mklink

#!/usr/bin/env bash
set -eu -o pipefail

backup_and_link() {
  local source=${1}
  local target=$2
  local __dry_run="${DRYRUN+echo dryrun-would-exec:}"

  if [[ -L ${target} || -f ${target} || -d ${target} ]]; then
    # If already a symlink to desired source, we're done.
    [[ -L ${target} && $(readlink "${target}") == "${source}" ]] && return

    datestamp=${datestamp:-$(date -u +%Y%m%dT%H%M%SZ)}  # cached
    local backup="${target}.bak.${datestamp}"
    echo "Old ${target} backed up as ${backup}" >&2
    ${__dry_run} mv "${target}" "${backup}"
  fi

  ${__dry_run} ln -s "${source}" "${target}"
}

link() {
  local source target

  source="${HERE}/$1"
  target="${HOME}/$2"

  backup_and_link "${source}" "${target}"
}

link:dotfiles() {
  local source target

  for dotfile in $(find ${HERE} -mindepth 1 -maxdepth 1 -type f -name 'dot.*'); do
    source="${dotfile}"
    target="$(basename "${dotfile}")"
    target="${HOME}/${target##dot}"
    backup_and_link "${source}" "${target}"
  done
}

link:dot_config() {
  local source target

   mkdir -p "${HOME}/.config"

  for dir in $(find ${HERE}/dot.config -mindepth 1 -maxdepth 1 -type d); do
    source="${dir}"
    target="${HOME}/.config/$(basename "${dir}")"
    backup_and_link "${source}" "${target}"
  done
}

link:dot_local_bin() {
  local source target

  mkdir -p "${HOME}/.local/bin"

  for f in $(find ${HERE}/dot.local/bin -mindepth 1 -maxdepth 1 -type f); do
    source="${f}"
    target="${HOME}/.local/bin/$(basename "${f}")"
    backup_and_link "${source}" "${target}"
  done
}

link:dot_local_share() {
  local source target

  mkdir -p "${HOME}/.local/share"

  for dir in $(find ${HERE}/dot.local/share -mindepth 1 -maxdepth 1 -type d); do
    source="${dir}"
    target="${HOME}/.local/share/$(basename "${dir}")"
    backup_and_link "${source}" "${target}"
  done
}

link:all() {
  link:dotfiles
  link:dot_config
  link:dot_local_bin
  link:dot_local_share
  link dot.config/vim .vim
}

is_phony_target() {
  for name in "${PHONY[@]}"; do
    [[ ${name} == "$1" ]] && return 0
  done
  return 1
}

usage() {
  IFS=\|
  echo "usage: $0 <${PHONY[*]}>" >&2
  exit 64  # EX_USAGE
}


HERE="$(cd "$(dirname "$0")"; pwd -P)"  # ugly but portable
PHONY=(dotfiles dot_config dot_local_bin dot_local_share)
PHONY+=(all)

if (($# != 1)) || ! is_phony_target "$1"; then
  usage
fi

link:$1