alter table public.profiles add column username text;
alter table public.profiles add constraint profiles_username_format check (username is null or username ~ '^[a-z0-9_]{3,32}$');
create unique index profiles_username_unique on public.profiles (username) where username is not null;

create table public.moderator_applications (
  id uuid primary key default gen_random_uuid(),
  platform text not null check (platform in ('telegram', 'discord')),
  platform_user_id text not null,
  platform_username text,
  requested_username text not null,
  profile_id uuid references public.profiles(id) on delete set null,
  confirmation_hash text not null unique,
  status text not null default 'confirming' check (status in ('confirming', 'pending', 'approved', 'declined')),
  expires_at timestamptz not null default (now() + interval '30 minutes'),
  created_at timestamptz not null default now(),
  reviewed_at timestamptz,
  reviewer_discord_id text,
  admin_notified_at timestamptz,
  applicant_notified_at timestamptz
);
create index moderator_applications_queue on public.moderator_applications (created_at) where status = 'pending';
create unique index moderator_applications_one_open on public.moderator_applications (platform, platform_user_id) where status = 'pending';
alter table public.moderator_applications enable row level security;
revoke all on public.moderator_applications from public, anon, authenticated;
grant all on public.moderator_applications to service_role;

create table public.moderator_bot_admin (id boolean primary key default true check (id), discord_user_id text not null);
alter table public.moderator_bot_admin enable row level security;
revoke all on public.moderator_bot_admin from public, anon, authenticated;
grant all on public.moderator_bot_admin to service_role;

create function public.review_moderator_application(p_application uuid, p_decision text, p_reviewer text)
returns text language plpgsql security invoker set search_path = '' as $$
declare application public.moderator_applications; current_role text; current_status text;
begin
  if not exists (select 1 from public.moderator_bot_admin where discord_user_id = p_reviewer) then raise exception 'Admin permission required'; end if;
  if p_decision not in ('approved', 'declined') then raise exception 'Invalid decision'; end if;
  select * into application from public.moderator_applications where id = p_application for update;
  if not found or application.status <> 'pending' then raise exception 'Application is no longer pending'; end if;
  if p_decision = 'approved' then
    select role, account_status into current_role, current_status from public.profiles where id = application.profile_id for update;
    if not found or current_status <> 'active' or current_role <> 'contributor' then raise exception 'Account cannot be promoted'; end if;
    update public.profiles set role = 'moderator' where id = application.profile_id;
  end if;
  update public.moderator_applications set status = p_decision, reviewed_at = now(), reviewer_discord_id = p_reviewer where id = p_application;
  return p_decision;
end; $$;
revoke all on function public.review_moderator_application(uuid,text,text) from public, anon, authenticated;
grant execute on function public.review_moderator_application(uuid,text,text) to service_role;