let getToken = true;

if (pm.collectionVariables.get('accessTokenExpiry') > (new Date()).getTime()){
    getToken = false;
}

if (getToken) {
    const echoPostRequest = {
        url: pm.collectionVariables.get('accessTokenURL'),
        method: 'POST',
        body: {
            mode: 'formdata',
            formdata: [
                {key: "client_id", value: pm.collectionVariables.get('clientID')},
                {key: "client_secret", value: pm.collectionVariables.get('clientSecret')},
                {key: "scope", value: pm.collectionVariables.get('scope')},
                {key: "grant_type", value:"client_credentials"}
            ]
        }
    };
    pm.sendRequest(echoPostRequest, function (err, res) {
        if (!err) {
            const responseJson = res.json();
            pm.collectionVariables.set('currentAccessToken', responseJson.access_token)
    
            const expiryDate = new Date();
            expiryDate.setSeconds(expiryDate.getSeconds() + responseJson.expires_in);
            pm.collectionVariables.set('accessTokenExpiry', expiryDate.getTime());
        }
    });
}