use the daylight saving time zone as default time zone rather than the current standard time zone during the DST

src/components/desktop/DateRangeSelectionDialog.vue

@@ -43,13 +43,6 @@ import { type CommonDateRangeSelectionProps, useDateRangeSelectionBase } from '@
 
 import { ThemeType } from '@/core/theme.ts';
 
-import {
-    getLocalDatetimeFromUnixTime,
-    getDummyUnixTimeForLocalUsage,
-    getTimezoneOffsetMinutes,
-    getBrowserTimezoneOffsetMinutes
-} from '@/lib/datetime.ts';
-
 interface DesktopDateRangeSelectionProps extends CommonDateRangeSelectionProps {
     persistent?: boolean;
 }
@@ -64,7 +57,14 @@ const emit = defineEmits<{
 const theme = useTheme();
 
 const { tt } = useI18n();
-const { dateRange, beginDateTime, endDateTime, presetRanges, getFinalDateRange } = useDateRangeSelectionBase(props);
+const {
+    dateRange,
+    beginDateTime,
+    endDateTime,
+    presetRanges,
+    getLocalDatetimeFromSameDateTimeOfUnixTime,
+    getFinalDateRange
+} = useDateRangeSelectionBase(props);
 
 const isDarkMode = computed<boolean>(() => theme.global.name.value === ThemeType.Dark);
 const showState = computed<boolean>({
@@ -94,13 +94,13 @@ function cancel(): void {
 
 watch(() => props.minTime, (newValue) => {
     if (newValue) {
-        dateRange.value[0] = getLocalDatetimeFromUnixTime(getDummyUnixTimeForLocalUsage(newValue, getTimezoneOffsetMinutes(), getBrowserTimezoneOffsetMinutes()));
+        dateRange.value[0] = getLocalDatetimeFromSameDateTimeOfUnixTime(newValue);
     }
 });
 
 watch(() => props.maxTime, (newValue) => {
     if (newValue) {
-        dateRange.value[1] = getLocalDatetimeFromUnixTime(getDummyUnixTimeForLocalUsage(newValue, getTimezoneOffsetMinutes(), getBrowserTimezoneOffsetMinutes()));
+        dateRange.value[1] = getLocalDatetimeFromSameDateTimeOfUnixTime(newValue);
     }
 });
 </script>

src/components/desktop/DateTimeSelect.vue

@@ -94,12 +94,9 @@ import {
 } from '@/core/datetime.ts';
 import {
     getHourIn12HourFormat,
-    getTimezoneOffsetMinutes,
-    getBrowserTimezoneOffsetMinutes,
     getLocalDatetimeFromUnixTime,
-    getUnixTimeFromLocalDatetime,
-    getActualUnixTimeForStore,
-    getDummyUnixTimeForLocalUsage,
+    getSameDateTimeWithBrowserTimezone,
+    parseDateTimeFromUnixTimeWithTimezoneOffset,
     parseDateTimeFromKnownDateTimeFormat,
     getAMOrPM,
     getCombinedDateAndTimeValues
@@ -108,6 +105,7 @@ import { setChildInputFocus } from '@/lib/ui/desktop.ts';
 
 const props = defineProps<{
     modelValue: number;
+    timezoneUtcOffset: number;
     disabled?: boolean;
     readonly?: boolean;
     label?: string;
@@ -124,7 +122,7 @@ const {
     getCurrentNumeralSystemType,
     parseDateTimeFromLongDateTime,
     parseDateTimeFromShortDateTime,
-    formatUnixTimeToLongDateTime
+    formatDateTimeToLongDateTime
 } = useI18n();
 
 const {
@@ -133,6 +131,8 @@ const {
     isMinuteTwoDigits,
     isSecondTwoDigits,
     isMeridiemIndicatorFirst,
+    getLocalDatetimeFromSameDateTimeOfUnixTime,
+    getUnixTimeFromSameDateTimeOfLocalDatetime,
     getDisplayTimeValue,
     generateAllHours,
     generateAllMinutesOrSeconds
@@ -147,10 +147,10 @@ const numeralSystem = computed<NumeralSystem>(() => getCurrentNumeralSystemType(
 
 const dateTime = computed<Date>({
     get: () => {
-        return getLocalDatetimeFromUnixTime(props.modelValue);
+        return getLocalDatetimeFromSameDateTimeOfUnixTime(props.modelValue, props.timezoneUtcOffset);
     },
     set: (value: Date) => {
-        const unixTime = getUnixTimeFromLocalDatetime(value);
+        const unixTime = getUnixTimeFromSameDateTimeOfLocalDatetime(value, props.timezoneUtcOffset);
 
         if (unixTime < 0) {
             emit('error', 'Date is too early');
@@ -161,7 +161,7 @@ const dateTime = computed<Date>({
     }
 });
 
