refactor: centralize lake metrics calculations into a utility module with comprehensive unit tests

scripts/buildIndex.ts

@@ -1,6 +1,7 @@
 import * as fs from 'fs';
 import * as path from 'path';
 import { lakesConfig } from './lakesConfig';
+import { calculateLakeMetrics } from './utils/calculations';
 
 interface DataRecord {
   timestamp: string;
@@ -53,22 +54,7 @@ const lakes = lakesConfig.map(lake => {
     }
   }
   
-  if (volume > 0 && lake.maxVolume && lake.maxVolume > 0) {
-    capacity = Math.max(0, Math.min(100, Math.round((volume / lake.maxVolume) * 1000) / 10));
-  } else if (lake.minLevel && lake.maxLevel && currentLevel > 0) {
-    const percentage = ((currentLevel - lake.minLevel) / (lake.maxLevel - lake.minLevel)) * 100;
-    capacity = Math.max(0, Math.min(100, Math.round(percentage * 10) / 10)); // Round to 1 decimal place
-    if (volume === 0) {
-      volume = Number(((capacity / 100) * (lake.maxVolume || 0)).toFixed(1));
-    }
-  } else {
-    if (volume === 0) volume = lake.maxVolume || 0;
-  }
-
-  let storageDiff = 0;
-  if (lake.storageLevel && currentLevel > 0) {
-    storageDiff = Number((currentLevel - lake.storageLevel).toFixed(2));
-  }
+  const metrics = calculateLakeMetrics(currentLevel, volume, lake);
 
   return {
     id: lake.id,
@@ -76,11 +62,11 @@ const lakes = lakesConfig.map(lake => {
     river: lake.text.includes('-') ? lake.text.split('-')[1].trim() : '',
     priority: lake.priority || false,
     level: currentLevel.toFixed(2),
-    capacity: capacity,
-    storageDiff: storageDiff,
+    capacity: metrics.capacity,
+    storageDiff: metrics.storageDiff,
     inflow: inflow.toFixed(1),
     outflow: currentFlow.toFixed(1),
-    volume: volume,
+    volume: metrics.volume,
     maxVolume: lake.maxVolume || 0,
     lat: lake.coords[0],
     lng: lake.coords[1],