New helper to help with quotes.

src/main/java/eu/siacs/conversations/ui/util/QuoteHelper.java

@@ -0,0 +1,51 @@
+package eu.siacs.conversations.ui.util;
+
+import eu.siacs.conversations.utils.UIHelper;
+
+public class QuoteHelper {
+
+    public static boolean isPositionQuoteCharacter(CharSequence body, int pos){
+        return body.charAt(pos) == '>';
+    }
+
+    public static boolean isPositionFollowedByQuoteChar(CharSequence body, int pos) {
+        return body.length() > pos + 1 && isPositionQuoteCharacter(body, pos +1 );
+    }
+
+    // 'Prequote' means anything we require or can accept in front of a QuoteChar
+    public static boolean isPositionPrecededByPrequote(CharSequence body, int pos){
+        return UIHelper.isPositionPrecededByLineStart(body, pos);
+    }
+
+    public static boolean isPositionQuoteStart (CharSequence body, int pos){
+        return isPositionQuoteCharacter(body, pos)
+                && isPositionPrecededByPrequote(body, pos)
+                && (UIHelper.isPositionFollowedByWhitespace(body, pos)
+                    || isPositionFollowedByQuoteChar(body, pos));
+    }
+
+    public static boolean bodyContainsQuoteStart (CharSequence body){
+       for (int i = 0; i < body.length(); i++){
+            if (isPositionQuoteStart(body, i)){
+                return true;
+            }
+        }
+        return false;
+    }
+    /*public static int getQuoteColors(XmppActivity activity, boolean darkBackground, int quoteDepth){
+        int[] colorsLight = R.style.ConversationsTheme_Dark;
+        int[] colorsDark = Config.QUOTE_COLOR_ARRAY_DARK;
+
+       Collections.rotate(Collections.singletonList(colorsLight), quoteDepth);
+       Collections.rotate(Collections.singletonList(colorsDark), quoteDepth);
+
+       Arrays.stream(colorsLight).toArray();
+
+        int quoteColors =  darkBackground ? ContextCompat.getColor(activity, colorsLight[quoteDepth-1])
+                : ContextCompat.getColor(activity, colorsDark[quoteDepth-1]);
+
+        Collections.rotate
+
+        return quoteColors;
+    };*/
+}

src/main/java/eu/siacs/conversations/utils/UIHelper.java

@@ -372,6 +372,34 @@ public class UIHelper {
         return input.length() > 256 ? StylingHelper.subSequence(input, 0, 256) : input;
     }
 
+    public static boolean isPositionFollowedByWhitespace(CharSequence body, int pos){
+        return Character.isWhitespace(body.charAt(pos + 1));
+    }
+
+    public static boolean isPositionPrecededByWhitespace(CharSequence body, int pos){
+        return Character.isWhitespace(body.charAt(pos -1 ));
+    }
+
+    public static boolean isPositionPrecededByBodyStart(CharSequence body, int pos){
+        // true if not a single linebreak before current position
+        for (int i = pos - 1; i >= 0; i--){
+            if (body.charAt(i) != ' '){
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static boolean isPositionPrecededByLineStart(CharSequence body, int pos){
+        if (isPositionPrecededByBodyStart(body, pos)){
+            return true;
+        }
+        if (body.charAt(pos - 1) == '\n'){
+            return true;
+        }
+        return false;
+    }
+
     public static boolean isPositionFollowedByQuoteableCharacter(CharSequence body, int pos) {
         return !isPositionFollowedByNumber(body, pos)
                 && !isPositionFollowedByEmoticon(body, pos)