#!/bin/sh
#
# tabssh.sh, Copyright © 2013, 2019 Matteo Cypriani <mcy@lm7.fr>
# (Formerly named cluster-ssh.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.
#
# Open an SSH interactive shell on a list of remote hosts, opening one
# GNU Screen tab per host.

#set -x
set -u

# Exit codes
readonly EXIT_SUCCESS=0
readonly EXIT_USAGE=127
readonly EXIT_DEPENDENCY=4
readonly EXIT_HOSTS_LIST=6

print_usage()
{
  echo "Usage: $0 [-l login] <hosts_list>"
}

bad_usage()
{
  err "$@"
  echo >&2
  print_usage >&2
  exit $EXIT_USAGE
}

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

LOGIN=

# We must have either 3 arguments...
if [ $# -eq 3 ] ; then
  # Only -l is a valid option
  [ "$1" = "-l" ] || bad_usage "Option '$1' unknown."
  LOGIN="$2"
  shift
  shift

# ... or only 1 argument
elif [ $# -ne 1 ] ; then
  bad_usage "Wrong number of arguments."
fi

# Check dependencies
TMUX_CMD=$(command -v tmux)
SCREEN_CMD=$(command -v screen)
if [ -n "$TMUX_CMD" ] ; then
  echo "tmux is available, we'll be using it."
elif [ -n "$SCREEN_CMD" ] ; then
  echo "tmux is not available, we'll be using GNU screen instead."
else
  err "Either tmux or GNU screen is required by this script."
  exit $EXIT_DEPENDENCY
fi

# Hosts list file
[ -z ${XDG_CONFIG_HOME+x} ] && XDG_CONFIG_HOME="$HOME/.config"
HOSTS_LIST_NAME="$1"
shift
HOSTS="$XDG_CONFIG_HOME/ssh_tools/${HOSTS_LIST_NAME}.lst"
echo "Using file '$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

# Login
if [ -n "$LOGIN" ] ; then
  echo "Login: $LOGIN"
  LOGIN="${LOGIN}@"
fi

# Create the screen tabs
while read -r HOST ; do
  SSH="ssh ${LOGIN}${HOST}"
  if [ -n "$TMUX_CMD" ] ; then
    $TMUX_CMD new-window -d -n "$SSH" -- "$SSH"
  else
    # shellcheck disable=SC2086
    $SCREEN_CMD -t "$SSH" $SSH
  fi
done <"$HOSTS"