slack-to-mail.gas

const configs = {
  slackMessageTrigger: "slackToMail",
  slackAcceptedMessage: "受け付けました",
  slackIncomingWebhookUrl: "", // ★
  spreadSheetFileId: "", // ★
  spreadSheetSheetName: "シート1", // ★
  mailTo: "to@example.co.jp", // ★
  mailFrom: "from@example.co.jp", // ★
  mailSubjectPrefix: "【テスト】",
};

const emailSectionMap = [
  ["title", "タイトル"],
  ["body", "本文"],
  ["requester", "リクエスタ"],
];

function doPost(e) {
  const postMessage = detectPostMessageOrDebugString(e);
  const payload = convertPostMessageToPayload(postMessage);

  writeSpreadSheet(
    configs.spreadSheetFileId,
    configs.spreadSheetSheetName,
    payload,
  );

  sendEmail(
    configs.mailTo,
    configs.mailFrom,
    configs.mailSubjectPrefix,
    payload
  );

  sendToSlackAcceptedMessage(
    configs.slackIncomingWebhookUrl,
    configs.slackAcceptedMessage,
  );

  return ContentService.createTextOutput("処理が完了しました");
}

/*
  @param {eventParameter} event - POSTイベントパラメータ @see https://developers.google.com/apps-script/guides/web?hl=ja#request_parameters
  @return {string} - 文字列変換したもの、またはデバッグ実行した文字列
 */
function detectPostMessageOrDebugString(event) {
  if (event?.postData) {
    return event.postData.getDataAsString();
  }

  return "token=xx" + 
    "&team_id=xx" + 
    "&team_domain=xx" +
    "&service_id=xx" + 
    "&channel_id=xx" + 
    "&channel_name=xx" + 
    "&timestamp=0.0" + 
    "&user_id=xx" + 
    "&user_name=xx" +
    "&text=" + encodeURIComponent(`${configs.slackMessageTrigger}` + 
      ",,title::TEST_TITLE" + 
      ",,body::TEST_BODY" + 
      ",,requester::TEST_USER") + 
    `&trigger_word=${configs.slackMessageTrigger}`
  ;
}

/*
  @param {string} postMessage - POSTされた文字列 e.g. "token=xx&text=trigger,,title::a,,body::b"
  @return {object} - textフィールドをオブジェクトに変換したもの e.g. { title: "a", body: "b" }
 */
function convertPostMessageToPayload(postMessage) {
  const textField = postMessage
    .split("&")
    .map(v => v.split("="))
    .find(v => v[0] === "text")
  ;

  const payload = decodeURIComponent(textField[1])
    .split(",,")
    .map(v => v.split("::"))
    .reduce((acc, [key, value]) => {
      if (value) {
        acc[key] = value;
      }
      return acc;
    }, {})
  ;

  return {
    postMessage,
    ...payload,
  }
}

/*
  @param {string} spreadSheetFileId - 書き込みするファイルのID
  @param {string} spreadSheetName - 書き込みするシート名
  @param {object} payload - POSTされた内容
 */
function writeSpreadSheet(spreadSheetFileId, spreadSheetName, payload) {
  const sheet = SpreadsheetApp
    .openById(spreadSheetFileId)
    .getSheetByName(spreadSheetName)
  ;

  const values = [
    Utilities.formatDate(new Date(), "JST", "yyyy/MM/dd HH:mm:ss"),
    ...Object.values(payload),
  ];

  sheet.insertRows(1, 1);
  sheet.getRange(1, 1, 1, values.length).setValues([values]);
}

/*
  @param {string} mailTo - 送信先アドレス e.g. "foo@bar.com"
  @param {string} mailFrom - 送信元アドレス e.g. "foo@bar.com"
  @param {string} mailSubjectPrefix - メールの件名 e.g. "XXXのお知らせ"
  @param {object} payload - POSTされた内容
 */
function sendEmail(mailTo, mailFrom, mailSubjectPrefix, payload) {
  const subject = `${mailSubjectPrefix}${payload.title}`;

  const body = emailSectionMap.map(([key, label]) => {
    return `【${label}】\r\n${payload[key]}\r\n`;
  }).join("\r\n");

  const options = {
    from: mailFrom,
  };

  GmailApp.sendEmail(mailTo, subject, body, options);
}

/*
  @param {string} message - Slackに受付完了を知らせるメッセージ
 */
function sendToSlackAcceptedMessage(url, message) {
  if (!url) {
    return;
  }

  const payload = JSON.stringify({
    text: message,
    icon_emoji: ":robot_face:"
  });

  const options = {
    method: "post",
    contentType: "application/json",
    payload,
  };

  UrlFetchApp.fetch(url, options);
}