-- @param {String} $1:regionCode
-- Monthly average electricity price and cumulative datacenter capacity for a region
WITH months AS (
  SELECT generate_series(
    '2019-01-01'::timestamptz,
    date_trunc('month', now()),
    '1 month'
  ) AS month
),
monthly_prices AS (
  SELECT
    date_trunc('month', ep.timestamp) AS month,
    AVG(ep.price_mwh) AS avg_price
  FROM electricity_prices ep
  JOIN grid_regions r ON ep.region_id = r.id
  WHERE r.code = $1
  GROUP BY 1
),
dc_capacity AS (
  SELECT
    make_timestamptz(d.year_opened, 1, 1, 0, 0, 0) AS opened_month,
    SUM(d.capacity_mw) AS added_mw
  FROM datacenters d
  JOIN grid_regions r ON d.region_id = r.id
  WHERE r.code = $1
  GROUP BY d.year_opened
)
SELECT
  m.month,
  mp.avg_price,
  COALESCE(
    SUM(dc.added_mw) OVER (ORDER BY m.month ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW),
    0
  )::float AS cumulative_capacity_mw
FROM months m
LEFT JOIN monthly_prices mp ON mp.month = m.month
LEFT JOIN dc_capacity dc ON dc.opened_month <= m.month
  AND dc.opened_month > m.month - INTERVAL '1 month'
ORDER BY m.month ASC