changes

apps/edr-freight-api/src/modules/train-scheduling/utils/wagon-plan.util.ts

@@ -502,20 +502,48 @@ export function sumWagonsRequired(booking: Booking, wagonPlan?: WagonPlanSlot[])
 }
 
 /**
- * One wagon carries one kind of cargo: a slot with a BULK allocation holds
- * nothing else — no container beside it and no second bulk booking. Container
- * allocations may still share a wagon with each other (TEU rules apply).
+ * One wagon carries one kind of cargo AT A TIME: while a bulk load rides, the
+ * wagon holds nothing else — no container beside it and no second bulk
+ * booking. Container allocations may share a wagon with each other (TEU rules
+ * apply).
+ *
+ * "At a time" is the whole rule: a wagon whose cargo alights at Dire Dawa is
+ * empty steel for whatever boards there, so an import container on
+ * Doraleh→Dire and bulk on Dire→Kality legitimately share one wagon. Pass
+ * `legs` (booking id → stop-index span) to check per corridor edge; without
+ * it every allocation is treated as riding the whole route, which is the
+ * correct reading for a single-leg train.
  */
-export function validateWagonCargoExclusivity(wagonPlan: WagonPlanSlot[]): string[] {
+export function validateWagonCargoExclusivity(
+  wagonPlan: WagonPlanSlot[],
+  legs?: Map<string, { from: number; to: number }>,
+  edgeCount = 1,
+): string[] {
   const violations: string[] = [];
+  const edges = Math.max(1, edgeCount);
+  const spanOf = (bookingId: string) => {
+    const leg = legs?.get(bookingId);
+    if (!leg || leg.from < 0 || leg.to > edges || leg.from >= leg.to) {
+      return { from: 0, to: edges };
+    }
+    return leg;
+  };
+
   for (const slot of wagonPlan) {
-    const hasBulk = slot.allocations.some(
-      (a) => a.loadType === AllocationLoadType.Bulk,
-    );
-    if (hasBulk && slot.allocations.length > 1) {
-      violations.push(
-        `Wagon #${slot.sequenceNo} mixes bulk with other cargo — a wagon carrying bulk takes that one load only`,
-      );
+    if (slot.allocations.length < 2) continue;
+    // Per edge: who is on this wagon while it rides that edge?
+    for (let edge = 0; edge < edges; edge += 1) {
+      const riding = slot.allocations.filter((a) => {
+        const span = spanOf(a.bookingId);
+        return span.from <= edge && edge < span.to;
+      });
+      if (riding.length < 2) continue;
+      if (riding.some((a) => a.loadType === AllocationLoadType.Bulk)) {
+        violations.push(
+          `Wagon #${slot.sequenceNo} mixes bulk with other cargo — a wagon carrying bulk takes that one load only`,
+        );
+        break;
+      }
     }
   }
   return violations;
@@ -547,6 +575,9 @@ export function validateTrainLimits(
   wagonPlan: WagonPlanSlot[],
   wagonType: Pick<WagonType, 'lengthMeters'>,
   limits?: TrainLimitConfig,
+  /** Leg-aware cargo exclusivity — see {@link validateWagonCargoExclusivity}. */
+  legs?: Map<string, { from: number; to: number }>,
+  edgeCount?: number,
 ): string[] {
   const maxWeightTons = limits?.maxWeightTons ?? MAX_TRAIN_WEIGHT_TONS;
   const maxLengthMeters = limits?.maxLengthMeters ?? MAX_TRAIN_LENGTH_METERS;
@@ -564,7 +595,7 @@ export function validateTrainLimits(
   );
 
   violations.push(...validateBulkWagonSlotWeights(wagonPlan));
-  violations.push(...validateWagonCargoExclusivity(wagonPlan));
+  violations.push(...validateWagonCargoExclusivity(wagonPlan, legs, edgeCount));
 
   return violations;
 }
@@ -578,6 +609,8 @@ export function validateMixedTrainLimits(
   wagonPlan: WagonPlanSlot[],
   wagonTypes: Array<Pick<WagonType, 'lengthMeters'>>,
   limits?: TrainLimitConfig,
+  legs?: Map<string, { from: number; to: number }>,
+  edgeCount?: number,
 ): string[] {
   const maxLengthMeters = limits?.maxLengthMeters ?? MAX_TRAIN_LENGTH_METERS;
   const minWagonLength = Math.min(
@@ -591,6 +624,8 @@ export function validateMixedTrainLimits(
     wagonPlan,
     { lengthMeters: minWagonLength },
     { ...limits, maxWagonsPerTrain },
+    legs,
+    edgeCount,
   );
 }
 
@@ -608,8 +643,13 @@ export function validateMixedTrainLimitsPerEdge(
   stops: string[],
   /** Display names parallel to `stops` — violations then name the leg they hit. */
   stopLabels?: string[],
+  /** Booking id → stop-index span, so cargo exclusivity is judged per edge. */
+  legs?: Map<string, { from: number; to: number }>,
 ): string[] {
-  if (stops.length <= 2) return validateMixedTrainLimits(wagonPlan, wagonTypes, limits);
+  const edges = Math.max(1, stops.length - 1);
+  if (stops.length <= 2) {
+    return validateMixedTrainLimits(wagonPlan, wagonTypes, limits, legs, edges);
+  }
   const spans = slotSpans(wagonPlan, stops);
   const label = (i: number) => stopLabels?.[i] ?? stops[i];
   const violations = new Set<string>();
@@ -618,7 +658,13 @@ export function validateMixedTrainLimitsPerEdge(
       (_, i) => spans[i].from <= edge && edge < spans[i].to,
     );
     if (!active.length) continue;
-    for (const violation of validateMixedTrainLimits(active, wagonTypes, limits)) {
+    for (const violation of validateMixedTrainLimits(
+      active,
+      wagonTypes,
+      limits,
+      legs,
+      edges,
+    )) {
       violations.add(`Leg ${label(edge)} → ${label(edge + 1)}: ${violation}`);
     }
   }