#!/bin/bash
# Simple netplan static IP setup script

# Helper functions
have() { command -v "$1" >/dev/null 2>&1; }

as_root() {
    if [ "$(id -u)" -eq 0 ]; then
        sh -c "$*"
    elif have sudo; then
        sudo sh -c "$*"
    else
        echo "ERROR: need root or sudo: $*" >&2
        exit 1
    fi
}

# Validate IPv4 address
validate_ip() {
    echo "$1" | grep -qE '^([0-9]{1,3}\.){3}[0-9]{1,3}$' || return 1
    echo "$1" | IFS='.' read -ra octets
    for octet in "${octets[@]}"; do
        [ "$octet" -le 255 ] || return 1
    done
}

# Auto-detect network settings
detect_network() {
    echo "Detecting network settings..."
    
    # Detect interface
    PRIMARY_INTERFACE=$(ip route show default 2>/dev/null | awk '/default/ {print $5; exit}')
    [ -z "$PRIMARY_INTERFACE" ] && PRIMARY_INTERFACE=$(ip -br link show type ethernet 2>/dev/null | head -1 | cut -d' ' -f1)
    [ -z "$PRIMARY_INTERFACE" ] && PRIMARY_INTERFACE=$(ip link show 2>/dev/null | grep -v "lo:" | head -1 | cut -d: -f2 | tr -d ' ')
    
    # Detect gateway
    GATEWAY=$(ip route show default 2>/dev/null | awk '/default/ {print $3; exit}')
    
    # Detect current IP and subnet - get the main/primary IP only
    CURRENT_IP_CIDR=$(ip -4 addr show "$PRIMARY_INTERFACE" 2>/dev/null | grep -E "^\s*inet\s+" | head -1 | awk '{print $2}')
    if [ -n "$CURRENT_IP_CIDR" ]; then
        CURRENT_IP=$(echo "$CURRENT_IP_CIDR" | cut -d'/' -f1 | tr -d '[:space:]')
        SUBNET=$(echo "$CURRENT_IP_CIDR" | cut -d'/' -f2 | tr -d '[:space:]')
        # Ensure subnet has a value
        [ -z "$SUBNET" ] && SUBNET="24"
    else
        CURRENT_IP="192.168.1.100"
        SUBNET="24"
    fi
    
    DNS="1.1.1.1,9.9.9.9"
    

    
    echo "Interface: $PRIMARY_INTERFACE"
    echo "Current IP: $CURRENT_IP_CIDR"
    echo "Gateway: $GATEWAY"
    echo "Default DNS: $DNS"
    
    # Debug variables to identify contamination
    echo "DEBUG: CURRENT_IP='$CURRENT_IP'"
    echo "DEBUG: SUBNET='$SUBNET'"
}

# Get user input
get_config() {
    echo
    echo "=== Network Configuration ==="
    
    echo -n "Static IP address [$CURRENT_IP]: "
    read -r input
    STATIC_IP="${input:-$CURRENT_IP}"
    
    while ! validate_ip "$STATIC_IP"; do
        echo "Invalid IP. Try again:"
        read -r STATIC_IP
    done
    
    # Sanitize user input - ensure only one clean IP
    STATIC_IP=$(echo "$STATIC_IP" | tr -d '[:space:]')
    
    echo -n "Delete existing netplan files? [y/N]: "
    read -r cleanup
    CLEANUP_NETPLAN="${cleanup,,}"
}

# Create netplan config
create_config() {
    echo "Creating netplan configuration..."
    config="/etc/netplan/20-static-ip.yaml"
    
    # Delete existing netplan files if requested
    if [ "$CLEANUP_NETPLAN" = "y" ]; then
        echo "Deleting existing netplan files..."
        as_root "rm -f /etc/netplan/*.yaml" 2>/dev/null || true
    fi
    
    # Backup existing
    [ -f "$config" ] && as_root "cp '$config' '$config.backup.$(date +%s)'"
    
    # Format DNS and sanitize
    DNS_ADDRESSES=$(echo "$DNS" | sed 's/,/, /g' | tr -d '[:space:]')
    
    # Build clean address string - ensure only one IP with subnet
    STATIC_IP_CLEAN=$(echo "$STATIC_IP" | tr -d '[:space:]')
    SUBNET_CLEAN=$(echo "$SUBNET" | tr -d '[:space:]')
    FULL_ADDRESS="${STATIC_IP_CLEAN}/${SUBNET_CLEAN}"
    
