Migrate to kotlinx.serialization for download store and deleter

app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadPendingDeleter.kt

@@ -1,10 +1,13 @@
 package eu.kanade.tachiyomi.data.download
 
 import android.content.Context
-import com.github.salomonbrys.kotson.fromJson
+import androidx.core.content.edit
-import com.google.gson.Gson
 import eu.kanade.tachiyomi.data.database.models.Chapter
 import eu.kanade.tachiyomi.data.database.models.Manga
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import uy.kohesive.injekt.injectLazy
 
 /**
@@ -14,15 +17,12 @@ import uy.kohesive.injekt.injectLazy
  */
 class DownloadPendingDeleter(context: Context) {
 
-    /**
+    private val json: Json by injectLazy()
-     * Gson instance to encode and decode chapters.
-     */
-    private val gson by injectLazy<Gson>()
 
     /**
      * Preferences used to store the list of chapters to delete.
      */
-    private val prefs = context.getSharedPreferences("chapters_to_delete", Context.MODE_PRIVATE)
+    private val preferences = context.getSharedPreferences("chapters_to_delete", Context.MODE_PRIVATE)
 
     /**
      * Last added chapter, used to avoid decoding from the preference too often.
@@ -49,10 +49,10 @@ class DownloadPendingDeleter(context: Context) {
             // Last entry matches the manga, reuse it to avoid decoding json from preferences
             lastEntry.copy(chapters = newChapters)
         } else {
-            val existingEntry = prefs.getString(manga.id!!.toString(), null)
+            val existingEntry = preferences.getString(manga.id!!.toString(), null)
             if (existingEntry != null) {
                 // Existing entry found on preferences, decode json and add the new chapter
-                val savedEntry = gson.fromJson<Entry>(existingEntry)
+                val savedEntry = json.decodeFromString<Entry>(existingEntry)
 
                 // Append new chapters
                 val newChapters = savedEntry.chapters.addUniqueById(chapters)
@@ -68,8 +68,10 @@ class DownloadPendingDeleter(context: Context) {
         }
 
         // Save current state
-        val json = gson.toJson(newEntry)
+        val json = json.encodeToString(newEntry)
-        prefs.edit().putString(newEntry.manga.id.toString(), json).apply()
+        preferences.edit {
+            putString(newEntry.manga.id.toString(), json)
+        }
         lastAddedEntry = newEntry
     }
 
@@ -82,37 +84,23 @@ class DownloadPendingDeleter(context: Context) {
     @Synchronized
     fun getPendingChapters(): Map<Manga, List<Chapter>> {
         val entries = decodeAll()
-        prefs.edit().clear().apply()
+        preferences.edit {
+            clear()
+        }
         lastAddedEntry = null
 
-        return entries.associate { entry ->
+        return entries.associate { (chapters, manga) ->
-            entry.manga.toModel() to entry.chapters.map { it.toModel() }
+            manga.toModel() to chapters.map { it.toModel() }
         }
     }
 
-    /**
-     * Returns the list of chapters to be deleted grouped by its manga.
-     *
-     * Note: the returned list of manga and chapters only contain basic information needed by the
-     * downloader, so don't use them for anything else.
-     */
-    @Synchronized
-    fun getPendingChapters(manga: Manga): List<Chapter>? {
-        val entries = decodeAll()
-        prefs.edit().clear().apply()
-        lastAddedEntry = null
-
-        val entry = entries.find { it.manga.id == manga.id }
-        return entry?.chapters?.map { it.toModel() }
-    }
-
     /**
      * Decodes all the chapters from preferences.
      */
     private fun decodeAll(): List<Entry> {
-        return prefs.all.values.mapNotNull { rawEntry ->
+        return preferences.all.values.mapNotNull { rawEntry ->
             try {
-                (rawEntry as? String)?.let { gson.fromJson<Entry>(it) }
+                (rawEntry as? String)?.let { json.decodeFromString<Entry>(it) }
             } catch (e: Exception) {
                 null
             }
@@ -135,29 +123,32 @@ class DownloadPendingDeleter(context: Context) {
     /**
      * Class used to save an entry of chapters with their manga into preferences.
      */
+    @Serializable
     private data class Entry(
         val chapters: List<ChapterEntry>,
-        val manga: MangaEntry
+        val manga: MangaEntry,
     )
 
