/*
 * Source: https://stackoverflow.com/questions/21087710/how-to-write-update-function-stored-procedure-in-postgresql
 */
CREATE OR REPLACE FUNCTION update_user(
    nickname   LABEL,
    full_name  TEXT   DEFAULT NULL,
    email      EMAIL  DEFAULT NULL,
    uri        URI    DEFAULT NULL,
    twitter    CITEXT DEFAULT NULL
) RETURNS BOOLEAN LANGUAGE plpgsql SECURITY DEFINER AS $$
/*
    % SELECT update_user(
        nickname  := 'theory',
        full_name := 'David E. Wheeler',
        email     := 'justatheory@pgxn.org',
        uri       := 'http://www.justatheory.com/',
        twitter   :- 'theory'
    );
     update_user 
    ─────────────
     t

Update the specified user. The user must be active. The nickname cannot be
changed. The password can only be changed via `change_password()` or
`reset_password()`. Pass other attributes as:

full_name
: The full name of the user.

email
: The email address of the user. Must be a valid email address as verified by
  [Email::Valid](http://search.cpan.org/perldoc?Email::Valid).

uri
: Optional URI for the user. Should be a valid URI as verified by
  [Data::Validate::URI](http://search.cpan.org/perldoc?Data::Validate::URI).

twitter
: Optional Twitter username. A leading "@" wil be removed.

Returns true if the user was updated, and false if not.

*/
BEGIN
    UPDATE users
       SET full_name      = COALESCE(update_user.full_name, users.full_name),
           email          = COALESCE(update_user.email,     users.email),
           uri            = COALESCE(update_user.uri,       users.uri),
           twitter        = COALESCE(trim(leading '@' FROM update_user.twitter), users.twitter),
           updated_at     = NOW()
     WHERE users.nickname = update_user.nickname
       AND users.status   = 'active';
    RETURN FOUND;
END;
$$;