sipher/supabase/sql_snippets/Create Private Thread Function.sql

CREATE OR REPLACE FUNCTION public.create_private_thread(
    participant_suuid TEXT
) RETURNS UUID AS $$
DECLARE
    current_user_uuid UUID;
    current_user_suuid TEXT;
    target_user_uuid UUID;
    new_thread_id UUID;
    existing_thread_id UUID;
BEGIN
    -- Get current user's UUID and SUUID
    SELECT uuid, suuid INTO STRICT current_user_uuid, current_user_suuid
    FROM public.users
    WHERE uuid = auth.uid();

    -- Get target user's UUID
    SELECT uuid INTO STRICT target_user_uuid
    FROM public.users
    WHERE suuid = participant_suuid;

    -- Check if thread already exists between these users
    SELECT tp1.thread_id INTO existing_thread_id
    FROM thread_participants tp1
    JOIN thread_participants tp2 ON tp1.thread_id = tp2.thread_id
    WHERE tp1.user_uuid = current_user_uuid
    AND tp2.user_uuid = target_user_uuid
    AND (
        SELECT COUNT(*)
        FROM thread_participants tp3
        WHERE tp3.thread_id = tp1.thread_id
    ) = 2;

    -- If thread exists, return it
    IF existing_thread_id IS NOT NULL THEN
        RETURN existing_thread_id;
    END IF;

    -- Create new thread
    INSERT INTO message_threads DEFAULT VALUES
    RETURNING id INTO new_thread_id;

    -- Add participants
    INSERT INTO thread_participants (thread_id, user_uuid)
    VALUES
        (new_thread_id, current_user_uuid),
        (new_thread_id, target_user_uuid);

    -- Update users with both requests array and a timestamp update to force change detection
    UPDATE users
    SET
        requests = array_remove(COALESCE(requests, ARRAY[]::text[]), participant_suuid),
        created_at = created_at  -- This forces a row update
    WHERE uuid = current_user_uuid;

    UPDATE users
    SET
        requests = array_remove(COALESCE(requests, ARRAY[]::text[]), current_user_suuid),
        created_at = created_at  -- This forces a row update
    WHERE uuid = target_user_uuid;

    RETURN new_thread_id;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;