Replaced the regex gunk in the composer with something more readable and more reliable.

Also, put in a fix for a crash related to failing while loading the vector image for the media picker button.

app/src/main/java/com/keylesspalace/tusky/ComposeActivity.java

@@ -87,7 +87,6 @@ public class ComposeActivity extends AppCompatActivity {
     private static final int STATUS_MEDIA_SIZE_LIMIT = 4000000; // 4MB
     private static final int MEDIA_PICK_RESULT = 1;
     private static final int PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE = 1;
-    private static final Pattern mentionPattern = Pattern.compile("\\B@[^\\s@]+@?[^\\s@]+");
 
     private String inReplyToId;
     private String domain;
@@ -175,9 +174,37 @@ public class ComposeActivity extends AppCompatActivity {
         Snackbar.make(findViewById(R.id.activity_compose), stringId, Snackbar.LENGTH_LONG).show();
     }
 
-    private static class Interval {
-        public int start;
-        public int end;
+    private static int findStartOfMention(String string, int fromIndex) {
+        final int length = string.length();
+        while (fromIndex < length) {
+            int at = string.indexOf('@', fromIndex);
+            if (at < 0) {
+                break;
+            } else if (at == 0 || at >= 1 && Character.isWhitespace(string.codePointBefore(at))) {
+                return at;
+            } else {
+                fromIndex = at + 1;
+            }
+        }
+        return -1;
+    }
+
+    private static int findEndOfMention(String string, int fromIndex) {
+        int atCount = 0;
+        final int length = string.length();
+        for (int i = fromIndex; i < length; ) {
+            int codepoint = string.codePointAt(i);
+            if (Character.isWhitespace(codepoint)) {
+                return i;
+            } else if (codepoint == '@') {
+                atCount += 1;
+                if (atCount > 2) {
+                    return -1;
+                }
+            }
+            i += Character.charCount(codepoint);
+        }
+        return length;
     }
 
     private static void colourMentions(Spannable text, int colour) {
@@ -187,44 +214,20 @@ public class ComposeActivity extends AppCompatActivity {
         for (int i = oldSpans.length - 1; i >= 0; i--) {
             text.removeSpan(oldSpans[i]);
         }
-        // Match a list of new colour spans.
-        List<Interval> intervals = new ArrayList<>();
-        Matcher matcher = mentionPattern.matcher(text);
-        while (matcher.find()) {
-            Interval interval = new Interval();
-            interval.start = matcher.start();
-            interval.end = matcher.end();
-            intervals.add(interval);
-        }
-        // Make sure intervals don't overlap.
-        Collections.sort(intervals, new Comparator<Interval>() {
-            @Override
-            public int compare(Interval a, Interval b) {
-                return a.start - b.start;
-            }
-        });
-        for (int i = 0, j = 0; i < intervals.size() - 1; i++, j++) {
-            if (j != 0) {
-                Interval a = intervals.get(j - 1);
-                Interval b = intervals.get(i);
-                if (a.start <= b.end) {
-                    while (j != 0 && a.start <= b.end) {
-                        a = intervals.get(j - 1);
-                        b = intervals.get(i);
-                        a.end = Math.max(a.end, b.end);
-                        a.start = Math.min(a.start, b.start);
-                        j--;
-                    }
-                } else {
-                    intervals.set(j, b);
-                }
-            } else {
-                intervals.set(j, intervals.get(i));
+        // Colour the mentions.
+        String string = text.toString();
+        int start;
+        int end = 0;
+        while (end < n) {
+            start = findStartOfMention(string, end);
+            if (start < 0 || start >= n) {
+                break;
             }
+            end = findEndOfMention(string, start);
+            if (end < 0) {
+                break;
             }
-        // Finally, set the spans.
-        for (Interval interval : intervals) {
-            text.setSpan(new ForegroundColorSpan(colour), interval.start, interval.end,
+            text.setSpan(new ForegroundColorSpan(colour), start, end,
                     Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
         }
     }
@@ -508,10 +511,12 @@ public class ComposeActivity extends AppCompatActivity {
 
     private void enableMediaPicking() {
         mediaPick.setEnabled(true);
+        mediaPick.setImageResource(R.drawable.ic_media);
     }
 
     private void disableMediaPicking() {
         mediaPick.setEnabled(false);
+        mediaPick.setImageResource(R.drawable.ic_media_disabled);
     }
 
     private void addMediaToQueue(QueuedMedia.Type type, Bitmap preview, Uri uri, long mediaSize) {

app/src/main/res/color/media_button_dark.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:color="#8F8F8F" android:state_enabled="false" />
+    <item android:color="#FFFFFF" />
+</selector>

app/src/main/res/drawable/media_selector.xml

@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:state_enabled="true" android:drawable="@drawable/ic_media" />
-    <item android:state_enabled="false" android:drawable="@drawable/ic_media_disabled" />
-</selector>

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

@@ -14,8 +14,9 @@
         <ImageButton
             android:layout_width="48dp"
             android:layout_height="48dp"
-            app:srcCompat="@drawable/media_selector"
+            app:srcCompat="@drawable/ic_media"
             style="?attr/image_button_style"
+            android:tint="?attr/compose_media_button_tint"
             android:id="@+id/compose_photo_pick"
             android:layout_marginLeft="8dp" />
 

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

@@ -21,5 +21,6 @@
     <attr name="status_divider_color" format="reference|color" />
     <attr name="tab_page_margin_color" format="reference|color" />
     <attr name="account_header_background_color" format="reference|color" />
+    <attr name="compose_media_button_tint" format="reference|color" />
 
 </resources>

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

@@ -29,6 +29,7 @@
         <item name="status_divider_color">@color/status_divider_dark</item>
         <item name="tab_page_margin_color">@color/tab_page_margin_dark</item>
         <item name="account_header_background_color">@color/account_header_background_dark</item>
+        <item name="compose_media_button_tint">@color/media_button_dark</item>
     </style>
 
     <style name="AppTheme.ImageButton.Dark" parent="@style/Widget.AppCompat.Button.Borderless.Colored">