lib/app/menu.rb

#
# Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
# or more contributor license agreements. Licensed under the Elastic License;
# you may not use this file except in compliance with the Elastic License.
#
# frozen_string_literal: true
#
require 'remedy'

module App
  class Menu
    attr_reader :items
    attr_reader :title
    attr_reader :index

    def initialize(title, items)
      super()
      @index = 0
      @title = title
      @items = items.map.with_index do |item, i|
        item.is_a?(String) ? MenuItem.new(item, nil, i == 0) : MenuItem.new(item[:command], item[:hint], i == 0)
      end
    end

    def select_item(index)
      @index = index
      @items.each_with_index { |item, i| item.selected = (i == index) }
      display
    end

    def select_command
      display
      interaction = Remedy::Interaction.new
      interaction.loop do |key|
        if key.nil?
          break
        end
        case key.to_s.to_sym
        when :down
          index = @index + 1
          index = 0 if index >= @items.size
          select_item(index)
        when :up
          index = @index - 1
          index = 0 if index < 0
          select_item(index)
        when :control_m
          return @items[@index].command
        end
      end
    end

    private

    def display
      clear_screen
      puts(title)
      @items.each do |item|
        print(item.selected ? '--> ' : '    ')
        puts item.hint.present? ? "#{item.hint} (#{item.command})" : item.command
      end
    end

    def clear_screen
      system('clear') || system('cls')
    end

    def read_char
      STDIN.echo = false
      STDIN.raw!

      input = STDIN.getc
      if input == "\e"
        begin
          input << STDIN.read_nonblock(3)
        rescue StandardError
          nil
        end
        begin
          input << STDIN.read_nonblock(2)
        rescue StandardError
          nil
        end
      end
      input
    ensure
      STDIN.echo = true
      STDIN.cooked!
    end
  end

  class MenuItem
    attr_reader :command
    attr_reader :hint
    attr_accessor :selected

    def initialize(command, hint = nil, selected = false)
      super()
      @command = command
      @hint = hint
      @selected = selected
    end
  end
end