-- Phase 5A: per-conversation synchronized YouTube playback.
--
-- conversation_watch_sessions: one row per Watch-Together session. The bubble
-- in the chat is a normal `messages` row whose plaintext payload is
-- `{v:1, type:'watch_together', session_id:<id>}`. The owner's player drives
-- current_state (jsonb {playing, position_seconds, updated_at_ms}); other
-- joiners reconcile via realtime postgres_changes UPDATE when local drift
-- exceeds 2 seconds.

create table if not exists public.conversation_watch_sessions (
  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,
  video_id        text not null,
  started_at      timestamptz not null default now(),
  ended_at        timestamptz null,
  current_state   jsonb not null default '{"playing":false,"position_seconds":0,"updated_at_ms":0}'::jsonb,
  constraint conversation_watch_sessions_video_id_len check (length(video_id) between 1 and 64)
);

create index if not exists conversation_watch_sessions_conv_idx
  on public.conversation_watch_sessions(conversation_id, started_at desc);

alter table public.conversation_watch_sessions enable row level security;

drop policy if exists conversation_watch_sessions_select on public.conversation_watch_sessions;
drop policy if exists conversation_watch_sessions_insert on public.conversation_watch_sessions;
drop policy if exists conversation_watch_sessions_update on public.conversation_watch_sessions;

create policy conversation_watch_sessions_select
  on public.conversation_watch_sessions
  for select
  using (public.is_conversation_member(conversation_id));

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

create policy conversation_watch_sessions_update
  on public.conversation_watch_sessions
  for update
  using (owner_user_id = auth.uid())
  with check (owner_user_id = auth.uid());

alter table public.conversation_watch_sessions replica identity full;

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