fix wagon cncellation

apps/edr-freight-api/src/migrations/3300000000000-BookingWagonCancellations.ts

@@ -0,0 +1,65 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+/**
+ * Partial wagon cancellation with rebooking credit.
+ *
+ * One row per cancellation cycle on a PAID booking: the customer asks to drop
+ * N wagons, pays a per-wagon cancellation fee (rates row
+ * rate_type = 'CANCELLATION_FEE', rate_unit = 'PER_WAGON'), and the dropped cargo becomes a
+ * rebookable credit. The credit is redeemed by creating a fresh booking
+ * through the normal under-contract create path (which re-checks contract
+ * validity and caps), immediately marked PAID — the freight was already paid
+ * on the original booking, only the fee is new money.
+ *
+ * cancelled_quantities carries what was cut, in the booking's own terms:
+ * `{ bulkTons }` for bulk, `{ bySize: { "20": 4, "40": 3 } }` for container.
+ * Container numbers are NOT stored here — they are recovered at rebook time
+ * from the unit rows the reduction soft-deleted (same hybrid pattern as
+ * RemainderPlacementService).
+ */
+export class BookingWagonCancellations3300000000000 implements MigrationInterface {
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`
+      CREATE TABLE IF NOT EXISTS freight.booking_wagon_cancellations (
+        id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+        booking_id uuid NOT NULL REFERENCES freight.bookings(id),
+        rebooked_booking_id uuid REFERENCES freight.bookings(id),
+        wagons_cancelled numeric(6,2) NOT NULL CHECK (wagons_cancelled > 0),
+        weight_tons numeric(12,3) NOT NULL DEFAULT 0,
+        cancelled_quantities jsonb NOT NULL,
+        credit_amount numeric(14,2) NOT NULL DEFAULT 0,
+        fee_rate_id uuid REFERENCES freight.rates(id),
+        fee_amount numeric(14,2) NOT NULL CHECK (fee_amount >= 0),
+        fee_currency varchar(8) NOT NULL DEFAULT 'ETB',
+        fee_invoice_id uuid REFERENCES freight.invoices(id),
+        fee_paid_at timestamptz,
+        status varchar(30) NOT NULL DEFAULT 'FEE_PENDING',
+        reason text,
+        requested_by_user_id uuid,
+        rebooked_at timestamptz,
+        created_at timestamptz NOT NULL DEFAULT now(),
+        updated_at timestamptz NOT NULL DEFAULT now(),
+        deleted_at timestamptz
+      )
+    `);
+    // One open (fee-unpaid) cancellation per booking — closes the double-click
+    // race without app-level locking.
+    await queryRunner.query(`
+      CREATE UNIQUE INDEX IF NOT EXISTS uq_open_wagon_cancellation_per_booking
+        ON freight.booking_wagon_cancellations (booking_id)
+        WHERE status = 'FEE_PENDING' AND deleted_at IS NULL
+    `);
+    await queryRunner.query(`
+      CREATE INDEX IF NOT EXISTS idx_bwc_booking
+        ON freight.booking_wagon_cancellations (booking_id)
+    `);
+    await queryRunner.query(`
+      CREATE INDEX IF NOT EXISTS idx_bwc_status
+        ON freight.booking_wagon_cancellations (status)
+    `);
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`DROP TABLE IF EXISTS freight.booking_wagon_cancellations`);
+  }
+}