added duplicate manga check

When adding a manga to your library, the app will go through each manga previously added and compare their names. If a match is detected, it will prompt the user and ask for confirmation. On this prompt there is also an option to view the other manga.

app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaController.kt

@@ -2,6 +2,7 @@ package eu.kanade.tachiyomi.ui.manga
 
 import android.app.Activity
 import android.app.ActivityOptions
+import android.app.AlertDialog
 import android.content.Context
 import android.content.Intent
 import android.graphics.Bitmap
@@ -516,9 +517,54 @@ class MangaController :
             activity?.toast(activity?.getString(R.string.manga_removed_library))
             activity?.invalidateOptionsMenu()
         } else {
+            if (!isDuplicateOfOtherSource(manga)) {
                 addToLibrary(manga)
             }
         }
+    }
+
+    private fun isDuplicateOfOtherSource(origin: Manga): Boolean {
+        var result = false
+        val mangas = presenter.getAllMangaMutableList()
+
+        mangas.forEach { item ->
+            if (isSameManga(origin, item)) {
+                showAddDuplicateDialog(
+                    origin,
+                    item,
+                    getSourceFromLong(item.source)
+                )
+                result = true
+                return@forEach
+            }
+        }
+
+        return result
+    }
+
+    private fun isSameManga(origin: Manga, other: Manga): Boolean {
+        return origin.title.equals(other.title, ignoreCase = true) &&
+            // Source check, just in case we fetched the library list before it got removed
+            origin.source != other.source
+    }
+
+    private fun getSourceFromLong(sourceId: Long): Source {
+        return Injekt.get<SourceManager>().getOrStub(sourceId)
+    }
+
+    private fun showAddDuplicateDialog(manga: Manga, other: Manga, source: Source) {
+        AlertDialog.Builder(activity).apply {
+            setMessage(activity?.getString(R.string.confirm_manga_add_duplicate, source.name))
+            setPositiveButton(activity?.getString(R.string.action_add)) { _, _, ->
+                addToLibrary(manga)
+            }
+            setNegativeButton(activity?.getString(R.string.action_cancel)) { _, _, -> }
+            setNeutralButton(activity?.getString(R.string.action_show_manga)) { _, _, ->
+                router.pushController(MangaController(other).withFadeTransaction())
+            }
+            setCancelable(true)
+        }.create().show()
+    }
 
     fun onTrackingClick() {
         trackSheet?.show()

app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaPresenter.kt

@@ -12,6 +12,7 @@ import eu.kanade.tachiyomi.data.cache.CoverCache
 import eu.kanade.tachiyomi.data.database.DatabaseHelper
 import eu.kanade.tachiyomi.data.database.models.Category
 import eu.kanade.tachiyomi.data.database.models.Chapter
+import eu.kanade.tachiyomi.data.database.models.LibraryManga
 import eu.kanade.tachiyomi.data.database.models.Manga
 import eu.kanade.tachiyomi.data.database.models.MangaCategory
 import eu.kanade.tachiyomi.data.database.models.Track
@@ -174,6 +175,10 @@ class MangaPresenter(
         fetchTrackers()
     }
 
+    fun getAllMangaMutableList(): MutableList<LibraryManga> {
+        return db.getLibraryMangas().executeAsBlocking()
+    }
+
     // Manga info - start
 
     private fun getMangaObservable(): Observable<Manga> {

app/src/main/res/values/strings.xml

@@ -81,6 +81,7 @@
     <string name="action_start">Start</string>
     <string name="action_resume">Resume</string>
     <string name="action_open_in_browser">Open in browser</string>
+    <string name="action_show_manga">Show manga</string>
     <!-- Do not translate "WebView" -->
     <string name="action_open_in_web_view">Open in WebView</string>
     <string name="action_web_view" translatable="false">WebView</string>
@@ -571,6 +572,7 @@
     <string name="in_library">In library</string>
     <string name="remove_from_library">Remove from library</string>
     <string name="manga_info_full_title_label">Title</string>
+    <string name="confirm_manga_add_duplicate">We found a manga in your library with the same name, but from a different source (%1$s).\n\nDo you still wish to continue?</string>
     <string name="manga_added_library">Added to library</string>
     <string name="manga_removed_library">Removed from library</string>
     <string name="manga_info_expand">More</string>