-- For generate_short_uuid
CREATE
OR REPLACE FUNCTION public.generate_short_uuid () RETURNS TEXT AS $$
DECLARE
    chars TEXT := 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
    result TEXT := '';
    i INTEGER := 0;
    max_attempts INTEGER := 10;
    current_attempt INTEGER := 0;
    is_unique BOOLEAN := false;
BEGIN
    WHILE NOT is_unique AND current_attempt < max_attempts LOOP
        result := '';
        FOR i IN 1..8 LOOP
            result := result || substr(chars, floor(random() * length(chars) + 1)::integer, 1);
        END LOOP;

        SELECT COUNT(*) = 0 INTO is_unique 
        FROM public.users 
        WHERE suuid = result;

        current_attempt := current_attempt + 1;
    END LOOP;

    IF NOT is_unique THEN
        RAISE EXCEPTION 'Could not generate unique short UUID after % attempts', max_attempts;
    END IF;

    RETURN result;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION public.search_users(search_term TEXT) 
RETURNS TABLE (
    uuid UUID,
    suuid TEXT,
    username TEXT,
    indexable BOOLEAN
) AS $$
BEGIN
    RETURN QUERY
    SELECT 
        u.uuid,
        u.suuid::TEXT,
        -- Simplified CASE logic: show username if SUUID match OR (username match AND indexable)
        CASE 
            WHEN u.suuid = search_term OR u.indexable THEN u.username
            ELSE NULL 
        END,
        u.indexable
    FROM public.users u
    WHERE 
        u.suuid = search_term  -- Case 1: SUUID match (always show)
        OR (
            u.indexable = true AND  -- Case 2: Username match + indexable
            u.username ILIKE '%' || search_term || '%'
        );
END;
$$ LANGUAGE plpgsql;

-- For is_thread_participant
CREATE
OR REPLACE FUNCTION public.is_thread_participant (thread_uuid UUID) RETURNS BOOLEAN AS $$
BEGIN
  RETURN EXISTS (
    SELECT 1 
    FROM public.thread_participants 
    WHERE thread_id = thread_uuid 
    AND user_uuid = auth.uid()
  );
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

-- For get_user_threads
CREATE
OR REPLACE FUNCTION public.get_user_threads (user_id UUID) RETURNS TABLE (
  thread_id UUID,
  participants TEXT[],
  messages JSON[]
) AS $$
BEGIN
    IF NOT EXISTS (
        SELECT 1 
        FROM public.thread_participants 
        WHERE user_uuid = user_id
    ) THEN
        -- Return empty result if user has no threads
        RETURN;
    END IF;

    RETURN QUERY
    SELECT 
        mt.id,
        array_agg(DISTINCT u.username),
        COALESCE(array_agg(
            CASE WHEN m.id IS NOT NULL THEN
                json_build_object(
                    'id', m.id,
                    'content', m.content,
                    'created_at', m.created_at
                )
            ELSE NULL END
        ) FILTER (WHERE m.id IS NOT NULL), ARRAY[]::JSON[])
    FROM public.message_threads mt
    JOIN public.thread_participants tp ON mt.id = tp.thread_id
    JOIN public.users u ON tp.user_uuid = u.uuid
    LEFT JOIN public.messages m ON mt.id = m.thread_id
    WHERE mt.id IN (
        SELECT thread_id 
        FROM public.thread_participants 
        WHERE user_uuid = user_id
    )
    GROUP BY mt.id;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;