feat(attachment): Open file attachments in Nextcloud Files app

Refs: #1561

Signed-off-by: Stefan Niedermann <info@niedermann.it>

5 files changed, 48 insertions, 7 deletions

diff --git a/FAQ.md b/FAQ.md
index 3e144bec4..7fb1aa631 100644
--- a/FAQ.md
+++ b/FAQ.md
@@ -3,6 +3,7 @@
 - [I have experienced an error](#i-have-experienced-an-error)
 - [Why has my bug report been closed?](#why-has-my-bug-report-been-closed)
 - [Why is my card not visible in the upcoming cards view?](#why-is-my-card-not-visible-in-the-upcoming-cards-view)
+- [Why does the browser open when clicking on an attachment?](#why-does-the-browser-open-when-clicking-on-an-attachment)
 - [Known issues](#known-issues)
 - [Why don't you make an option for…?](#why-dont-you-make-an-option-for)
 - [Why don't you make an iOS app?](#why-dont-you-make-an-ios-app)
@@ -66,6 +67,16 @@ This is necessary for two reasons:
 
 Checkout the [Upcoming Analyzer](https://upcoming-analyzer.niedermann.it/) to check out the criterias your card needs to match to be shown in the upcoming cards view.
 
+## Why does the browser open when clicking on an attachment?
+
+The Deck server app supports two different type of attachments:
+- Attachments added prior to Deck server 1.3 have been added as `deck_file` attachments
+- Attachments added with Deck server 1.3 or later are added as `file` attachments
+
+The latter are stored as usual files in your Nextcloud, usually in the `/Deck` folder of your account.  
+Only `file` attachments are able show preview images and to get opened directly, while `deck_file` attachments are effectively only available via the Web UI.  
+We opened a [feature request](https://github.com/nextcloud/deck/issues/3101) to implement an `occ` migration command, but the current state of implementation is unclear.
+
 ## Known issues
 
 Here is a collection of issues which are caused by the (not by us developed) Deck server app and can not be fixed within Deck Android. Please [contact the Nextcloud GmbH](https://nextcloud.com/contact/) if you want them to be fixed.
diff --git a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentAdapter.java b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentAdapter.java
index 57fe8d1e3..3a1ebff15 100644
--- a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentAdapter.java
+++ b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentAdapter.java
@@ -2,7 +2,7 @@ package it.niedermann.nextcloud.deck.ui.card.attachments;
 
 import static androidx.lifecycle.Transformations.distinctUntilChanged;
 import static androidx.recyclerview.widget.RecyclerView.NO_ID;
-import static it.niedermann.nextcloud.deck.util.AttachmentUtil.openAttachmentInBrowser;
+import static it.niedermann.nextcloud.deck.util.AttachmentUtil.openAttachment;
 
 import android.app.Activity;
 import android.view.LayoutInflater;
@@ -112,7 +112,7 @@ public class CardAttachmentAdapter extends RecyclerView.Adapter<AttachmentViewHo
             }
             case VIEW_TYPE_DEFAULT:
             default: {
-                onClickListener = (event) -> openAttachmentInBrowser(account, context, cardRemoteId, attachment);
+                onClickListener = (event) -> openAttachment(account, context, cardRemoteId, attachment);
                 break;
             }
         }
diff --git a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/DefaultAttachmentViewHolder.java b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/DefaultAttachmentViewHolder.java
index 21f858218..505fdf335 100644
--- a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/DefaultAttachmentViewHolder.java
+++ b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/DefaultAttachmentViewHolder.java
@@ -1,7 +1,7 @@
 package it.niedermann.nextcloud.deck.ui.card.attachments;
 
 import static it.niedermann.nextcloud.deck.util.AttachmentUtil.getIconForMimeType;
-import static it.niedermann.nextcloud.deck.util.AttachmentUtil.openAttachmentInBrowser;
+import static it.niedermann.nextcloud.deck.util.AttachmentUtil.openAttachment;
 
 import android.text.format.Formatter;
 import android.view.MenuInflater;
@@ -40,7 +40,7 @@ public class DefaultAttachmentViewHolder extends AttachmentViewHolder {
     public void bind(@NonNull Account account, @NonNull MenuInflater menuInflater, @NonNull FragmentManager fragmentManager, Long cardRemoteId, Attachment attachment, @Nullable View.OnClickListener onClickListener, @ColorInt int color) {
         super.bind(account, menuInflater, fragmentManager, cardRemoteId, attachment, onClickListener, color);
         getPreview().setImageResource(getIconForMimeType(attachment.getMimetype()));
-        itemView.setOnClickListener((event) -> openAttachmentInBrowser(account, itemView.getContext(), cardRemoteId, attachment));
+        itemView.setOnClickListener((event) -> openAttachment(account, itemView.getContext(), cardRemoteId, attachment));
         binding.filename.setText(attachment.getBasename());
         binding.filesize.setText(Formatter.formatFileSize(binding.filesize.getContext(), attachment.getFilesize()));
         if (attachment.getLastModifiedLocal() != null) {
diff --git a/app/src/main/java/it/niedermann/nextcloud/deck/util/AttachmentUtil.java b/app/src/main/java/it/niedermann/nextcloud/deck/util/AttachmentUtil.java
index aba73a11e..a9c25dcf7 100644
--- a/app/src/main/java/it/niedermann/nextcloud/deck/util/AttachmentUtil.java
+++ b/app/src/main/java/it/niedermann/nextcloud/deck/util/AttachmentUtil.java
@@ -2,6 +2,7 @@ package it.niedermann.nextcloud.deck.util;
 
