yegor256#276 RsWithStatus puzzle resolution

src/main/java/org/takes/rs/RsWithStatus.java

@@ -26,14 +26,16 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.HttpURLConnection;
-import java.util.Collection;
 import java.util.Collections;
-import java.util.LinkedList;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
+import java.util.regex.Pattern;
 import lombok.EqualsAndHashCode;
 import org.takes.Response;
+import org.takes.misc.Concat;
+import org.takes.misc.Condition;
+import org.takes.misc.Select;
 
 /**
  * Response decorator, with status code.
@@ -46,7 +48,12 @@
  */
 @EqualsAndHashCode(callSuper = true)
 public final class RsWithStatus extends RsWrap {
-
+    /**
+     * Pattern for first header line.
+     */
+    private static final Pattern FIRST = Pattern.compile(
+        "HTTP/1\\.1 \\d{3} [a-zA-Z ]+"
+    );
     /**
      * Statuses and their reasons.
      */
@@ -94,11 +101,6 @@ public InputStream body() throws IOException {
 
     /**
      * Make head.
-     * @todo #160:30min/DEV To implement concatenation and selection with the
-     *  conjunction Concat and Select class to get rid of List.add()
-     *  between line 118 to line 127. That is, replacing the block using
-     *  something like this:
-     *  return new Concat(head,new Select(origin.head(),new FilterFirstCond()))
      * @param origin Original response
      * @param status Status
      * @param reason Reason
@@ -117,17 +119,20 @@ private static Iterable<String> head(final Response origin,
                 )
             );
         }
-        final Collection<String> head = new LinkedList<String>();
-        head.add(String.format("HTTP/1.1 %d %s", status, reason));
-        boolean first = true;
-        for (final String hdr : origin.head()) {
-            if (first) {
-                first = false;
-            } else {
-                head.add(hdr);
-            }
-        }
-        return head;
+        return new Concat<String>(
+            Collections.singletonList(
+                String.format("HTTP/1.1 %d %s", status, reason)
+            ),
+            new Select<String>(
+                origin.head(),
+                new Condition<String>() {
+                    @Override
+                    public boolean fits(final String element) {
+                        return !RsWithStatus.FIRST.matcher(element).matches();
+                    }
+                }
+            )
+        );
     }
 
     /**

src/test/java/org/takes/rs/RsWithStatusTest.java

@@ -0,0 +1,65 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 Yegor Bugayenko
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package org.takes.rs;
+
+import com.google.common.base.Joiner;
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import org.hamcrest.MatcherAssert;
+import org.hamcrest.Matchers;
+import org.junit.Test;
+
+/**
+ * Test case for {@link RsWithStatus}..
+ *
+ * <p>The class is immutable and thread-safe.
+ * @author Dmitry Zaytsev ([email protected])
+ * @version $Id$
+ * @since 0.16.9
+ */
+public final class RsWithStatusTest {
+    /**
+     * RsWithStatus can add status.
+     * @throws IOException If some problem inside
+     */
+    @Test
+    public void addsStatus() throws IOException {
+        MatcherAssert.assertThat(
+            new RsPrint(
+                new RsWithStatus(
+                    new RsWithHeader("Host", "example.com"),
+                    HttpURLConnection.HTTP_NOT_FOUND
+                )
+            ).print(),
+            Matchers.equalTo(
+                Joiner.on("\r\n").join(
+                    "HTTP/1.1 404 Not Found",
+                    "Host: example.com",
+                    "",
+                    ""
+                )
+            )
+        );
+    }
+}