feat: implement DateService with timezone support and add EncryptionService with unit tests

.vscode/settings.json

@@ -3,5 +3,6 @@
     {
       "mode": "auto"
     }
-  ]
+  ],
+  "cSpell.words": ["Ujung", "Pandang", "WITA"]
 }

apps/web/src/apps/modules/index.tsx

@@ -1,9 +1,10 @@
+import { DateServiceComponent } from '@repo/ui';
 import { Route, Routes } from 'react-router-dom';
 
 export default function AppModule() {
   return (
     <Routes>
-      <Route path="/example/*" element={<div>1</div>} />
+      <Route path="/example/*" element={<DateServiceComponent />} />
     </Routes>
   );
 }

packages/ui/src/components/date-example.tsx

@@ -122,6 +122,9 @@ export const DateServiceComponent: React.FC = () => {
                   <span className="opacity-60 text-xs ml-1">({currentTime.format('Z')})</span>
                 </div>
               </div>
+              <div className="text-sm font-bold text-blue-700 bg-blue-100 px-2 py-1 rounded border border-blue-200">
+                {currentTime.timezoneWithOffset}
+              </div>
             </div>
 
             <div className="text-lg text-gray-500 mt-2">{currentTime.format('dddd, DD MMMM YYYY')}</div>

packages/utils/src/date-service/date-service.test.ts

@@ -0,0 +1,227 @@
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+import { DateService } from './date-service';
+
+describe('DateService', () => {
+  // Setup standard environment before each test
+  beforeEach(() => {
+    // 1. Reset Global Timezone to UTC for deterministic results across environments
+    DateService.setGlobalConfig('UTC');
+
+    // 2. Mock console warn/error to keep the terminal clean during error handling tests
+    vi.spyOn(console, 'warn').mockImplementation(() => {});
+    vi.spyOn(console, 'error').mockImplementation(() => {});
+  });
+
+  afterEach(() => {
+    // Clean up all mocks and restore real timers after each test
+    vi.restoreAllMocks();
+    vi.useRealTimers();
+  });
+
+  describe('Initialization', () => {
+    it('should create an instance with the current time (now) using static method', () => {
+      const date = DateService.now();
+      expect(date).toBeInstanceOf(DateService);
+      expect(date.toDate()).toBeInstanceOf(Date);
+    });
+
+    it('should create an instance from a specific ISO string', () => {
+      // Use full ISO format (.000Z) for precision
+      const input = '2025-01-01T10:00:00.000Z';
+      const date = new DateService(input);
+      expect(date.toISOString()).toBe(input);
+    });
+
+    it('should create a clone from another DateService instance', () => {
+      const original = new DateService('2025-01-01T00:00:00.000Z');
+      const clone = new DateService(original);
+
+      expect(clone.toISOString()).toBe(original.toISOString());
+      expect(clone).not.toBe(original); // Ensure references are different (Memory Address check)
+    });
+
+    it('should handle invalid input by falling back to current time (Graceful Fallback)', () => {
+      // Freeze system time for precise assertions
+      const fixedTime = new Date('2025-01-01T12:00:00.000Z');
+      vi.useFakeTimers();
+      vi.setSystemTime(fixedTime);
+
+      const invalidDate = new DateService('invalid-date-string-xyz');
+
+      expect(console.warn).toHaveBeenCalledWith(expect.stringContaining('Invalid date input'));
