Download manager rewrite (#535)

* Saving to SD working

* Rename imagePath to uri

* Handle android < 21

* Minor changes

* Separate downloader from the manager. Optimize folder lookups

* Persist downloads across restarts

* Fix for #511

* Updated ReactiveNetwork. Add some documentation

* More documentation and minor fixes

* Handle persistent notifications. Other minor changes

* Improve downloader and add documentation

* Rename pageNumber to index in Page class

* Remove unused methods

* Use chop method

* Make sure dest dir is created

* Reset downloads dir preference

* Use invalidate options menu in download fragment and fix wrong condition

* Fix empty download queue after application restart

* Use addAll method in download queue to avoid too many notifications

* Inform download manager changes

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

@@ -132,6 +132,9 @@ class ChaptersPresenter : BasePresenter<ChaptersFragment>() {
                     chapters.map { it.toModel() }
                 }
                 .doOnNext { chapters ->
+                    // Find downloaded chapters
+                    setDownloadedChapters(chapters)
+
                     // Store the last emission
                     this.chapters = chapters
 
@@ -157,16 +160,25 @@ class ChaptersPresenter : BasePresenter<ChaptersFragment>() {
         if (download != null) {
             // If there's an active download, assign it.
             model.download = download
-        } else {
-            // Otherwise ask the manager if the chapter is downloaded and assign it to the status.
-            model.status = if (downloadManager.isChapterDownloaded(source, manga, this))
-                Download.DOWNLOADED
-            else
-                Download.NOT_DOWNLOADED
         }
         return model
     }
 
+    /**
+     * Finds and assigns the list of downloaded chapters.
+     *
+     * @param chapters the list of chapter from the database.
+     */
+    private fun setDownloadedChapters(chapters: List<ChapterModel>) {
+        val files = downloadManager.findMangaDir(source, manga)?.listFiles() ?: return
+        val cached = mutableMapOf<Chapter, String>()
+        files.mapNotNull { it.name }
+                .mapNotNull { name -> chapters.find {
+                    name == cached.getOrPut(it) { downloadManager.getChapterDirName(it) }
+                } }
+                .forEach { it.status = Download.DOWNLOADED }
+    }
+
     /**
      * Requests an updated list of chapters from the source.
      */
@@ -318,10 +330,6 @@ class ChaptersPresenter : BasePresenter<ChaptersFragment>() {
      * @param chapters the list of chapters to delete.
      */
     fun deleteChapters(chapters: List<ChapterModel>) {
-        val wasRunning = downloadManager.isRunning
-        if (wasRunning) {
-            DownloadService.stop(context)
-        }
         Observable.from(chapters)
                 .doOnNext { deleteChapter(it) }
                 .toList()
@@ -330,9 +338,6 @@ class ChaptersPresenter : BasePresenter<ChaptersFragment>() {
                 .observeOn(AndroidSchedulers.mainThread())
                 .subscribeFirst({ view, result ->
                     view.onChaptersDeleted()
-                    if (wasRunning) {
-                        DownloadService.start(context)
-                    }
                 }, { view, error ->
                     view.onChaptersDeletedError(error)
                 })
@@ -343,7 +348,7 @@ class ChaptersPresenter : BasePresenter<ChaptersFragment>() {
      * @param chapter the chapter to delete.
      */
     private fun deleteChapter(chapter: ChapterModel) {
-        downloadManager.queue.del(chapter)
+        downloadManager.queue.remove(chapter)
         downloadManager.deleteChapter(source, manga, chapter)
         chapter.status = Download.NOT_DOWNLOADED
         chapter.download = null