fix: complexe calendar system conversions are now working, example: p…

…ersian to islamic to gregory to persian....

src/index.js

@@ -322,15 +322,12 @@ export default (options, dayjsClass, dayjsFactory) => {
     // If the instance is not already in the required calendar system, initialize it
     // You would also convert the date to the specified calendar here.
     if (newInstance.$C !== calendar) {
-      // Store the current calendar system in $C
-      newInstance.$C = calendar;
-      // if calendar is gregorian, convert to gregorian, otherwise convert to calendar
+      // if target calendar is gregorian, convert to gregorian, otherwise convert to calendar
       if (calendar === "gregory") {
-        const gregoryDate = newInstance.toDate();
-        const convertedDate = calendarSystems[calendar].convertToGregorian(
-          gregoryDate.getFullYear(),
-          gregoryDate.getMonth(),
-          gregoryDate.getDate()
+        const convertedDate = calendarSystems[newInstance.$C || "gregory"].convertToGregorian(
+          newInstance.$y,
+          newInstance.$M,
+          newInstance.$D
         );
         newInstance.$G_y = convertedDate.year;
         newInstance.$G_M = convertedDate.month;
@@ -355,6 +352,9 @@ export default (options, dayjsClass, dayjsFactory) => {
         newInstance.$M = convertedDate.month;
         newInstance.$D = convertedDate.day;
       }
+
+      // Store the target calendar system in $C
+      newInstance.$C = calendar;
     }
     // Update the locale to reflect the new calendar system
     dayjsFactory.updateLocale(

test/calendarSystemConversions.test.js

@@ -0,0 +1,64 @@
+import dayjs from "dayjs";
+import calendarSystems from "../src/index";
+import GregoryCalendarSystem from "../src/calendarSystems/GregoryCalendarSystem";
+import PersianCalendarSystem from "../src/calendarSystems/PersianCalendarSystem";
+import HijriCalendarSystem from "../src/calendarSystems/HijriCalendarSystem";
+
+describe('Calendar Systems Conversion', () => {
+  const targetDate = "2023-05-24";
+  const targetPersianDate = "1402-03-03";
+  const targetIslamicDate = "1444-11-04";
+
+  beforeAll(() => {
+    dayjs.extend(calendarSystems);
+    dayjs.registerCalendarSystem("gregory", new GregoryCalendarSystem());
+    dayjs.registerCalendarSystem("persian", new PersianCalendarSystem());
+    dayjs.registerCalendarSystem("islamic", new HijriCalendarSystem());
+  });
+
+  test('Convert to Persian', () => {
+    const persianDate = dayjs(targetDate).toCalendarSystem("persian").format("YYYY-MM-DD");
+    expect(persianDate).toEqual(targetPersianDate);
+  });
+
+  test('Convert to Gregorian', () => {
+    const gregorianDate = dayjs(targetDate).toCalendarSystem("gregory").format("YYYY-MM-DD");
+    expect(gregorianDate).toEqual(targetDate); // Gregorian date should be the same as targetDate
+  });
+
+  test('Convert to Islamic', () => {
+    const hijriDate = dayjs(targetDate).toCalendarSystem("islamic").format("YYYY-MM-DD");
+    expect(hijriDate).toEqual(targetIslamicDate);
+  });
+
+  test('Convert Persian to Gregorian', () => {
+    const persianToGregorian = dayjs(targetDate).toCalendarSystem("persian").toCalendarSystem("gregory").format("YYYY-MM-DD");
+    expect(persianToGregorian).toEqual(targetDate);
+  });
+
+  test('Convert Persian to Islamic', () => {
+    const persianToIslamic = dayjs(targetDate).toCalendarSystem("persian").toCalendarSystem("islamic").format("YYYY-MM-DD");
+    expect(persianToIslamic).toEqual(targetIslamicDate);
+  });
+
+  test('Convert Gregorian to Persian', () => {
+    const gregorianToPersian = dayjs(targetDate).toCalendarSystem("gregory").toCalendarSystem("persian").format("YYYY-MM-DD");
+    expect(gregorianToPersian).toEqual(targetPersianDate);
+  });
+
+  test('Convert Gregorian to Islamic', () => {
+    const gregorianToIslamic = dayjs(targetDate).toCalendarSystem("gregory").toCalendarSystem("islamic").format("YYYY-MM-DD");
+    expect(gregorianToIslamic).toEqual(targetIslamicDate);
+  });
+
+  test('Convert Islamic to Persian', () => {
+    const islamicToPersian = dayjs(targetDate).toCalendarSystem("islamic").toCalendarSystem("persian").format("YYYY-MM-DD");
+    expect(islamicToPersian).toEqual(targetPersianDate);
+  });
+
+  test('Convert Islamic to Gregorian', () => {
+    const islamicToGregorian = dayjs(targetDate).toCalendarSystem("islamic").toCalendarSystem("gregory").format("YYYY-MM-DD");
+    expect(islamicToGregorian).toEqual(targetDate);
+  });
+
+});