fix(CustomExport): 修复导出章节列表越界的问题，优化导出逻辑

app/src/main/java/io/legado/app/help/book/BookExtensions.kt

@@ -243,4 +243,25 @@ fun Book.getExportFileName(suffix: String): String {
     }.onFailure {
         AppLog.put("导出书名规则错误,使用默认规则\n${it.localizedMessage}", it)
     }.getOrDefault("${name} 作者：${getRealAuthor()}.$suffix")
+}
+
+/**
+ * 获取分割文件后的文件名
+ */
+fun Book.getExportFileName(suffix: String, epubIndex: Int): String {
+    val jsStr = AppConfig.bookExportFileName
+    // 默认规则
+    val default = "$name 作者：${getRealAuthor()} [${epubIndex}].$suffix"
+    if (jsStr.isNullOrBlank()) {
+        return default
+    }
+    val bindings = SimpleBindings()
+    bindings["name"] = name
+    bindings["author"] = getRealAuthor()
+    bindings["epubIndex"] = epubIndex
+    return kotlin.runCatching {
+        RhinoScriptEngine.eval(jsStr, bindings).toString() + "." + suffix
+    }.onFailure {
+        AppLog.put("导出书名规则错误,使用默认规则\n${it.localizedMessage}", it)
+    }.getOrDefault(default)
 }

app/src/main/java/io/legado/app/ui/book/cache/CacheViewModel.kt

@@ -689,10 +689,11 @@ class CacheViewModel(application: Application) : BaseViewModel(application) {
          */
         private suspend fun exportEpub(doc: DocumentFile, book: Book) {
             val (contentModel, epubList) = createEpubs(doc, book)
-            epubList.forEachIndexed { index, epubBook ->
+            epubList.forEachIndexed { index, ep ->
+                val (filename, epubBook) = ep
                 //设置正文
                 this.setEpubContent(contentModel, book, epubBook, index)
-                save2Drive(book.name + index + ".epub", epubBook, doc)
+                save2Drive(filename, epubBook, doc)
             }
 
         }
@@ -717,13 +718,17 @@ class CacheViewModel(application: Application) : BaseViewModel(application) {
                 if (scope.indexOf(index) >= 0) {
                     chapterList.add(chapter)
                 }
+                if (scope.size == chapterList.size) {
+                    return@forEachIndexed
+                }
             }
             val totalChapterNum = book.totalChapterNum / scope.size
-            chapterList = chapterList.subList(epubBookIndex * size, (epubBookIndex + 1) * size)
+            chapterList = chapterList.subList(epubBookIndex * size, if((epubBookIndex + 1) * size > scope.size) scope.size else (epubBookIndex + 1) * size)
             chapterList.forEachIndexed { index, chapter ->
                 coroutineContext.ensureActive()
                 context.upAdapterLiveData.postValue(book.bookUrl)
-                context.exportProgress[book.bookUrl] = totalChapterNum * (epubBookIndex * size + index)
+                context.exportProgress[book.bookUrl] =
+                    totalChapterNum * (epubBookIndex * size + index)
                 BookHelp.getContent(book, chapter).let { content ->
                     var content1 = context.fixPic(
                         epubBook,
@@ -764,13 +769,21 @@ class CacheViewModel(application: Application) : BaseViewModel(application) {
 
         /**
          * 创建多个epub 对象
+         *
+         * @param doc 导出文档
+         * @param book 书籍
+         *
+         * @return <内容模板字符串, <epub文件名, epub对象>>
          */
-        private fun createEpubs(doc: DocumentFile, book: Book): Pair<String, List<EpubBook>> {
+        private fun createEpubs(
+            doc: DocumentFile,
+            book: Book
+        ): Pair<String, List<Pair<String, EpubBook>>> {
             val paresNumOfEpub = paresNumOfEpub(scope.size, size)
-            val result: MutableList<EpubBook> = ArrayList(paresNumOfEpub)
+            val result: MutableList<Pair<String, EpubBook>> = ArrayList(paresNumOfEpub)
             var contentModel = ""
             for (i in 1..paresNumOfEpub) {
-                val filename = book.getExportFileName("epub")
+                val filename = book.getExportFileName("epub", i)
                 DocumentUtils.delete(doc, filename)
                 val epubBook = EpubBook()
                 epubBook.version = "2.0"
@@ -782,7 +795,7 @@ class CacheViewModel(application: Application) : BaseViewModel(application) {
                 contentModel = context.setAssets(doc, book, epubBook)
 
                 // add epubBook
-                result.add(epubBook)
+                result.add(Pair(filename, epubBook))
             }
             return Pair(contentModel, result)
         }