Fix encoding error

src/Faker/Provider/zh_TW/Text.php

@@ -131,20 +131,57 @@ protected static function appendEnd($text)
         if ($mbAvailable) {
             $last = mb_substr($text, mb_strlen($text, static::$encoding) - 1, null, static::$encoding);
         } else {
-            $chars = static::explode($text);
-            $last = end($chars);
+            $chars = static::utf8Encoding($text);
+            $last = $chars[count($chars) - 1];
         }
 
         // if the last char is a not-valid-end punctuation, remove it
         if (in_array($last, static::$notEndPunct)) {
             if ($mbAvailable) {
                 $text = mb_substr($text, 0, mb_strlen($text, static::$encoding) - 1, static::$encoding);
             } else {
-                $text = substr($text, 0, strlen($text) - 1);
+                array_pop($chars);
+                $text = implode('', $chars);
             }
         }
 
         // if the last char is not a valid punctuation, append a default one.
         return in_array($last, static::$endPunct) ? $text : $text . '。';
     }
+
+    /**
+     * Convert original string to utf-8 encoding.
+     *
+     * @param string $text
+     * @return array
+     */
+    protected static function utf8Encoding($text)
+    {
+        $encoding = array();
+
+        $chars = str_split($text);
+
+        for ($i = 0; $i < count($chars); ++$i) {
+            $temp = $chars[$i];
+
+            $ord = ord($chars[$i]);
+
+            switch (true) {
+                case $ord > 251:
+                    $temp .= $chars[++$i];
+                case $ord > 247:
+                    $temp .= $chars[++$i];
+                case $ord > 239:
+                    $temp .= $chars[++$i];
+                case $ord > 223:
+                    $temp .= $chars[++$i];
+                case $ord > 191:
+                    $temp .= $chars[++$i];
+            }
+
+            $encoding[] = $temp;
+        }
+
+        return $encoding;
+    }
 }