dots

#!/bin/sh

dir="$(cd "$(dirname "$0")" && pwd)"
prefix="$HOME"

usage() {
  printf "usage: %s [options] <command> [arguments] <tag...>\n" $(basename $0)
  echo
  echo "options"
  echo
  echo "    -p <prefix>  prefix directory [$prefix]"
  echo
  echo "commands"
  echo
  echo "    diff         compare tag(s) with existing ones"
  echo "    help         display this help"
  echo "    install      symlink the given tag(s)"
  echo "    uninstall    remove symlinks for the given tag(s)"
  echo
  echo "arguments"
  echo
  echo "    -a           apply command to all available tag(s)"
  echo "    -f           force operation"
  echo
}

log() {
  red="\e[0;31m"
  green="\e[0;32m"
  yellow="\e[0;33m"
  blue="\e[0;34m"
  magenta="\e[0;35m"
  cyan="\e[0;36m"
  reset="\e[0;0m"
  if [ "$1" = "red" ] || [ "$1" = "error" ]; then
    color=$red
  elif [ "$1" = "green" ]; then
    color=$green
  elif [ "$1" = "yellow" ]; then
    color=$yellow
  elif [ "$1" = "blue" ]; then
    color=$blue
  elif [ "$1" = "cyan" ] || [ "$1" = "info" ]; then
    color=$cyan
  elif [ "$1" = "magenta" ]; then
    color=$magenta
  else
    color=$reset
  fi
  shift
  printf "$color%s$reset\n" "$*"
}

list() {
  git ls-files "$1" | awk -F / "$2" | uniq
}

execute() {
  command=$1
  tag=$2
  if ! [ -d "$dir/$tag" ]; then
    log error "no such tag: $tag"
    exit 1
  fi
  if [ "$command" = "install" ]; then
    if [ -n "$force" ]; then
      ln="ln -sf"
    else
      ln="ln -s"
    fi
    log info "installing $tag into $prefix"
    for entry in $(list "$tag" '{print $2}'); do
      # If the target exists and is a directory, we keep it and install the
      # files inside. Otherwise we simply create the symlink
      if [ -d "$prefix/$entry" ]; then
        if ! [ -d "$dir/$tag/$entry" ]; then
          log error "source is a file but target a directory"
          exit 1
        fi
        for file in $(list "$tag/$entry" '{print $2 "/" $3}'); do
          eval "$ln \"$dir/$tag/$file\" \"$prefix/$entry\""
          log info "  + $file"
        done
      else
        eval "$ln \"$dir/$tag/$entry\" \"$prefix\""
        log info "  + $entry"
      fi
    done
  elif [ "$command" = "uninstall" ]; then
    if [ -n "$force" ]; then
      rm="rm -rf"
    else
      rm="rm"
    fi
    log info "uninstalling $tag from $prefix"
    for entry in $(list "$tag" '{print $2}'); do
      # Analoguous to install command: if we have a non-symlink directory, we
      # look for installed symlinks inside to remove.
      if [ -d "$prefix/$entry" ]; then
        if ! [ -d "$dir/$tag/$entry" ]; then
          log error "source is a file but target a directory"
          exit 1
        fi
        for file in $(list "$tag/$entry" '{print $2 "/" $3}'); do
          log info "  - $file"
          eval "$rm \"$prefix/$file\""
        done
      elif [ -L "$prefix/$entry" ]; then
        log info "  - $entry"
        eval "$rm \"$prefix/$entry\""
      fi
    done
  elif [ "$command" = "diff" ]; then
    diff=diff
    if which colordiff > /dev/null 2>&1; then
      diff=colordiff
    fi
    for entry in $(list "$tag" '{print $2}'); do
      $diff -ru "$dir/$tag/$entry" "$prefix/$entry" | grep -v '^Only in'
    done
  elif [ -z "$command" ]; then
    log error "no command given"
    exit 1
  else
    log error "unknown command: $command"
    exit 1
  fi
}

main() {
  cd "$dir"
  # Parse options.
  while getopts "hp:" opt; do
    case "$opt" in
      h)
        usage
        exit 0
        ;;
      p)
        prefix="$OPTARG"
        ;;
    esac
  done
  shift $(expr $OPTIND - 1)
  if ! [ -d "$prefix" ]; then
    log error "no such prefix: $prefix"
    exit 1
  fi
  # Parse command.
  command=$1
  shift
  if [ "$command" = "help" ]; then
    usage
    exit 0
  fi
  # Parse arguments.
  OPTIND=1
  while getopts "af" opt; do
    case "$opt" in
      a)
        all=1
        ;;
      f)
        force=1
        ;;
    esac
  done
  shift $(expr $OPTIND - 1)
  if [ -n "$all" ]; then
    cd $dir
    set -- *
    cd -
  fi
  if [ "${#@}" -eq 0 ]; then
    log error "no tag(s) provided"
    exit 1
  fi
  # Execute command on every tag.
  for tag in "$@"; do
    if ! [ -f "$dir/$tag" ]; then
      execute "$command" "$tag"
    fi
  done
}

main "$@"