feat: more trade when there are few ports worldwide (#242)

src/core/configuration/Config.ts

@@ -160,7 +160,7 @@ export interface Config {
   defaultDonationAmount(sender: Player): number;
   unitInfo(type: UnitType): UnitInfo;
   tradeShipGold(dist: number): Gold;
-  tradeShipSpawnRate(): number;
+  tradeShipSpawnRate(numberOfPorts: number): number;
   defensePostRange(): number;
   defensePostDefenseBonus(): number;
   falloutDefenseModifier(percentOfFallout: number): number;

src/core/configuration/DefaultConfig.ts

@@ -156,7 +156,12 @@ export class DefaultConfig implements Config {
   tradeShipGold(dist: number): Gold {
     return 10000 + 150 * Math.pow(dist, 1.1);
   }
-  tradeShipSpawnRate(): number {
+  tradeShipSpawnRate(numberOfPorts: number): number {
+    if (numberOfPorts <= 3) return 180;
+    if (numberOfPorts <= 5) return 250;
+    if (numberOfPorts <= 8) return 350;
+    if (numberOfPorts <= 10) return 400;
+    if (numberOfPorts <= 12) return 450;
     return 500;
   }