const users = [
    {
        username: 'admin',
        password: 'admin1',
        roles: ['admin', 'user']
    },
    {
        username: 'user',
        password: 'user1',
        roles: ['user']
    }
];

app.post('/users/logon', (req, res) => {
    const username = req.body.username;
    const password = req.body.password;

    const user = users.find(user =>
        user.username === username &&
        user.password === password
    );

    if (!user) {
        res.status(401).send('Invalid credentials');
    } else {
        res.send({
            username: user.username,
            roles: user.roles,
            sessionId: uuid.v1()
        });
    }
});