-- Backup original sell_cost values (just in case)
-- Run this once: will add a column original_sell_cost and copy existing sell_cost into it
ALTER TABLE IF EXISTS falukant_type.product
  ADD COLUMN IF NOT EXISTS original_sell_cost numeric;

UPDATE falukant_type.product
SET sell_cost = sell_cost * ((6 * 7 / 100) + 100);

-- Compute min and max cumulative tax across all regions
WITH RECURSIVE ancestors AS (
  SELECT id AS start_id, id, parent_id, tax_percent FROM falukant_data.region
  UNION ALL
  SELECT a.start_id, r.id, r.parent_id, r.tax_percent
  FROM falukant_data.region r
  JOIN ancestors a ON r.id = a.parent_id
), totals AS (
  SELECT start_id, COALESCE(SUM(tax_percent),0) AS total FROM ancestors GROUP BY start_id
), mm AS (
  SELECT COALESCE(MIN(total),0) AS min_total, COALESCE(MAX(total),0) AS max_total FROM totals
)
SELECT * FROM mm;

-- Choose one of the following update blocks to run:

-- 1) MIN-STRATEGY: increase sell_cost so that taxes at the minimal cumulative tax have no effect
-- (this will set sell_cost = CEIL(original_sell_cost * (1 / (1 - min_total/100))))

-- BEGIN MIN-STRATEGY
-- WITH mm AS (
--   WITH RECURSIVE ancestors AS (
--     SELECT id AS start_id, id, parent_id, tax_percent FROM falukant_data.region
--     UNION ALL
--     SELECT a.start_id, r.id, r.parent_id, r.tax_percent
--     FROM falukant_data.region r
--     JOIN ancestors a ON r.id = a.parent_id
--   ), totals AS (
--     SELECT start_id, COALESCE(SUM(tax_percent),0) AS total FROM ancestors GROUP BY start_id
--   )
--   SELECT COALESCE(MIN(total),0) AS min_total FROM totals
-- )
-- UPDATE falukant_type.product
-- SET sell_cost = CEIL(original_sell_cost * (CASE WHEN (1 - (SELECT min_total FROM mm)/100) <= 0 THEN 1 ELSE (1 / (1 - (SELECT min_total FROM mm)/100)) END));
-- END MIN-STRATEGY

-- 2) MAX-STRATEGY: increase sell_cost so that taxes at the maximal cumulative tax have no effect
-- (this will set sell_cost = CEIL(original_sell_cost * (1 / (1 - max_total/100))))

-- BEGIN MAX-STRATEGY
-- WITH mm AS (
--   WITH RECURSIVE ancestors AS (
--     SELECT id AS start_id, id, parent_id, tax_percent FROM falukant_data.region
--     UNION ALL
--     SELECT a.start_id, r.id, r.parent_id, r.tax_percent
--     FROM falukant_data.region r
--     JOIN ancestors a ON r.id = a.parent_id
--   ), totals AS (
--     SELECT start_id, COALESCE(SUM(tax_percent),0) AS total FROM ancestors GROUP BY start_id
--   )
--   SELECT COALESCE(MAX(total),0) AS max_total FROM totals
-- )
-- UPDATE falukant_type.product
-- SET sell_cost = CEIL(original_sell_cost * (CASE WHEN (1 - (SELECT max_total FROM mm)/100) <= 0 THEN 1 ELSE (1 / (1 - (SELECT max_total FROM mm)/100)) END));
-- END MAX-STRATEGY

-- Notes:
-- 1) Uncomment exactly one strategy block (MIN or MAX) and run the script.
-- 2) The script creates `original_sell_cost` as a backup; keep it for safety.
-- 3) CEIL is used to avoid undercompensating due to rounding. If you prefer ROUND use ROUND(...).
-- 4) Test on a staging DB first.