#!/bin/bash

#---------------------------------------------------------------------------
#                            Variables declaration
#---------------------------------------------------------------------------

# Uncomment if broadcast-relaying is necessary
#bcRelay_ON=1

wlanCXed=0

idx=0
err_ON=0

scriptPath=""

#---------------------------------------------------------------------------
#                               Local Functions
#---------------------------------------------------------------------------

arp_routing(){
    local __iface1=$1
    local __iface2=$2

    parprouted $__iface1 $__iface2 >> "$scriptPath" 2>&1
    if [ "$(echo $?)" -ne 0 ]
    then
        sleep 1
        return 1
    fi
    return 0
}

dhcp_relay(){
    local __iface1=$1
    local __iface2=$2

    #local dhcp_server=$(grep -w "dhcp-server" \
    #/var/lib/dhcp/dhclient.$__iface1.leases | tail -n1 | awk '{print $3}' \
    #| cut -d';' -f1)
    local dhcp_server=$(grep -R "offered" \
    /var/log/* | tail -n1 | awk '{print $(NF)}')

    dhcp-helper -s "$dhcp_server" -i "$__iface2" >> "$scriptPath" 2>&1
    if [ "$(echo $?)" -ne 0 ]
    then
        sleep 1
        return 1
    fi
    return 0
}

host_ap(){
    hostapd -B /etc/hostapd/hostapd.conf >> "$scriptPath" 2>&1
    if [ "$(echo $?)" -ne 0 ]
    then
        sleep 1
        return 1
    fi
    return 0
}

bc_relay(){
    local __iface1=$1
    local __iface2=$2

    bcrelay -d -n -i "$__iface1" -o "$__iface2" >> "$scriptPath" 2>&1
    if [ "$(echo $?)" -ne 0 ]
    then
        sleep 1
        return 1
    fi
    return 0
}

kill_process(){
    local __proc2kill=$1
    local CMDresult=$(ps aux | grep -v grep | grep "$__proc2kill")
    if [ -n "$CMDresult" ]
    then
        killall "$__proc2kill" >> "$scriptPath" 2>&1
        #while read line
        #do
        #    kill $(echo $line | cut -d' ' -f2) >> "$scriptPath" 2>&1
        #done <<< $CMDresult
    fi
}
RST_process(){
    until ( ifconfig wlan1 down >> "$scriptPath" 2>&1 )
    do
        sleep 1
    done
    sleep 1

    until (ip addr flush dev wlan1 >> "$scriptPath" 2>&1)
    do
        sleep 1
    done

    kill_process "parprouted"

    kill_process "dhcp-helper"

    kill_process "hostapd"

    # Executes this section if bcRelay_ON is enabled (not commented)
    if [ -v bcRelay_ON ]
    then
        kill_process "bcrelay"
    fi

    sleep 1
}

CX_start(){
    err_ON=0
    RST_process

    wlan0Info=""
    while [ "$wlan0Info" == "" ]
    do
        # Check if wlan0 has an IP. Drops results and logs error messages
        if [ "$(ifconfig wlan0 2>>"$scriptPath" | grep -w "inet" | awk '{print $2}')" != "" ]
        then
            # Using wlan0Info just as a test condition to help exit this loop.
            #  wlan0Info is reused later
            wlan0Info="exit"
        else
            sleep 1
        fi
    done

    wlan0Info=$(ip a show wlan0)
    wlan0IP=$(echo "$wlan0Info" | grep -w "inet" | awk '{print $2}' | cut -d'/' -f1)
    wlanIPMask=$(echo "$wlan0Info" | grep -w "inet" | awk '{print $2}' | cut -d'/' -f2)
    wlanbrd=$(echo "$wlan0Info" | grep -w "inet" | awk '{print $4}')
    wlan1IP1=$(echo "$wlanbrd" | cut -d'.' -f1)
    wlan1IP2=$(echo "$wlanbrd" | cut -d'.' -f2)
    wlan1IP3=$(echo "$wlanbrd" | cut -d'.' -f3)
    wlan1IP4=$(($(echo "$wlanbrd" | cut -d'.' -f4) - 1))
    wlan1IP=$(echo "$wlan1IP1"'.'"$wlan1IP2"'.'"$wlan1IP3"'.'"$wlan1IP4")

