create or replace function ems.fn_negative_price_predictions(p_site_id int)
returns jsonb
language sql
stable
as $fn$
  with hist as (
    select count(distinct (mip.interval_start at time zone 'Europe/Prague')::date)::int as ndays
    from ems.market_interval_price mip
    where mip.market_source in ('OTE_CZ', 'OTE_CZ_DAM')
      and mip.interval_start >= now() - interval '400 days'
  ),
  rows as (
    select
      p.predicted_date,
      p.window_start_hour,
      p.window_end_hour,
      p.probability_pct,
      p.expected_min_price,
      p.reason
    from ems.predicted_negative_price_window p
    where p.site_id = p_site_id
      and p.predicted_date > (
        current_timestamp at time zone coalesce(
          nullif(trim((select s.timezone from ems.site s where s.id = p_site_id)), ''),
          'Europe/Prague'
        )
      )::date
      and p.predicted_date <= (
        current_timestamp at time zone coalesce(
          nullif(trim((select s.timezone from ems.site s where s.id = p_site_id)), ''),
          'Europe/Prague'
        )
      )::date + 7
    order by p.predicted_date, p.window_start_hour
  )
  select jsonb_build_object(
    'predictions',
    coalesce(
      (
        select jsonb_agg(
          jsonb_build_object(
            'predicted_date', r.predicted_date,
            'window_start_hour', r.window_start_hour,
            'window_end_hour', r.window_end_hour,
            'probability_pct', r.probability_pct,
            'expected_min_price', r.expected_min_price,
            'reason', coalesce(r.reason, '')
          )
        )
        from rows r
      ),
      '[]'::jsonb
    ),
    'insufficient_history', (select ndays < 28 from hist)
  );
$fn$;

comment on function ems.fn_negative_price_predictions(int) is
  'Predikovaná okna záporných cen + flag nedostatečné historie OTE.';