-- Map owners can invite other accounts to manage their maps together. Invites
-- stay pending until the invitee accepts from their dashboard; accepted admins
-- act through the owner, so map RPC checks keep working unchanged.
create table public.map_admins (
  id uuid primary key default gen_random_uuid(),
  dataset_id uuid not null references public.datasets(id) on delete cascade,
  user_id uuid not null references auth.users(id) on delete cascade,
  invited_by uuid not null references auth.users(id) on delete cascade,
  state text not null default 'pending' check(state in ('pending','accepted')),
  created_at timestamptz not null default now(),
  responded_at timestamptz,
  constraint map_admins_unique unique(dataset_id,user_id),
  constraint map_admins_no_self check(user_id<>invited_by),
  constraint map_admins_response check(
    (state='pending' and responded_at is null) or
    (state='accepted' and responded_at is not null)
  )
);
create index map_admins_user_state on public.map_admins(user_id,state);
create index map_admins_dataset on public.map_admins(dataset_id);

-- Service role only: invites and membership are managed through the API.
alter table public.map_admins enable row level security;