Adding secret emojis to reactions

commons/src/main/java/com/vitorpamplona/amethyst/commons/emojicoder/EmojiCoder.kt

@@ -106,4 +106,27 @@ object EmojiCoder {
         val decodedArray = ByteArray(decoded.size) { decoded[it].toByte() }
         return String(decodedArray, Charsets.UTF_8)
     }
+
+    @JvmStatic
+    fun cropToFirstMessage(text: String): String {
+        val decoded = mutableListOf<Int>()
+
+        var i = 0
+        while (i < text.length) {
+            val codePoint = text.codePointAt(i)
+            val byte = fromVariationSelector(codePoint)
+
+            if (byte == null && decoded.isNotEmpty()) {
+                break
+            } else if (byte == null) {
+                i += Character.charCount(codePoint) // Advance index by correct number of chars
+                continue
+            }
+
+            decoded.add(byte)
+            i += Character.charCount(codePoint) // Advance index by correct number of chars
+        }
+
+        return text.substring(0, i)
+    }
 }

commons/src/test/java/com/vitorpamplona/amethyst/commons/emojicoder/EmojiCoderTest.kt

@@ -38,6 +38,7 @@ class EmojiCoderTest {
             )
 
         val HELLO_WORLD = "\uD83D\uDE00\uDB40\uDD38\uDB40\uDD55\uDB40\uDD5C\uDB40\uDD5C\uDB40\uDD5F\uDB40\uDD1C\uDB40\uDD10\uDB40\uDD47\uDB40\uDD5F\uDB40\uDD62\uDB40\uDD5C\uDB40\uDD54\uDB40\uDD11"
+        val HELLO_WORLD_WITH_EXTRAS = HELLO_WORLD + "askfasdf"
     }
 
     @Test
@@ -55,6 +56,11 @@ class EmojiCoderTest {
         assertEquals("Hello, World!", EmojiCoder.decode(HELLO_WORLD))
     }
 
+    @Test
+    fun testCrop() {
+        assertEquals(HELLO_WORLD, EmojiCoder.cropToFirstMessage(HELLO_WORLD_WITH_EXTRAS))
+    }
+
     @Test
     fun testEncodeDecode() {
         for (emoji in EMOJI_LIST) {