feat: add per-ton cargo loading limits and update related services

apps/edr-freight-api/src/modules/rule-engine/services/cargo-types.service.ts

@@ -6,6 +6,7 @@ import {
   Injectable,
   NotFoundException,
 } from '@nestjs/common';
+import { In } from 'typeorm';
 import { generateCode } from '../../../common/utils/generate-code.util';
 import { CreateCargoTypeDto } from '../dto/create-cargo-type.dto';
 import { ListCargoTypesQueryDto } from '../dto/list-rule-engine-query.dto';
@@ -13,6 +14,7 @@ import { ReorderItemsDto } from '../dto/reorder-items.dto';
 import { UpdateCargoTypeDto } from '../dto/update-cargo-type.dto';
 import { CargoType } from '../entities/cargo-type.entity';
 import { WagonType } from '../../wagon-types/entities/wagon-type.entity';
+import { WagonTypesRepository } from '../../wagon-types/wagon-types.repository';
 import {
   CARGO_TYPES_REPOSITORY,
   ICargoTypesRepository,
@@ -27,6 +29,7 @@ export class CargoTypesService {
     private readonly repository: ICargoTypesRepository,
     @Inject(RATES_REPOSITORY)
     private readonly ratesRepository: IRatesRepository,
+    private readonly wagonTypesRepository: WagonTypesRepository,
     private readonly displayOrder: DisplayOrderService,
   ) {}
 
@@ -75,6 +78,63 @@ export class CargoTypesService {
     return map;
   }
 
+  /**
+   * PER_TON (bulk) cargo may cap how many tons ride one wagon, BELOW that
+   * wagon's rated capacity: sugar at 50T on a 70T wagon means 200T takes 4
+   * wagons, not 3. Unlike the PER_ITEM fit this is optional — an absent key
+   * means the full rated capacity, so existing cargo types are unaffected.
+   *
+   * A cap ABOVE the rated capacity is rejected: nobody loads 90T on a 70T
+   * wagon, so it is a typo, and silently clamping it would leave the config
+   * screen showing a number the trains never honour. (Allocation clamps too, via
+   * `bulkTonsPerWagon`, for caps left stale by a later wagon-type edit — this
+   * check cannot see those, since the cargo type is never re-saved.)
+   *
+   * Returns the map trimmed to the allowed wagon types, or null when the cargo
+   * is not PER_TON / nothing is capped.
+   */
+  private async resolveTonsPerWagonMap(input: {
+    unitOfMeasure?: CargoUnitOfMeasure | null;
+    wagonTypeIds: string[];
+    tonsPerWagonMap?: Record<string, number> | null;
+  }): Promise<Record<string, number> | null> {
+    if (input.unitOfMeasure !== CargoUnitOfMeasure.PerTon || !input.wagonTypeIds.length) {
+      return null;
+    }
+    const capped = input.wagonTypeIds.filter(
+      (id) => input.tonsPerWagonMap?.[id] !== undefined && input.tonsPerWagonMap[id] !== null,
+    );
+    if (!capped.length) return null;
+
+    const wagonTypes = await this.wagonTypesRepository.findAll({
+      where: { id: In(capped) },
+    });
+    const capacityById = new Map(
+      wagonTypes.map((wt) => [wt.id, Number(wt.capacityTons) || 0]),
+    );
+
+    const map: Record<string, number> = {};
+    for (const wagonTypeId of capped) {
+      const tons = Number(input.tonsPerWagonMap?.[wagonTypeId]);
+      if (!Number.isFinite(tons) || tons <= 0) {
+        throw new BadRequestException(
+          `tonsPerWagonMap for wagon type ${wagonTypeId} must be a number greater than 0`,
+        );
+      }
+      const capacity = capacityById.get(wagonTypeId);
+      if (capacity === undefined) {
+        throw new BadRequestException(`Wagon type ${wagonTypeId} not found`);
+      }
+      if (capacity > 0 && tons > capacity) {
+        throw new BadRequestException(
+          `Max tons per wagon (${tons}T) exceeds wagon type ${wagonTypeId} rated capacity ${capacity}T`,
+        );
+      }
+      map[wagonTypeId] = tons;
+    }
+    return map;
+  }
+
   /** Create a new cargo type. */
   async create(dto: CreateCargoTypeDto): Promise<CargoType> {
     const code = generateCode(dto.cargoTypeName);
@@ -90,6 +150,12 @@ export class CargoTypesService {
       insertAfterId: dto.insertAfterId,
     });
 
+    const tonsPerWagonMap = await this.resolveTonsPerWagonMap({
+      unitOfMeasure: dto.unitOfMeasure ?? null,
+      wagonTypeIds: dto.wagonTypeIds ?? [],
+      tonsPerWagonMap: dto.tonsPerWagonMap,
+    });
+
     return this.repository.create({
       code,
       cargoTypeName: dto.cargoTypeName,
@@ -104,6 +170,7 @@ export class CargoTypesService {
         wagonTypeIds: dto.wagonTypeIds ?? [],
         itemsPerWagonMap: dto.itemsPerWagonMap,
       }),
+      tonsPerWagonMap,
       displayOrder,
     });
   }
@@ -116,12 +183,32 @@ export class CargoTypesService {
       const parent = await this.repository.findById(dto.parentGroupId);
       if (!parent) throw new NotFoundException(`Parent cargo type ${dto.parentGroupId} not found`);
     }
-    const { wagonTypeIds, itemsPerWagonMap, insertAfterId: _insertAfterId, ...columns } = dto;
+    const {
+      wagonTypeIds,
+      itemsPerWagonMap,
+      tonsPerWagonMap,
+      insertAfterId: _insertAfterId,
+      ...columns
+    } = dto;
     // Re-validate the fit map whenever anything it depends on moves — a partial
     // update merges with the stored values so e.g. adding a wagon type without
     // its fit still 400s. Untouched fields leave the stored map alone.
     const touchesItemsFit =
       wagonTypeIds !== undefined || itemsPerWagonMap !== undefined || dto.unitOfMeasure !== undefined;
+    // Same merge rule for the tonnage cap: re-resolve whenever the uom, the
+    // allowed wagon types, or the caps themselves move, so a wagon type added
+    // without a cap keeps its full rated capacity and a uom flip drops stale caps.
+    const touchesTonsCap =
+      wagonTypeIds !== undefined || tonsPerWagonMap !== undefined || dto.unitOfMeasure !== undefined;
+    const resolvedTonsPerWagonMap = touchesTonsCap
+      ? await this.resolveTonsPerWagonMap({
+          unitOfMeasure:
+            dto.unitOfMeasure !== undefined ? dto.unitOfMeasure : existing.unitOfMeasure,
+          wagonTypeIds: wagonTypeIds ?? (existing.wagonTypes ?? []).map((wt) => wt.id),
+          tonsPerWagonMap:
+            tonsPerWagonMap !== undefined ? tonsPerWagonMap : existing.tonsPerWagonMap,
+        })
+      : undefined;
     const updated = await this.repository.update(id, {
       ...columns,
       ...(wagonTypeIds
@@ -138,6 +225,7 @@ export class CargoTypesService {
             }),
           }
         : {}),
+      ...(touchesTonsCap ? { tonsPerWagonMap: resolvedTonsPerWagonMap } : {}),
     });
     if (!updated) throw new NotFoundException(`Cargo type ${id} not found`);
     // A uom flip renames how existing rates bill (PER_TON ↔ PER_ITEM name the