Fix #186 - Add RTL support to the compose form textarea and statuses output

app/assets/javascripts/components/rtl.jsx

@@ -0,0 +1,27 @@
+// U+0590  to U+05FF  - Hebrew
+// U+0600  to U+06FF  - Arabic
+// U+0700  to U+074F  - Syriac
+// U+0750  to U+077F  - Arabic Supplement
+// U+0780  to U+07BF  - Thaana
+// U+07C0  to U+07FF  - N'Ko
+// U+0800  to U+083F  - Samaritan
+// U+08A0  to U+08FF  - Arabic Extended-A
+// U+FB1D  to U+FB4F  - Hebrew presentation forms
+// U+FB50  to U+FDFF  - Arabic presentation forms A
+// U+FE70  to U+FEFF  - Arabic presentation forms B
+
+const rtlChars = /[\u0590-\u083F]|[\u08A0-\u08FF]|[\uFB1D-\uFDFF]|[\uFE70-\uFEFF]/mg;
+
+export function isRtl(text) {
+  if (text.length === 0) {
+    return false;
+  }
+
+  const matches = text.match(rtlChars);
+
+  if (!matches) {
+    return false;
+  }
+
+  return matches.length / text.trim().length > 0.3;
+};