請教前輩用的文章。
放在此處，較方便閱讀。
程式碼參考卡米狗作者的教學文章，一步一腳印照本宣科而成。
因為不清楚是否有影響，主要程式位置已用OOO取代。
金鑰跟串聯碼也拿掉了。

require 'line/bot'
class OOOController < ApplicationController
  protect_from_forgery with: :null_session

  def webhook
    # 學說話
    reply_text = learn(channel_id, received_text)

    # 關鍵字回覆
    reply_text = keyword_reply(channel_id, received_text) if reply_text.nil?



    # 傳送訊息到 line
    response = reply_to_line(reply_text)

    # 回應 200
    head :ok
  end

  # 頻道 ID
  def channel_id
    source = params['events'][0]['source']
    source['groupId'] || source['roomId'] || source['userId']
  end

  # 儲存對話
  def save_to_received(channel_id, received_text)
    return if received_text.nil?
    Received.create(channel_id: channel_id, text: received_text)
  end

  # 儲存回應
  def save_to_reply(channel_id, reply_text)
    return if reply_text.nil?
    Reply.create(channel_id: channel_id, text: reply_text)
  end
  


  # 取得對方說的話
  def received_text
    message = params['events'][0]['message']
    message['text'] unless message.nil?
  end

    # 學說話
#  def learn(received_text)
   def learn(channel_id, received_text)
    #如果開頭不是 學說話這樣說; 就跳出
    return nil unless received_text[0..6] == '學說話這樣說;'
    
    received_text = received_text[7..-1]
    semicolon_index = received_text.index(';')

    # 找不到分號就跳出
    return nil if semicolon_index.nil?

    keyword = received_text[0..semicolon_index-1]
    message = received_text[semicolon_index+1..-1]

  #  KeywordMapping.create(keyword: keyword, message: message)
    KeywordMapping.create(channel_id: channel_id, keyword: keyword, message: message)
    '記住了。'
  end
    
  # 關鍵字回覆
  def keyword_reply(channel_id, received_text)
    message = KeywordMapping.where(channel_id: channel_id, keyword: received_text).last&.message
    return message unless message.nil?
    KeywordMapping.where(keyword: received_text).last&.message
  end
 
  # 傳送訊息到 line
  def reply_to_line(reply_text)
    return nil if reply_text.nil?
    
    # 取得 reply token
    reply_token = params['events'][0]['replyToken']
    
    # 設定回覆訊息
    message = {
      type: 'text',
       text: reply_text
    #   text: '天氣很好。'
    } 

    # 傳送訊息
    line.reply_message(reply_token, message)
  end

  # Line Bot API 物件初始化
  def line
    @line ||= Line::Bot::Client.new { |config|
      config.channel_secret = ''
      config.channel_token = ''
    }
  end

  def eat
    render plain: "好。"
  end

  def request_headers
    render plain: request.headers.to_h.reject{ |key, value|
      key.include? '.'
    }.map{ |key, value|
      "#{key}: #{value}"
    }.sort.join("\n")
  end

  def response_headers
    response.headers['別難過。'] = 'QQ'
    render plain: response.headers.to_h.map{ |key, value|
      "#{key}: #{value}"
    }.sort.join("\n")
  end

  def request_body
    render plain: request.body
  end

  def show_response_body
    puts "===這是設定前的response.body:#{response.body}==="
    render plain: "請注意這邊文字。"
    puts "===這是設定後的response.body:#{response.body}==="
  end

  def sent_request
    uri = URI('http://localhost:3000/OOO/eat')
    http = Net::HTTP.new(uri.host, uri.port)
    http_request = Net::HTTP::Get.new(uri)
    http_response = http.request(http_request)

    render plain: JSON.pretty_generate({
      request_class: request.class,
      response_class: response.class,
      http_request_class: http_request.class,
      http_response_class: http_response.class
    })
  end

  def translate_to_korean(message)
    "#{message}，我明白了。"
  end



end