Show manga with no installed source. Based on PR #1345

app/src/main/java/eu/kanade/tachiyomi/source/SourceManager.kt

@@ -1,17 +1,24 @@
 package eu.kanade.tachiyomi.source
 
 import android.content.Context
+import eu.kanade.tachiyomi.R
+import eu.kanade.tachiyomi.source.model.Page
+import eu.kanade.tachiyomi.source.model.SChapter
+import eu.kanade.tachiyomi.source.model.SManga
 import eu.kanade.tachiyomi.source.online.HttpSource
 import eu.kanade.tachiyomi.source.online.english.*
 import eu.kanade.tachiyomi.source.online.german.WieManga
 import eu.kanade.tachiyomi.source.online.russian.Mangachan
 import eu.kanade.tachiyomi.source.online.russian.Mintmanga
 import eu.kanade.tachiyomi.source.online.russian.Readmanga
+import rx.Observable
 
 open class SourceManager(private val context: Context) {
 
     private val sourcesMap = mutableMapOf<Long, Source>()
 
+    private val stubSourcesMap = mutableMapOf<Long, StubSource>()
+
     init {
         createInternalSources().forEach { registerSource(it) }
     }
@@ -20,13 +27,19 @@ open class SourceManager(private val context: Context) {
         return sourcesMap[sourceKey]
     }
 
+    fun getOrStub(sourceKey: Long): Source {
+        return sourcesMap[sourceKey] ?: stubSourcesMap.getOrPut(sourceKey) {
+            StubSource(sourceKey)
+        }
+    }
+
     fun getOnlineSources() = sourcesMap.values.filterIsInstance<HttpSource>()
 
     fun getCatalogueSources() = sourcesMap.values.filterIsInstance<CatalogueSource>()
 
     internal fun registerSource(source: Source, overwrite: Boolean = false) {
         if (overwrite || !sourcesMap.containsKey(source.id)) {
-            sourcesMap.put(source.id, source)
+            sourcesMap[source.id] = source
         }
     }
 
@@ -47,4 +60,30 @@ open class SourceManager(private val context: Context) {
             Mangasee(),
             WieManga()
     )
+
+    private inner class StubSource(override val id: Long) : Source {
+
+        override val name: String
+            get() = id.toString()
+
+        override fun fetchMangaDetails(manga: SManga): Observable<SManga> {
+            return Observable.error(getSourceNotInstalledException())
+        }
+
+        override fun fetchChapterList(manga: SManga): Observable<List<SChapter>> {
+            return Observable.error(getSourceNotInstalledException())
+        }
+
+        override fun fetchPageList(chapter: SChapter): Observable<List<Page>> {
+            return Observable.error(getSourceNotInstalledException())
+        }
+
+        override fun toString(): String {
+            return name
+        }
+
+        private fun getSourceNotInstalledException(): Exception {
+            return Exception(context.getString(R.string.source_not_installed, id.toString()))
+        }
+    }
 }