Feature/improve automatic chapter downloads (#680)

* Rename "newChapters" to "updatedChapterList"

* Do not auto download new chapters of entries with unread chapters

Makes it possible to prevent unnecessary chapter downloads in case the entry hasn't yet been caught up

* Optionally limit auto new chapter downloads

* Prevent downloading new chapters for mangas not in the library

server/src/main/kotlin/suwayomi/tachidesk/manga/impl/Chapter.kt

@@ -196,28 +196,48 @@ object Chapter {
             }
         }
 
-        downloadNewChapters(mangaId, numberOfCurrentChapters, newChapters)
+        if (manga.inLibrary) {
+            downloadNewChapters(mangaId, numberOfCurrentChapters, newChapters)
+        }
 
         return chapterList
     }
 
-    private fun downloadNewChapters(mangaId: Int, prevNumberOfChapters: Int, newChapters: List<ResultRow>) {
+    private fun downloadNewChapters(mangaId: Int, prevNumberOfChapters: Int, updatedChapterList: List<ResultRow>) {
         // convert numbers to be index based
         val currentNumberOfChapters = (prevNumberOfChapters - 1).coerceAtLeast(0)
-        val updatedNumberOfChapters = (newChapters.size - 1).coerceAtLeast(0)
+        val updatedNumberOfChapters = (updatedChapterList.size - 1).coerceAtLeast(0)
+        val numberOfNewChapters = updatedNumberOfChapters - currentNumberOfChapters
 
-        val areNewChaptersAvailable = currentNumberOfChapters < updatedNumberOfChapters
+        val areNewChaptersAvailable = numberOfNewChapters > 0
         val wasInitialFetch = currentNumberOfChapters == 0
 
         // make sure to ignore initial fetch
-        val downloadNewChapters = serverConfig.autoDownloadNewChapters.value && !wasInitialFetch && areNewChaptersAvailable
+        val isDownloadPossible =
-        if (!downloadNewChapters) {
+            serverConfig.autoDownloadNewChapters.value && areNewChaptersAvailable && !wasInitialFetch
+        if (!isDownloadPossible) {
             return
         }
 
-        val numberOfNewChapters = updatedNumberOfChapters - currentNumberOfChapters
+        val newChapters = updatedChapterList.subList(0, numberOfNewChapters)
-        val chapterIdsToDownload = newChapters.subList(0, numberOfNewChapters)
+
-            .filter { !it[ChapterTable.isRead] && !it[ChapterTable.isDownloaded] }.map { it[ChapterTable.id].value }
+        // make sure to only consider the latest chapters. e.g. old unread chapters should be ignored
+        val latestReadChapterIndex =
+            updatedChapterList.indexOfFirst { it[ChapterTable.isRead] }.takeIf { it > -1 } ?: return
+        val unreadChapters = updatedChapterList.subList(numberOfNewChapters, latestReadChapterIndex)
+            .filter { !it[ChapterTable.isRead] }
+
+        val skipDueToUnreadChapters = serverConfig.excludeEntryWithUnreadChapters.value && unreadChapters.isNotEmpty()
+        if (skipDueToUnreadChapters) {
+            return
+        }
+
+        val firstChapterToDownloadIndex =
+            (numberOfNewChapters - serverConfig.autoDownloadAheadLimit.value).coerceAtLeast(0)
+
+        val chapterIdsToDownload = newChapters.subList(firstChapterToDownloadIndex, numberOfNewChapters)
+            .filter { !it[ChapterTable.isRead] && !it[ChapterTable.isDownloaded] }
+            .map { it[ChapterTable.id].value }
 
         if (chapterIdsToDownload.isEmpty()) {
             return

server/src/main/kotlin/suwayomi/tachidesk/server/ServerConfig.kt

@@ -73,6 +73,8 @@ class ServerConfig(getConfig: () -> Config, val moduleName: String = SERVER_CONF
     val downloadAsCbz: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
     val downloadsPath: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
     val autoDownloadNewChapters: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
+    val excludeEntryWithUnreadChapters: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
+    val autoDownloadAheadLimit: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
 
     // requests
     val maxSourcesInParallel: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)

server/src/main/resources/server-reference.conf

@@ -20,6 +20,8 @@ server.webUIUpdateCheckInterval = 23 # time in hours - 0 to disable auto update
 server.downloadAsCbz = false
 server.downloadsPath = ""
 server.autoDownloadNewChapters = false # if new chapters that have been retrieved should get automatically downloaded
+server.excludeEntryWithUnreadChapters = true # ignore automatic chapter downloads of entries with unread chapters
+server.autoDownloadAheadLimit = 5 # 0 to disable it - how many unread downloaded chapters should be available - if the limit is reached, new chapters won't be downloaded automatically
 
 # requests
 server.maxSourcesInParallel = 6 # range: 1 <= n <= 20 - default: 6 - sets how many sources can do requests (updates, downloads) in parallel. updates/downloads are grouped by source and all mangas of a source are updated/downloaded synchronously

server/src/test/resources/server-reference.conf

@@ -10,6 +10,8 @@ server.socksProxyPort = ""
 # downloader
 server.downloadAsCbz = false
 server.autoDownloadNewChapters = false
+server.excludeEntryWithUnreadChapters = true
+server.autoDownloadAheadLimit = 5
 
 # requests
 server.maxSourcesInParallel = 10