW_SETTING' >> $SSHD_CONFIG
    fi"

    if run_privileged "$PRIV_CMD"; then
        printf "Setting changed to: %b%s%b\n" "$GREEN" "$NEW_SETTING" "$NC"
        
        printf "Restarting SSH service...\n"
        # Restarting the service also requires sudo
        if run_privileged "/etc/init.d/sshd restart"; then
            printf '\n%bSSHD service restarted. Password authentication is now set to %s.%b\n' "$GREEN" "$NEW_SETTING" "$NC"
        fi
    fi
}

# d. Download kubeconfig from master (NO SUDO REQUIRED)
download_kubeconfig() {
    printf "\n--- Download Kubeconfig ---\n"
    printf "Enter k3s master IP address: "
    read MASTER_IP
    
    if [ -z "$MASTER_IP" ]; then
        printf '%b\n' "${RED}Master IP cannot be empty. Aborting.${NC}"
        return
    fi

    printf "Attempting to download /etc/rancher/k3s/k3s.yaml from rancher@%s\n" "$MASTER_IP"
    printf "(You will be prompted for the 'rancher' user's password on the remote master.)\n"

    # Create .kube directory in the current user's home directory
    mkdir -p "$USER_HOME/.kube"
    
    # Use scp to copy the file to the user's local path
    if scp "rancher@$MASTER_IP:/etc/rancher/k3s/k3s.yaml" "$KUBECONFIG_PATH"; then
        printf '\n%bSuccessfully downloaded kubeconfig to %s%b\n' "$GREEN" "$KUBECONFIG_PATH" "$NC"
        printf "The config file is ready for use by 'kubectl' or 'k3s kubectl'.\n"
    else
        printf '\n%bError: Kubeconfig download failed.%b\n' "${RED}" "${NC}"
        printf "Check the master IP, password for 'rancher', and SSH connectivity.\n"
    fi
}

# --- Main Menu Logic ---

main_menu() {
    while true; do
        show_status
        printf '%bSelect an option (1, 2, 3 require sudo):%b\n' "$BOLD" "$NC"
        printf '  %b1%b) Update hostname (k3os reboot required)\n' "$CYAN" "$NC"
        printf '  %b2%b) Configure static IP (k3os reboot required)\n' "$CYAN" "$NC"
        printf '  %b3%b) Toggle sshd PasswordAuthentication (SSHD service restart)\n' "$CYAN" "$NC"
        printf '  %b4%b) Download kubeconfig from master (Runs as user, NO local sudo)\n' "$CYAN" "$NC"
        printf '  %bQ%b) Quit\n' "$RED" "$NC"
        printf "\nOption: "
        read CHOICE

        case "$CHOICE" in
            1) update_hostname ;;
            2) configure_ip ;;
            3) toggle_ssh_auth ;;
            4) download_kubeconfig ;;
            [Qq]*) printf "\nExiting K3OS configuration utility. Goodbye.\n"; exit 0 ;;
            *) printf '\n%bInvalid option. Please choose 1, 2, 3, 4, or Q.%b\n' "${RED}" "${NC}" ;;
        esac
        printf "\nPress ENTER to return to the menu...\n"
        read DUMMY
    done
}

# --- Script Execution ---
main_menu