问如何使用gmail api检查给定标头的所有传入消息

EN

const fs = require('fs')
const readline = require('readline')
const { google } = require('googleapis')

const TOKEN_PATH = 'token.json'

// Load client secrets from a local file.
fs.readFile('credentials.json', (err, content) => {
  if (err) return console.log('Error loading client secret file:', err)
  // Authorize a client with credentials, then call the Gmail API.
  authorize(JSON.parse(content), listMessages)
})

/**
 * Create an OAuth2 client with the given credentials, and then execute the
 * given callback function.
 * @param {Object} credentials The authorization client credentials.
 * @param {function} callback The callback to call with the authorized client.
 */
function authorize(credentials, callback) {
  const { client_secret, client_id, redirect_uris } = credentials.installed
  const oAuth2Client = new google.auth.OAuth2(
    client_id,
    client_secret,
    redirect_uris[0],
  )

  // Check if we have previously stored a token.
  fs.readFile(TOKEN_PATH, (err, token) => {
    if (err) return getNewToken(oAuth2Client, callback)
    oAuth2Client.setCredentials(JSON.parse(token))
    callback(oAuth2Client)
  })
}

/**
 * Get and store new token after prompting for user authorization, and then
 * execute the given callback with the authorized OAuth2 client.
 * @param {google.auth.OAuth2} oAuth2Client The OAuth2 client to get token for.
 * @param {getEventsCallback} callback The callback for the authorized client.
 */
function getNewToken(oAuth2Client, callback) {
  const authUrl = oAuth2Client.generateAuthUrl({
    access_type: 'offline',
    scope: SCOPES,
  })
  console.log('Authorize this app by visiting this url:', authUrl)
  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  })
  rl.question('Enter the code from that page here: ', (code) => {
    rl.close()
    oAuth2Client.getToken(code, (err, token) => {
      if (err) return console.error('Error retrieving access token', err)
      oAuth2Client.setCredentials(token)
      // Store the token to disk for later program executions
      fs.writeFile(TOKEN_PATH, JSON.stringify(token), (err) => {
        if (err) return console.error(err)
        console.log('Token stored to', TOKEN_PATH)
      })
      callback(oAuth2Client)
    })
  })
}

/**
 * Lists the labels in the user's account.
 *
 * @param {google.auth.OAuth2} auth An authorized OAuth2 client.
 */
function listLabels(auth) {
  const gmail = google.gmail({ version: 'v1', auth })
  gmail.users.labels.list(
    {
      userId: 'me',
    },
    (err, res) => {
      if (err) return console.log('The API returned an error: ' + err)
      const labels = res.data.labels
      if (labels.length) {
        console.log('Labels:')
        labels.forEach((label) => {
          console.log(`- ${label.name}`)
        })
      } else {
        console.log('No labels found.')
      }
    },
  )
}
function listMessages(auth) {
  const gmail = google.gmail({ version: 'v1', auth })
  const arr = []
  gmail.users.messages.list(
    {
      userId: 'me',
    },
    (err, res) => {
      if (err) return console.log('The API returned an error: ' + err)
      const labels = res.data
      const lab = labels.messages
      lab.map((x) => arr.push(x.id))
    },
  )
  for (let i = 0; i < arr.length; i++) {
    gmail.users.messages.get(
      {
        id: i,
        userId: 'me',
      },
      (err, res) => {
        if (err) return console.log('The API returned an error: ' + err)
        const label = res.data
        console.log(i)
        console.log(label)
      },
    )
  }
}