-- Phase 4B: per-conversation whiteboards.
--
-- conversation_whiteboards: one row per whiteboard. Created by a member; the
-- bubble that appears in the chat message timeline is a normal `messages`
-- row whose plaintext payload is `{v:1, type:'whiteboard', whiteboard_id:<id>}`.
--
-- whiteboard_strokes: append-only stream of drawing operations. Each row is
-- one user gesture (pen-down → pen-up); stroke_json carries the tool/color/
-- width/points. Realtime subscribers replay rows in created_at order.

create table if not exists public.conversation_whiteboards (
  id              uuid primary key default gen_random_uuid(),
  conversation_id uuid not null references public.conversations(id) on delete cascade,
  owner_user_id   uuid not null references auth.users(id) on delete cascade,
  created_at      timestamptz not null default now()
);

create index if not exists conversation_whiteboards_conv_idx
  on public.conversation_whiteboards(conversation_id, created_at desc);

create table if not exists public.whiteboard_strokes (
  id              uuid primary key default gen_random_uuid(),
  whiteboard_id   uuid not null references public.conversation_whiteboards(id) on delete cascade,
  author_user_id  uuid not null references auth.users(id) on delete cascade,
  stroke_json     jsonb not null,
  created_at      timestamptz not null default now()
);

create index if not exists whiteboard_strokes_board_idx
  on public.whiteboard_strokes(whiteboard_id, created_at asc);

alter table public.conversation_whiteboards enable row level security;
alter table public.whiteboard_strokes enable row level security;

drop policy if exists conversation_whiteboards_select on public.conversation_whiteboards;
drop policy if exists conversation_whiteboards_insert on public.conversation_whiteboards;
drop policy if exists conversation_whiteboards_delete on public.conversation_whiteboards;
drop policy if exists whiteboard_strokes_select on public.whiteboard_strokes;
drop policy if exists whiteboard_strokes_insert on public.whiteboard_strokes;
drop policy if exists whiteboard_strokes_delete on public.whiteboard_strokes;

create policy conversation_whiteboards_select
  on public.conversation_whiteboards
  for select
  using (public.is_conversation_member(conversation_id));

create policy conversation_whiteboards_insert
  on public.conversation_whiteboards
  for insert
  with check (
    public.is_conversation_member(conversation_id)
    and owner_user_id = auth.uid()
  );

create policy conversation_whiteboards_delete
  on public.conversation_whiteboards
  for delete
  using (owner_user_id = auth.uid());

create policy whiteboard_strokes_select
  on public.whiteboard_strokes
  for select
  using (
    exists (
      select 1
        from public.conversation_whiteboards w
        where w.id = whiteboard_strokes.whiteboard_id
          and public.is_conversation_member(w.conversation_id)
    )
  );

create policy whiteboard_strokes_insert
  on public.whiteboard_strokes
  for insert
  with check (
    author_user_id = auth.uid()
    and exists (
      select 1
        from public.conversation_whiteboards w
        where w.id = whiteboard_id
          and public.is_conversation_member(w.conversation_id)
    )
  );

create policy whiteboard_strokes_delete
  on public.whiteboard_strokes
  for delete
  using (
    exists (
      select 1
        from public.conversation_whiteboards w
        where w.id = whiteboard_strokes.whiteboard_id
          and public.is_conversation_member(w.conversation_id)
    )
  );

alter table public.conversation_whiteboards replica identity full;
alter table public.whiteboard_strokes replica identity full;

do $$
begin
  if not exists (
    select 1
      from pg_publication_tables
      where pubname = 'supabase_realtime'
        and schemaname = 'public'
        and tablename = 'conversation_whiteboards'
  ) then
    execute 'alter publication supabase_realtime add table public.conversation_whiteboards';
  end if;

  if not exists (
    select 1
      from pg_publication_tables
      where pubname = 'supabase_realtime'
        and schemaname = 'public'
        and tablename = 'whiteboard_strokes'
  ) then
    execute 'alter publication supabase_realtime add table public.whiteboard_strokes';
  end if;
end
$$;