git_backup

#!/usr/bin/env bash

sync_base=$(cat $HOME/.sync 2> /dev/null)
tracker=$sync_base/.tracks

go_sync() {
  cd "$sync_base"
}

go_back() {
  cd - 
}

check_install() {
  if [ ! -d $sync_base/.git ]
  then
    go_sync
    echo "Initializing global backup repo"
    git init -q
    go_back
  fi
}

track_to_folder() {
  grep "=$1$" $tracker | awk -F= '{ print $1 }'
}

track() {
  if [ ! $# -eq 2 ]
  then
    echo "track <path> <track_name>"
    exit 1
  fi

  local abs_folder=$(make_absolute "$1")
  local name=$2

  #check track name is not already in use
  if [[ $name =~ "/" ]]
  then
    echo Track name cannot contains any slash
  elif [[ -d $sync_base/$name ]]
  then
    echo "Have already a track name called : $name"
    exit 1
  else
    #get absolute path before changing from working directory
    go_sync
    echo "$abs_folder=$name" >> $tracker
    git add ".tracks"
    mkdir "$name" && touch "$name/.gitkeep"
    git add "$name/.gitkeep"
    git commit -q -m "Track: $name"
    #separate backup folder in branches, it should be easier to manipulate them
    #individually after that.
    git branch $name
    go_back
  fi
}

backup() {
  if [ ! $# -eq 1 ]
  then
    echo "backup <track_name>"
    exit 1
  fi

  local name=$1
  local folder=$(track_to_folder $name)
  
  if [[ -e $folder ]]
  then
    #a : archive
    #r : recursive
    #u : update
    #c : skip on checksum and not mod time or size
    #z : compress during transfer
    #NOTE: need to experiment --delete option

    local timestamp=$(date "+%Y-%m-%d %H:%M:%S")
    go_sync
    git checkout "$name"

    rsync -arcuzv --delete "$folder/" "$sync_base/$name"
    git add -A .
    git commit -q -m "$timestamp"

    git checkout master
    go_back
  else
    echo "$folder does not exist on your system"
    exit 1
  fi
}


restore() {
  if [ ! $# -eq 1 ]
  then
    echo "restore <track_name>"
    exit 1
  fi

  local name=$1
  local folder=$(track_to_folder $name)
  
  [[ ! -e $folder ]] &&  mkdir -p "$folder"

  #NOTE: fix this awful thing
  go_sync
  git checkout "$name"
  go_back

  rsync -arcuzv --delete "$sync_base/$name/" "$folder/"

  go_sync
  git checkout master
  go_back
}

init() {
  if [ $1 ]
  then
    sync_base=$1
  else
    sync_base=$PWD
  fi

  if [ ! -e $sync_base ]
  then
    mkdir -p $sync_base
  fi


  make_absolute $sync_base > $HOME/.sync 
  sync_base=$(cat $HOME/.sync)
  check_install
}

list_tracks() {
  while read entry
  do
    echo $entry | awk -F"=" '{ print $2 " \t=> " $1 }'
  done < "$sync_base/.tracks"
}

# === utility functions ===

#As readlink is not available on all distro or OSX, provide a portable way to get an 
#absolute path from a relative one.
make_absolute() {
  local ret=false
  local rel_path=$1

  if [[ ! -z $rel_path ]]; then
    #strip eventual last slash
    rel_path=${rel_path%/}

    if [ "$rel_path" = "" ]; then
      rel_path="/"
    fi

    base_name=${rel_path##*/}
    rel_dir=${rel_path%$base_name}

    if [[ $rel_dir = "" ]]; then
        rel_dir="."
    fi

    if cd -P "$rel_dir" 1>/dev/null; then
      #we jump in the directory and use $PWD
      if [[ $(pwd) = "/" ]]; then
        echo "/$base_name"
      else
        echo "$(pwd)/$base_name"
      fi

      cd - 1>&2 > /dev/null #get back to OLD_PATH
      ret=true
    fi
  fi

  $ret
}

case $1 in
  "init")
    shift
    init $@
    ;;
  "backup")
    shift
    backup $@
    ;;
  "restore")
    shift
    restore $@
    ;;
  "track")
    shift
    track $@
    ;;
  "tracks")
    list_tracks
    ;;
  *)
    echo "Usage:"
    ;;
esac