#!/bin/bash

function error {
echo "$\*"
echo 'usage: newhost address [hostname] [alias] [category]'
exit 42
}

if [["${1}"]]
then
ADDR=${1}
else
error "Address required but not given"
fi

if [["${2}"]]
then
HOST_NAME=${2}
else
	HOST_NAME=${1}
fi

if [["${3}"]]
then
ALIAS=${3}
else
	ALIAS=${1}
fi

if [["${4}"]]
then
CATEGORY=${4}
else
CATEGORY="generic-host"
fi

HOST_TEMPLATE="define host{
use ${CATEGORY}
host_name ${HOST_NAME}
alias ${ALIAS}
address ${ADDR}
}"

echo "$HOST_TEMPLATE"

#!/bin/bash

OBJ_DIR='/etc/nagios/objects'
HOSTS="${OBJ_DIR}/hosts.cfg"
HOSTGROUPS="${OBJ_DIR}/hostgroups.cfg"

function debug {
#print debugging messages

# $1 error string

    [[ "${DEBUG}" ]] && echo "DEBUG:: $* " >&2

}

function error {
#throw an error and exit

# $1 error string

    echo "ERROR:: $* " >&2
    exit 1

}

function reWriteLine {

# replaces the text $4 on line number $1 in file $2 with the text $3

# $1 line number $2 filename $3 replacement text $4 text to replace

    tmp=$(mktemp)
    cat ${2} | sed -e "${1}s/${3}/${4}/" > ${tmp}
    mv ${tmp} ${2}
    rm -f ${tmp}

}

function insertLine {

# insert text $3 on line number $1 in file $2 (moving the current contents of $1 down one line)

# $1 line number $2 filename $3 insert text

    tmp=$(mktemp)
    M=$((${1}-1))
    PRE=$(cat ${2} | sed -ne "1,${M}p")
    POST=$(cat ${2} | sed -ne "${1},\$p")
    echo "${PRE}" > ${tmp}
    echo "${3}" >> ${tmp}
    echo "${POST}" >> ${tmp}
    mv ${tmp} ${2}
    rm -f ${tmp}

}

function deleteLine {

# Delete line number $1 from file $2

    tmp=$(mktemp)
    cat ${2} | sed -e "${1}d" > ${tmp}
    mv ${tmp} ${2}
    rm -f ${tmp}

}

function getValue {
#return the attribute value on line $1 of file $2

# $1 Line number $2 file name

    cat ${2} | sed -ne "${1}p" | awk '{print $2}'

}

function checkMembership {
#return true if $1 is a member of $2

# $1 thing $2 comma separated list of things

    for i in $(echo ${2} | tr ',' ' ')
    do
    	if [ ${i} == ${1} ]
    	then
    		return 0
    	fi
    done
    return 1

}

function findUseLine {

# finds the line number of the use line for host $1

# $1 host name

c=0
while read LINE
do
c=$((c+1))
      if echo ${LINE} | egrep -q 'use'
      then
         USE=${c}
elif echo ${LINE} | grep -q 'host_name'
      then
         HOST=${LINE}
elif echo ${LINE} | grep -q '}'
      then
         if echo "${HOST}" | grep -q "${1}"
then
echo ${USE}
return
fi
fi
done < ${HOSTS}
}

function findMembersLine {

# finds the line number of the use line for host $1

# $1 host name

c=0
while read LINE
do
c=$((c+1))
      if echo ${LINE} | egrep -q 'members'
      then
         MEMBERS=${c}
elif echo ${LINE} | grep -q 'hostgroup_name'
      then
         HOSTGROUP=${LINE}
elif echo ${LINE} | grep -q '}'
      then
         if echo "${HOSTGROUP}" | grep -q "${1}"
         then
				if [ -n "${MEMBERS}" ]
then
echo "${MEMBERS}"
				else
					echo "append,${c}"
fi
return
fi
unset MEMBERS HOSTGROUP
fi
done < ${HOSTGROUPS}
}

function setTemplate {
#replace the currently used template for host $1 with template $2

# $1 hostname $2 template name

    LINE=$(findUseLine "${1}")
    CUR=$(getValue "${LINE}" "${HOSTS}")
    reWriteLine ${LINE} ${HOSTS} "${CUR}" "${2}"

}

function joinGroup {
#Add host $1 to the list of hosts on the members line of hostgroup $2

# $1 hostname $2 hostgroup

    LINE=$(findMembersLine "${2}")

    if echo ${LINE} | grep -q 'append'
    then
    	LN=$(echo ${LINE} | cut -d, -f2)
    	insertLine ${LN} ${HOSTGROUPS} "       members        ${1}"
    	return
    fi

    CUR=$(getValue "${LINE}" "${HOSTGROUPS}")
    if checkMembership ${1} ${CUR}
    then
    	error "${1} is already a member of ${2} (${CUR})"
    else
    	NEW="${CUR},${1}"
    	reWriteLine ${LINE} ${HOSTGROUPS} ${CUR} ${NEW}
    fi

}

function leaveGroup {
#remove host $1 from the list of hosts on the members line of hostgroup $2

# $1 hostname $2 hostgroup

    LINE=$(findMembersLine "${2}")

    if echo ${LINE} | grep 'append'
    then
    	error "${2} has no members attribute"
    fi

    CUR=$(getValue "${LINE}" "${HOSTGROUPS}")
    if echo ${CUR} | grep -q ','
    then
    	if checkMembership ${1} ${CUR}
    	then
    		NEW=$(echo ${CUR} | sed -e "s/${1}//" | tr -s ',')
    		reWriteLine ${LINE} ${HOSTGROUPS} ${CUR} ${NEW}
    	else
    		error "${1} is not a member of ${2}"
    	fi
    else
    	deleteLine ${LINE} ${HOSTGROUPS}
    fi

}