Changes:

- Add a new cache to store library covers without relying on Glide's cache, making sure they are always available.
- Use Observable's defer instead of create in NetworkHelper.
- Fix Kissmanga showing only one genre.

app/src/main/java/eu/kanade/mangafeed/data/cache/CoverCache.java

@@ -0,0 +1,129 @@
+package eu.kanade.mangafeed.data.cache;
+
+import android.content.Context;
+import android.widget.ImageView;
+
+import com.bumptech.glide.Glide;
+import com.bumptech.glide.load.engine.DiskCacheStrategy;
+import com.bumptech.glide.load.model.GlideUrl;
+import com.bumptech.glide.load.model.LazyHeaders;
+import com.bumptech.glide.request.animation.GlideAnimation;
+import com.bumptech.glide.request.target.SimpleTarget;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import eu.kanade.mangafeed.util.DiskUtils;
+
+public class CoverCache {
+
+    private static final String PARAMETER_CACHE_DIRECTORY = "cover_disk_cache";
+
+    private Context context;
+    private File cacheDir;
+
+    public CoverCache(Context context) {
+        this.context = context;
+        cacheDir = new File(context.getCacheDir(), PARAMETER_CACHE_DIRECTORY);
+        createCacheDir();
+    }
+
+    private boolean createCacheDir() {
+        return !cacheDir.exists() && cacheDir.mkdirs();
+    }
+
+    // Download the cover with Glide (it can avoid repeating requests) and save the file on this cache
+    public void save(String cover, LazyHeaders headers) {
+        GlideUrl url = new GlideUrl(cover, headers);
+        Glide.with(context)
+                .load(url)
+                .downloadOnly(new SimpleTarget<File>() {
+                    @Override
+                    public void onResourceReady(File resource, GlideAnimation<? super File> anim) {
+                        try {
+                            add(cover, resource);
+                        } catch (IOException e) {
+                            e.printStackTrace();
+                        }
+                    }
+                });
+    }
+
+    // Copy the cover from Glide's cache to this cache
+    public void add(String key, File source) throws IOException {
+        File dest = new File(cacheDir, DiskUtils.hashKeyForDisk(key));
+        if (dest.exists())
+            dest.delete();
+
+        InputStream in = new FileInputStream(source);
+        try {
+            OutputStream out = new FileOutputStream(dest);
+            try {
+                // Transfer bytes from in to out
+                byte[] buf = new byte[1024];
+                int len;
+                while ((len = in.read(buf)) > 0) {
+                    out.write(buf, 0, len);
+                }
+            } finally {
+                out.close();
+            }
+        } finally {
+            in.close();
+        }
+    }
+
+    // Get the cover from cache
+    public File get(String key) {
+        return new File(cacheDir, DiskUtils.hashKeyForDisk(key));
+    }
+
+    // Delete the cover from cache
+    public boolean delete(String key) {
+        File file = new File(cacheDir, DiskUtils.hashKeyForDisk(key));
+        return file.exists() && file.delete();
+    }
+
+    // Load the cover from cache or network if it doesn't exist
+    public void loadOrFetchInto(ImageView imageView, String cover, LazyHeaders headers) {
+        File localCover = get(cover);
+        if (localCover.exists()) {
+            loadLocalInto(context, imageView, localCover);
+        } else {
+            loadRemoteInto(context, imageView, cover, headers);
+        }
+    }
+
+    // Load the cover from cache
+    public static void loadLocalInto(Context context, ImageView imageView, String cover) {
+        File cacheDir = new File(context.getCacheDir(), PARAMETER_CACHE_DIRECTORY);
+        File localCover = new File(cacheDir, DiskUtils.hashKeyForDisk(cover));
+        if (localCover.exists()) {
+            loadLocalInto(context, imageView, localCover);
+        }
+    }
+
+    // Load the cover from the cache directory into the specified image view
+    private static void loadLocalInto(Context context, ImageView imageView, File file) {
+        Glide.with(context)
+                .load(file)
+                .diskCacheStrategy(DiskCacheStrategy.NONE)
+                .centerCrop()
+                .into(imageView);
+    }
+
+    // Load the cover from network into the specified image view. It does NOT save the image in cache
+    private static void loadRemoteInto(Context context, ImageView imageView, String cover, LazyHeaders headers) {
+        GlideUrl url = new GlideUrl(cover, headers);
+        Glide.with(context)
+                .load(url)
+                .diskCacheStrategy(DiskCacheStrategy.SOURCE)
+                .centerCrop()
+                .into(imageView);
+    }
+
+}

app/src/main/java/eu/kanade/mangafeed/data/network/NetworkHelper.java

@@ -16,95 +16,85 @@ import rx.Observable;
 
 public final class NetworkHelper {
 
-    private OkHttpClient mClient;
+    private OkHttpClient client;
     private CookieManager cookieManager;
 
     public final CacheControl NULL_CACHE_CONTROL = new CacheControl.Builder().noCache().build();
     public final Headers NULL_HEADERS = new Headers.Builder().build();
 
