gistfile1.txt

getAuthorizationHeader() {
    if (cacheToken.access_token && cacheToken.expires_on > moment(new Date().getTime()).unix()) {
        return $q.when({'Authorization': 'Bearer ' + cacheToken.access_token});        
    } else {
        cacheToken.access_token = storage.getItem('access_token');
        cacheToken.refresh_token = storage.getItem('refresh_token');
        cacheToken.expires_on = storage.getItem('expires_on');                         
        if (cacheToken.access_token && cacheToken.expires_on > moment(new Date().getTime()).unix()) {
            return $q.when({'Authorization': 'Bearer ' + cacheToken.access_token});        
        } else {
            return $http.post('/refreshToken', {'token': cacheToken.refresh_token}).then(
                response => {
                    var token = response.data;
                    cacheToken.access_token = token.access_token;
                    storage.setItem('access_token', cacheToken.access_token);
                    cacheToken.refresh_token = token.refresh_token;
                    storage.setItem('refresh_token', cacheToken.refresh_token);
                    cacheToken.expires_on = token.expires_on;
                    storage.setItem('expires_on', cacheToken.expires_on);                                                                                                                                                
                    return {'Authorization': 'Bearer ' + cacheToken.access_token};    
                }, 
                err => {
                    console.log('Error refreshing token ' + err)
                }
            );
        }
    }                     
}