今会社で使ってる奴。

imananishiton.gs

function myFunction() {
  var email = ''//メールアドレス
  var token = '' // https://api.slack.com/custom-integrations/legacy-tokens で発行できるトークン
  var default_emoji = ':satisfied:' // 予定が無いか限定公開の場合に表示する emoji
  var default_message = 'わーわー' // 予定が無いか限定公開の場合に表示するメッセージ
  var ima = new Imananishiton(email, token, default_emoji, default_message)
  ima.nanishiton()
}

var Imananishiton = function(email, token, default_emoji, default_message) {
    this.email = email
    this.token = token
    this.default_emoji = default_emoji
    this.default_message = default_message
}

Imananishiton.prototype = {
  nanishiton: function() {
    var events = this.getCurrentEvents()
    var status = [
      CalendarApp.GuestStatus.OWNER,
      CalendarApp.GuestStatus.YES,
      CalendarApp.GuestStatus.MAYBE,
      CalendarApp.GuestStatus.INVITED
    ]
    var filtered_events = events.filter(function(e) {
      return (status.indexOf(e.getMyStatus()) >= 0)
    })
    if(filtered_events.length == 0){
      this.changeSlackStatus("", "")
    }
    filtered_events.forEach(function(filtered_event){
      var message = this.createStatusMessage(filtered_event)
      this.changeSlackStatus(message, filtered_event)
    },this)
},
  getCurrentEvents: function() {
    var start = new Date()
    var end = new Date(start.getTime() + 60 * 1000)
    var calendar = CalendarApp.getCalendarById(this.email)
    return calendar.getEvents(start, end)
  },
  createStatusMessage: function(event) {
    if (!event || this.isPrivateEvent(event) || this.isAlldayEvent(event)  ) {
      return this.default_message
    }
    var schedule = this.getEventSchedule(event)
    var message = event.getTitle() + '' 
    if (event.getLocation() !== '') {
      message += ' @ ' + event.getLocation()
    }
    return message + '【' + schedule['start'] + ' ～ ' + schedule['end'] + '】'
  },
  isPrivateEvent: function(event) {
    return event.getVisibility() !== CalendarApp.Visibility.DEFAULT
  },
  isAlldayEvent:function(event) {
    return event.isAllDayEvent()
  },
  getEventSchedule: function(event) {
    return {
      start: Utilities.formatDate(event.getStartTime(), 'Asia/Tokyo', 'HH:mm'),
      end: Utilities.formatDate(event.getEndTime(), 'Asia/Tokyo', 'HH:mm'),
    }
  },
  changeSlackStatus: function(message, event) {
    if (!event || this.isPrivateEvent(event) || this.isAlldayEvent(event)  ) {
      var emoji = this.default_emoji
      message = this.default_message
    } else {
      if(message.slice(message,3) == "[休]"){
        var emoji = ':yasumi:'
        message = message.substr(3)
      }else{
        var emoji = ':date:'
      }
    }
    var profile = {
      'status_text': message,
      'status_emoji': emoji,
    }
    UrlFetchApp.fetch("https://slack.com/api/users.profile.set?token=" + this.token + "&profile=" + encodeURIComponent(JSON.stringify(profile)));
  }
}