Need to download UNREAD attachment, I'm able to download attachments of whole Inbox

[N-pharmarack]

I'm able to download attachments from this code, but the problem is, it is downloading all attachments in Inbox, My use case is to download attachments only from unread Mails and then mark them read.

const config = require('./config.json');

const fs = require('fs');
const { Base64Decode } = require('base64-stream')

const Imap = require('imap');
const imap = new Imap(config.imap);

function findAttachmentParts(struct, attachments) {
  attachments = attachments ||  [];
  for (var i = 0, len = struct.length, r; i < len; ++i) {
    if (Array.isArray(struct[i])) {
      findAttachmentParts(struct[i], attachments);
    } else {
      if (struct[i].disposition && ['inline', 'attachment'].indexOf(struct[i].disposition.type.toLowerCase()) > -1) {
        attachments.push(struct[i]);
      }
    }
  }
  return attachments;
}

function buildAttMessageFunction(attachment) {
  var filename = attachment.params.name;
  var encoding = attachment.encoding;

  return function (msg, seqno) {
    var prefix = '(#' + seqno + ') ';
    msg.on('body', function(stream, info) {
      //Create a write stream so that we can stream the attachment to file;
      console.log(prefix + 'Streaming this attachment to file', filename, info);
      var writeStream = fs.createWriteStream( (config.downloads && config.downloads.directory) ? `${config.downloads.directory}/${filename}` : filename);
      writeStream.on('finish', function() {
        console.log(prefix + 'Done writing to file %s', filename);
      });

      //so we decode during streaming using
      if (encoding.toLowerCase() === 'base64') {
        //the stream is base64 encoded, so here the stream is decode on the fly and piped to the write stream (file)
        stream.pipe(new Base64Decode()).pipe(writeStream)
      } else  {
        //here we have none or some other decoding streamed directly to the file which renders it useless probably
        stream.pipe(writeStream);
      }
    });
    msg.once('end', function() {
      console.log(prefix + 'Finished attachment %s', filename);
    });
  };
}

imap.once('ready', function() {
  imap.openBox('INBOX', true, function(err, box) {
    if (err) throw err;
    var f = imap.seq.fetch('1:*', {
      bodies: ['HEADER.FIELDS (FROM TO SUBJECT DATE)'],
      struct: true
    });
    f.on('message', function (msg, seqno) {
      console.log('Message #%d', seqno);
      const prefix = '(#' + seqno + ') ';
      msg.on('body', function(stream, info) {
        var buffer = '';
        stream.on('data', function(chunk) {
          buffer += chunk.toString('utf8');
        });
        stream.once('end', function() {
          console.log(prefix + 'Parsed header: %s', Imap.parseHeader(buffer));
          console.log(Imap.parseHeader(buffer).from)
          console.log(Imap.parseHeader(buffer).subject)
        });
      });
      msg.once('attributes', function(attrs) {
        const attachments = findAttachmentParts(attrs.struct);
        console.log(prefix + 'Has attachments: %d', attachments.length);
        for (var i = 0, len=attachments.length ; i < len; ++i) {
          const attachment = attachments[i];
          console.log(prefix + 'Fetching attachment %s', attachment.params.name);
          var f = imap.fetch(attrs.uid , {
            bodies: [attachment.partID],
            struct: true
          });
          //build function to process attachment message
          f.on('message', buildAttMessageFunction(attachment));
        }
      });
      msg.once('end', function() {
        console.log(prefix + 'Finished email');
      });
    });
    f.once('error', function(err) {
      console.log('Fetch error: ' + err);
    });
    f.once('end', function() {
      console.log('Done fetching all messages!');
      imap.end();
    });
  });
});

imap.once('error', function(err) {
  console.log(err);
});

imap.once('end', function() {
  console.log('Connection ended');
});

imap.connect();

[mscdex]

imap.openBox('INBOX', true, ...) opens the inbox in read-only mode. With that set, you won't be able to update anything (e.g. message statuses) in the mailbox.

[N-pharmarack]

https://github.com/mscdex/node-imap/issues/407#issuecomment-1096557833

This helped me to achieve my use case, please refer to this