From 03849e5c4330725a3dd81524c6a9d827fd8f336f Mon Sep 17 00:00:00 2001
From: dvmarinoff <dvmarinoff@gmail.com>
Date: Wed, 26 Feb 2025 19:11:02 +0200
Subject: [PATCH] fix isoDate to return correctly local or utc date

---
 src/utils.js       | 14 ++++++---
 test/utils.test.js | 74 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+), 4 deletions(-)
 create mode 100644 test/utils.test.js

diff --git a/src/utils.js b/src/utils.js
index 69ed72b..9d3f0c1 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -56,10 +56,16 @@ function time() {
     return `${hours}:${minutes}:${seconds}:${milliseconds}`;
 }
 
-function isoDate(date = new Date(), utc = false) {
-    const offset = utc ? 0 : date.getTimezoneOffset()*60*1000;
-    const d = new Date(date.getTime() - offset);
-    return date.toISOString().split('T')[0];
+function isoDate(date = new Date(), local = true) {
+    if(local) {
+        const day   = (date.getDate()).toString().padStart(2, '0');
+        const month = (date.getMonth()+1).toString().padStart(2, '0');
+        const year  = date.getFullYear().toString();
+        return `${year}-${month}-${day}`;
+    } else {
+        // toISOString returns always the utc date
+        return date.toISOString().split('T')[0];
+    }
 }
 
 function format(x, precision = 1000) {
diff --git a/test/utils.test.js b/test/utils.test.js
new file mode 100644
index 0000000..c1fd904
--- /dev/null
+++ b/test/utils.test.js
@@ -0,0 +1,74 @@
+/**
+ * @jest-environment jsdom
+ */
+
+import { isoDate, } from '../src/utils.js';
+
+// nyc        utc        hel
+//
+// 24 16:00   24 21:00   24 23:00
+// 24 17:00   24 22:00   25 00:00
+//
+// 24 18:00   25 23:00   25 01:00
+// 24 19:00   25 00:00   25 02:00
+// 24 20:00   25 01:00   25 03:00
+//
+// 24 23:00   25 04:00   25 06:00
+// 25 00:00   25 05:00   25 07:00
+// 25 01:00   25 06:00   25 08:00
+
+describe('isoDate', () => {
+    // TODO: make the test machine env timezone independent
+
+    describe('hel', () => {
+        describe('local = true', () => {
+            test('utc 24 21:00 - hel 24 23:00 -> 24', () => {
+                const localDate = new Date('2025-02-24T23:00:00');
+                expect(isoDate(localDate)).toBe('2025-02-24');
+            });
+
+            test('utc 24 22:00 - hel 25 00:00 -> 25', () => {
+                const localDate = new Date('2025-02-25T00:00:00');
+                expect(isoDate(localDate)).toBe('2025-02-25');
+            });
+
+            test('utc 24 23:00 - hel 25 01:00 -> 25', () => {
+                const localDate = new Date('2025-02-25T00:00:00');
+                expect(isoDate(localDate)).toBe('2025-02-25');
+            });
+
+            test('utc 25 00:00 - hel 25 02:00 -> 25', () => {
+                const localDate = new Date('2025-02-25T02:00:00');
+                expect(isoDate(localDate)).toBe('2025-02-25');
+            });
+
+            test('utc 25 01:00 - hel 25 03:00 -> 25', () => {
+                const localDate = new Date('2025-02-25T02:00:00');
+                expect(isoDate(localDate)).toBe('2025-02-25');
+            });
+        });
+
+        describe('local = false', () => {
+            test('utc 24 21:00 - hel 24 23:00 -> 24', () => {
+                const localDate = new Date('2025-02-24T23:00:00');
+                expect(isoDate(localDate, false)).toBe('2025-02-24');
+            });
+
+            test('utc 24 22:00 - hel 25 00:00 -> 24', () => {
+                const localDate = new Date('2025-02-25T00:00:00');
+                expect(isoDate(localDate, false)).toBe('2025-02-24');
+            });
+
+            test('utc 25 00:00 - hel 25 02:00 -> 25', () => {
+                const localDate = new Date('2025-02-25T02:00:00');
+                expect(isoDate(localDate, false)).toBe('2025-02-25');
+            });
+
+            test('utc 25 01:00 - hel 25 03:00 -> 25', () => {
+                const localDate = new Date('2025-02-25T02:00:00');
+                expect(isoDate(localDate, false)).toBe('2025-02-25');
+            });
+        });
+    });
+});
+