maybe finish the parse/modify string logic

app/src/main/AndroidManifest.xml

@@ -17,11 +17,18 @@
         android:label="@string/app_name"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
-
+        <meta-data
-        <meta-data android:name="firebase_crashlytics_collection_enabled" android:value="false" />
+            android:name="firebase_crashlytics_collection_enabled"
-        <meta-data android:name="firebase_analytics_collection_enabled" android:value="false" />
+            android:value="false" />
-        <meta-data android:name="google_analytics_adid_collection_enabled" android:value="false" />
+        <meta-data
-        <meta-data android:name="firebase_messaging_auto_init_enabled" android:value="false" />
+            android:name="firebase_analytics_collection_enabled"
+            android:value="false" />
+        <meta-data
+            android:name="google_analytics_adid_collection_enabled"
+            android:value="false" />
+        <meta-data
+            android:name="firebase_messaging_auto_init_enabled"
+            android:value="false" />
 
         <activity
             android:name=".activities.main.MainActivity"
@@ -118,8 +125,8 @@
         </activity>
         <activity
             android:name=".activities.bookmarks.BookmarkActivity"
-            android:parentActivityName=".activities.main.MainActivity"
             android:launchMode="singleTop"
+            android:parentActivityName=".activities.main.MainActivity"
             android:theme="@style/AppTheme.NoActionBar">
             <meta-data
                 android:name="android.support.PARENT_ACTIVITY"
@@ -127,8 +134,8 @@
         </activity>
         <activity
             android:name=".activities.settings.SettingsActivity"
-            android:parentActivityName=".activities.main.MainActivity"
             android:launchMode="singleTop"
+            android:parentActivityName=".activities.main.MainActivity"
             android:theme="@style/AppTheme.PreferenceTheme">
             <meta-data
                 android:name="android.support.PARENT_ACTIVITY"
@@ -166,6 +173,7 @@
                 android:name="android.support.PARENT_ACTIVITY"
                 android:value=".activities.main.MainActivity" />
         </activity>
+        <activity android:name=".activities.TestActivity"></activity>
     </application>
 
 </manifest>

app/src/main/java/gr/thmmy/mthmmy/activities/TestActivity.java

@@ -0,0 +1,28 @@
+package gr.thmmy.mthmmy.activities;
+
+import androidx.appcompat.app.AppCompatActivity;
+import gr.thmmy.mthmmy.R;
+import gr.thmmy.mthmmy.utils.parsing.BBParser;
+import timber.log.Timber;
+
+import android.os.Bundle;
+import android.text.SpannableStringBuilder;
+import android.widget.TextView;
+
+public class TestActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_test);
+
+        String bb = "[b]An [i]elep[u]hant[/i][/b] swi[/u]ms in [s]the[/s] tree";
+        SpannableStringBuilder result = BBParser.bb2span(bb);
+
+        TextView bbRaw = findViewById(R.id.bb_raw);
+        TextView bb2Text = findViewById(R.id.bb2text);
+
+        bbRaw.setText(bb);
+        bb2Text.setText(result);
+    }
+}

app/src/main/java/gr/thmmy/mthmmy/activities/main/MainActivity.java

@@ -19,6 +19,7 @@ import androidx.preference.PreferenceManager;
 import androidx.viewpager.widget.ViewPager;
 import gr.thmmy.mthmmy.R;
 import gr.thmmy.mthmmy.activities.LoginActivity;
+import gr.thmmy.mthmmy.activities.TestActivity;
 import gr.thmmy.mthmmy.activities.board.BoardActivity;
 import gr.thmmy.mthmmy.activities.downloads.DownloadsActivity;
 import gr.thmmy.mthmmy.activities.main.forum.ForumFragment;
@@ -137,6 +138,8 @@ public class MainActivity extends BaseActivity implements RecentFragment.RecentF
                     , Toast.LENGTH_SHORT).show();
         }
         mBackPressed = System.currentTimeMillis();
+
+        startActivity(new Intent(this, TestActivity.class));
     }
 
     @Override

app/src/main/java/gr/thmmy/mthmmy/model/BBTag.java

@@ -1,5 +1,7 @@
 package gr.thmmy.mthmmy.model;
 
