Daily Email Summary posts to Google Chat webhook - Number of emails, labels used, unique senders;

Email Summary Bot.gs

const dateBoundaryFactory = (today = new Date()) => {
  const yesterday = new Date(today)
  const yesternight = new Date(today)

  // set yesterday to 00:00:00
  yesterday.setDate(today.getDate() - 1)
  yesterday.setHours(0)
  yesterday.setMinutes(0)
  yesterday.setSeconds(0)

  // set yesternight to 23:59:59
  yesternight.setDate(today.getDate() - 1)
  yesternight.setHours(23)
  yesternight.setMinutes(59)
  yesternight.setSeconds(59)

  return {
    yesterdayStart: yesterday,
    yesterdayEnd: yesternight,
    todayQueryString: `${today.getFullYear()}/${today.getMonth() + 1}/${today.getDate()}`,
    yesterdayQueryString: `${yesterday.getFullYear()}/${yesterday.getMonth() + 1}/${yesterday.getDate()}`
  }
}

function bot() {
  const webhook = "<PASTE CHAT WEBHOOK HERE>"
  const dateInfo = dateBoundaryFactory(new Date())
  const query = "newer:"+ dateInfo.yesterdayQueryString + " older:" + dateInfo.todayQueryString + " -in:sent -in:drafts -in:chats -in:spam"
  const threads = GmailApp.search(query)

  let allLabels = {}, allSenders = {}, messageCount = 0

  threads.forEach( thread => {

    const labels = thread.getLabels()
    labels.forEach( label => {
      const labelName = label.getName()
      if(allLabels.hasOwnProperty(labelName)) allLabels[labelName]++
      else allLabels[labelName] = 1
    })

    const messages = thread.getMessages()
    messages.forEach( message => {
      const messageTime = message.getDate().getTime()

      if(messageTime >= dateInfo.yesterdayStart.getTime() && messageTime <= dateInfo.yesterdayEnd.getTime()) {
        messageCount ++

        const senderInfo = { name: "", email: "" }
        const sender = message.getFrom().replace(/\"/g, "")
        const emails = sender.match(/[^@<\s]+@[^@\s>]+/g)
        senderInfo.email = emails[0]
        let names = sender.split(/\s+/)
        if(names.length > 1) {
          names.pop()
          senderInfo.name = names.join(" ").replace(/"/g, "")
        }
  
        if(allSenders.hasOwnProperty[senderInfo.email]) allSenders[senderInfo.email]++
        else allSenders[senderInfo.email] = 1
      }
    })
  })

  // NOW FOR THE STATS
  const theLabels = Object.keys(allLabels)
  const labelString = theLabels.sort().join("\n")
  const theSenders = Object.keys(allSenders)
  const senderString = theSenders.sort().join("\n")
  const payload = {
    sender: {
      displayName: "Robot",
      avatarUrl: "https://goo.gl/8oz4jG"
    },
    cards: [
      {
        header: {
          title: `Email Summary for ${dateInfo.yesterdayStart.toDateString()}`
        },
        sections: [
          {
            widgets: [
              {
                keyValue: {
                  topLabel: "Number of messages",
                  content: messageCount.toString()
                } 
              },
              {
                keyValue: {
                  topLabel: "Number of labels",
                  content: theLabels.length.toString()
                }  
              },
              {
                keyValue: {
                  topLabel: "Labels used",
                  content: labelString
                }  
              },
              {
                keyValue: {
                  topLabel: "Number of unique senders",
                  content: theSenders.length.toString()
                }  
              },
              {
                keyValue: {
                  topLabel: "Senders",
                  content: senderString
                }  
              }
            ]
          }
        ]
      }
    ]
  }

  const response = UrlFetchApp.fetch(webhook, {
    headers: {
      'Content-Type': 'application/json; charset=UTF-8'
    },
    method: "POST",
    payload: JSON.stringify(payload)
  })

  Logger.log(response.getContentText())
}