Fix indexing and path for downloaded chapter images and update padding logic

lib/modules/manga/download/providers/download_provider.dart

@@ -281,7 +281,7 @@ Future<void> downloadChapter(
 
         if (itemType == ItemType.manga) {
           final file = File(
-            p.join(chapterDirectory.path, "${padIndex(index + 1)}.jpg"),
+            p.join(chapterDirectory.path, "${padIndex(index)}.jpg"),
           );
           if (!file.existsSync()) {
             pages.add(
@@ -290,7 +290,7 @@ Future<void> downloadChapter(
                 headers: pageHeaders,
                 fileName: p.join(
                   chapterDirectory.path,
-                  "${padIndex(index + 1)}.jpg",
+                  "${padIndex(index)}.jpg",
                 ),
               ),
             );

lib/services/get_chapter_pages.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
+import 'package:path/path.dart' as p;
 import 'package:mangayomi/eval/lib.dart';
 import 'package:mangayomi/eval/javascript/http.dart';
 import 'package:mangayomi/main.dart';
@@ -93,10 +94,7 @@ Future<GetChapterPagesModel> getChapterPages(
     } else {
       for (var i = 0; i < pageUrls.length; i++) {
         archiveImages.add(null);
-        if (await File(
-          "${path!.path}"
-          "${padIndex(i + 1)}.jpg",
-        ).exists()) {
+        if (await File(p.join(path!.path, '${padIndex(i)}.jpg')).exists()) {
           isLocaleList.add(true);
         } else {
           isLocaleList.add(false);

lib/utils/extensions/others.dart

@@ -12,6 +12,7 @@ import 'package:mangayomi/utils/headers.dart';
 import 'package:mangayomi/utils/reg_exp_matcher.dart';
 import 'package:path/path.dart';
 import 'package:path_provider/path_provider.dart';
+import 'package:path/path.dart' as p;
 
 extension LetExtension<T> on T {
   R let<R>(R Function(T) block) {
@@ -49,7 +50,7 @@ extension UChapDataPreloadExtensions on UChapDataPreload {
       imageBytes = archiveImage;
     } else if (isLocale!) {
       imageBytes = File(
-        '${directory!.path}${padIndex(index! + 1)}.jpg',
+        p.join(directory!.path, "${padIndex(index!)}.jpg"),
       ).readAsBytesSync();
     } else {
       File? cachedImage;
@@ -86,7 +87,10 @@ extension UChapDataPreloadExtensions on UChapDataPreload {
                         ? ExtendedMemoryImageProvider(archiveImage)
                         : ExtendedFileImageProvider(
                             File(
-                              '${data.directory!.path}${padIndex(data.index! + 1)}.jpg',
+                              p.join(
+                                data.directory!.path,
+                                "${padIndex(data.index!)}.jpg",
+                              ),
                             ),
                           )
                   : CustomExtendedNetworkImageProvider(

lib/utils/reg_exp_matcher.dart

@@ -38,5 +38,5 @@ String regCustomMatcher(String input, String source, int group) {
 }
 
 String padIndex(int index) {
-  return index.toString().padLeft(3, "0");
+  return (index + 1).toString().padLeft(3, "0");
 }