+      expect(invalidDate.toISOString()).toBe(fixedTime.toISOString());
+    });
+  });
+
+  describe('Global Configuration', () => {
+    it('should update global timezone correctly', () => {
+      DateService.setGlobalConfig('Asia/Jakarta');
+      expect(DateService.getGlobalTimezone()).toBe('Asia/Jakarta');
+    });
+
+    it('should handle invalid timezone gracefully', () => {
+      const initialTz = DateService.getGlobalTimezone();
+      DateService.setGlobalConfig('Mars/Alien_City');
+
+      expect(console.error).toHaveBeenCalled();
+      expect(DateService.getGlobalTimezone()).toBe(initialTz);
+    });
+
+    it('should apply timezone to new instances', () => {
+      const utcString = '2025-01-01T00:00:00Z';
+
+      // Test UTC
+      DateService.setGlobalConfig('UTC');
+      const dateUtc = new DateService(utcString);
+      expect(dateUtc.format('HH:mm')).toBe('00:00');
+
+      // Test Jakarta (UTC+7)
+      DateService.setGlobalConfig('Asia/Jakarta');
+      const dateJkt = new DateService(utcString);
+      expect(dateJkt.format('HH:mm')).toBe('07:00');
+    });
+  });
+
+  describe('Immutability & Manipulation', () => {
+    // This verifies that .clone() is working effectively
+    it('should be immutable on "add"', () => {
+      const start = new DateService('2025-01-01T00:00:00.000Z');
+      const nextDay = start.add(1, 'day');
+
+      expect(start.format('DD')).toBe('01'); // Original instance MUST NOT change
+      expect(nextDay.format('DD')).toBe('02'); // New instance should reflect the change
+      expect(start).not.toBe(nextDay); // Ensure they are different objects
+    });
+
+    it('should be immutable on "subtract"', () => {
+      const start = new DateService('2025-01-02T00:00:00.000Z');
+      const prevDay = start.subtract(1, 'day');
+
+      expect(start.format('DD')).toBe('02'); // Original instance MUST NOT change
+      expect(prevDay.format('DD')).toBe('01');
+      expect(start).not.toBe(prevDay);
+    });
+
+    it('should be immutable on "startOf"', () => {
+      const date = new DateService('2025-01-15T12:00:00.000Z');
+      const startOfMonth = date.startOf('month');
+
+      expect(date.format('DD')).toBe('15'); // Original remains 15th
+      expect(startOfMonth.format('DD')).toBe('01'); // New instance is 1st
+      expect(startOfMonth).not.toBe(date);
+    });
+
+    it('should be immutable on "endOf"', () => {
+      const date = new DateService('2025-01-01T00:00:00.000Z');
+      const endOfDay = date.endOf('day');
+
+      // Format HH:mm:ss depends on global timezone (currently UTC)
+      expect(endOfDay.format('HH:mm:ss')).toBe('23:59:59');
+      expect(endOfDay).not.toBe(date);
+    });
+  });
+
+  describe('Formatting & Comparison', () => {
+    it('should format date string correctly', () => {
+      const date = new DateService('2025-12-25T00:00:00.000Z');
+      expect(date.format('DD/MM/YYYY')).toBe('25/12/2025');
+    });
+
+    it('should return strict ISO 8601 string (always UTC)', () => {
+      DateService.setGlobalConfig('Asia/Jakarta');
+      // Input Jakarta local time 7 AM = 0 AM UTC
+      const date = new DateService('2025-01-01T07:00:00+07:00');
+      expect(date.toISOString()).toBe('2025-01-01T00:00:00.000Z');
+    });
+
+    it('should compare dates correctly', () => {