-const displayTime = computed<string>(() => formatUnixTimeToLongDateTime(getActualUnixTimeForStore(getUnixTimeFromLocalDatetime(dateTime.value), getTimezoneOffsetMinutes(), getBrowserTimezoneOffsetMinutes())));
+const displayTime = computed<string>(() => formatDateTimeToLongDateTime(parseDateTimeFromUnixTimeWithTimezoneOffset(props.modelValue, props.timezoneUtcOffset)));
 
 const hourItems = computed<TimePickerValue[]>(() => generateAllHours(1, isHourTwoDigits.value));
 const minuteItems = computed<TimePickerValue[]>(() => generateAllMinutesOrSeconds(1, isMinuteTwoDigits.value));
@@ -252,7 +252,7 @@ function onPaste(event: ClipboardEvent): void {
         dt = parseDateTimeFromKnownDateTimeFormat(text, formats[0] as KnownDateTimeFormat);
 
         if (dt) {
-            dateTime.value = getLocalDatetimeFromUnixTime(getDummyUnixTimeForLocalUsage(dt.getUnixTime(), getTimezoneOffsetMinutes(), getBrowserTimezoneOffsetMinutes()));
+            dateTime.value = getLocalDatetimeFromUnixTime(getSameDateTimeWithBrowserTimezone(dt).getUnixTime());
             return;
         }
     }
@@ -260,14 +260,14 @@ function onPaste(event: ClipboardEvent): void {
     dt = parseDateTimeFromLongDateTime(text);
 
     if (dt) {
-        dateTime.value = getLocalDatetimeFromUnixTime(getDummyUnixTimeForLocalUsage(dt.getUnixTime(), getTimezoneOffsetMinutes(), getBrowserTimezoneOffsetMinutes()));
+        dateTime.value = getLocalDatetimeFromUnixTime(getSameDateTimeWithBrowserTimezone(dt).getUnixTime());
         return;
     }
 
     dt = parseDateTimeFromShortDateTime(text);
 
     if (dt) {
-        dateTime.value = getLocalDatetimeFromUnixTime(getDummyUnixTimeForLocalUsage(dt.getUnixTime(), getTimezoneOffsetMinutes(), getBrowserTimezoneOffsetMinutes()));
+        dateTime.value = getLocalDatetimeFromUnixTime(getSameDateTimeWithBrowserTimezone(dt).getUnixTime());
         return;
     }
 

src/components/desktop/TrendsChart.vue

@@ -43,6 +43,7 @@ import {
     isNumber
 } from '@/lib/common.ts';
 import {
+    parseDateTimeFromUnixTime,
     getYearMonthFirstUnixTime,
     getYearMonthLastUnixTime,
     getDateTypeByDateRange,
@@ -95,11 +96,11 @@ const theme = useTheme();
 const {
     tt,
     getCurrentLanguageTextDirection,
-    formatUnixTimeToShortDate,
-    formatUnixTimeToGregorianLikeShortYear,
-    formatUnixTimeToGregorianLikeShortYearMonth,
+    formatDateTimeToShortDate,
+    formatDateTimeToGregorianLikeShortYear,
+    formatDateTimeToGregorianLikeShortYearMonth,
     formatYearQuarterToGregorianLikeYearQuarter,
-    formatUnixTimeToGregorianLikeFiscalYear,
+    formatDateTimeToGregorianLikeFiscalYear,
     formatAmountToWesternArabicNumeralsWithoutDigitGrouping,
     formatAmountToLocalizedNumeralsWithCurrency
 } = useI18n();
@@ -151,16 +152,18 @@ const allDisplayDateRanges = computed<string[]>(() => {
     const allDisplayDateRanges: string[] = [];
 
     for (const dateRange of allDateRanges.value) {
+        const minDateTime = parseDateTimeFromUnixTime(dateRange.minUnixTime);
+
         if (props.dateAggregationType === ChartDateAggregationType.Year.type) {
-            allDisplayDateRanges.push(formatUnixTimeToGregorianLikeShortYear(dateRange.minUnixTime));
+            allDisplayDateRanges.push(formatDateTimeToGregorianLikeShortYear(minDateTime));
         } else if (props.dateAggregationType === ChartDateAggregationType.FiscalYear.type && 'year' in dateRange) {
-            allDisplayDateRanges.push(formatUnixTimeToGregorianLikeFiscalYear(dateRange.minUnixTime));
+            allDisplayDateRanges.push(formatDateTimeToGregorianLikeFiscalYear(minDateTime));
         } else if (props.dateAggregationType === ChartDateAggregationType.Quarter.type && 'quarter' in dateRange) {
             allDisplayDateRanges.push(formatYearQuarterToGregorianLikeYearQuarter(dateRange.year, dateRange.quarter));
         } else if (props.dateAggregationType === ChartDateAggregationType.Month.type) {
-            allDisplayDateRanges.push(formatUnixTimeToGregorianLikeShortYearMonth(dateRange.minUnixTime));
+            allDisplayDateRanges.push(formatDateTimeToGregorianLikeShortYearMonth(minDateTime));
         } else if (props.dateAggregationType === ChartDateAggregationType.Day.type && props.chartMode === 'daily') {
-            allDisplayDateRanges.push(formatUnixTimeToShortDate(dateRange.minUnixTime));
+            allDisplayDateRanges.push(formatDateTimeToShortDate(minDateTime));
         }
     }