#!/bin/sh
set -eu

# See `parse_args()` for enabling dry run.
dry_run="no"

is_dry_run() {
  test "${dry_run}" = "yes"
}

setup_colors() {
  if [ -t 1 ]; then
    sgr0="$(printf      '\033[0m')"
    bold="$(printf      '\033[1m')"
    red="$(printf       '\033[31m')"
    green="$(printf     '\033[32m')"
    yellow="$(printf    '\033[33m')"
    blue="$(printf      '\033[34m')"
  else
    sgr0=''
    bold=''
    red=''
    green=''
    yellow=''
    blue=''
  fi
}

setup_commands() {
  dry=''
  is_dry_run && dry="echo "

  APT="${dry}apt"
  APT_FILE="${dry}apt-file"
  CD="${dry}cd"
  CHSH="${dry}chsh"
  LN="${dry}ln"
  MKDIR="${dry}mkdir"
  RM="${dry}rm"
  RMDIR="${dry}rmdir"
  SED="${dry}sed"
  SU="${dry}su"
  UPDATE_GRUB="${dry}update-grub"
  USERADD="${dry}useradd"
  USERMOD="${dry}usermod"
}

usage() {
  echo "Usage: $(basename "$0") [-h] [-n]"
  echo ""
  echo "  -h  print this help and exit."
  echo "  -n  dry run, don't make changes."
}

error() {
  printf "${red}ERROR:${sgr0} %s\n"  "$1" >&2
  exit 1
}

info() {
  printf "${green}->${sgr0} %s\n"  "$1"
}

title() {
  echo "${blue}${bold}=> ${1}${sgr0}"
}

skipped() {
  echo "${yellow}SKIPPED:${sgr0} ${1}"
}

apt_install() {
  title "Install APT packages"

  info "Updating package database"
  ${APT} update

  info "Installing APT packages"
  ${APT} install -y \
    apt-file \
    ascii \
    build-essential \
    ca-certificates \
    cmake \
    cmake-doc \
    curl \
    exuberant-ctags \
    g++ \
    gcc \
    git \
    git-crypt \
    gnupg \
    help2man \
    htop \
    jq \
    make \
    man-db \
    nodejs \
    pandoc \
    pkg-config \
    psmisc \
    python3 \
    python3-virtualenv \
    ripgrep \
    rsync \
    shellcheck \
    sshpass \
    stow \
    sudo \
    tmux \
    unzip \
    zsh

  info "Updating apt-file database"
  ${APT_FILE} update
}

grub_disable_timeout() {
  title "Disable GRUB timeout"

  ${SED} -i.original -e 's/^GRUB_TIMEOUT=.*/GRUB_TIMEOUT=0/' /etc/default/grub
  ${UPDATE_GRUB}
}

ensure_usr_bin_fd() {
  title "Make 'fd' available with the correct name"

  fd_executable='/usr/local/bin/fdfind'
  if [ -x "${fd_executable}" ]; then
    ${LN} -svf "${fd_executable}" /usr/local/bin/fd
  else
    skipped "${fd_executable} does not exist"
  fi
}

ensure_usr_local_man_manN() {
  title "Make sure we have directories for all man page sections"

  for dir in $(seq -f '/usr/local/man/man%.0f' 9); do
    ${MKDIR} -vp "${dir}"
  done
}

user_setup() {
  title "Setup user: $1"

  if user_exists "$1"; then
    info "User $1 exists. Updating..."
    user_update "$1"
  else
    info "Creating user $1"
    user_new "$1"
  fi

  user_allow_sudo_nopasswd "$1"
}

user_exists() {
	id -u "$1" >/dev/null 2>&1
}

user_new() {
  empty_skel="$(mktemp -d)"

  ${USERADD} \
    -m                ` # Create home directory.` \
    -k "$empty_skel"  ` # Copy files from this directory into the new home.` \
    -U                ` # Create a groups with the same name as the user.` \
    -G staff          ` # Other groups the new user will be a member of.` \
    -s /bin/zsh       ` # The new user's login shell. ` \
    "$1"              ` # The new user's name.` \
    2>&1              ` # Silently.` \

  ${RMDIR} "$empty_skel"
}

# Add user $1 to the `staff` group...
# ...and change shell to `zsh` and get rid of bash files.
user_update() {
  info "Adding $1 to group staff"
  ${USERMOD} -aG staff "$1"

  info "Changing login shell to zsh"
  ${CHSH} -s /bin/zsh "$1"

  info "Removing bash leftover files"
  for f in .bash_history .bash_logout .bashrc .profile; do
    ${RM} -vf "/home/${1}/${f}"
  done
}

# Allow `sudo` without password for user $1.
user_allow_sudo_nopasswd() {
  info "Enabling sudo without password for ${1}"
  contents="$1 ALL=(ALL:ALL) NOPASSWD:ALL"
  sudoers_file="/etc/sudoers.d/${1}_nopasswd"
  if is_dry_run; then
    echo "echo \"$contents\" >$sudoers_file"
  else
    echo "$contents" >"$sudoers_file"
  fi
}

# Deploy dotfiles for user $1 from URL $2.
deploy_dotfiles() {
  title "Deploy dotfiles"

  dotfiles_dir="/home/$1/.dotfiles"
  if [ -d "${dotfiles_dir}" ]; then
    skipped "${dotfiles_dir} exists"
  else
    info "Cloning dotfiles"
    ${SU} "$1" -c "git clone $2 ${dotfiles_dir}"
    (
      info "Installing dotfiles"
      ${CD} "${dotfiles_dir}"
      ${SU} "$1" -c "./install.sh -y"
    )
  fi
}

parse_args() {
  while getopts 'hn' opt; do
    case "$opt" in
    h)  # help
      usage
      exit 0
      ;;
    n)  # dry run
      dry_run="yes"
      ;;
    *)  # invalid argument
      usage
      exit 1
      ;;
    esac
  done
}

require_root() {
  [ "$(id -u)" -eq 0 ] || error "This script must be run as root!"
}

user="fernando"
dotfiles_url="https://git.schauenburg.me/fernando/dotfiles.git"

main() {
  setup_colors
  parse_args "$@"
  is_dry_run || require_root
  setup_commands

  apt_install
  grub_disable_timeout
  ensure_usr_bin_fd
  ensure_usr_local_man_manN
  user_setup "$user"
  deploy_dotfiles "$user" "$dotfiles_url"
}

main "$@"