#!/bin/bash
set -euo pipefail

logo() {
  printf '\033[2J\033[H'
  echo "   _____ _                 _       "
  echo "  / ____(_)               | |      "
  echo " | (___  _ _ __ ___  _ __ | |_   _ "
  echo "  \\___ \\| | '_ \` _ \\| '_ \\| | | | |"
  echo "  ____) | | | | | | | |_) | | |_| |"
  echo " |_____/|_|_| |_| |_| .__/|_|\\__, |"
  echo "    _    _          | |       __/ |"
  echo "   | |  | |         | |      |___/ "
  echo "   | |__| | ___  ___| |_           "
  echo "   |  __  |/ _ \\/ __| __|          "
  echo "   | |  | | (_) \\__ \\ |_           "
  echo "   |_|  |_|\\___/|___/\\__|          "
  echo "                                   "
  echo "                                   "
}

# Usage: choice=$(choose "Title" "Option 1" "Option 2" ...)
choose() {
  if (($# < 2)); then
    printf 'Usage: choose "Title" "Option 1" ["Option 2" ...]\n' >&2
    return 2
  fi
  local title="$1"
  shift
  local options=("$@")
  local selected=0 index key sequence
  printf '%s (Up/Down, Enter)\n' "$title" >&2
  while :; do
    for index in "${!options[@]}"; do
      printf '\r\033[2K' >&2
      if [[ "$index" -eq "$selected" ]]; then
        printf '\033[7m > %s \033[0m\n' "${options[$index]}" >&2
      else
        printf '   %s\n' "${options[$index]}" >&2
      fi
    done
    IFS= read -r -s -n 1 key </dev/tty || return 1
    case "$key" in
    $'\033')
      sequence=''
      IFS= read -r -s -n 2 -t 1 sequence </dev/tty || true
      case "$sequence" in
      '[A' | 'OA') selected=$(((selected + ${#options[@]} - 1) % ${#options[@]})) ;;
      '[B' | 'OB') selected=$(((selected + 1) % ${#options[@]})) ;;
      esac
      ;;
    '')
      printf '%s\n' "${options[$selected]}"
      return 0
      ;;
    esac
    printf '\033[%sA' "${#options[@]}" >&2
  done
}

# Returns selected options on stdout, one per line; an empty selection returns nothing.
# Usage: selections=$(choose_multi "Install what?" "Neovim" "Docker" "Git")
choose_multi() {
  if (($# < 2)); then
    printf 'Usage: choose_multi "Title" "Option 1" ["Option 2" ...]\n' >&2
    return 2
  fi
  local title="$1"
  shift
  local options=("$@")
  local checked=()
  local selected=0 index key sequence marker
  for index in "${!options[@]}"; do
    checked[$index]=0
  done
  printf '%s (Up/Down, Space to toggle, Enter to confirm)\n' "$title" >&2
  while :; do
    for index in "${!options[@]}"; do
      marker=' '
      if [[ "${checked[$index]}" -eq 1 ]]; then marker='x'; fi
      printf '\r\033[2K' >&2
      if [[ "$index" -eq "$selected" ]]; then
        printf '\033[7m > [%s] %s \033[0m\n' "$marker" "${options[$index]}" >&2
      else
        printf '   [%s] %s\n' "$marker" "${options[$index]}" >&2
      fi
    done
    IFS= read -r -s -n 1 key </dev/tty || return 1
    case "$key" in
    $'\033')
      sequence=''
      IFS= read -r -s -n 2 -t 1 sequence </dev/tty || true
      case "$sequence" in
      '[A' | 'OA') selected=$(((selected + ${#options[@]} - 1) % ${#options[@]})) ;;
      '[B' | 'OB') selected=$(((selected + 1) % ${#options[@]})) ;;
      esac
      ;;
    ' ') checked[$selected]=$((1 - checked[$selected])) ;;
    '')
      for index in "${!options[@]}"; do
        if [[ "${checked[$index]}" -eq 1 ]]; then
          printf '%s\n' "${options[$index]}"
        fi
      done
      return 0
      ;;
    esac
    printf '\033[%sA' "${#options[@]}" >&2
  done
}

logo

# Example: choice=$(choose "What would you like to do?" "Install" "Quit")