#!/bin/sh
#
# multiping.sh, Copyright © 2013, 2019 Matteo Cypriani <mcy@lm7.fr>
# (Formerly named cluster-ping.sh)
#
# This program is free software. It comes without any warranty, to
# the extent permitted by applicable law. You can redistribute it
# and/or modify it under the terms of the Do What The Fuck You Want
# To Public License, Version 2, as published by Sam Hocevar. See
# http://sam.zoy.org/wtfpl/COPYING for more details.
#
# Ping a list of remote hosts using fping.

#set -x
set -u

readonly EXIT_USAGE=127
readonly EXIT_HOSTS_LIST=6

err()
{
  printf 'Error! ' >&2
  printf '%s\n' "$@" >&2
}

warn()
{
  printf 'Warning! ' >&2
  printf '%s\n' "$@" >&2
}

ping_hosts()
{
  grep -v '^#' "$HOSTS" | while read -r host ; do
    [ -z "$host" ] && continue
    ping -c 1 -W 1 "$host" >/dev/null 2>&1 && echo "$host is alive"
  done
}

# Check arguments
if [ $# -ne 1 ] ; then
  echo "Usage: $0 <hosts_list>" >&2
  exit $EXIT_USAGE
fi

FPING=$(command -v fping)
[ -z "$FPING" ] && warn "fping is not available. Install it for best results."

# Hosts list file
[ -z ${XDG_CONFIG_HOME+x} ] && XDG_CONFIG_HOME="$HOME/.config"
HOSTS="$XDG_CONFIG_HOME/ssh_tools/$1.lst"
echo "Using file '$HOSTS' as hosts list."
if [ ! -f "$HOSTS" ] ; then
  err "The hosts list file doesn't exist or is not a regular file."
  exit $EXIT_HOSTS_LIST
fi

if [ -n "$FPING" ] ; then
  # shellcheck disable=SC2046
  exec "$FPING" $(cat "$HOSTS") 2>/dev/null
fi

# Fall back to good old ping if fping is not available
ping_hosts