Fix locale inconsistencies between intl and moment

The month names used by moment are different than the ones
in intl, leading to validation errors.
Get the month and weekday names from intl, and patch
the moment locale to use those.

DateTimePicker.php

@@ -187,9 +187,29 @@ protected function registerLocale($view)
         if ($file === false) {
             return;
         }
+
         $view->registerJsFile(Yii::$app->assetManager->publish($file)[1], [
             'depends' => '\nkovacs\datetimepicker\MomentAsset',
         ]);
+
+        // use the same strings intl uses, to avoid validation errors.
+        if (extension_loaded('intl')) {
+            $weekdays = LocaleConverter::getWeekdays('EEEE', $this->locale); // dddd
+            $weekdaysShort = LocaleConverter::getWeekdays('EEE', $this->locale); // ddd
+            $weekdaysMin = LocaleConverter::getWeekdays('EEEEEE', $this->locale); // dd
+            $months = LocaleConverter::getMonths('MMMM', $this->locale);
+            $monthsShort = LocaleConverter::getMonths('MMM', $this->locale);
+            $override = Json::encode([
+                'months' => $months,
+                'monthsShort' => $monthsShort,
+                'weekdays' => $weekdays,
+                'weekdaysShort' => $weekdaysShort,
+                'weekdaysMin' => $weekdaysMin,
+            ]);
+            // POS_END is the default for js files.
+            $view->registerJs("moment.locale('$locale', $override)", \yii\web\View::POS_END);
+        }
+
         $this->clientOptions['locale'] = $locale;
     }
 

LocaleConverter.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace nkovacs\datetimepicker;
+
+use Yii;
+use IntlDateFormatter;
+
+class LocaleConverter
+{
+    protected static $cache = [];
+
+    public static function getMonths($format, $locale = null) {
+        if ($locale === null) {
+            $locale = Yii::$app->language;
+        }
+
+        if (!isset(static::$cache['months'][$locale][$format])) {
+            $formatter = new IntlDateFormatter($locale, IntlDateFormatter::NONE, IntlDateFormatter::NONE, Yii::$app->timeZone, null, $format);
+            $localized = [];
+            for ($month = 0; $month < 12; $month++) {
+                $localized[] = $formatter->format([
+                    'tm_sec' => 0,
+                    'tm_min' => 0,
+                    'tm_hour' => 12,
+                    'tm_mday' => 15,
+                    'tm_mon' => $month,
+                    'tm_year' => 2016,
+                ]);
+            }
+            static::$cache['months'][$locale][$format] = $localized;
+        }
+        return static::$cache['months'][$locale][$format];
+    }
+
+    public static function getWeekdays($format, $locale = null) {
+        if ($locale === null) {
+            $locale = Yii::$app->language;
+        }
+        if (!isset(static::$cache['weekdays'][$locale][$format])) {
+            $formatter = new IntlDateFormatter($locale, IntlDateFormatter::NONE, IntlDateFormatter::NONE, Yii::$app->timeZone, null, $format);
+            $localized = [];
+            for ($day = 0; $day < 7; $day++) {
+                $localized[] = $formatter->format([
+                    'tm_sec' => 0,
+                    'tm_min' => 0,
+                    'tm_hour' => 12,
+                    'tm_mon' => 6,
+                    'tm_year' => 2016,
+                    'tm_mday' => 2 + $day, // 2016-06-02 is a sunday
+                ]);
+            }
+            static::$cache['weekdays'][$locale][$format] = $localized;
+        }
+        return static::$cache['weekdays'][$locale][$format];
+    }
+}