#!/bin/bash

# Configuration =======================================================================================================
WLAN0_IFACE="wlan0"
DHCP_IP="10.10.10.1"
DHCP_START="10.10.10.100"
DHCP_END="10.10.10.250"

SSID="$HOSTNAME"
PASSWORD="guesswhatitis"
# End of Configuration ================================================================================================

is_connected() {
    [ -n "$(iwgetid -r 2>/dev/null)" ]
}

is_ap_on() {
    [ "$(systemctl is-active hostapd 2>/dev/null)" == "active" ]
}

enable_ap() {
    if is_ap_on; then return; fi
    echo "[$(date '+%H:%M:%S')] Enabling AP: $SSID"
    # Bring down wlan0 and reset it
    ip link set $WLAN0_IFACE down 2>/dev/null || true
    sleep 1
    ip link set $WLAN0_IFACE up 2>/dev/null || true
    sleep 1
    # Assign static IP for AP
    ip addr flush dev $WLAN0_IFACE 2>/dev/null || true
    ip addr add "$DHCP_IP/24" dev $WLAN0_IFACE
    # Configure hostapd
    cat > /etc/hostapd/hostapd.conf <<EOF
interface=$WLAN0_IFACE
ssid=$SSID
hw_mode=g
channel=6
wpa=2
wpa_passphrase=$PASSWORD
wpa_key_mgmt=WPA-PSK
wpa_pairwise=CCMP
EOF
    systemctl unmask hostapd 2>/dev/null || true
    systemctl start hostapd
    # Configure dnsmasq for DHCP
    cat > /etc/dnsmasq.conf <<EOF
interface=$WLAN0_IFACE
dhcp-range=$DHCP_START,$DHCP_END,255.255.255.0,24h
EOF
    systemctl restart dnsmasq
}

disable_ap() {
    if ! is_ap_on; then return; fi
    echo "[$(date '+%H:%M:%S')] Disabling AP"
    systemctl stop hostapd 2>/dev/null || true
    systemctl restart dnsmasq 2>/dev/null || true
    ip addr del "$DHCP_IP/24" dev $WLAN0_IFACE 2>/dev/null || true
}

# Main loop
echo "AP Failover Service started"
while true; do
    is_connected && disable_ap || enable_ap
    sleep 30
done
root@radio:/# ls
access-point.sh  boot  etc   lib         media  opt   root  sbin  sys  usr
bin              dev   home  lost+found  mnt    proc  run   srv   tmp  var
root@radio:/# cat access-point.sh
#!/bin/bash

# Configuration =======================================================================================================
WLAN0_IFACE="wlan0"
DHCP_IP="10.10.10.1"
DHCP_START="10.10.10.100"
DHCP_END="10.10.10.250"

SSID="$HOSTNAME"
PASSWORD="guesswhatitis"
# End of Configuration ================================================================================================

is_connected() {
    [ -n "$(iwgetid -r 2>/dev/null)" ]
}

is_ap_on() {
    [ "$(systemctl is-active hostapd 2>/dev/null)" == "active" ]
}

enable_ap() {
    if is_ap_on; then return; fi
    echo "[$(date '+%H:%M:%S')] Enabling AP: $SSID"
    # Bring down wlan0 and reset it
    ip link set $WLAN0_IFACE down 2>/dev/null || true
    sleep 1
    ip link set $WLAN0_IFACE up 2>/dev/null || true
    sleep 1
    # Assign static IP for AP
    ip addr flush dev $WLAN0_IFACE 2>/dev/null || true
    ip addr add "$DHCP_IP/24" dev $WLAN0_IFACE
    # Configure hostapd
    cat > /etc/hostapd/hostapd.conf <<EOF
interface=$WLAN0_IFACE
ssid=$SSID
hw_mode=g
channel=6
wpa=2
wpa_passphrase=$PASSWORD
wpa_key_mgmt=WPA-PSK
wpa_pairwise=CCMP
EOF
    systemctl unmask hostapd 2>/dev/null || true
    systemctl start hostapd
    # Configure dnsmasq for DHCP
    cat > /etc/dnsmasq.conf <<EOF
interface=$WLAN0_IFACE
dhcp-range=$DHCP_START,$DHCP_END,255.255.255.0,24h
EOF
    systemctl restart dnsmasq
}

disable_ap() {
    if ! is_ap_on; then return; fi
    echo "[$(date '+%H:%M:%S')] Disabling AP"
    systemctl stop hostapd 2>/dev/null || true
    systemctl restart dnsmasq 2>/dev/null || true
    ip addr del "$DHCP_IP/24" dev $WLAN0_IFACE 2>/dev/null || true
}

# Main loop
echo "AP Failover Service started"
while true; do
    is_connected && disable_ap || enable_ap
    sleep 30
done