function changePassword(email, oldPassword, newPassword) {
    var user = getUser(email);
    var oldPasswordDecrypted = decrypt(oldPassword)
    var newPasswordDecrypted = decrypt(newPassword)
    var existingPasswordDecrypted = decrypt(user.password)

    if (user === null || existingPasswordDecrypted !== oldPasswordDecrypted) {
        throw new EmailPasswordMissMatchException();
    }
    if (oldPasswordDecrypted === newPasswordDecrypted) {
        throw new PasswordAlreadyInUseException();
    }
    if (user.isAdmin) {
        changeAdminPassword(user, newPassword);
    } else {
        changeUserPassword(user, oldPassword, newPassword);
    }

}

function changeUserPassword(user, newPassword) {
    if (!user.isEnabled) {
        throw new UnsupporedOperationException();
    }
    try {
        user.password = newPassword;
        save(user);
        // clear the session when the user changes the password
        // so that he/she has to log in again
        clearSession(user);
    } catch (e) {
        throw new SomethingWentWrongException();
    }
}

function changeAdminPassword(user, oldPassword, newPassword) {
    var isError = false;
    try {
        user.password = newPassword;
        save(user);
        // clear the session when the user changes the password
        // so that he/she has to log in again
        clearSession(user);
    } catch (e) {
        isError = true;
        throw new SomethingWentWrongException();
    } finally {
        if (!isError) {
            sendPasswordChangeConfirmationEmails(user);
        }
    }
}

function sendPasswordChangeConfirmationEmails(user) {
    var emails = user.getEmails();
    var token = generatePasswordRevertToken(user.email, user.password);
    for (i = 0; i < emails.length; i++) {
        // Confirm with admin that he as in fact changed the password,
        // if he has not, give him option to reset the password using token
        sendConfirmationEmail(email[i], token);
    }
}