-- Add per-user recipient/sender columns so conv-keys can be wrapped to a
-- user identity instead of a specific device. Old per-device columns stay
-- nullable through the transition; a follow-up migration drops them once
-- migration telemetry shows >=95% adoption.

alter table public.conversation_keys
  add column if not exists recipient_user_id uuid references auth.users(id) on delete cascade,
  add column if not exists sender_user_id    uuid references auth.users(id) on delete restrict;

alter table public.conversation_keys
  alter column recipient_device_id drop not null,
  alter column sender_device_id    drop not null;

create unique index if not exists conversation_keys_user_recipient_uniq
  on public.conversation_keys(conversation_id, recipient_user_id, key_version)
  where recipient_user_id is not null;

create index if not exists conversation_keys_recipient_user_idx
  on public.conversation_keys(recipient_user_id);

drop policy if exists conversation_keys_select_owner on public.conversation_keys;
create policy conversation_keys_select_owner
  on public.conversation_keys
  for select
  to authenticated
  using (
    recipient_user_id = auth.uid()
    or exists (
      select 1
        from public.devices d
       where d.id = recipient_device_id
         and d.user_id = auth.uid()
    )
  );

drop policy if exists conversation_keys_insert_member on public.conversation_keys;
create policy conversation_keys_insert_member
  on public.conversation_keys
  for insert
  to authenticated
  with check (
    exists (
      select 1
        from public.conversation_members m
       where m.conversation_id = conversation_keys.conversation_id
         and m.user_id = auth.uid()
         and m.accepted = true
    )
    and (
      sender_user_id = auth.uid()
      or exists (
        select 1
          from public.devices d
         where d.id = sender_device_id
           and d.user_id = auth.uid()
      )
    )
    and (
      (recipient_user_id is not null and exists (
        select 1
          from public.conversation_members m
         where m.conversation_id = conversation_keys.conversation_id
           and m.user_id = recipient_user_id
           and m.accepted = true
      ))
      or (recipient_device_id is not null and exists (
        select 1
          from public.devices d
          join public.conversation_members m
            on m.user_id = d.user_id
           and m.conversation_id = conversation_keys.conversation_id
         where d.id = recipient_device_id
           and m.accepted = true
      ))
    )
  );