#!/bin/bash
#
# Usage: gsync [rsync-options] source destination
#
# Synchronize a git source directory with a remote directory, excluding files according to then
# rules found in .gitignore. If subdirectories also contain .gitignore files, then those rules
# will be applied (but only in each respective subdirectory).
#
# Note that ONLY .gitignore files in the directory where this command is run from will be considered
# Thus, when the source or destination is a local path, it should be specified relative to the current
# directory.
#
# There will be two rsync statements - one to exclude everything that should be excluded,
# and a second to handle the exceptions to the exclusion rules - the lines in .gitignore that begin with !
#
# The exceptions to the exclusions are rsync'd first, and if that succeeds, the second rsync
# copies everything else.
#
#
# --- SUPPORT OPEN SOURCE ---
# If you find this script has saved you a decent amount time, please consider dropping me some coin.
# I will be forever grateful and your name will be permanently emblazoned on my Wall of Honor.
# My bitcoin wallet address is 1HoiSHKxYM4EtsP3xFGsY2xWYvh4hAuJ2q
# Paypal or Dwolla: jonathan (replace this with the 'AT' sign on your keyboard) kyuss.org
#
# Thank You.
#
#    - jonathan.
#

if [[ -z "${1}" || -z "${2}" || "${1}" == "--help" || "${1}" == "-help" || "${1}" == "-h" ]] ; then
  echo "Usage: gsync [rsync-options] source destination"
  exit 1
fi

includes=""
excludes='--exclude=.git*'
base="$(pwd)"

function process_git_ignore () {

  git_ignore="${1}"
  if [ "$(dirname ${git_ignore})" = "${base}" ] ; then
    prefix=""
  else
    prefix=".$(echo -n "$(dirname ${git_ignore})" | sed -e 's,^'${base}',,')"
  fi

  while read -r line || [[ -n "${line}" ]] ; do
    # todo: there is probably a cleaner test for "first char == !"
    if [ $(echo "${line}" | head -c 1 | grep -- '!' | wc -l) -gt 0 ] ; then
      includes="${includes}
      --include='${prefix}$(echo "${line}" | sed -e 's/^!//' | sed -e 's/ /\\ /g')'"
    else
      excludes="${excludes}
      --exclude='${prefix}$(echo "${line}" | sed -e 's/ /\\ /g')'"
    fi
  done < ${git_ignore}

}

# root .gitignore file
if [ -f .gitignore ] ; then
  process_git_ignore "$(pwd)/.gitignore"
fi

# check for other .gitignore files
for i in $(find $(pwd) -mindepth 2 -type f -name .gitignore) ; do
  process_git_ignore "${i}"
done

rsync ${includes} --exclude="*" ${@} && rsync ${excludes} ${@}

# for debugging
#echo "rsync ${includes} --exclude=\"*\" ${@}" && echo "rsync ${excludes} ${@}"
#echo "rsync ${excludes} ${@}"