#!/bin/bash

hosts=
group=
user=root
pdsh=`which pdsh 2>/dev/null`
ssh=`which qarsh 2>/dev/null`
scp=`which qacp 2>/dev/null`
command=list
format=oneline
replace="{}"

if [ x$ssh = "x" ]; then
    ssh=ssh
    scp=scp
fi

function helptext() {
    echo "cluster-helper - A tool for running commands on multiple hosts"
    echo ""
    echo "Attempt to use pdsh, qarsh, or ssh (in that order) to execute commands"
    echo "on mutiple hosts"
    echo ""
    echo "DSH groups can be configured and specified with -g instead of listing"
    echo "the individual hosts every time"
    echo ""
    echo "Usage: cluster-helper [options] [command]"
    echo ""
    echo "Options:"
    echo "--ssh            Force the use of ssh instead of qarsh even if it available"
    echo "-g, --group      Specify the group to operate on/with"
    echo "-w, --host       Specify a host to operate on/with.  May be specified multiple times"
    echo "-f, --format     Specifiy the output format When listing hosts or group contents"
    echo "                 Allowed values: [oneline], long, short, pdsh, bullet"
    echo ""
    echo ""
    echo "Commands:"
    echo "--list   format  List the contents of a group in the specified format"
    echo "--add    name    Add supplied (-w) hosts to the named group"
    echo "--create name    Create the named group with the supplied (-w) hosts"
    echo "--run, --        Treat all subsequent arguments as a command to perform on"
    echo "                 the specified command on the hosts or group"
    echo "--xargs          Run the supplied command having replaced any occurances"
    echo "                 of {} with the node name"
    echo ""
    echo "--copy file(s) host:file   Pass subsequent arguments to scp or qacp"
    echo "                           Any occurances of {} are replaced with the node name"
    echo ""
    exit $1
}

while true ; do
    case "$1" in
	--help|-h|-\?) helptext 0;;
	-x)  set -x; shift;;
	--ssh) ssh="ssh"; scp="scp"; shift;;
	-g|--group) group="$2"; shift; shift;;
	-w|--host) for h in $2; do
		hosts="$hosts -w $h";
	    done
	    shift; shift;;
	-f|--format) format=$2; shift; shift;;
	-I) replace=$2; shift; shift;;
	--list|list) format=$2; command=list; shift; shift;;
	--add|add) command=group-add; shift;;
	--create|create) group="$2", command=group-create; shift; shift;;
	--run|run) command=run; shift;;
	--copy|copy) command=copy; shift; break ;;
	--xargs) command=xargs; shift; break ;;
	--) command=run; shift; break ;;
	"") break;;
	*) helptext 1;;
    esac
done	

if [ x"$group" = x -a x"$hosts" = x ]; then
    group=$CTS_GROUP
fi

function expand() {
    fmt=$1
    if [ x$group != x -a -f ~/.dsh/group/$group ]; then
	hosts=`cat ~/.dsh/group/$group`
    elif [ x$group != x ]; then
	echo "Unknown group: $group" >&2
	exit 1
    fi
    
    if [ "x$hosts" != x -a $fmt = oneline ]; then
	echo $hosts
	
    elif [ "x$hosts" != x -a $fmt = short ]; then
	( for h in $hosts; do
		echo $h | sed 's:\..*::'
		done ) | tr '\n' ' '
	echo ""
	
    elif [ "x$hosts" != x -a $fmt = pdsh ]; then
	( for h in $hosts; do
		echo "-w $h"
	    done ) | tr '\n' ' '
	echo ""
	
    elif [ "x$hosts" != x -a $fmt = long ]; then
	for h in $hosts; do
	    echo $h
	done

    elif [ "x$hosts" != x -a $fmt = bullet ]; then
	for h in $hosts; do
	    echo " * $h"
	done

    elif [ "x$hosts" != x ]; then
	echo "Unknown format: $fmt" >&2
    fi
}

if [ $command = list ]; then
    expand $format

elif [ $command = group-create ]; then

    f=`mktemp`
    mkdir -p ~/.dsh/group

    if [ -f ~/.dsh/group/$group ]; then
	echo "Overwriting existing group $group"
    fi

    for h in $hosts; do
	echo $h >> $f
    done

    echo "Creating group $group in ~/.dsh/group"
    sort -u $f > ~/.dsh/group/$group
    rm -f $f

elif [ $command = group-add ]; then
    if [ x$group = x ]; then
	echo "Please specify a group to append to"
	exit 1
    fi
    
    f=`mktemp`
    mkdir -p ~/.dsh/group

    if [ -f ~/.dsh/group/$group ]; then
	cat ~/.dsh/group/$group > $f
    fi

    for h in $hosts; do
	echo $h >> $f
    done

    echo "Appending hosts to group $group in ~/.dsh/group"
    sort -u $f > ~/.dsh/group/$group
    rm -f $f

elif [ $command = run ]; then
    if [ x$pdsh != x ]; then
	hosts=`expand pdsh`
	$pdsh -l $user $hosts -- $*

    else
	hosts=`expand oneline`
	for n in $hosts; do
	    $ssh -l $user $n -- $* < /dev/null
	done
	if [ x"$hosts" = x ]; then
	    echo "No hosts specified"
	fi
    fi
elif [ $command = copy ]; then
    hosts=`expand oneline`
    for n in $hosts; do
	$scp `echo $* | sed 's@'$replace'@'$n'@'`
    done

elif [ $command = xargs ]; then
    hosts=`expand oneline`
    for n in $hosts; do
	eval `echo $* | sed 's@'$replace'@'$n'@'`
    done
fi