Fix #1005 - Avoid duplicate tags when following

app/src/main/java/app/fedilab/android/mastodon/activities/FollowedTagActivity.java

@@ -32,6 +32,7 @@ import androidx.recyclerview.widget.LinearLayoutManager;
 import com.google.android.material.dialog.MaterialAlertDialogBuilder;
 
 import java.util.ArrayList;
+import java.util.Objects;
 
 import app.fedilab.android.BaseMainActivity;
 import app.fedilab.android.R;
@@ -145,6 +146,11 @@ public class FollowedTagActivity extends BaseBarActivity implements FollowedTagA
             dialogBuilder.setView(popupAddFollowedTagtBinding.getRoot());
             popupAddFollowedTagtBinding.addTag.setFilters(new InputFilter[]{new InputFilter.LengthFilter(255)});
             dialogBuilder.setPositiveButton(R.string.validate, (dialog, id) -> {
+                String name = Objects.requireNonNull(popupAddFollowedTagtBinding.addTag.getText()).toString().trim();
+                if(tagList.contains(new Tag(name))) {
+                    Toasty.error(FollowedTagActivity.this, getString(R.string.tag_already_followed), Toasty.LENGTH_LONG).show();
+                    return;
+                }
                 if (popupAddFollowedTagtBinding.addTag.getText() != null && popupAddFollowedTagtBinding.addTag.getText().toString().trim().length() > 0) {
                     tagVM.follow(BaseMainActivity.currentInstance, BaseMainActivity.currentToken, popupAddFollowedTagtBinding.addTag.getText().toString().trim())
                             .observe(FollowedTagActivity.this, newTag -> {
@@ -162,7 +168,7 @@ public class FollowedTagActivity extends BaseBarActivity implements FollowedTagA
                                     tagList.add(0, newTag);
                                     followedTagAdapter.notifyItemInserted(0);
                                 } else {
-                                    Toasty.error(FollowedTagActivity.this, getString(R.string.toast_feature_not_supported), Toasty.LENGTH_LONG).show();
+                                    Toasty.error(FollowedTagActivity.this, getString(R.string.not_valid_tag_name), Toasty.LENGTH_LONG).show();
                                 }
                             });
                     dialog.dismiss();

app/src/main/java/app/fedilab/android/mastodon/client/entities/api/Tag.java

@@ -32,6 +32,12 @@ public class Tag implements Serializable {
     @SerializedName("following")
     public boolean following = false;
 
+    public Tag() {}
+
+    public Tag(String name) {
+        this.name = name;
+    }
+
     public int getWeight() {
         int weight = 0;
         if (history != null && history.size() > 0) {

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

@@ -28,6 +28,7 @@
     <string name="clipboard">The content of the message has been copied to the clipboard</string>
     <string name="clipboard_url">The URL of the message has been copied to the clipboard</string>
     <string name="clipboard_version">Information have been copied to the clipboard</string>
+    <string name="tag_already_followed">You already follow that tag!</string>
     <string name="camera">Camera</string>
     <string name="delete_all">Delete all</string>
     <string name="schedule">Schedule</string>