-- Before/after price comparison for each datacenter opening event (year_opened >= 2019)
WITH dc_events AS (
  SELECT
    d.name AS dc_name,
    d.capacity_mw,
    d.year_opened,
    r.code AS region_code,
    r.name AS region_name,
    make_timestamptz(d.year_opened, 1, 1, 0, 0, 0) AS event_date
  FROM datacenters d
  JOIN grid_regions r ON d.region_id = r.id
  WHERE d.year_opened >= 2019
),
price_before AS (
  SELECT
    de.dc_name,
    AVG(ep.price_mwh) AS avg_price_before
  FROM dc_events de
  JOIN grid_regions r ON r.code = de.region_code
  JOIN electricity_prices ep ON ep.region_id = r.id
    AND ep.timestamp >= de.event_date - INTERVAL '6 months'
    AND ep.timestamp < de.event_date
  GROUP BY de.dc_name
),
price_after AS (
  SELECT
    de.dc_name,
    AVG(ep.price_mwh) AS avg_price_after
  FROM dc_events de
  JOIN grid_regions r ON r.code = de.region_code
  JOIN electricity_prices ep ON ep.region_id = r.id
    AND ep.timestamp >= de.event_date
    AND ep.timestamp < de.event_date + INTERVAL '6 months'
  GROUP BY de.dc_name
)
SELECT
  de.dc_name,
  de.capacity_mw,
  de.year_opened,
  de.region_code,
  de.region_name,
  pb.avg_price_before,
  pa.avg_price_after,
  CASE
    WHEN pb.avg_price_before > 0
    THEN ((pa.avg_price_after - pb.avg_price_before) / pb.avg_price_before * 100)
    ELSE NULL
  END AS pct_change
FROM dc_events de
LEFT JOIN price_before pb ON pb.dc_name = de.dc_name
LEFT JOIN price_after pa ON pa.dc_name = de.dc_name
WHERE pb.avg_price_before IS NOT NULL
  AND pa.avg_price_after IS NOT NULL
ORDER BY ABS(COALESCE(pa.avg_price_after - pb.avg_price_before, 0)) DESC