#!/bin/sh
#
# cluster-deploy.sh, Copyright © 2013 Matteo Cypriani <mcy@lm7.fr>
#
# 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.
#
# Deploy files on a number of remote hosts using Parallel SCP.

#set -x

print_usage()
{
  echo "Usage:"
  echo "  $0 [-P] [-r|-R] [-l login] <hosts_list> <file1> [file2 [...]]"
  echo
  echo "Options:"
  echo "  -P: transfer files in parallel instead of one by one if possible"
  echo "      (ignored when -r or -R is used)."
  echo "  -r: use prsync instead of pscp."
  echo "  -R: use prsync with option --delete (delete remote files that are"
  echo "      not in the local copy)."
}

# Parse the optional arguments
while [ $# -gt 2 ] ; do
  case $1 in
    "-l")
      LOGIN="$2"
      shift
      shift
      ;;
    "-P")
      PARALLEL=1
      shift
      ;;
    "-r")
      RSYNC=1
      shift
      ;;
    "-R")
      DELETE=1
      shift
      ;;
    *)
      break
      ;;
  esac
done

# Do we still have at least a host list and a file?
# Note: if the program was wrongly called but still has 2 arguments, for
# example with "cluster-deploy -l root -P my_file", it will try to use
# "-P" as hosts' list and "my_file" as the file to be transfered.
if [ $# -lt 2 ] ; then
  print_usage
  exit 1
fi

# Check the usage of -r and -R
if [ "$DELETE" = "1" ] ; then
  if [ "$RSYNC" = "1" ] ; then
    echo "Use either -r or -R, but not both!"
    echo
    print_usage
    exit 2
  fi
  RSYNC=1
  DELETE="-X --delete"
fi

# Ignore -P if rsync is going to be used
if [ "$RSYNC" = "1" ] && [ "$PARALLEL" = "1" ] ; then
  echo "Cannot transfer in parallel when using rsync: ignoring -P."
  PARALLEL=""
fi

# Check dependencies
PSCP=$(command -v parallel-scp || command -v pscp.pssh || command -v pscp)
PRSYNC=$(command -v parallel-rsync || command -v prsync)
CLUSTERPING=$(command -v cluster-ping)
if [ -z "$RSYNC" ] && [ -z "$PSCP" ] ; then
  echo "Parallel SSH (pssh) is required for this script to work."
  exit 4
elif [ -z "$PRSYNC" ] ; then
  echo "Parallel rsync (prsync) is required for this script to work."
  exit 5
elif [ -z "$CLUSTERPING" ] ; then
  echo "cluster-ping (which should have been provided along with this"
  echo "script) is required for this script to work."
  exit 6
fi

# Hosts' list file
HOSTS_LIST_NAME="$1"
if [ -z "$XDG_CONFIG_HOME" ] ; then
  XDG_CONFIG_HOME="$HOME/.config"
fi
HOSTS="$XDG_CONFIG_HOME/cluster/${HOSTS_LIST_NAME}.lst"
shift
echo "Using file '$HOSTS' as hosts' list."
if [ ! -f "$HOSTS" ] ; then
  echo "The hosts' list file doesn't exist or is not a regular file."
  exit 3
fi

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

# Test the connection to the first host and get the destination
# directory (home directory of the remote user)
FIRST_HOST=$($CLUSTERPING "$HOSTS_LIST_NAME" 2>/dev/null \
           | sed -n "s/ is alive$//p" | head -n1)
if [ -z "$FIRST_HOST" ] ; then
  echo "None of the remote hosts is alive."
  exit 7
fi
echo "Testing connection to $FIRST_HOST..."
DEST_DIR="$(ssh "${SSH_LOGIN}${FIRST_HOST}" 'echo $HOME' 2>/dev/null)"
if [ -z "$DEST_DIR" ] ; then
  echo "Cannot connect to the first alive host. Aborting."
  exit 7
fi
echo "Destination directory: $DEST_DIR"

# Transfer the files in parallel...
if [ "$PARALLEL" = "1" ] ; then
  # shellcheck disable=SC2086
  exec $PSCP -r $LOGIN -h "$HOSTS" -- "$@" "$DEST_DIR"
fi

# ... or one by one
for FILE in "$@" ; do
  echo "Deploying '$FILE'..."
  if [ ! -e "$FILE" ] ; then
    echo "This file doesn't exist, skipping."
    continue
  fi
  if [ "$RSYNC" = "1" ] ; then
    # shellcheck disable=SC2086
    $PRSYNC -a $DELETE $LOGIN -h "$HOSTS" -- "$FILE" "$DEST_DIR"
  else
    # shellcheck disable=SC2086
    $PSCP -r $LOGIN -h "$HOSTS" -- "$FILE" "$DEST_DIR"
  fi
done