setup

#!/usr/bin/env bash -eu

COLOR_OFF='\033[0m'
GREEN='\033[0;32m'
RED='\033[0;31m'
YELLOW='\033[0;33m'
CYAN='\033[0;36m'

pushd `dirname $0` > /dev/null
SCRIPT_PATH=`pwd`
popd > /dev/null

pushd $HOME > /dev/null

backup_existing_file() {
  if [ ! -e "$1.bak" ] ; then
    mv $1 $1.bak
    echo -e "${CYAN}A backup [$1.bak] is created.${COLOR_OFF}"
    return 0
  fi

  i=1

  while [ -e "$1.bak.$i" ] ; do
    let i=$i+1
  done

  mv $1 $1.bak.$i
  echo -e "${CYAN}A backup [$1.bak.$i] is created.${COLOR_OFF}"
  return 0
}

symlink_existence_message() {
  echo
  echo -e "${YELLOW}A symbolic link [$1] (points to $(readlink "$1")) already exists.${COLOR_OFF}"
}

symlink_overwrite_confirmation() {
  read -p "Are you really sure you want to overwrite it? (Y/n): " -n 1 -r
  echo
  if [[ $REPLY =~ ^[Yy]$ ]] ; then
    rm "$1"
  else
    echo
    echo -e "${RED}Setup is aborted.${COLOR_OFF}"
    exit 1
  fi
}

link_items=(.vim .vimrc)

for item in "${link_items[@]}"; do
  if [ "$(readlink "$HOME/$item")" ]; then
    symlink_existence_message "$HOME/$item"
    symlink_overwrite_confirmation "$HOME/$item"
  fi

  if [ -e "$HOME/$item" ] ; then
    backup_existing_file "$HOME/$item"
  fi

  ln -s "$SCRIPT_PATH/$item" "$HOME/$item"
  echo -e "${GREEN}A symbolic link [$HOME/$item] is created.${COLOR_OFF}"
done

if [ -e "$HOME/.vimrc.preset" ] ; then
  echo

  if cmp -s "$SCRIPT_PATH/.vimrc.preset.sample" "$HOME/.vimrc.preset" ; then
    echo -e "${CYAN}A user's local preset file [$HOME/.vimrc.preset] has not been modified from the default.${COLOR_OFF}"
  else
    echo -e "${YELLOW}A user's local preset file [$HOME/.vimrc.preset] has been modified.${COLOR_OFF}"
    echo -e "Please review the differences between two files by the following command and manually apply updates:${COLOR_OFF}"
    echo "diff $SCRIPT_PATH/.vimrc.preset.sample $HOME/.vimrc.preset"
  fi
else
  cp "$SCRIPT_PATH/.vimrc.preset.sample" "$HOME/.vimrc.preset"
  echo -e "${GREEN}A preset file [$HOME/.vimrc.preset] is copied.${COLOR_OFF}"
fi

if hash nvim 2>/dev/null; then
  XDG_CONFIG_HOME=${XDG_CONFIG_HOME:=$HOME/.config}

  if [ ! -d "$XDG_CONFIG_HOME" ] ; then
    mkdir -p $XDG_CONFIG_HOME
    echo -e "${GREEN}[$XDG_CONFIG_HOME] is created.${COLOR_OFF}"
  fi

  if [ "$(readlink "$XDG_CONFIG_HOME/nvim")" ]; then
    symlink_existence_message "$XDG_CONFIG_HOME/nvim"
    symlink_overwrite_confirmation "$XDG_CONFIG_HOME/nvim"
  fi

  if [ -e "$XDG_CONFIG_HOME/nvim" ] ; then
    backup_existing_file "$XDG_CONFIG_HOME/nvim"
  fi

  ln -s "$SCRIPT_PATH/.vim" "$XDG_CONFIG_HOME/nvim"
  echo -e "${GREEN}A symbolic link [$XDG_CONFIG_HOME/nvim] is created.${COLOR_OFF}"

  if [ "$(readlink "$XDG_CONFIG_HOME/nvim/init.vim")" ]; then
    symlink_existence_message "$XDG_CONFIG_HOME/nvim/init.vim"
    symlink_overwrite_confirmation "$XDG_CONFIG_HOME/nvim/init.vim"
  fi

  if [ -e "$XDG_CONFIG_HOME/nvim/init.vim" ] ; then
    backup_existing_file "$XDG_CONFIG_HOME/nvim/init.vim"
  fi

  ln -s "$SCRIPT_PATH/.vimrc" "$XDG_CONFIG_HOME/nvim/init.vim"
  echo -e "${GREEN}A symbolic link [$XDG_CONFIG_HOME/nvim/init.vim] is created.${COLOR_OFF}"
fi

popd > /dev/null