+      const d1 = new DateService('2025-01-01T00:00:00.000Z');
+      const d2 = new DateService('2025-01-02T00:00:00.000Z');
+
+      expect(d1.isBefore(d2)).toBe(true);
+      expect(d2.isAfter(d1)).toBe(true);
+      expect(d1.isSame(d1)).toBe(true);
+    });
+
+    it('should calculate precise diff', () => {
+      const d1 = new DateService('2025-01-01T00:00:00.000Z');
+      const d2 = new DateService('2025-01-03T00:00:00.000Z');
+      expect(d2.diff(d1, 'day')).toBe(2);
+    });
+
+    it('should calculate calendar day diff (ignoring time)', () => {
+      // Case: 23:00 vs 01:00 the next day
+      // Technically only 2 hours difference (0 full days), but 1 calendar day difference.
+      const d1 = new DateService('2025-01-01T23:00:00.000Z');
+      const d2 = new DateService('2025-01-02T01:00:00.000Z');
+
+      expect(d2.diff(d1, 'day')).toBe(0); // Standard diff (less than 24h)
+      expect(d2.diffCalendarDay(d1)).toBe(1); // Calendar diff
+    });
+  });
+
+  describe('Timezone Utilities (Indonesian & Offset)', () => {
+    it('should return custom mapping for Indonesia (WIB)', () => {
+      DateService.setGlobalConfig('Asia/Jakarta');
+      const date = new DateService();
+      expect(date.timezoneAbbr).toBe('WIB');
+    });
+
+    it('should return custom mapping for Indonesia (WITA)', () => {
+      DateService.setGlobalConfig('Asia/Makassar');
+      const date = new DateService();
+      expect(date.timezoneAbbr).toBe('WITA');
+    });
+
+    it('should return custom mapping for Indonesia (WIT)', () => {
+      DateService.setGlobalConfig('Asia/Jayapura');
+      const date = new DateService();
+      expect(date.timezoneAbbr).toBe('WIT');
+    });
+
+    it('should fallback to standard abbr for other zones', () => {
+      DateService.setGlobalConfig('UTC');
+      const date = new DateService();
+      expect(date.timezoneAbbr).toBe('UTC');
+    });
+
+    // NEW FEATURE TEST: timezoneWithOffset
+    it('should return combined timezone abbreviation and offset', () => {
+      const isoInput = '2025-01-01T12:00:00Z'; // Input in UTC
+
+      // Case 1: Jakarta
+      DateService.setGlobalConfig('Asia/Jakarta');
+      const dateJkt = new DateService(isoInput);
+      // Jakarta = UTC+7
+      expect(dateJkt.timezoneWithOffset).toBe('WIB (+07:00)');
+
+      // Case 2: Makassar
+      DateService.setGlobalConfig('Asia/Makassar');
+      const dateMks = new DateService(isoInput);
+      // Makassar = UTC+8
+      expect(dateMks.timezoneWithOffset).toBe('WITA (+08:00)');
+
+      // Case 3: UTC
+      DateService.setGlobalConfig('UTC');
+      const dateUtc = new DateService(isoInput);
+      expect(dateUtc.timezoneWithOffset).toBe('UTC (+00:00)');
+    });
+  });
+
+  describe('Epoch & Helpers', () => {
+    it('should return correct epoch values', () => {
+      const input = 1704067200000; // 2024-01-01 00:00:00 UTC
+      const date = new DateService(input);
+
+      expect(date.timestamp).toBe(input);
+      expect(date.epochMillis).toBe(input);
+      expect(date.epochSeconds).toBe(1704067200);
+    });
+
+    it('should return supported timezones list', () => {
+      const timezones = DateService.getSupportedTimezones();
+      expect(Array.isArray(timezones)).toBe(true);
+      expect(timezones).toContain('Asia/Jakarta');
+    });
+  });
+});

