oauth.js

var SERVICE_NAME = 'strava'
var AUTHORIZATION_BASE_URL = 'https://www.strava.com/oauth/authorize'
var TOKEN_URL = 'https://www.strava.com/oauth/token'
var CALLBACK_FUNCTION_NAME = 'authCallback'
var STRAVA_API_SCOPE = 'activity:read_all'

/** Returns a parameterized OAuth2 Service object. */
function getOAuthService() {
    var scriptProps = PropertiesService.getScriptProperties()
    var clientId = scriptProps.getProperty('OAUTH_CLIENT_ID')
    var clientSecret = scriptProps.getProperty('OAUTH_CLIENT_SECRET')

    return OAuth2.createService(SERVICE_NAME)
        .setAuthorizationBaseUrl(AUTHORIZATION_BASE_URL)
        .setTokenUrl(TOKEN_URL)
        .setClientId(clientId)
        .setClientSecret(clientSecret)
        .setGrantType('offline')
        .setPropertyStore(PropertiesService.getUserProperties())
        .setScope(STRAVA_API_SCOPE)
        .setCallbackFunction(CALLBACK_FUNCTION_NAME)
}

/** The callback that is invoked after an authentication attempt. */
function authCallback(request) {
    var authorized = getOAuthService().handleCallback(request)
    // close window automatically
    var autoclose =
        '(Tab should automatically close.) <script>setTimeout(function() { top.window.close() }, 1);</script>'
    if (authorized) {
        return HtmlService.createHtmlOutput('Success!' + autoclose)
    } else {
        return HtmlService.createHtmlOutput('Denied.' + autoclose)
    }
}

/** Returns {boolean} `true` if successfully authenticated--false otherwise. */
function isAuthValid() {
    return getOAuthService().hasAccess()
}

/** Resets the OAuth2 service. */
function resetAuth() {
    getOAuthService().reset()
}

/** Returns the 3P authorization urls for the service. */
function get3PAuthorizationUrls() {
    return getOAuthService().getAuthorizationUrl()
}