styling: introduce support for code blocks

2 files changed, 47 insertions, 17 deletions

diff --git a/src/main/java/de/pixart/messenger/utils/ImStyleParser.java b/src/main/java/de/pixart/messenger/utils/ImStyleParser.java
index 0046ba464..5c41c95e2 100644
--- a/src/main/java/de/pixart/messenger/utils/ImStyleParser.java
+++ b/src/main/java/de/pixart/messenger/utils/ImStyleParser.java
@@ -34,19 +34,29 @@ import java.util.Arrays;
 import java.util.List;
 
 public class ImStyleParser {
-    final static List<Character> KEYWORDS = Arrays.asList('*', '_', '~', '`');
-    final static List<Character> NO_SUB_PARSING_KEYWORDS = Arrays.asList('`');
-    final static boolean ALLOW_EMPTY = false;
+    private final static List<Character> KEYWORDS = Arrays.asList('*', '_', '~', '`');
+    private final static List<Character> NO_SUB_PARSING_KEYWORDS = Arrays.asList('`');
+    private final static List<Character> BLOCK_KEYWORDS = Arrays.asList('`');
+    private final static boolean ALLOW_EMPTY = false;
 
     public static List<Style> parse(CharSequence text) {
         return parse(text, 0, text.length() - 1);
     }
 
-    public static List<Style> parse(CharSequence text, int start, int end) {
+    private static List<Style> parse(CharSequence text, int start, int end) {
         List<Style> styles = new ArrayList<>();
         for (int i = start; i <= end; ++i) {
             char c = text.charAt(i);
             if (KEYWORDS.contains(c) && precededByWhiteSpace(text, i, start) && !followedByWhitespace(text, i, end)) {
+                if (BLOCK_KEYWORDS.contains(c) && isCharRepeatedTwoTimes(text, c, i + 1, end)) {
+                    int to = seekEndBlock(text, c, i + 3, end);
+                    if (to != -1 && (to != i + 5 || ALLOW_EMPTY)) {
+                        String keyword = String.valueOf(c) + String.valueOf(c) + String.valueOf(c);
+                        styles.add(new Style(keyword, i, to));
+                        i = to;
+                        continue;
+                    }
+                }
                 int to = seekEnd(text, c, i + 1, end);
                 if (to != -1 && (to != i + 1 || ALLOW_EMPTY)) {
                     styles.add(new Style(c, i, to));
@@ -60,6 +70,10 @@ public class ImStyleParser {
         return styles;
     }
 
+    private static boolean isCharRepeatedTwoTimes(CharSequence text, char c, int index, int end) {
+        return index + 1 <= end && text.charAt(index) == c && text.charAt(index) == c;
+    }
+
     private static boolean precededByWhiteSpace(CharSequence text, int index, int start) {
         return index == start || Character.isWhitespace(text.charAt(index - 1));
     }
@@ -80,20 +94,34 @@ public class ImStyleParser {
         return -1;
     }
 
+    private static int seekEndBlock(CharSequence text, char needle, int start, int end) {
+        for (int i = start; i <= end; ++i) {
+            char c = text.charAt(i);
+            if (c == needle && isCharRepeatedTwoTimes(text, needle, i + 1, end)) {
+                return i + 2;
+            }
+        }
+        return -1;
+    }
+
     public static class Style {
 
-        private final char c;
+        private final String keyword;
         private final int start;
         private final int end;
 
-        public Style(char c, int start, int end) {
-            this.c = c;
+        public Style(char character, int start, int end) {
+            this(String.valueOf(character), start, end);
+        }
+
+        public Style(String keyword, int start, int end) {
+            this.keyword = keyword;
             this.start = start;
             this.end = end;
         }
 
-        public char getCharacter() {
-            return c;
+        public String getKeyword() {
+            return keyword;
         }
 
         public int getStart() {
diff --git a/src/main/java/de/pixart/messenger/utils/StylingHelper.java b/src/main/java/de/pixart/messenger/utils/StylingHelper.java
index 8d5e73ccf..b04a1f8a2 100644
--- a/src/main/java/de/pixart/messenger/utils/StylingHelper.java
+++ b/src/main/java/de/pixart/messenger/utils/StylingHelper.java
@@ -67,21 +67,23 @@ public class StylingHelper {
 
     public static void format(final Editable editable, @ColorInt int textColor) {
         for (ImStyleParser.Style style : ImStyleParser.parse(editable)) {
-            editable.setSpan(createSpanForStyle(style), style.getStart() + 1, style.getEnd(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
-            makeKeywordOpaque(editable, style.getStart(), style.getStart() + 1, textColor);
-            makeKeywordOpaque(editable, style.getEnd(), style.getEnd() + 1, textColor);
+            final int keywordLength = style.getKeyword().length();
+            editable.setSpan(createSpanForStyle(style), style.getStart() + keywordLength, style.getEnd() - keywordLength + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+            makeKeywordOpaque(editable, style.getStart(), style.getStart() + keywordLength, textColor);
+            makeKeywordOpaque(editable, style.getEnd() - keywordLength + 1, style.getEnd() + 1, textColor);
         }
     }
 
     private static ParcelableSpan createSpanForStyle(ImStyleParser.Style style) {
-        switch (style.getCharacter()) {
-            case '*':
+        switch (style.getKeyword()) {
+            case "*":
                 return new StyleSpan(Typeface.BOLD);
-            case '_':
+            case "_":
                 return new StyleSpan(Typeface.ITALIC);
-            case '~':
+            case "~":
                 return new StrikethroughSpan();
-            case '`':
+            case "`":
+            case "```":
                 return new TypefaceSpan("monospace");
             default:
                 throw new AssertionError("Unknown Style");