     public NetworkHelper() {
-        mClient = new OkHttpClient();
+        client = new OkHttpClient();
         cookieManager = new CookieManager();
         cookieManager.setCookiePolicy(CookiePolicy.ACCEPT_ALL);
-        mClient.setCookieHandler(cookieManager);
+        client.setCookieHandler(cookieManager);
     }
 
     public Observable<Response> getResponse(final String url, final Headers headers, final CacheControl cacheControl) {
-        return Observable.<Response>create(subscriber -> {
+        return Observable.defer(() -> {
             try {
-                if (!subscriber.isUnsubscribed()) {
-                    Request request = new Request.Builder()
-                            .url(url)
-                            .cacheControl(cacheControl != null ? cacheControl : NULL_CACHE_CONTROL)
-                            .headers(headers != null ? headers : NULL_HEADERS)
-                            .build();
-                    subscriber.onNext(mClient.newCall(request).execute());
-                }
-                subscriber.onCompleted();
+                Request request = new Request.Builder()
+                        .url(url)
+                        .cacheControl(cacheControl != null ? cacheControl : NULL_CACHE_CONTROL)
+                        .headers(headers != null ? headers : NULL_HEADERS)
+                        .build();
+
+                return Observable.just(client.newCall(request).execute());
             } catch (Throwable e) {
-                subscriber.onError(e);
+                return Observable.error(e);
             }
         }).retry(3);
     }
 
     public Observable<String> mapResponseToString(final Response response) {
-        return Observable.create(subscriber -> {
+        return Observable.defer(() -> {
             try {
-                subscriber.onNext(response.body().string());
-                subscriber.onCompleted();
+                return Observable.just(response.body().string());
             } catch (Throwable e) {
-                subscriber.onError(e);
+                return Observable.error(e);
             }
         });
     }
 
     public Observable<String> getStringResponse(final String url, final Headers headers, final CacheControl cacheControl) {
-
         return getResponse(url, headers, cacheControl)
                 .flatMap(this::mapResponseToString);
     }
 
     public Observable<Response> postData(final String url, final RequestBody formBody, final Headers headers) {
-        return Observable.create(subscriber -> {
+        return Observable.defer(() -> {
             try {
-                if (!subscriber.isUnsubscribed()) {
-                    Request request = new Request.Builder()
-                            .url(url)
-                            .post(formBody)
-                            .headers(headers != null ? headers : NULL_HEADERS)
-                            .build();
-                    subscriber.onNext(mClient.newCall(request).execute());
-                }
-                subscriber.onCompleted();
+                Request request = new Request.Builder()
+                        .url(url)
+                        .post(formBody)
+                        .headers(headers != null ? headers : NULL_HEADERS)
+                        .build();
+                return Observable.just(client.newCall(request).execute());
             } catch (Throwable e) {
-                subscriber.onError(e);
+                return Observable.error(e);
             }
-        });
+        }).retry(3);
     }
 
     public Observable<Response> getProgressResponse(final String url, final Headers headers, final ProgressListener listener) {
-        return Observable.<Response>create(subscriber -> {
+        return Observable.defer(() -> {
             try {
-                if (!subscriber.isUnsubscribed()) {
-                    Request request = new Request.Builder()
-                            .url(url)
-                            .cacheControl(NULL_CACHE_CONTROL)
-                            .headers(headers != null ? headers : NULL_HEADERS)
+                Request request = new Request.Builder()
+                        .url(url)
+                        .cacheControl(NULL_CACHE_CONTROL)
+                        .headers(headers != null ? headers : NULL_HEADERS)
+                        .build();
+
+                OkHttpClient progressClient = client.clone();
+
+                progressClient.networkInterceptors().add(chain -> {
+                    Response originalResponse = chain.proceed(chain.request());
+                    return originalResponse.newBuilder()
+                            .body(new ProgressResponseBody(originalResponse.body(), listener))
                             .build();
-
-                    OkHttpClient progressClient = mClient.clone();
-
-                    progressClient.networkInterceptors().add(chain -> {
-                        Response originalResponse = chain.proceed(chain.request());
-                        return originalResponse.newBuilder()
-                                .body(new ProgressResponseBody(originalResponse.body(), listener))
-                                .build();
-                    });
-                    subscriber.onNext(progressClient.newCall(request).execute());
-                }
-                subscriber.onCompleted();
+                });
+                return Observable.just(progressClient.newCall(request).execute());
             } catch (Throwable e) {
-                subscriber.onError(e);
+                return Observable.error(e);
             }
         }).retry(3);
     }

app/src/main/java/eu/kanade/mangafeed/data/source/online/english/Kissmanga.java

@@ -151,7 +151,7 @@ public class Kissmanga extends Source {
         Element infoElement = parsedDocument.select("div.barContent").first();
         Element titleElement = infoElement.select("a.bigChar").first();
         Element authorElement = infoElement.select("p:has(span:contains(Author:)) > a").first();
-        Element genreElement = infoElement.select("p:has(span:contains(Genres:)) > *:gt(0)").first();
+        Elements genreElement = infoElement.select("p:has(span:contains(Genres:)) > *:gt(0)");
         Elements descriptionElement = infoElement.select("p:has(span:contains(Summary:)) ~ p");
         Element thumbnailUrlElement = parsedDocument.select(".rightBox:eq(0) img").first();