create or replace function fsm.trig_check_no_transition_for_final() returns trigger as
$$
  declare
      bad_transitions jsonb;
  begin
    select jsonb_agg(c.*) into bad_transitions
    from changed c
    join fsm.state s
      on  s.statechart_id = c.statechart_id
      and s.id = c.source_state
      and s.is_final;

    if jsonb_array_length(bad_transitions)
    then
      raise exception 'cannot add transitions from final states: %', jsonb_pretty(bad_transitions);
    end if;

    return null;
  end;
$$ language plpgsql;

comment on function fsm.trig_check_no_transition_for_final is $comment$
    Checks that there are no transitions added from final states.
$comment$;

-- create a similar function for states
create or replace function fsm.trig_check_no_final_state_with_transition() returns trigger as
$$
  declare
      bad_states jsonb;
  begin
    select jsonb_agg(c.*) into bad_states
    from changed c
    join fsm.transition t
      on  t.statechart_id = c.statechart_id
      and t.source_state = c.id
    where c.is_final;

    if jsonb_array_length(bad_states)
    then
      raise exception 'cannot add states with transitions from final states: %', jsonb_pretty(bad_states);
    end if;

    return null;
  end;
$$ language plpgsql;

comment on function fsm.trig_check_no_final_state_with_transition is $comment$
    Checks that there are no states added which have transitions from final states.
$comment$;

set client_min_messages TO warning;
drop trigger if exists check_no_transition_for_final_insert on fsm.transition;
drop trigger if exists check_no_transition_for_final_update on fsm.transition;
drop trigger if exists check_no_transition_for_final_update on fsm.state;
reset client_min_messages;

create trigger check_no_transition_for_final_insert
after insert
on fsm.transition
referencing new table as changed
for each statement
execute function fsm.trig_check_no_transition_for_final();

comment on trigger check_no_transition_for_final_insert on fsm.transition is $comment$
    Checks that there are no transitions inserted from final states.
$comment$;

create trigger check_no_transition_for_final_update
after update
on fsm.transition
referencing new table as changed
for each statement
execute function fsm.trig_check_no_transition_for_final();

comment on trigger check_no_transition_for_final_update on fsm.transition is $comment$
    Checks that there are no transitions added from final states.
$comment$;

create trigger check_no_transition_for_final_update
after update
on fsm.state
referencing new table as changed
for each statement
execute function fsm.trig_check_no_final_state_with_transition();

comment on trigger check_no_transition_for_final_update on fsm.transition is $comment$
    Checks that there are no states inserted with transitions from final states.
$comment$;