assets/js: make new flatpickr language aware and fix some small issues

- selecting a start date in a later month than the end date wouldn't
  move the end date picker to the new month
- remove the possibility to select a start date past the current end
  date

adhocracy-plus/assets/js/init-picker.js

@@ -1,24 +1,34 @@
 import django from 'django'
 import flatpickr from 'flatpickr'
+import { German } from 'flatpickr/dist/l10n/de.js'
+import { Russian } from 'flatpickr/dist/l10n/ru.js'
+import { Dutch } from 'flatpickr/dist/l10n/nl.js'
+import English from 'flatpickr/dist/l10n/default.js'
 
-function link (f0, f1) {
-  const date = f0.selectedDates[0]
-  if (date) {
-    // if p0 has a date set that date as minDate for p1
-    f1.set('minDate', f0.formatDate(date, f0.config.dateFormat))
+// Helper to link start and end date pickers
+function linkPair (startPicker, endPicker) {
+  const selectedDate = startPicker.selectedDates[0]
+  if (selectedDate) {
+    endPicker.set(
+      'minDate',
+      startPicker.formatDate(selectedDate, startPicker.config.dateFormat)
+    )
   }
-  f0.config.onChange.push((selectedDates, dateStr) => {
-    // if date of p0 is changed adapt minDate for p1
-    f1.set('minDate', dateStr)
+  startPicker.config.onChange.push((selectedDates, dateStr) => {
+    if (selectedDates[0] > endPicker.selectedDates[0]) endPicker.clear()
+    endPicker.set('minDate', dateStr)
+  })
+
+  endPicker.config.onChange.push((selectedDates, dateStr) => {
+    if (selectedDates[0] < startPicker.selectedDates[0]) startPicker.clear()
+    startPicker.set('maxDate', dateStr)
   })
 }
 
-function linkDatePickers (flatpickrs) {
-  // normal flatpickers
-  const idStart = 'id_start_date_date'
-  const idEnd = 'id_end_date_date'
-  // (multi-)phase flatpickrs
-  const phaseIds = [
+// Initializes linked date pickers for start and end date fields
+function linkDatePickers (flatpickrsMap) {
+  const singlePhaseIds = ['id_start_date_date', 'id_end_date_date']
+  const multiPhaseIds = [
     'id_phase_set-0-start_date_date',
     'id_phase_set-0-end_date_date',
     'id_phase_set-1-start_date_date',
@@ -27,50 +37,55 @@ function linkDatePickers (flatpickrs) {
     'id_phase_set-2-end_date_date'
   ]
 
-  // link non-phase datepickers if exist
-  const fStart = flatpickrs.get(idStart)
-  const fEnd = flatpickrs.get(idEnd)
-  if (fStart && fEnd) {
-    link(fStart, fEnd)
-  }
+  // Link single-phase pickers
+  const startPicker = flatpickrsMap.get(singlePhaseIds[0])
+  const endPicker = flatpickrsMap.get(singlePhaseIds[1])
+  if (startPicker && endPicker) linkPair(startPicker, endPicker)
 
-  // link phase datepickers if exist
-  for (let i = 0; i < phaseIds.length - 1; i++) {
-    if (flatpickrs.length <= i) {
-      return
-    }
-    const p0 = flatpickrs.get(phaseIds[i])
-    const p1 = flatpickrs.get(phaseIds[i + 1])
-    if (p0 && p1) {
-      link(p0, p1)
-    }
+  // Link multi-phase pickers in pairs
+  for (let i = 0; i < multiPhaseIds.length - 1; i += 2) {
+    const phaseStartPicker = flatpickrsMap.get(multiPhaseIds[i])
+    const phaseEndPicker = flatpickrsMap.get(multiPhaseIds[i + 1])
+    if (phaseStartPicker && phaseEndPicker) { linkPair(phaseStartPicker, phaseEndPicker) }
   }
 }
 
+// Returns the appropriate language object based on the document language
+function getLanguage () {
+  const languages = { de: German, nl: Dutch, ru: Russian }
+  return languages[document.documentElement.lang] || English
+}
+
+// Initializes all date and time pickers on the page
 function initDatePicker () {
-  const datepickers = document.querySelectorAll('.datepicker')
-  const format = django.get_format('DATE_INPUT_FORMATS')[0].replaceAll('%', '')
-  const flatpickrs = new Map()
-  datepickers.forEach((e) => {
-    e.classList.add('form-control')
-    const f = flatpickr(e, { dateFormat: format })
-    flatpickrs.set(e.id, f)
-  })
+  const lang = getLanguage()
+  const dateFormat = django
+    .get_format('DATE_INPUT_FORMATS')[0]
+    .replaceAll('%', '')
+  const flatpickrsMap = new Map()
 
-  linkDatePickers(flatpickrs)
+  // Initialize date pickers
+  document.querySelectorAll('.datepicker').forEach((element) => {
+    element.classList.add('form-control')
+    const datePicker = flatpickr(element, { dateFormat, locale: lang })
+    flatpickrsMap.set(element.id, datePicker)
+  })
 
-  const timepickers = document.querySelectorAll('.timepicker')
+  // Link date pickers if needed
+  linkDatePickers(flatpickrsMap)
 
-  timepickers.forEach((e) => {
-    const f = flatpickr(e, {
-      defaultHour: e.id.endsWith('start_date_time') ? '00' : '23',
-      defaultMinute: e.id.endsWith('start_date_time') ? '00' : '59',
+  // Initialize time pickers
+  document.querySelectorAll('.timepicker').forEach((element) => {
+    const timePicker = flatpickr(element, {
+      defaultHour: element.id.endsWith('start_date_time') ? '00' : '23',
+      defaultMinute: element.id.endsWith('start_date_time') ? '00' : '59',
       dateFormat: 'H:i',
       enableTime: true,
       noCalendar: true,
-      time_24hr: true
+      time_24hr: true,
+      locale: lang
     })
-    flatpickrs.set(e.id, f)
+    flatpickrsMap.set(element.id, timePicker)
   })
 }