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

scripts/utils/calculations.ts

@@ -0,0 +1,52 @@
+export interface LakeCalculationConfig {
+  maxVolume?: number;
+  minLevel?: number;
+  maxLevel?: number;
+  storageLevel?: number;
+}
+
+export interface LakeMetrics {
+  capacity: number; // 0-100 percentage
+  volume: number; // in mil. m3
+  storageDiff: number; // in meters
+}
+
+export function calculateLakeMetrics(
+  currentLevel: number,
+  reportedVolume: number,
+  config: LakeCalculationConfig
+): LakeMetrics {
+  let capacity = 0;
+  let volume = reportedVolume;
+  let storageDiff = 0;
+
+  // 1. Calculate capacity and volume
+  if (volume > 0 && config.maxVolume && config.maxVolume > 0) {
+    // If real volume is available, calculate capacity from volume
+    capacity = Math.max(0, Math.min(100, Math.round((volume / config.maxVolume) * 1000) / 10));
+  } else if (config.minLevel && config.maxLevel && currentLevel > 0) {
+    // Fallback: estimate capacity and volume from level difference
+    const percentage = ((currentLevel - config.minLevel) / (config.maxLevel - config.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) * (config.maxVolume || 0)).toFixed(1));
+    }
+  } else {
+    // Missing required config data or bad level
+    if (volume === 0) {
+      volume = config.maxVolume || 0;
+    }
+  }
+
+  // 2. Calculate storage difference
+  if (config.storageLevel && currentLevel > 0) {
+    storageDiff = Number((currentLevel - config.storageLevel).toFixed(2));
+  }
+
+  return {
+    capacity,
+    volume,
+    storageDiff
+  };
+}