    until ( ifconfig wlan1 up >> "$scriptPath" 2>&1 )
    do
        sleep 1
    done
    sleep 1

    until (ip addr flush dev wlan1 >> "$scriptPath" 2>&1)
    do
        sleep 1
    done

    until ( ip addr add $(echo "$wlan1IP"'/'"$wlanIPMask") brd + dev wlan1 \
    >> "$scriptPath" 2>&1 )
    do
        sleep 1
    done

    until ( $(arp_routing "wlan0" "wlan1") )
    do
        idx=$(("$idx"+1))
        if [ "$idx" -eq 5 ]
        then
            echo "parprouted failed" >> "$scriptPath" 1>&1
            err_ON=1
            break
        fi
    done

#    echo "here1"

    if [ $err_ON -eq 0 ]
    then
        idx=0
        until ( $(dhcp_relay "wlan0" "wlan1") )
        do
            idx=$(("$idx"+1))
            if [ "$idx" -eq 5 ]
            then
                echo "dhcp-relay failed" >> "$scriptPath" 1>&1
                err_ON=1
                break
            fi
        done
    fi

    if [ $err_ON -eq 0 ]
    then
        idx=0
        until ( $(host_ap) )
        do
            idx=$(("$idx"+1))
            if [ "$idx" -eq 5 ]
            then
                echo "Host AP failed" >> "$scriptPath" 1>&1
                err_ON=1
                break
            fi
        done
    fi

    # Executes this section if bcRelay_ON is enabled (not commented)
    if [ -v bcRelay_ON ]
    then
        for i in $(seq 1 2)
        do
            if [ $err_ON -eq 0 ]
            then
                idx=0
                iface1="wlan0"
                iface2="wlan1"
                if [ $i -eq 2 ]
                then
                    iface1="wlan1"
                    iface2="wlan0"
                fi
                until ( $(bc_relay "$iface1" "$iface2") )
                do
                    idx=$(("$idx"+1))
                    if [ "$idx" -eq 5 ]
                    then
                        echo "BC_Relay failed" >> "$scriptPath" 1>&1
                        err_ON=1
                        break
                    fi
                done
            fi
        done
    fi

    if [ $err_ON -eq 0 ]
    then
        wlanCXed=1
    else
        sleep 10
    fi
}

check_processes(){
    if [ "$(ps aux | grep -v grep | grep parprouted)" == "" ]
    then
        return 1
    elif [ "$(ps aux | grep -v grep | grep dhcp-helper)" == "" ]
    then
        return 1
    elif [ "$(ps aux | grep -v grep | grep hostapd)" == "" ]
    then
        return 1
    elif [ -v bcRelay_ON ]
    then
        if [ "$(ps aux | grep -v grep | grep bcrelay)" == "" ]
        then
            return 1
        fi
    fi
    return 0
}
CX_check(){
    if [ "$(ifconfig wlan0 | grep inet)" != "" ] && \
       [ $(check_processes; echo $?) -eq 0 ]
    then
        sleep 1m
    else
        RST_process
        wlanCXed=0
    fi
}


#---------------------------------------------------------------------------
#                                    Main
#---------------------------------------------------------------------------

scriptPath="$(cd "$(dirname $0)"; pwd -P)""/log_err"
echo "Start" > "$scriptPath" 1>&1

# Main Loop. Starts and keep checking on connection to not to break, and
#  all of the packages used to not to be ended. If any of this two conditions
#  happen, kills all processes, wait the connection to the router
#  to be re-stablished and start all processes again
while true
do
    if [ $wlanCXed -eq 0 ]
    then
        CX_start
    else
        CX_check
    fi
done

exit 0

#---------------------------------------------------------------------------
#                                    END
#---------------------------------------------------------------------------