gdrive-downloader.js

const fs = require("fs");
const path = require("path");
const readline = require("readline");
const { google } = require("googleapis");

// If modifying these scopes, delete token.json.
const SCOPES = [
    "https://www.googleapis.com/auth/drive",
    "https://www.googleapis.com/auth/drive.appdata",
    "https://www.googleapis.com/auth/drive.file",
    "https://www.googleapis.com/auth/drive.metadata",
    "https://www.googleapis.com/auth/drive.metadata.readonly",
    "https://www.googleapis.com/auth/drive.photos.readonly",
    "https://www.googleapis.com/auth/drive.readonly"
];
// The file token.json stores the user's access and refresh tokens, and is
// created automatically when the authorization flow completes for the first
// time.
const TOKEN_PATH = "token.json";

/**
 * 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 getAccessToken(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 getAccessToken(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) console.error(err);
                console.log("Token stored to", TOKEN_PATH);
            });
            callback(oAuth2Client);
        });
    });
}

function processArray(array, fn) {
    var index = 0;

    function next() {
        if (index < array.length) {
            fn(array[index++]).then(next);
        }
    }
    next();
}

/**
 * Lists the names and IDs of up to 10 files.
 * @param {google.auth.OAuth2} auth An authorized OAuth2 client.
 */
function listFiles(auth) {
    const drive = google.drive({ version: "v3", auth });
    drive.files.list(
        {
            pageSize: 10,
            fields: "nextPageToken, files(id, name)"
        },
        (err, res) => {
            if (err) return console.log("The API returned an error: " + err);
            const files = res.data.files;
            if (files.length) {
                console.log("Files:");
                processArray(files, (file) => downloadFile(drive, file))
            } else {
                console.log("No files found.");
            }
        }
    );
}

function downloadFile(drive, file) {
    return new Promise(result => {
        if (!fs.existsSync(path.join(__dirname, 'public'))) {
            fs.mkdirSync(path.join(__dirname, 'public'));
        }
        const filePath = path.join(__dirname, 'public', file.name);
        if (fs.existsSync(filePath)) {
            return result();
        }

        var dest = fs.createWriteStream(filePath);
        let progress = 0;
        console.log(`${file.name}`);
        drive.files.get(
            { fileId: file.id, alt: "media" },
            { responseType: "stream" },
            function(err, res) {
                res.data
                    .on("end", () => {
                        readline.clearLine(process.stdout, 0);
                        readline.cursorTo(process.stdout, 0, null);
                        console.log(`Done`);
                        result();
                    })
                    .on("error", err => {
                        readline.clearLine(process.stdout, 0);
                        readline.cursorTo(process.stdout, 0, null);
                        console.log("Error", err);
                        result();
                    })
                    .on('data', d => {
                        progress += d.length;
                        readline.clearLine(process.stdout, 0);
                        readline.cursorTo(process.stdout, 0, null);
                        let text = `${progress} bytes`;
                        process.stdout.write(text);
                    })
                    .pipe(dest);
            }
        );
    });
}

const downloadFiles = () => {
    // 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 Google Drive API.
        authorize(JSON.parse(content), listFiles);
    });
};

module.exports = {
    downloadFiles,
}