#!/bin/bash
### BEGIN INIT INFO
# Provides: ynh-hotspot
# Required-Start:    $network $remote_fs $syslog
# Required-Stop:     $network $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Set prerequisites for wifi hotspot.
# Description:       Set prerequisites for wifi hotspot.
### END INIT INFO

# Functions
## State functions

is_ndproxy_set() {
  proxy=$(ip -6 neighbour show proxy)
  [ ! -z "${proxy}" ]
}

is_nat_set() {
  internet_device=$1

  iptables -nvt nat -L POSTROUTING | grep MASQUERADE | grep -q "${internet_device}"
}

is_ip4nataddr_set() {
  ip address show dev "${ynh_wifi_device}" 2> /dev/null | grep -q "${ynh_ip4_nat_prefix}.1/24"
}

is_ip6addr_set() {
  ip address show dev "${ynh_wifi_device}" 2> /dev/null | grep -q "${ynh_ip6_addr}/64"
}

is_forwarding_set() {
  ip6=$(sysctl net.ipv6.conf.all.forwarding | awk '{ print $NF; }')
  ip4=$(sysctl net.ipv4.conf.all.forwarding | awk '{ print $NF; }')

  [ "${ip6}" -eq 1 -a "${ip4}" -eq 1 ]
}

is_hostapd_running() {
  service hostapd status &> /dev/null
}

is_radvd_running() {
  service radvd status &> /dev/null
}

is_dhcpd_running() {
  service isc-dhcp-server status &> /dev/null
}

is_running() {
  is_ndproxy_set && is_nat_set "${new_internet_device}" && is_ip4nataddr_set\
  && is_ip6addr_set && is_forwarding_set && is_hostapd_running\
  && is_radvd_running && is_dhcpd_running
}

## Setters

set_ndproxy() {
  ip -6 neighbour add proxy "${ynh_ip6_addr}" dev "${ynh_wifi_device}"
}

set_nat() {
  internet_device=$1

  iptables -t nat -A POSTROUTING -o "${internet_device}" -j MASQUERADE
}

set_ip4nataddr() {
  ip address add "${ynh_ip4_nat_prefix}.1/24" dev "${ynh_wifi_device}"
}

set_ip6addr() {
  ip address add "${ynh_ip6_addr}/64" dev "${ynh_wifi_device}"
}

set_forwarding() {
  sysctl -w net.ipv6.conf.all.forwarding=1 > /dev/null
  sysctl -w net.ipv4.conf.all.forwarding=1 > /dev/null
}

start_hostapd() {
  cp /etc/hostapd/hostapd.conf{.tpl,}

  sed "s|<TPL:WIFI_DEVICE>|${ynh_wifi_device}|g" -i /etc/hostapd/hostapd.conf
  sed "s|<TPL:WIFI_SSID>|${ynh_wifi_ssid}|g" -i /etc/hostapd/hostapd.conf
  sed "s|<TPL:WIFI_PASSPHRASE>|${ynh_wifi_passphrase}|g" -i /etc/hostapd/hostapd.conf

  service hostapd start
}

start_radvd() {
  cp /etc/radvd.conf{.tpl,}

  sed "s|<TPL:WIFI_DEVICE>|${ynh_wifi_device}|g" -i /etc/radvd.conf
  sed "s|<TPL:IP6_NET>|${ynh_ip6_net}|g" -i /etc/radvd.conf
  sed "s|<TPL:IP6_DNS0>|${ynh_ip6_dns0}|g" -i /etc/radvd.conf
  sed "s|<TPL:IP6_DNS1>|${ynh_ip6_dns1}|g" -i /etc/radvd.conf

  service radvd start
}

start_dhcpd() {
  cp /etc/dhcp/dhcpd.conf{.tpl,}

  sed "s|<TPL:IP4_DNS0>|${ynh_ip4_dns0}|g" -i /etc/dhcp/dhcpd.conf
  sed "s|<TPL:IP4_DNS1>|${ynh_ip4_dns1}|g" -i /etc/dhcp/dhcpd.conf
  sed "s|<TPL:WIFI_DEVICE>|${ynh_wifi_device}|g" -i /etc/dhcp/dhcpd.conf
  sed "s|<TPL:IP4_NAT_PREFIX>|${ynh_ip4_nat_prefix}|g" -i /etc/dhcp/dhcpd.conf

  service isc-dhcp-server start
}

## Unsetters

unset_ndproxy() {
  ip -6 neighbour delete proxy "${ynh_ip6_addr}" dev "${ynh_wifi_device}"
}

unset_nat() {
  internet_device=$1

  iptables -t nat -D POSTROUTING -o "${internet_device}" -j MASQUERADE
}

unset_ip4nataddr() {
  ip address delete "${ynh_ip4_nat_prefix}.1/24" dev "${ynh_wifi_device}"
}

unset_ip6addr() {
  ip address delete "${ynh_ip6_addr}/64" dev "${ynh_wifi_device}"
}

unset_forwarding() {
  sysctl -w net.ipv6.conf.all.forwarding=0 > /dev/null
  sysctl -w net.ipv4.conf.all.forwarding=0 > /dev/null
}

stop_hostapd() {
  service hostapd stop
}

stop_radvd() {
  service radvd stop
}

stop_dhcpd() {
  service isc-dhcp-server stop
}

## Tools

moulinette_get() {
  var=$1

  value=$(yunohost app setting hotspot "${var}")

  if [[ "${value}" =~ "An instance is already running" ]]; then
    echo "${value}" >&2
    exit 1
  fi

