[MSITE-1033] Improve heuristics to detect inheritance for SCM site URLs

pom.xml

@@ -415,6 +415,12 @@ under the License.
       </exclusions>
     </dependency>
 
+    <dependency>
+      <groupId>org.apache.maven.scm</groupId>
+      <artifactId>maven-scm-api</artifactId>
+      <version>2.1.0</version>
+    </dependency>
+
     <dependency>
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-lang3</artifactId>

src/it/projects/site-inheritance/sub_module/pom.xml

@@ -30,6 +30,14 @@ under the License.
     <relativePath>../module</relativePath>
   </parent>
 
+  <distributionManagement>
+    <site>
+      <id>website</id>
+      <!-- automatic inheritance calculation would incorrectly yield file:///@project.build.directory@/it/site-inheritance/webhost.company.com/deploy/www/website/submodule -->
+      <url>file:///@project.build.directory@/it/site-inheritance/webhost.company.com/deploy/www/website/module/submodule</url>
+    </site>
+  </distributionManagement>
+
   <artifactId>sub_module</artifactId>
   <name>Sub-Module</name>
 

src/main/java/org/apache/maven/plugins/site/deploy/AbstractDeployMojo.java

@@ -20,9 +20,11 @@
 
 import java.io.File;
 import java.net.MalformedURLException;
+import java.net.URI;
 import java.net.URL;
 import java.util.List;
 import java.util.Locale;
+import java.util.Objects;
 
 import org.apache.maven.doxia.site.inheritance.URIPathDescriptor;
 import org.apache.maven.doxia.tools.SiteTool;
@@ -35,6 +37,7 @@
 import org.apache.maven.plugins.annotations.Parameter;
 import org.apache.maven.plugins.site.AbstractSiteMojo;
 import org.apache.maven.project.MavenProject;
+import org.apache.maven.scm.provider.ScmUrlUtils;
 import org.apache.maven.settings.Proxy;
 import org.apache.maven.settings.Server;
 import org.apache.maven.settings.Settings;
@@ -523,18 +526,69 @@ protected MavenProject getTopLevelProject(MavenProject project) throws MojoExecu
                 return oldProject;
             }
 
-            // MSITE-600
-            URIPathDescriptor siteURI = new URIPathDescriptor(URIEncoder.encodeURI(site.getUrl()), "");
-            URIPathDescriptor oldSiteURI = new URIPathDescriptor(URIEncoder.encodeURI(oldSite.getUrl()), "");
-
-            if (!siteURI.sameSite(oldSiteURI.getBaseURI())) {
+            try {
+                if (!isSameSite(site.getUrl(), oldSite.getUrl())) {
+                    return oldProject;
+                }
+            } catch (IllegalArgumentException e) {
+                getLog().warn("Failed to parse distributionManagement.site.url of project \"" + getFullName(oldProject)
+                        + "\" or project \"" + getFullName(parent) + "\": " + e.getMessage());
                 return oldProject;
             }
         }
-
         return parent;
     }
 
