#!/bin/bash

if [ -z "$RAINBOW_STATEDIR" ]; then
    echo "ERROR: Required configuration is missing. Please check configuraiton file."
    exit 1
fi

DHCP_LEASES_FILE=${DHCP_LEASES_FILE:-/var/lib/dhcpd/dhcpd.leases}
DHCP_CONFIG_FILE=${DHCP_CONFIG_FILE:-/etc/dhcp/dhcpd.conf}
DHCP_PARSED_CACHE=$RAINBOW_STATEDIR/dhcp.cache

regex_lease="lease[[:space:]]+([0-9.]+)[[:space:]]+\{"
regex_starts="starts[[:space:]][0-9][[:space:]](.*)\;"
regex_ends="ends[[:space:]][0-9][[:space:]](.*)\;"
regex_hwaddr="hardware[[:space:]]ethernet[[:space:]](.*)\;"
regex_fixedaddr="fixed-address[[:space:]](.*)\;"
regex_blockstart="\{"
regex_blockend="\}"

dhcp_parse_leases () {
    local cachefile="${DHCP_PARSED_CACHE}-leases"
    if [ "$cachefile" -nt "$DHCP_LEASES_FILE" ]; then
        cat $cachefile
        return 0
    fi

    cat "$DHCP_LEASES_FILE" | \
    while read line; do
        [[ "$line" =~ $regex_lease ]] && \
            leased_ip="${BASH_REMATCH[1]}"

        [[ "$line" =~ $regex_starts ]] && \
            starts_date=$( export TZ=UTC; date +%s --date "${BASH_REMATCH[1]}" )
        [[ "$line" =~ $regex_ends ]] && \
            ends_date=$( export TZ=UTC; date +%s --date "${BASH_REMATCH[1]}" )
        [[ "$line" =~ $regex_hwaddr ]] && \
            lladdr="${BASH_REMATCH[1]}"

        if [[ "$line" =~ $regex_blockend ]]; then
            if [ -n "$leased_ip" ]; then
                current_date=$(date +%s)
                [ "$current_date" -lt "$ends_date" ] && echo "${lladdr//:/} $leased_ip"
            fi
            unset starts_date ends_date lladdr leased_ip
        fi
    done > $cachefile
    cat $cachefile
}

dhcp_parse_config () {
    local cachefile="${DHCP_PARSED_CACHE}-config"
    if [ "$cachefile" -nt "$DHCP_CONFIG_FILE" ]; then
        cat $cachefile
        return 0
    fi

    cat "$DHCP_CONFIG_FILE" | sed -e 's/{/ {\n/g' -e 's/}/ }\n/g' -e 's/;/;\n/g' | \
    while read line; do
        if [[ "$line" =~ $regex_blockstart ]]; then
            [[ "$line" =~ host ]] && hostentry=1 || hostentry=0
        fi

        [[ "$line" =~ $regex_hwaddr ]] && \
            hwether="${BASH_REMATCH[1]}"
        [[ "$line" =~ $regex_fixedaddr ]] && \
            fixedaddr="${BASH_REMATCH[1]}"

        if [[ "$line" =~ $regex_blockend ]]; then
            if [ "$hostentry" = "1" ]; then
               [ -n "$hwether" -a -n "$fixedaddr" ] && echo "${hwether//:/} $fixedaddr"
               unset hwether fixedaddr
            fi
        fi
    done > $cachefile
    cat $cachefile
}

dhcp_mac2ip_mapping () {
    dhcp_parse_config
    dhcp_parse_leases
}

mac_colons () {
    echo $@ | sed 's/\(..\)/\1:/g' | sed 's/:$//' 
}

get_dhcp_ip () {
    local macaddr=$1
    macaddr=${macaddr//:/}
    dhcp_mac2ip_mapping | while read lmac lip; do
        if [ "$lmac" = $macaddr ]; then
            echo $lip
            return 0
        fi
    done
}