packages/utils/src/date-service/date-service.ts

@@ -192,19 +192,19 @@ export class DateService implements IDateManager {
    * ---------------------------------------------------------------- */
 
   add(value: number, unit: TimeUnit): DateService {
-    return new DateService(this._date.add(value, unit as ManipulateType));
+    return new DateService(this._date.clone().add(value, unit as ManipulateType));
   }
 
   subtract(value: number, unit: TimeUnit): DateService {
-    return new DateService(this._date.subtract(value, unit as ManipulateType));
+    return new DateService(this._date.clone().subtract(value, unit as ManipulateType));
   }
 
   startOf(unit: TimeUnit): DateService {
-    return new DateService(this._date.startOf(unit as OpUnitType));
+    return new DateService(this._date.clone().startOf(unit as OpUnitType));
   }
 
   endOf(unit: TimeUnit): DateService {
-    return new DateService(this._date.endOf(unit as OpUnitType));
+    return new DateService(this._date.clone().endOf(unit as OpUnitType));
   }
 
   /* ----------------------------------------------------------------
@@ -293,4 +293,22 @@ export class DateService implements IDateManager {
     const tz = DateService._defaultTimezone;
     return INDONESIA_TZ_MAP[tz] ?? this._date.format('z');
   }
+
+  /* ----------------------------------------------------------------
+   * Timezone Utilities
+   * ---------------------------------------------------------------- */
+
+  // ... (method getSupportedTimezones dan get timezoneAbbr yang sudah ada)
+
+  /**
+   * Returns timezone abbreviation combined with GMT offset.
+   * Useful for UI labels.
+   *
+   * @example
+   * "WIB (+07:00)"
+   * "UTC (+00:00)"
+   */
+  get timezoneWithOffset(): string {
+    return `${this.timezoneAbbr} (${this._date.format('Z')})`;
+  }
 }

packages/utils/src/encryption/encryption-service.test.ts

@@ -0,0 +1,123 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import { EncryptionService } from './encryption-service';
+import { AES } from 'crypto-js';
+
+// 1. Mock the key module to ensure test consistency
+vi.mock('./encryption-key', () => ({
+  ENC_STORAGE_KEY: 'default-test-key-123',
+}));
+
+describe('EncryptionService', () => {
+  const TEST_KEY = 'secret-key-xyz';
+  let service: EncryptionService;
+
+  beforeEach(() => {
+    // Reset the Singleton instance to ensure clean state for every test
+    (EncryptionService as any).instance = undefined;
+    service = new EncryptionService(TEST_KEY);
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  describe('Constructor', () => {
+    it('should create an instance with the provided key', () => {
+      const instance = new EncryptionService('custom-key');
+      expect(instance).toBeInstanceOf(EncryptionService);
+    });
+
+    it('should use the default ENC_STORAGE_KEY if no key is provided', () => {
+      const instance = new EncryptionService();
+      // Verify functionality with default key
+      const data = 'test-default';
+      const encrypted = instance.encrypt(data);
+      expect(instance.decrypt(encrypted)).toBe(data);
+    });
+
+    it('should throw an Error if the provided key is empty', () => {
+      expect(() => new EncryptionService('')).toThrow('[EncryptionService] Encryption key is missing/empty.');
+    });
+  });
+
+  describe('encrypt()', () => {
+    it('should return an encrypted string different from the plain text', () => {
+      const plainText = 'Hello World';
+      const encrypted = service.encrypt(plainText);
+
+      expect(encrypted).not.toBe(plainText);
+      expect(encrypted).not.toBe('');
+      expect(typeof encrypted).toBe('string');
+    });
+
+    it('should return an empty string if input is empty', () => {
+      expect(service.encrypt('')).toBe('');
+    });
+  });
+
+  describe('decrypt()', () => {
+    it('should decrypt data back to the original text correctly', () => {
+      const plainText = 'Secret Data 123';
+      const encrypted = service.encrypt(plainText);
+      const decrypted = service.decrypt(encrypted);
+
+      expect(decrypted).toBe(plainText);
+    });
+
+    it('should return an empty string if input is empty', () => {
+      expect(service.decrypt('')).toBe('');
+    });
+
+    it('should return an empty string if decrypted with the WRONG key', () => {
+      const plainText = 'Sensitive Data';
+
+      // Encrypt with Service A (TEST_KEY)
+      const encrypted = service.encrypt(plainText);
+
+      // Decrypt with Service B (WRONG_KEY)
+      const wrongService = new EncryptionService('wrong-key-999');
+      const result = wrongService.decrypt(encrypted);
+
+      expect(result).toBe('');
+    });
+
+    it('should return an empty string if input is malformed (Graceful Fail)', () => {
+      const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+
+      const malformedData = 'invalid-base64-string-@@@';
+      const result = service.decrypt(malformedData);
+
+      expect(result).toBe('');
+      // NOTE: crypto-js handles garbage input gracefully without throwing,
+      // so console.error is NOT called here.
+    });
+
+    it('should catch error and log it when decryption throws an exception (Critical Fail)', () => {
+      /**
+       * Spy on console.error to suppress and track error logging during the test.
+       * Mocked to prevent error messages from appearing in test output.
+       */
+      const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+
+      // FORCE an error by mocking AES.decrypt implementation
+      vi.spyOn(AES, 'decrypt').mockImplementationOnce(() => {
+        throw new Error('Simulated Crypto Failure');
+      });
+
+      const result = service.decrypt('any-data');
+
+      expect(result).toBe('');
+      // Now we expect the catch block to be executed
+      expect(consoleSpy).toHaveBeenCalledWith('[EncryptionService] Decryption failed:', expect.any(Error));
+    });
+  });
+
+  describe('getInstance() (Singleton)', () => {
+    it('should return the same instance reference', () => {
+      const instance1 = EncryptionService.getInstance();
+      const instance2 = EncryptionService.getInstance();
+
+      expect(instance1).toBe(instance2);
+    });
+  });
+});