+    /**
+     * Returns {@code true} if the URIs are probably pointing to the same site which means
+     * <ul>
+     * <li>both arguments are hierarchical URIs,</li>
+     * <li>both arguments share the same host and</li>
+     * <li>the path of the latter URI is a subpath of the first URI</li>
+     * </ul>.
+     * @param parentUri
+     * @param uri
+     * @return {@code true} if the URIs are probably pointing to the same site
+     * @throws IllegalArgumentException if the given URIs cannot be parsed
+     */
+    static boolean isSameSite(String parentUri, String uri) {
+        // this just normalizes the paths in it
+        URIPathDescriptor siteURI =
+                new URIPathDescriptor(URIEncoder.encodeURI(extractProviderSpecificPartFromScmUri(parentUri)), "");
+        URIPathDescriptor oldSiteURI =
+                new URIPathDescriptor(URIEncoder.encodeURI(extractProviderSpecificPartFromScmUri(uri)), "");
+        // compare host and path (port and scheme should not matter)
+        return isSameSite(siteURI.getBaseURI(), oldSiteURI.getBaseURI());
+    }
+
+    private static boolean isSameSite(URI parentUri, URI uri) {
+        // host must be equal
+        if (!Objects.equals(uri.getHost(), parentUri.getHost())) {
+            return false;
+        }
+        // path must be a subpath
+        if (uri.getPath() == null
+                || parentUri.getPath() == null
+                || !uri.getPath().startsWith(parentUri.getPath())) {
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Unwraps <a href="https://maven.apache.org/scm/scm-url-format.html">SCM URLs</a> to get the provider specific part.
+     * @param uri
+     * @return the provider specific part if the given URI is a SCM URI, otherwise just the uri
+     *
+     */
+    static String extractProviderSpecificPartFromScmUri(String uri) {
+        if (ScmUrlUtils.isValid(uri)) {
+            return ScmUrlUtils.getProviderSpecificPart(uri);
+        } else {
+            return uri;
+        }
+    }
+
     private static class URIEncoder {
         private static final String MARK = "-_.!~*'()";
         private static final String RESERVED = ";/?:@&=+$,";

src/test/java/org/apache/maven/plugins/site/deploy/AbstractDeployMojoTest.java

@@ -0,0 +1,62 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.plugins.site.deploy;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.assertTrue;
+
+public class AbstractDeployMojoTest {
+
+    @Test
+    public void testIsSameSite() {
+        assertTrue(AbstractDeployMojo.isSameSite(
+                "scm:svn:https://svn.apache.org/repos/asf/maven/website/components/${maven.site.path}",
+                "scm:svn:https://svn.apache.org/repos/asf/maven/website/components/${maven.site.path}"));
+        assertTrue(AbstractDeployMojo.isSameSite(
+                "https://svn.apache.org/repos/asf/maven/website/components/${maven.site.path}",
+                "https://svn.apache.org/repos/asf/maven/website/components/${maven.site.path}"));
+        // different scheme (encapsulated in SCM URL) and subpath
+        assertTrue(AbstractDeployMojo.isSameSite(
+                "scm:svn:http://svn.apache.org/repos/asf/maven/website",
+                "scm:svn:https://svn.apache.org/repos/asf/maven/website/components"));
+        assertTrue(AbstractDeployMojo.isSameSite(
+                "scm:git:ssh://github.com/codehaus-plexus/plexus-pom.git/",
+                "scm:git:ssh://github.com/codehaus-plexus/plexus-pom.git/"));
+        assertTrue(
+                AbstractDeployMojo.isSameSite(
+                        "file:////Users/konradwindszus/git/maven/maven-site-plugin/target/it/site-inheritance/webhost.company.com/deploy/www/website/module",
+                        "file:////Users/konradwindszus/git/maven/maven-site-plugin/target/it/site-inheritance/webhost.company.com/deploy/www/website/module/submodule"));
+        // sibling paths
+        assertFalse(AbstractDeployMojo.isSameSite(
+                "scm:svn:https://svn.apache.org/repos/asf/maven/website/a/${maven.site.path}",
+                "scm:svn:https://svn.apache.org/repos/asf/maven/website/b/${maven.site.path}"));
+        // sibling paths
+        assertFalse(AbstractDeployMojo.isSameSite(
+                "scm:git:ssh://github.com/codehaus-plexus/plexus-pom.git/",
+                "scm:git:ssh://[email protected]/codehaus-plexus/plexus-sec-dispatcher.git/"));
+        // SCM URLs which are opaque (i.e. non hierarchical URIs)
+        assertThrows(
+                IllegalArgumentException.class,
+                () -> AbstractDeployMojo.isSameSite(
+                        "scm:local:/usr/modules:my_module", "scm:local:/usr/modules:my_module"));
+    }
+}