Replace <a> tags with Slack <link|name>

Replace <a href...>text</a> with <url|text> before
escaping the remaining parts of the message

fixes #126
fixes nishio-dens/bitbucket-pullrequest-builder-plugin#59

src/main/java/jenkins/plugins/slack/ActiveNotifier.java

@@ -19,11 +19,15 @@
 import org.apache.commons.lang.StringUtils;
 
 import java.io.IOException;
+import java.text.MessageFormat;
+import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Set;
 import java.util.logging.Logger;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.SEVERE;
@@ -216,6 +220,8 @@ String getBuildStatusMessage(AbstractBuild r, boolean includeTestSummary, boolea
 
     public static class MessageBuilder {
 
+        private static final Pattern aTag = Pattern.compile("(?i)<a([^>]+)>(.+?)</a>");
+        private static final Pattern href = Pattern.compile("\\s*(?i)href\\s*=\\s*(\"([^\"]*\")|'[^']*'|([^'\">\\s]+))");
         private static final String STARTING_STATUS_MESSAGE = "Starting...",
                                     BACK_TO_NORMAL_STATUS_MESSAGE = "Back to normal",
                                     STILL_FAILING_STATUS_MESSAGE = "Still Failing",
@@ -383,14 +389,34 @@ private String createBackToNormalDurationString(){
             return Util.getTimeSpanString(backToNormalDuration);
         }
 
-        public String escape(String string) {
+        private String escapeCharacters(String string) {
             string = string.replace("&", "&amp;");
             string = string.replace("<", "&lt;");
             string = string.replace(">", "&gt;");
 
             return string;
         }
 
+        private String[] extractReplaceLinks(Matcher aTag, StringBuffer sb) {
+            int size = 0;
+            List<String> links = new ArrayList<String>();
+            while (aTag.find()) {
+                Matcher url = href.matcher(aTag.group(1));
+                if (url.find()) {
+                    aTag.appendReplacement(sb,String.format("{%s}", size++));
+                    links.add(String.format("<%s|%s>", url.group(1).replaceAll("\"", ""), aTag.group(2)));
+                }
+            }
+            aTag.appendTail(sb);
+            return links.toArray(new String[size]);
+        }
+
+        public String escape(String string) {
+            StringBuffer pattern = new StringBuffer();
+            String[] links = extractReplaceLinks(aTag.matcher(string), pattern);
+            return MessageFormat.format(escapeCharacters(pattern.toString()), links);
+        }
+
         public String toString() {
             return message.toString();
         }

src/test/java/jenkins/plugins/slack/workflow/MessageBuilderTest.java

@@ -0,0 +1,66 @@
+package jenkins.plugins.slack.workflow;
+
+import hudson.model.FreeStyleBuild;
+import hudson.model.FreeStyleProject;
+import hudson.model.ItemGroup;
+import jenkins.plugins.slack.ActiveNotifier;
+import junit.framework.TestCase;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.mockito.Mockito;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.concurrent.ExecutionException;
+
+@RunWith(Parameterized.class)
+public class MessageBuilderTest extends TestCase {
+
+    private ActiveNotifier.MessageBuilder messageBuilder;
+    private String expectedResult;
+    private FreeStyleBuild build;
+
+
+    @Before
+    @Override
+    public void setUp() throws IOException, ExecutionException, InterruptedException {
+        messageBuilder = new ActiveNotifier.MessageBuilder(null, build);
+    }
+
+    public MessageBuilderTest(String projectDisplayName, String buildDisplayName, String expectedResult) {
+        this.build = Mockito.mock(FreeStyleBuild.class);
+        FreeStyleProject project = Mockito.mock(FreeStyleProject.class);
+
+        Mockito.when(build.getProject()).thenReturn(project);
+        Mockito.when(build.getDisplayName()).thenReturn(buildDisplayName);
+
+        ItemGroup ig = Mockito.mock(ItemGroup.class);
+        Mockito.when(ig.getFullDisplayName()).thenReturn("");
+        Mockito.when(project.getParent()).thenReturn(ig);
+        Mockito.when(project.getDisplayName()).thenReturn(projectDisplayName);
+
+        this.expectedResult = expectedResult;
+
+    }
+
+    @Parameterized.Parameters
+    public static Collection businessTypeKeys() {
+        return Arrays.asList(new Object[][]{
+                {"", "", " -  "},
+                {"project", "#43 Started by changes from Bob", "project - #43 Started by changes from Bob "},
+                {"project", "#541 <a href=\"https://bitbucket.org/org/project/pull-request/125\">#125 Bug</a>",
+                        "project - #541 <https://bitbucket.org/org/project/pull-request/125|#125 Bug> "},
+                {"project", "#541 <b>Bold Project</b>", "project - #541 &lt;b&gt;Bold Project&lt;/b&gt; "},
+                {"project", "#541 <a no-url>bob</a>", "project - #541 &lt;a no-url&gt;bob&lt;/a&gt; "}
+        });
+    }
+
+    @Test
+    public void testStartMessage() {
+        assertEquals(expectedResult, messageBuilder.toString());
+    }
+
+}