+import androidx.annotation.NonNull;
+
 public class BBTag {
     private int start, end;
     private String name;
@@ -9,6 +11,12 @@ public class BBTag {
         this.name = name;
     }
 
+    @NonNull
+    @Override
+    public String toString() {
+        return "start:" + start + ",end:" + end + ",name:" + name;
+    }
+
     public int getStart() {
         return start;
     }

app/src/main/java/gr/thmmy/mthmmy/utils/parsing/BBParser.java

@@ -5,12 +5,17 @@ import android.text.Spannable;
 import android.text.SpannableStringBuilder;
 import android.text.SpannedString;
 import android.text.TextUtils;
+import android.text.style.StrikethroughSpan;
 import android.text.style.StyleSpan;
+import android.text.style.UnderlineSpan;
+
+import org.commonmark.node.Link;
 
 import java.nio.charset.UnsupportedCharsetException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.LinkedList;
+import java.util.function.Predicate;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -18,20 +23,49 @@ import gr.thmmy.mthmmy.model.BBTag;
 import timber.log.Timber;
 
 public class BBParser {
-    private static final String[] supportedTags = {"b"};
+    private static final String[] supportedTags = {"b", "i", "u", "s"};
 
-    public static SpannedString bb2span(String bb) {
+    public static SpannableStringBuilder bb2span(String bb) {
         SpannableStringBuilder builder = new SpannableStringBuilder(bb);
+        // store the original indices of the string
+        LinkedList<Integer> stringIndices = new LinkedList<>();
+        for (int i = 0; i < builder.length(); i++) {
+            stringIndices.add(i);
+        }
+
         BBTag[] tags = getTags(bb);
         for (BBTag tag : tags) {
+            int start = stringIndices.indexOf(tag.getStart());
+            int end = stringIndices.indexOf(tag.getEnd());
+            int startTagLength = tag.getName().length() + 2;
+            int endTagLength = tag.getName().length() + 3;
             switch (tag.getName()) {
                 case "b":
-                    builder.setSpan(new StyleSpan(Typeface.BOLD), tag.getStart(), tag.getEnd(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
+                    builder.setSpan(new StyleSpan(Typeface.BOLD), start, end, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
+                    break;
+                case "i":
+                    builder.setSpan(new StyleSpan(Typeface.ITALIC), start, end, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
+                    break;
+                case "u":
+                    builder.setSpan(new UnderlineSpan(), start, end, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
+                    break;
+                case "s":
+                    builder.setSpan(new StrikethroughSpan(), start, end, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
                     break;
                 default:
                     throw new UnsupportedCharsetException("Tag not supported");
             }
+            //remove starting and ending tag and and do the same changes in the list
+            builder.delete(start, start + startTagLength);
+            for (int i = start; i < start + startTagLength; i++) {
+                stringIndices.remove(start);
+            }
+            builder.delete(end - startTagLength, end - startTagLength + endTagLength);
+            for (int i = end - startTagLength; i < end - startTagLength + endTagLength; i++) {
+                stringIndices.remove(end - startTagLength);
+            }
         }
+        return builder;
     }
 
     public static BBTag[] getTags(String bb) {
@@ -40,7 +74,7 @@ public class BBParser {
         LinkedList<BBTag> tags = new LinkedList<>();
         Matcher bbMatcher = bbtagPattern.matcher(bb);
         while (bbMatcher.find()) {
-            String name = bbMatcher.group(0);
+            String name = bbMatcher.group(1);
             if (name.startsWith("/")) {
                 //closing tag
                 name = name.substring(1);
@@ -55,6 +89,10 @@ public class BBParser {
             if (isSupported(name))
                 tags.add(new BBTag(bbMatcher.start(), name));
         }
+        // remove parsed tags with no end tag
+        for (BBTag bbTag : tags)
+            if (bbTag.getEnd() == 0)
+                tags.remove(bbTag);
         return tags.toArray(new BBTag[0]);
     }
 

app/src/main/res/layout/activity_test.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    tools:context=".activities.TestActivity">
+
+    <TextView
+        android:id="@+id/bb_raw"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content" />
+
+    <TextView
+        android:id="@+id/bb2text"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content" />
+
+</LinearLayout>