  echo "${value}"
} 

moulinette_set() {
  var=$1
  value=$2

  msg=$(yunohost app setting hotspot "${var}" -v "${value}")

  if [ ! $? -eq 0 ]; then
    echo "${msg}" >&2
    exit 1
  fi
}

# Variables

echo -n "Retrieving Yunohost settings... "

ynh_wifi_device=$(moulinette_get wifi_device)
ynh_wifi_ssid=$(moulinette_get wifi_ssid)
ynh_wifi_passphrase=$(moulinette_get wifi_passphrase)
ynh_ip6_addr=$(moulinette_get ip6_addr)
ynh_ip6_net=$(moulinette_get ip6_net)
ynh_ip6_dns0=$(moulinette_get ip6_dns0)
ynh_ip6_dns1=$(moulinette_get ip6_dns1)
ynh_ip4_dns0=$(moulinette_get ip4_dns0)
ynh_ip4_dns1=$(moulinette_get ip4_dns1)
ynh_ip4_nat_prefix=$(moulinette_get ip4_nat_prefix)

old_internet_device=$(moulinette_get internet_device)
new_internet_device=$(ip route | awk '/default via/ { print $NF; }')

# Switch the NAT interface if there is a VPN
ip link show dev tun0 &> /dev/null
if [ "$?" -eq 0 ]; then
  new_internet_device=tun0
fi

echo "OK"

# Script

case "$1" in
  start)
    if is_running; then
      echo "Already started"
    else
      echo "Starting..."

      # Set NDP proxy
      if ! is_ndproxy_set; then
        echo "Set NDP proxy"
        set_ndproxy
      fi

      # Check old state of the ipv4 NAT settings
      if [ ! -z "${old_internet_device}" -a "${new_internet_device}" != "${old_internet_device}" ]\
         && is_nat_set "${old_internet_device}"; then

        unset_nat "${old_internet_device}"
      fi

      # Set ipv4 NAT
      if ! is_nat_set "${new_internet_device}"; then
        echo "Set NAT"
        set_nat "${new_internet_device}"
      fi

      # Set ipv4 NAT address
      if ! is_ip4nataddr_set; then
        echo "Set IPv4 NAT address"
        set_ip4nataddr
      fi

      # Set the ipv6 address
      if ! is_ip6addr_set; then
        echo "Set IPv6 address"
        set_ip6addr
      fi

      # Set forwarding for ipv6 and ipv4
      if ! is_forwarding_set; then
        echo "Set forwarding"
        set_forwarding
      fi

      # Run hostapd
      if ! is_hostapd_running; then
        echo "Run hostapd"
        start_hostapd
        sleep 1
      fi

      # Run radvd
      # must be running after hostapd
      if ! is_radvd_running; then
        echo "Run radvd"
        start_radvd
      fi

      # Run dhcpd
      # "options routers" addr (is_ip6addr_set) must be set before
      if ! is_dhcpd_running; then
        echo "Run dhcpd"
        start_dhcpd
      fi
    fi
  ;;
  stop)
    echo "Stopping..."

    if is_ndproxy_set; then
      echo "Unset NDP proxy"
      unset_ndproxy
    fi
  
    if is_nat_set "${old_internet_device}"; then
      echo "Unset NAT"
      unset_nat "${old_internet_device}"
    fi

    if is_ip4nataddr_set; then
      echo "Unset IPv4 NAT address"
      unset_ip4nataddr
    fi

    if is_ip6addr_set; then
      echo "Unset IPv6 address"
      unset_ip6addr
    fi 

    if is_forwarding_set; then
      echo "Unset forwarding"
      unset_forwarding
    fi
  
    if is_hostapd_running; then
      echo "Stop hostapd"
      stop_hostapd
    fi
  
    if is_radvd_running; then
      echo "Stop radvd"
      stop_radvd
    fi
  
    if is_dhcpd_running; then
      echo "Stop dhcpd"
      stop_dhcpd
    fi
  ;;
  restart)
    $0 stop
    $0 start
  ;;
  status)
    exitcode=0

    if is_ndproxy_set; then
      echo "NDP proxy is correctly set"
    else
      echo "NDP proxy is NOT set"
      exitcode=1
    fi

    if is_nat_set "${new_internet_device}"; then
      echo "NAT is correctly set"
    else
      echo "NAT is NOT set"
      exitcode=1
    fi

    if is_ip4nataddr_set; then
      echo "IPv4 NAT address is correctly set"
    else
      echo "IPv4 NAT address is NOT set"
      exitcode=1
    fi

    if is_ip6addr_set; then
      echo "IPv6 address is correctly set"
    else
      echo "IPv6 address is NOT set"
      exitcode=1
    fi

    if is_forwarding_set; then
      echo "Forwarding is correctly set"
    else
      echo "Forwarding is NOT set"
      exitcode=1
    fi

    if is_hostapd_running; then
      echo "Hostapd is running"
    else
      echo "Hostapd is NOT running"
      exitcode=1
    fi

    if is_radvd_running; then
      echo "Radvd is running"
    else
      echo "Radvd is NOT running"
      exitcode=1
    fi

    if is_dhcpd_running; then
      echo "Dhcpd is running"
    else
      echo "Dhcpd is NOT running"
      exitcode=1
    fi

    exit ${exitcode}
  ;;
  *)
    echo "Usage: $0 {start|stop|restart|status}"
    exit 1
  ;;
esac

exit 0