#!/usr/bin/env bash

set -Eeuo pipefail

readonly APP_PATH="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P)"
readonly VIM_PATH="${VIM_PATH:-$HOME/.vim}"
readonly MANAGED_START='# >>> dotfiles >>>'
readonly MANAGED_END='# <<< dotfiles <<<'

info() { printf '\033[34m[•]\033[0m %s\n' "$*"; }
success() { printf '\033[32m[✔]\033[0m %s\n' "$*"; }
warn() { printf '\033[33m[!]\033[0m %s\n' "$*" >&2; }
die() { printf '\033[31m[✘]\033[0m %s\n' "$*" >&2; exit 1; }

usage() {
  cat <<'USAGE'
Usage: ./install.sh [all|vim|shell|tmux|uninstall]...

With no arguments, installs every component. Components can be combined, for
example: ./install.sh vim tmux
USAGE
}

require() {
  command -v "$1" >/dev/null 2>&1 || die "Required program not found: $1"
}

backup_path() {
  local target=$1
  if [[ -e "$target" || -L "$target" ]]; then
    local backup="${target}.backup.$(date +%Y%m%d_%H%M%S)" suffix=0
    while [[ -e "$backup" || -L "$backup" ]]; do
      ((suffix += 1))
      backup="${target}.backup.$(date +%Y%m%d_%H%M%S).$suffix"
    done
    mv -- "$target" "$backup"
    warn "Backed up $target to $backup"
  fi
}

link_config() {
  local source=$1 target=$2
  if [[ -L "$target" && "$(readlink "$target" || true)" == "$source" ]]; then
    return
  fi
  backup_path "$target"
  ln -s "$source" "$target"
  success "Linked $target -> $source"
}

remove_managed_link() {
  local target=$1 expected=$2
  if [[ -L "$target" && "$(readlink "$target")" == "$expected" ]]; then
    rm -- "$target"
    info "Removed $target"
  fi
}

remove_managed_block() {
  local file=$1 temp
  [[ -f "$file" ]] || return 0
  temp=$(mktemp)
  awk -v start="$MANAGED_START" -v end="$MANAGED_END" '
    $0 == start { managed = 1; next }
    $0 == end { managed = 0; next }
    !managed { print }
  ' "$file" > "$temp"
  cat "$temp" > "$file"
  rm -f "$temp"
}

install_vim() {
  require vim
  require git
  if ! vim --clean -Nu NONE -n -es \
    '+if v:version < 900 | cquit | endif' '+qall'; then
    die 'Vim 9 or newer is required.'
  fi

  mkdir -p "$VIM_PATH/autoload"
  local temp
  temp=$(mktemp -d)
  git clone --depth 1 --quiet https://github.com/junegunn/vim-plug "$temp"
  cp "$temp/plug.vim" "$VIM_PATH/autoload/plug.vim"
  rm -rf "$temp"
  link_config "$APP_PATH/.vimrc" "$HOME/.vimrc"
  vim -Nu "$APP_PATH/.vimrc" -n -es \
    --cmd 'set nomore' '+PlugInstall --sync' '+qall'
  success 'Installed Vim configuration and plugins.'
}

install_shell() {
  local bashrc="$HOME/.bashrc" quoted_source
  touch "$bashrc"
  remove_managed_block "$bashrc"
  printf -v quoted_source '%q' "$APP_PATH/bash_tools.sh"
  {
    printf '\n%s\n' "$MANAGED_START"
    printf '[ -r %s ] && source %s\n' "$quoted_source" "$quoted_source"
    printf 'command -v zoxide >/dev/null 2>&1 && eval "$(zoxide init bash)"\n'
    printf '%s\n' "$MANAGED_END"
  } >> "$bashrc"
  success "Installed managed Bash block in $bashrc"
}

install_tmux() {
  require tmux
  link_config "$APP_PATH/.tmux.conf" "$HOME/.tmux.conf"
  success 'Installed tmux configuration.'
}

uninstall() {
  remove_managed_link "$HOME/.vimrc" "$APP_PATH/.vimrc"
  remove_managed_link "$HOME/.tmux.conf" "$APP_PATH/.tmux.conf"
  remove_managed_block "$HOME/.bashrc"
  success 'Removed dotfile links and the managed Bash block.'
  info 'The repository, Vim data/plugins, and backups were retained.'
}

main() {
  case "${1:-}" in
    -h|--help) usage; return ;;
  esac

  local components=("$@") component
  ((${#components[@]})) || components=(all)
  for component in "${components[@]}"; do
    case "$component" in
      all)
        install_vim
        install_shell
        install_tmux
        ;;
      vim) install_vim ;;
      shell) install_shell ;;
      tmux) install_tmux ;;
      uninstall) uninstall ;;
      *) usage; die "Unknown component: $component" ;;
    esac
  done
}

main "$@"