index.js

const Botkit = require('botkit');
const request = require('request');
const parseXML = require('xml2js').parseString;
const execSync = require('child_process').execSync;

let googlePhotoAccessToken;
let latestDate = new Date('1970/1/1');
let paperProcessRunning = false;

const googlePhotoAlbumID = process.env.google_photo_album_id;
const googlePhotoUserName = process.env.google_photo_user_name;
const paperAccessToken = process.env.paper_access_token;
const paperDocumentID = process.env.paper_document_id;

const controller = Botkit.slackbot( {
  debug: false
});

let entryQueue = [];

controller.spawn({
  token: process.env.slack_token
}).startRTM();

controller.on('file_share', function(bot, message) {
  if( message.file.mimetype === 'image/jpeg' ||
      message.file.mimetype === 'image/png' ||
      message.file.mimetype === 'image/gif') {
    const now = new Date();
    const diff = now.getTime() - latestDate.getTime();
    if((diff / (1000 * 60)) > 30) {
      getAccessToken();
      latestDate = new Date();
    }

    let commentMessage;

    if(message.file.initial_comment) commentMessage = message.file.title + ' / ' + message.file.initial_comment.comment;
    else commentMessage = message.file.title;

    download(message.file.url_private_download, process.env.slack_token)
      .then((data) => {
        return upload(data, message.file.mimetype);
      })
      .then((url) => {
        enqueue(
          url,
          message.file.mimetype,
          commentMessage,
          message.username);
      })
      .then(() => {
        if(!paperProcessRunning) {
          paperProcessRunning = true;
          paperDocumentProcess();
        }
      })
      .catch((error) => {
        console.log(error);
      })
  }
  else {
    console.log('File mimetype : ' + message.file.mimetype + ' is not supported.');
  }
});

function getAccessToken() {
  const result = execSync('sh ./get_access_token_by_refresh_token.sh').toString();
  let json;
  eval('json = ' + result);
  googlePhotoAccessToken = json.access_token;
}

function paperDocumentProcess() {
  downloadPaperDocument()
    .then(modifyPaperDocument)
    .then(uploadPaperDocument)
    .then((response) => {
      for(let i=0; i<response.entryCount; i++) {
        entryQueue.shift();
      }
      if(entryQueue.length > 0) paperDocumentProcess();
      else paperProcessRunning = false;
    })
    .catch((error) => {
      paperDocumentProcess();
    });
}

function download(url, token) {
  return new Promise(function(resolve, reject) {
    request({method: 'get',
      url: url,
      encoding: null,
      headers: { Authorization: 'Bearer ' + token }
    }, function(error, response, body) {
      if(error) {
        reject(error);
      } else {
        resolve(body);
      }
    })
  });
}

// Google Photo にアップロードする
function upload(data, fileType) {
  return new Promise(function(resolve, reject) {
    let endPoint = 'https://picasaweb.google.com/data/feed/api/user/' + googlePhotoUserName + '/albumid/' + googlePhotoAlbumID;
    request({
      method: 'post',
      url: endPoint + '?access_token=' + googlePhotoAccessToken,
      body: data,
      headers: {
        'Content-Type': fileType,
        'Content-Length': '' + data.length,
        'Slug': 'slack_uploaded_image',
      },
    }, function(error, response, body) {
      if(error) {
        reject(error);
      } else {
        let json;
        parseXML(body, (err, result) => {
          if(err) {
            throw err;
          } else {
            let imageURL = result.entry.content[0].$.src;
            resolve(imageURL.replace('slack_uploaded_image', 's10000/slack_uploaded_image'));
          }
        });
      }
    })
  })
}

function enqueue(url, contentType, comment, userName) {
  entryQueue.push({
    'url': url,
    'contentType': contentType,
    'comment': comment,
    'userName': userName });
  console.log(entryQueue);
}

function downloadPaperDocument() {
  return new Promise(function(resolve, reject) {
    request({
      method: 'get',
      url: 'https://api.dropboxapi.com/2/paper/docs/download',
      headers: {
        'Authorization': 'Bearer ' + paperAccessToken,
        'Dropbox-API-Arg': '{"doc_id": "' + paperDocumentID +'", "export_format": "markdown"}'
      }
    }, function(error, response, body) {
      if(error) {
        reject(error);
      } else {
        resolve(response);
      }
    });
  });
}

function modifyPaperDocument(response) {
  let temp;
  eval('temp = ' + response.caseless.dict['dropbox-api-result']);
  response.revision = temp.revision;

  response.entryCount = 0;
  response.modifiedDocument = response.body;

  for(let entry of entryQueue) {
    response.modifiedDocument = response.modifiedDocument + '![' + entry.comment + ' from ' + entry.userName + '](' + entry.url + ')\n';
    response.entryCount++;
  }
  response.modifiedDocument = response.modifiedDocument.replace('# Album', 'Album');
  return Promise.resolve(response);
}

function uploadPaperDocument(response) {
  return new Promise(function(resolve, reject) {
    request({
      method: 'post',
      url: 'https://api.dropboxapi.com/2/paper/docs/update',
      body: response.modifiedDocument,
      headers: {
        "Content-Type": "application/octet-stream",
        'Authorization': 'Bearer ' + paperAccessToken,
        'Dropbox-API-Arg': '{"doc_id": "' + paperDocumentID + '", "doc_update_policy": "overwrite_all", "revision": ' + response.revision + ', "import_format": "markdown"}'
      },
    }, function(error, res, body) {
      if(error) {
        reject(error);
      } else {
        resolve(response);
      }
    })
  })
}