#! /bin/bash
#
# hotspot_switcher       script to switch hotspot on/off
#
# Written by Nigel Bowden <wifinigel@gmail.com>.
#
# History:
#
# v0.01 - 25th July 2019 - Initial version based on Francois Verges' article
# v0.02 - 26th July 2019 - Added file checks before file copy/del operations
# v0.03 - 2nd Nov 2019 - Added bridging of interfaces
# v0.04 - 23rd Dec 2019 - Improved docs & added wlan adapter check
# v0.05 - 28th Jan 2020 - Added check for NICs that do not support AP mode
# v0.06 - 12th Jun 2020 - Added suport for new status file location
set -e

NAME=hotspot_switcher
DESC="Script to switch hotspot on/off"
VERSION=0.06
STATUS_FILE="/etc/wlanpi-state"

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

###############################################################################
#
# Activate hotspot:
#
# 1. Backup various existing files to allow restoration when hotspot
#    deactivated
# 2. Remove a number of existing files that need to be replaced
# 3. Create links from deleted file locations to hotspot config files
# 4. Create status file to indicate hotspot is active
# 5. Reboot the wlanpi to ensure clean activation
#
###############################################################################
hotspot_on () {

  echo "Starting switch from classic mode to hostpot mode"

  # check what state the WLAN Pi is in classic mode
  PI_STATUS=`cat $STATUS_FILE | grep 'classic'` || true
  if  [ -z "$PI_STATUS" ]; then
     echo "Failed - WLAN Pi is not in classic mode."
     exit 1
  fi

  # check if the WLAN NIC supports AP mode before switching
  # iw list | awk '/Supported interface modes/, /Band/' | grep '\* AP'
   AP_SUPPORT=`iw list | awk '/Supported interface modes/, /Band/' | grep '\* AP'` || true
   if  [ -z "$AP_SUPPORT" ]; then
     echo "Failed - AP Mode not supported by adapter."
     exit 1
  fi
  
  echo "Enabling hotspot..."
  #Backup existing config files
  echo "Backing up existing config files..."
  cp /etc/default/isc-dhcp-server /etc/default/isc-dhcp-server.hspt
  cp /etc/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf.hspt
  cp /etc/network/interfaces /etc/network/interfaces.hspt
  cp /etc/sysctl.conf /etc/sysctl.conf.hspt
  cp /etc/default/ufw /etc/default/ufw.hspt
  cp /etc/ufw/before.rules /etc/ufw/before.rules.hspt
  # This file may or may not exist
  if [ -e /etc/hostapd.conf ]; then
    cp /etc/hostapd.conf /etc/hostapd.conf.hspt
  fi
  # Remove existing config files
  echo "Removing existing config files..."
  rm /etc/default/isc-dhcp-server
  rm /etc/dhcp/dhcpd.conf
  rm /etc/network/interfaces
  rm /etc/sysctl.conf
  rm /etc/default/ufw
  rm /etc/ufw/before.rules
  # This file may or may not exist
  if [ -e /etc/hostapd.conf ]; then
    rm /etc/hostapd.conf
  fi
  # Link to hotspot config files
  echo "Creaing links to config files..."
  ln -s /etc/wlanpihotspot/default/isc-dhcp-server /etc/default/isc-dhcp-server 
  ln -s /etc/wlanpihotspot/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf
  ln -s /etc/wlanpihotspot/network/interfaces /etc/network/interfaces
  ln -s /etc/wlanpihotspot/conf/hostapd.conf /etc/hostapd.conf
  ln -s /etc/wlanpihotspot/sysctl/sysctl.conf /etc/sysctl.conf
  ln -s /etc/wlanpihotspot/default/ufw /etc/default/ufw
  ln -s /etc/wlanpihotspot/ufw/before.rules /etc/ufw/before.rules

  # Signal that wconsole active
  echo "hotspot" > $STATUS_FILE
  echo "WLANPi will now reboot"
  sleep 1
  sync
  reboot

  
}

###############################################################################
#
# Deactivate hotspot:
#
# 1. Remove links created during activation
# 2. Restore config files backed up during activation
# 3. Remove firewall rules added during activation
# 4. Remove status file to indicate hotspot no longer active
# 5. Reboot wlanpi to provide clean restoration of services
#
###############################################################################
hotspot_off () {

  # check what state the WLAN Pi is in
  PI_STATUS=`cat $STATUS_FILE | grep 'hotspot'` || true
  if  [ -z "$PI_STATUS" ]; then
     echo "Failed - WLAN Pi is not in wconsole mode."
     exit 1
  fi

  echo "Starting switch from hotspot mode to classic mode"

  # Remove links to config files
  echo "Removing links to config files..."
  unlink /etc/default/isc-dhcp-server
  unlink /etc/dhcp/dhcpd.conf
  unlink /etc/network/interfaces
  unlink /etc/hostapd.conf
  unlink /etc/sysctl.conf
  unlink /etc/default/ufw
  unlink /etc/ufw/before.rules

  # Restore original config files
  echo "Restoring original config files..."
  cp /etc/default/isc-dhcp-server.hspt /etc/default/isc-dhcp-server
  cp /etc/dhcp/dhcpd.conf.hspt /etc/dhcp/dhcpd.conf
  cp /etc/network/interfaces.hspt /etc/network/interfaces
  cp /etc/sysctl.conf.hspt /etc/sysctl.conf
  cp /etc/default/ufw.hspt /etc/default/ufw
  cp /etc/ufw/before.rules.hspt /etc/ufw/before.rules
  # This file may or may not exist
  if [ -e /etc/hostapd.conf.hspt ]; then
    cp /etc/hostapd.conf.hspt /etc/hostapd.conf
  fi

  echo "WLANPi will now reboot"
  echo "classic" > $STATUS_FILE
  sleep 1
  sync
  reboot
}

status () {
  PI_STATUS=`cat $STATUS_FILE | grep 'hotspot'` || true
  if  [ -z "$PI_STATUS" ]; then
    echo "hotspot is currently disabled"
    exit 0
  else
    echo "hotpot is currently enabled"
    exit 0
  fi

}

version () {
    N=/etc/wlanpihotspot/$NAME
        echo "Version: $N $VERSION" >&2
        exit 1

}

case "$1" in
  on)
        hotspot_on
        ;;
  off)
        hotspot_off
        ;;
  status)
        status
        ;;
  install)
        install
        ;;
  version)
        version;;
  *)
        N=/etc/wlanpihotspot/$NAME
        echo "Usage: $N {on|off|status|version}" >&2
        exit 1
        ;;
esac

exit 0