Feature/refresh outdated thumbnail url on fetch failure (#910)

* Extract thumbnail url fresh into function

* Remove incorrect non-null assertion

According to the typing there is no guarantee that fetching a manga from the source provides a thumbnail url

* Refresh manga thumbnail url on 404 error

* Refresh manga thumbnail url on unreachable origin cloudflare errors

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

@@ -8,13 +8,17 @@ package suwayomi.tachidesk.manga.impl
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 import eu.kanade.tachiyomi.network.GET
+import eu.kanade.tachiyomi.network.HttpException
 import eu.kanade.tachiyomi.network.NetworkHelper
+import eu.kanade.tachiyomi.network.awaitSuccess
 import eu.kanade.tachiyomi.source.local.LocalSource
 import eu.kanade.tachiyomi.source.model.SManga
 import eu.kanade.tachiyomi.source.model.UpdateStrategy
 import eu.kanade.tachiyomi.source.online.HttpSource
+import io.javalin.http.HttpCode
 import mu.KotlinLogging
 import okhttp3.CacheControl
+import okhttp3.Response
 import org.jetbrains.exposed.sql.ResultRow
 import org.jetbrains.exposed.sql.SortOrder
 import org.jetbrains.exposed.sql.and
@@ -251,9 +255,53 @@ object Manga {
         }
     }
 
+    private suspend fun fetchThumbnailUrl(mangaId: Int): String? {
+        getManga(mangaId, true)
+        return transaction {
+            MangaTable.select { MangaTable.id eq mangaId }.first()
+        }[MangaTable.thumbnail_url]
+    }
+
     private val applicationDirs by DI.global.instance<ApplicationDirs>()
     private val network: NetworkHelper by injectLazy()
 
+    private suspend fun fetchHttpSourceMangaThumbnail(
+        source: HttpSource,
+        mangaEntry: ResultRow,
+        refreshUrl: Boolean = false,
+    ): Response {
+        val mangaId = mangaEntry[MangaTable.id].value
+
+        val requiresInitialization = mangaEntry[MangaTable.thumbnail_url] == null && !mangaEntry[MangaTable.initialized]
+        val refreshThumbnailUrl = refreshUrl || requiresInitialization
+
+        val thumbnailUrl =
+            if (refreshThumbnailUrl) {
+                fetchThumbnailUrl(mangaId)
+            } else {
+                mangaEntry[MangaTable.thumbnail_url]
+            } ?: throw NullPointerException("No thumbnail found")
+
+        return try {
+            source.client.newCall(
+                GET(thumbnailUrl, source.headers, cache = CacheControl.FORCE_NETWORK),
+            ).awaitSuccess()
+        } catch (e: HttpException) {
+            val tryToRefreshUrl =
+                !refreshUrl &&
+                    listOf(
+                        HttpCode.NOT_FOUND.status,
+                        523, // (Cloudflare) Origin Is Unreachable
+                        522, // (Cloudflare) Connection timed out
+                    ).contains(e.code)
+            if (!tryToRefreshUrl) {
+                throw e
+            }
+
+            fetchHttpSourceMangaThumbnail(source, mangaEntry, refreshUrl = true)
+        }
+    }
+
     suspend fun fetchMangaThumbnail(mangaId: Int): Pair<InputStream, String> {
         val cacheSaveDir = applicationDirs.tempThumbnailCacheRoot
         val fileName = mangaId.toString()
@@ -264,22 +312,7 @@ object Manga {
         return when (val source = getCatalogueSourceOrStub(sourceId)) {
             is HttpSource ->
                 getImageResponse(cacheSaveDir, fileName) {
-                    val thumbnailUrl =
+                    fetchHttpSourceMangaThumbnail(source, mangaEntry)
-                        mangaEntry[MangaTable.thumbnail_url]
-                            ?: if (!mangaEntry[MangaTable.initialized]) {
-                                // initialize then try again
-                                getManga(mangaId)
-                                transaction {
-                                    MangaTable.select { MangaTable.id eq mangaId }.first()
-                                }[MangaTable.thumbnail_url]!!
-                            } else {
-                                // source provides no thumbnail url for this manga
-                                throw NullPointerException("No thumbnail found")
-                            }
-
-                    source.client.newCall(
-                        GET(thumbnailUrl, source.headers, cache = CacheControl.FORCE_NETWORK),
-                    ).await()
                 }
 
             is LocalSource -> {