     /**
      * Class used to save an entry for a chapter into preferences.
      */
+    @Serializable
     private data class ChapterEntry(
         val id: Long,
         val url: String,
         val name: String,
-        val scanlator: String?
+        val scanlator: String? = null,
     )
 
     /**
      * Class used to save an entry for a manga into preferences.
      */
+    @Serializable
     private data class MangaEntry(
         val id: Long,
         val url: String,
         val title: String,
-        val source: Long
+        val source: Long,
     )
 
     /**
@@ -189,9 +180,9 @@ class DownloadPendingDeleter(context: Context) {
     private fun ChapterEntry.toModel(): Chapter {
         return Chapter.create().also {
             it.id = id
-            it.scanlator = scanlator
             it.url = url
             it.name = name
+            it.scanlator = scanlator
         }
     }
 }

app/src/main/java/eu/kanade/tachiyomi/data/download/DownloadStore.kt

@@ -1,12 +1,16 @@
 package eu.kanade.tachiyomi.data.download
 
 import android.content.Context
-import com.google.gson.Gson
+import androidx.core.content.edit
 import eu.kanade.tachiyomi.data.database.DatabaseHelper
 import eu.kanade.tachiyomi.data.database.models.Manga
 import eu.kanade.tachiyomi.data.download.model.Download
 import eu.kanade.tachiyomi.source.SourceManager
 import eu.kanade.tachiyomi.source.online.HttpSource
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import uy.kohesive.injekt.injectLazy
 
 /**
@@ -16,7 +20,7 @@ import uy.kohesive.injekt.injectLazy
  */
 class DownloadStore(
     context: Context,
-    private val sourceManager: SourceManager
+    private val sourceManager: SourceManager,
 ) {
 
     /**
@@ -24,14 +28,7 @@ class DownloadStore(
      */
     private val preferences = context.getSharedPreferences("active_downloads", Context.MODE_PRIVATE)
 
-    /**
+    private val json: Json by injectLazy()
-     * Gson instance to serialize/deserialize downloads.
-     */
-    private val gson: Gson by injectLazy()
-
-    /**
-     * Database helper.
-     */
     private val db: DatabaseHelper by injectLazy()
 
     /**
@@ -45,9 +42,9 @@ class DownloadStore(
      * @param downloads the list of downloads to add.
      */
     fun addAll(downloads: List<Download>) {
-        val editor = preferences.edit()
+        preferences.edit {
-        downloads.forEach { editor.putString(getKey(it), serialize(it)) }
+            downloads.forEach { putString(getKey(it), serialize(it)) }
-        editor.apply()
+        }
     }
 
     /**
@@ -56,14 +53,18 @@ class DownloadStore(
      * @param download the download to remove.
      */
     fun remove(download: Download) {
-        preferences.edit().remove(getKey(download)).apply()
+        preferences.edit {
+            remove(getKey(download))
+        }
     }
 
     /**
      * Removes all the downloads from the store.
      */
     fun clear() {
-        preferences.edit().clear().apply()
+        preferences.edit {
+            clear()
+        }
     }
 
     /**
@@ -109,7 +110,7 @@ class DownloadStore(
      */
     private fun serialize(download: Download): String {
         val obj = DownloadObject(download.manga.id!!, download.chapter.id!!, counter++)
-        return gson.toJson(obj)
+        return json.encodeToString(obj)
     }
 
     /**
@@ -119,7 +120,7 @@ class DownloadStore(
      */
     private fun deserialize(string: String): DownloadObject? {
         return try {
-            gson.fromJson(string, DownloadObject::class.java)
+            json.decodeFromString<DownloadObject>(string)
         } catch (e: Exception) {
             null
         }
@@ -132,5 +133,6 @@ class DownloadStore(
      * @param chapterId the id of the chapter.
      * @param order the order of the download in the queue.
      */
+    @Serializable
     data class DownloadObject(val mangaId: Long, val chapterId: Long, val order: Int)
 }