    # Create new config
    cat > /tmp/netplan-config.yaml << EOF
network:
  version: 2
  renderer: networkd
  ethernets:
    $PRIMARY_INTERFACE:
      dhcp4: no
      dhcp6: no
      addresses:
        - ${FULL_ADDRESS}
      routes:
        - to: default
          via: $GATEWAY
      nameservers:
        addresses: [${DNS_ADDRESSES}]
EOF
    
    # Copy to system location
    as_root "cp /tmp/netplan-config.yaml '$config'"
    as_root "chmod 600 '$config'"
    rm -f /tmp/netplan-config.yaml
    
    echo "Configuration created: $config"
}

# Apply configuration
apply_config() {
    echo "Applying configuration..."
    as_root "netplan apply"
    
    echo "Configuration applied successfully!"
    
    # Reset networking
    echo "Resetting networking..."
    as_root "ip addr flush dev $PRIMARY_INTERFACE" 2>/dev/null || true
    as_root "netplan generate"
    as_root "netplan apply"
    as_root "systemctl restart systemd-networkd" 2>/dev/null || true
    as_root "systemctl restart NetworkManager" 2>/dev/null || true
    
    sleep 5
    
    # Verify - get the first IP address only, exclude secondary/old IPs
    local assigned_ip=$(ip -4 addr show "$PRIMARY_INTERFACE" 2>/dev/null | awk '/inet / {print $2; exit}' | cut -d'/' -f1)
    echo "Assigned IP: $assigned_ip"
    
    # Test gateway reachability without ping
    if timeout 5 bash -c "</dev/tcp/$GATEWAY/80" 2>/dev/null; then
        echo "✓ Gateway reachable"
    else
        echo "⚠ Cannot reach gateway"
    fi
    
    echo "Testing internet connectivity..."
    if timeout 10 curl -s ip.sgc.ai >/dev/null 2>&1; then
        local wan_ip=$(timeout 10 curl -s ip.sgc.ai 2>/dev/null)
        if [ -n "$wan_ip" ]; then
            echo "✓ SUCCESS: Internet connectivity confirmed"
            echo "Current WAN IP: $wan_ip"
        else
            echo "✗ SUCCESS: Internet connectivity confirmed"
        fi
    else
        echo "✗ FAILED: Cannot reach internet"
    fi
}

# Main execution
main() {
    echo "=== Netplan Static IP Setup ==="
    
    [ "$(id -u)" -ne 0 ] && {
        echo "This script requires root privileges. Using sudo..."
        exec sudo bash "$0" "$@"
    }
    
    have netplan || { echo "ERROR: netplan is not installed"; exit 1; }
    [ -d /etc/netplan ] || { echo "ERROR: /etc/netplan directory not found"; exit 1; }
    
    detect_network
    get_config
    
    # Build clean address string for display - ensure only one IP with subnet
    STATIC_IP_DISPLAY=$(echo "$STATIC_IP" | tr -d '[:space:]')
    SUBNET_DISPLAY=$(echo "$SUBNET" | tr -d '[:space:]')
    DISPLAY_ADDRESS="${STATIC_IP_DISPLAY}/${SUBNET_DISPLAY}"
    
    echo
    echo "=== Configuration Summary ==="
    echo "Interface: $PRIMARY_INTERFACE"
    echo "Static IP: ${DISPLAY_ADDRESS}"
    echo "Gateway: $GATEWAY (auto-detected)"
    echo "DNS: $DNS"
    echo
    
    echo -n "Apply this configuration? [y/N]: "
    read -r confirm
    [ "${confirm,,}" = "y" ] || { echo "Cancelled."; exit 0; }
    
    create_config
    apply_config
    
    echo
    echo "✓ Static IP configuration completed!"
    echo "Edit future changes: /etc/netplan/20-static-ip.yaml"
}

main "$@"