packages/utils/src/encryption/encryption-service.ts

@@ -2,7 +2,7 @@ import { AES, enc } from 'crypto-js';
 import { ENC_STORAGE_KEY } from './encryption-key';
 
 /**
- * Interface contract supaya method konsisten
+ * Interface defining encryption service methods.
  */
 interface IEncryptionService {
   encrypt(data: string): string;
@@ -13,7 +13,8 @@ export class EncryptionService implements IEncryptionService {
   private readonly _key: string;
 
   /**
-   * @param key (Optional) Jika tidak diisi, otomatis pakai ENC_STORAGE_KEY
+   * @param key - Encryption key used for encrypting and decrypting data.
+   * If not provided, defaults to ENC_STORAGE_KEY.
    */
   constructor(key: string = ENC_STORAGE_KEY) {
     if (!key) {
@@ -23,7 +24,8 @@ export class EncryptionService implements IEncryptionService {
   }
 
   /**
-   * Mengenkripsi string plain text.
+   * Encrypts the given data string.
+   * Returns an empty string '' if input data is empty.
    */
   public encrypt(data: string): string {
     if (!data) {
@@ -33,8 +35,8 @@ export class EncryptionService implements IEncryptionService {
   }
 
   /**
-   * Mendekripsi string terenkripsi.
-   * Mengembalikan string kosong '' jika gagal decrypt atau format salah.
+   * Decrypts the given encrypted data string.
+   * Returns an empty string '' if input is empty or decryption fails.
    */
   public decrypt(encryptedData: string): string {
     if (!encryptedData) {
@@ -45,7 +47,7 @@ export class EncryptionService implements IEncryptionService {
       const bytes = AES.decrypt(encryptedData, this._key);
       const originalText = bytes.toString(enc.Utf8);
 
-      // Validasi tambahan: jika hasil decrypt kosong, berarti key salah atau data corrupt
+      // If decryption yields an empty string, consider it a failure
       if (!originalText) {
         return '';
       }
@@ -57,8 +59,12 @@ export class EncryptionService implements IEncryptionService {
     }
   }
 
-  // --- Static Helper (Singleton Pattern sederhana) ---
-  // Supaya tidak perlu 'new EncryptionService()' berulang kali
+  /**
+   * Get the singleton instance of EncryptionService.
+   * Uses the default ENC_STORAGE_KEY.
+   * @return EncryptionService instance
+   */
+
   private static instance: EncryptionService;
 
   public static getInstance(): EncryptionService {

packages/utils/src/example/index.ts

@@ -1,3 +0,0 @@
-export function utilsExample() {
-  return 'This is an example utility function.';
-}

packages/utils/src/index.ts

@@ -1,3 +1,4 @@
-export * from './encryption';
-export * from './example';
-export * from './date-service';
+export * from './encryption/encryption-key';
+export * from './encryption/encryption-service';
+
+export * from './date-service/date-service';

packages/utils/src/testing-example/add.ts

@@ -1 +0,0 @@
-export const add = (a: number, b: number) => a + b;

packages/utils/src/testing-example/subtract.ts

@@ -1 +0,0 @@
-export const subtract = (a: number, b: number) => a - b;

packages/utils/src/testing-example/utils-testing-example.test.ts

@@ -1,11 +0,0 @@
-import { expect, test } from 'vitest';
-import { add } from './add';
-import { subtract } from './subtract';
-
-test('adds 1 + 2 to equal 3', () => {
-  expect(add(1, 2)).toBe(3);
-});
-
-test('subtracts 2 - 1 to equal 1', () => {
-  expect(subtract(2, 1)).toBe(1);
-});