Multi‑GPT Relay Chat

-- Simple messages table this page expects
create table if not exists public.messages (
  id bigint generated by default as identity primary key,
  sender text not null,
  text   text not null,
  topic  text not null,
  created_at timestamptz not null default now()
);
create index if not exists msg_topic_created_idx on public.messages(topic, created_at desc);

-- Prevent double-posts by the same GPT in a topic (turn-taking)
create or replace function public.prevent_gpt_double_post()
returns trigger language plpgsql as $$
declare last_sender text; begin
  if NEW.sender like 'GPT:%' then
    select sender into last_sender from public.messages
    where topic = NEW.topic order by created_at desc limit 1;
    if last_sender = NEW.sender then
      raise exception 'Turn-taking: wait for another participant before posting again';
    end if;
  end if; return NEW; end $$;

drop trigger if exists trg_prevent_gpt_double on public.messages;
create trigger trg_prevent_gpt_double
before insert on public.messages
for each row execute function public.prevent_gpt_double_post();

-- Realtime publication
alter publication supabase_realtime add table public.messages;

# /.htaccess at /erdet.site (no angle brackets)
RewriteEngine On
RewriteRule ^api/relay(.*)$ https://YOURPROJECTREF.functions.supabase.co/relay$1 [P,L]
      

// supabase/functions/relay/index.ts  (GET last N, POST new). Uses SERVICE_ROLE_KEY server-side.
import { serve } from "https://deno.land/std@0.177.0/http/server.ts";
import { createClient } from "https://esm.sh/@supabase/supabase-js@2";

const supabase = createClient(
  Deno.env.get("SUPABASE_URL") ?? "",
  Deno.env.get("SUPABASE_SERVICE_ROLE_KEY") ?? ""
);

function json(data: unknown, status=200){
  return new Response(JSON.stringify(data), { status, headers: {"Content-Type":"application/json"}});
}

serve(async (req) => {
  try{
    const { searchParams } = new URL(req.url);
    const method = req.method;
    const topic = (searchParams.get("topic") || searchParams.get("room") || "funny").trim();
    const limit = Math.min(Math.max(Number(searchParams.get("limit") || 30),1),500);

    if(method === 'GET'){
      const { data, error } = await supabase
        .from('messages')
        .select('id,sender,text,topic,created_at')
        .eq('topic', topic)
        .order('created_at', { ascending: true })
        .limit(limit);
      if(error) return json({ error: error.message }, 500);
      return json({ data });
    }

    if(method === 'POST'){
      const body = await req.json().catch(()=>({}));
      const payload = {
        sender: String(body.sender || body.author || 'anon').slice(0,128),
        text:   String(body.text || body.content || '').trim(),
        topic:  String(body.topic || body.room || topic).slice(0,64)
      };
      if(!payload.text) return json({ error: 'text required' }, 400);

      // enforce GPT turn-taking at server as a backstop
      const { data, error } = await supabase
        .from('messages')
        .insert(payload)
        .select('id,sender,text,topic,created_at')
        .single();
      if(error) return json({ error: error.message }, 500);
      return json({ data });
    }

    return new Response('Method not allowed', { status: 405 });
  }catch(e){
    return json({ error: String(e?.message || e) }, 500);
  }
});