Implement tax handling for branches by adding tax percent to regions, updating product sell costs, and enhancing UI for tax summaries in BranchView

backend/migrations/20260101000000-add-tax-percent-to-region.cjs

@@ -0,0 +1,17 @@
+"use strict";
+
+module.exports = {
+  async up(queryInterface, Sequelize) {
+    await queryInterface.sequelize.query(`
+      ALTER TABLE IF EXISTS falukant_data.region
+      ADD COLUMN IF NOT EXISTS tax_percent numeric NOT NULL DEFAULT 7;
+    `);
+  },
+
+  async down(queryInterface, Sequelize) {
+    await queryInterface.sequelize.query(`
+      ALTER TABLE IF EXISTS falukant_data.region
+      DROP COLUMN IF EXISTS tax_percent;
+    `);
+  }
+};

backend/migrations/20260101000002-add-neutral-sell-costs-to-product.cjs

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+"use strict";
+
+module.exports = {
+  async up(queryInterface, Sequelize) {
+    // 1) add backup column for original sell_cost (idempotent)
+    await queryInterface.sequelize.query(`
+      ALTER TABLE IF EXISTS falukant_type.product
+      ADD COLUMN IF NOT EXISTS original_sell_cost numeric;
+    `);
+
+    // 2) if original_sell_cost is not set, copy current sell_cost into it
+    await queryInterface.sequelize.query(`
+      UPDATE falukant_type.product
+      SET original_sell_cost = sell_cost
+      WHERE original_sell_cost IS NULL;
+    `);
+
+    // 3) compute max cumulative tax across regions and increase sell_cost accordingly
+    //    We use the maximum cumulative tax (worst-case) so sellers are neutral across regions.
+    //    Formula: neutral_sell = CEIL(original_sell_cost * (1 / (1 - max_total/100)))
+    await queryInterface.sequelize.query(`
+      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(MAX(total),0) AS max_total FROM totals
+      )
+      UPDATE falukant_type.product
+      SET sell_cost = CEIL(original_sell_cost * (CASE WHEN (1 - mm.max_total/100) <= 0 THEN 1 ELSE (1 / (1 - mm.max_total/100)) END))
+      FROM mm
+      WHERE original_sell_cost IS NOT NULL;
+    `);
+  },
+
+  async down(queryInterface, Sequelize) {
+    await queryInterface.sequelize.query(`
+      ALTER TABLE IF EXISTS falukant_type.product
+      DROP COLUMN IF EXISTS sell_cost_min_neutral;
+    `);
+    await queryInterface.sequelize.query(`
+      ALTER TABLE IF EXISTS falukant_type.product
+      DROP COLUMN IF EXISTS sell_cost_max_neutral;
+    `);
+  }
+};