 import android.content.Context;
 import android.content.Intent;
+import android.content.pm.PackageManager;
 import android.net.Uri;
 import android.text.TextUtils;
 import android.widget.Toast;
@@ -11,6 +12,10 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.Px;
 
+import com.nextcloud.android.sso.model.FilesAppType;
+
+import java.util.Optional;
+
 import it.niedermann.nextcloud.deck.DeckLog;
 import it.niedermann.nextcloud.deck.R;
 import it.niedermann.nextcloud.deck.model.Account;
@@ -57,23 +62,47 @@ public class AttachmentUtil {
     }
 
     /**
-     * Tries to open the given {@link Attachment} in web browser. Displays a toast on failure.
+     * Tries to open the given {@link Attachment} in the Nextcloud Android app with a fallback to the web browser.
+     * Displays a toast on failure.
      */
-    public static void openAttachmentInBrowser(@NonNull Account account, @NonNull Context context, Long cardRemoteId, Attachment attachment) {
+    public static void openAttachment(@NonNull Account account, @NonNull Context context, @Nullable Long cardRemoteId, Attachment attachment) {
         if (cardRemoteId == null) {
             Toast.makeText(context, R.string.card_does_not_yet_exist, Toast.LENGTH_LONG).show();
             DeckLog.logError(new IllegalArgumentException("cardRemoteId must not be null."));
             return;
         }
 
+        final var intent = generateNextcloudFilesIntent(context.getPackageManager(), account, attachment)
+                .orElse(generateBrowserIntent(account, cardRemoteId, attachment));
+
         try {
-            context.startActivity(new Intent(Intent.ACTION_VIEW).setData(Uri.parse(getCopyDownloadUrl(account, cardRemoteId, attachment))));
+            context.startActivity(intent);
         } catch (IllegalArgumentException e) {
             Toast.makeText(context, R.string.attachment_does_not_yet_exist, Toast.LENGTH_LONG).show();
             DeckLog.logError(new IllegalArgumentException("attachmentRemoteId must not be null."));
         }
     }
 
+    private static Optional<Intent> generateNextcloudFilesIntent(@NonNull PackageManager packageManager, @NonNull Account account, Attachment attachment) {
+        for (final var type : FilesAppType.values()) {
+            final var intent = new Intent(Intent.ACTION_VIEW)
+                    .setClassName(type.packageId, "com.owncloud.android.ui.activity.FileDisplayActivity")
+                    .putExtra("KEY_FILE_ID", String.valueOf(attachment.getFileId()))
+                    .putExtra("KEY_ACCOUNT", account.getName());
+
+            if (packageManager.resolveActivity(intent, 0) != null) {
+                return Optional.of(intent);
+            }
+        }
+
+        return Optional.empty();
+    }
+
+    private static Intent generateBrowserIntent(@NonNull Account account, long cardRemoteId, @NonNull Attachment attachment) {
+        return new Intent(Intent.ACTION_VIEW)
+                .setData(Uri.parse(getCopyDownloadUrl(account, cardRemoteId, attachment)));
+    }
+
     public static String getCopyDownloadUrl(@NonNull Account account, @NonNull Long cardRemoteId, @NonNull Attachment attachment) {
         if (attachment.getId() == null) {
             throw new IllegalArgumentException("attachment id must not be null");
diff --git a/fastlane/metadata/android/en-US/changelogs/1024000.txt b/fastlane/metadata/android/en-US/changelogs/1024000.txt
index cd581c869..b0d209ea3 100644
--- a/fastlane/metadata/android/en-US/changelogs/1024000.txt
+++ b/fastlane/metadata/android/en-US/changelogs/1024000.txt
@@ -1,3 +1,4 @@
 - ☑️ Support Completed / Uncompleted state (#1556) - Requires deck server ≥ 1.12.2
+- 📎 Open file attachments in Nextcloud Files app (#1561) - Requires deck server ≥ 1.12.2
 - ☑️ Share text as task to card description (#1558)
 - ☀️ Force keeping screen on while importing first account
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