[MRESOLVER-303] Make checksum detection reusable (s4u#227)

Expose it on selector..

---

https://issues.apache.org/jira/browse/MRESOLVER-303

maven-resolver-connector-basic/src/test/java/org/eclipse/aether/connector/basic/TestChecksumAlgorithmSelector.java

@@ -98,6 +98,12 @@ public List<ChecksumAlgorithmFactory> selectList( Collection<String> algorithmNa
                 .collect( toList() );
     }
 
+    @Override
+    public boolean isChecksumExtension( String extension )
+    {
+        throw new RuntimeException( "not implemented" );
+    }
+
     private static class MessageDigestChecksumAlgorithmFactory
             extends ChecksumAlgorithmFactorySupport
     {

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/Maven2RepositoryLayoutFactory.java

@@ -134,7 +134,7 @@ public RepositoryLayout newInstance( RepositorySystemSession session, RemoteRepo
         }
 
         return new Maven2RepositoryLayout(
-                new ArrayList<>( checksumAlgorithmFactorySelector.getChecksumAlgorithmFactories() ),
+                checksumAlgorithmFactorySelector,
                 checksumsAlgorithms,
                 omitChecksumsForExtensions
         );
@@ -143,17 +143,17 @@ public RepositoryLayout newInstance( RepositorySystemSession session, RemoteRepo
     private static class Maven2RepositoryLayout
             implements RepositoryLayout
     {
-        private final List<ChecksumAlgorithmFactory> allChecksumAlgorithms;
+        private final ChecksumAlgorithmFactorySelector checksumAlgorithmFactorySelector;
 
         private final List<ChecksumAlgorithmFactory> configuredChecksumAlgorithms;
 
         private final Set<String> extensionsWithoutChecksums;
 
-        private Maven2RepositoryLayout( List<ChecksumAlgorithmFactory> allChecksumAlgorithms,
+        private Maven2RepositoryLayout( ChecksumAlgorithmFactorySelector checksumAlgorithmFactorySelector,
                                         List<ChecksumAlgorithmFactory> configuredChecksumAlgorithms,
                                         Set<String> extensionsWithoutChecksums )
         {
-            this.allChecksumAlgorithms = Collections.unmodifiableList( allChecksumAlgorithms );
+            this.checksumAlgorithmFactorySelector = requireNonNull( checksumAlgorithmFactorySelector );
             this.configuredChecksumAlgorithms = Collections.unmodifiableList( configuredChecksumAlgorithms );
             this.extensionsWithoutChecksums = requireNonNull( extensionsWithoutChecksums );
         }
@@ -269,7 +269,7 @@ private List<ChecksumLocation> getChecksumLocations( URI location )
 
         private boolean isChecksum( String extension )
         {
-            return allChecksumAlgorithms.stream().anyMatch( a -> extension.endsWith( "." + a.getFileExtension() ) );
+            return checksumAlgorithmFactorySelector.isChecksumExtension( extension );
         }
     }
 }

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/checksum/DefaultChecksumAlgorithmFactorySelector.java

@@ -23,8 +23,8 @@
 import javax.inject.Named;
 import javax.inject.Singleton;
 
-import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -94,8 +94,22 @@ public List<ChecksumAlgorithmFactory> selectList( Collection<String> algorithmNa
     }
 
     @Override
-    public List<ChecksumAlgorithmFactory> getChecksumAlgorithmFactories()
+    public Collection<ChecksumAlgorithmFactory> getChecksumAlgorithmFactories()
     {
-        return new ArrayList<>( factories.values() );
+        return Collections.unmodifiableCollection( factories.values() );
+    }
+
+    @Override
+    public boolean isChecksumExtension( String extension )
+    {
+        requireNonNull( extension );
+        if ( extension.contains( "." ) )
+        {
+            return factories.values().stream().anyMatch( a -> extension.endsWith( "." + a.getFileExtension() ) );
+        }
+        else
+        {
+            return factories.values().stream().anyMatch( a -> extension.equals( a.getFileExtension() ) );
+        }
     }
 }

maven-resolver-impl/src/test/java/org/eclipse/aether/internal/impl/resolution/TrustedChecksumsArtifactResolverPostProcessorTest.java

@@ -108,6 +108,12 @@ public Collection<ChecksumAlgorithmFactory> getChecksumAlgorithmFactories()
             {
                 return Collections.singletonList( checksumAlgorithmFactory );
             }
+
+            @Override
+            public boolean isChecksumExtension( String extension )
+            {
+                throw new RuntimeException( "not implemented" );
+            }
         };
         subject = new TrustedChecksumsArtifactResolverPostProcessor( selector,
                 Collections.singletonMap( TRUSTED_SOURCE_NAME, this ) );

maven-resolver-spi/src/main/java/org/eclipse/aether/spi/connector/checksum/ChecksumAlgorithmFactory.java

@@ -37,6 +37,7 @@ public interface ChecksumAlgorithmFactory
     /**
      * Returns the file extension to be used for given checksum file (without leading dot), never {@code null}. The
      * extension should be file and URL path friendly, and may differ from value returned by {@link #getName()}.
+     * The checksum extension SHOULD NOT contain dot (".") character.
      * Example: "sha1".
      */
     String getFileExtension();

maven-resolver-spi/src/main/java/org/eclipse/aether/spi/connector/checksum/ChecksumAlgorithmFactorySelector.java

@@ -41,7 +41,7 @@ public interface ChecksumAlgorithmFactorySelector
     ChecksumAlgorithmFactory select( String algorithmName );
 
     /**
-     * Returns a list of factories for given algorithm names in order as collection is ordered, or throws if any of the
+     * Returns a list of factories in same order as algorithm names are ordered, or throws if any of the
      * algorithm name is not supported. The returned list has equal count of elements as passed in collection of names,
      * and if names contains duplicated elements, the returned list of algorithms will have duplicates as well.
      *
@@ -52,10 +52,19 @@ public interface ChecksumAlgorithmFactorySelector
     List<ChecksumAlgorithmFactory> selectList( Collection<String> algorithmNames );
 
     /**
-     * Returns a collection of supported algorithms. This set represents ALL the algorithms supported by Resolver,
-     * and is NOT in any relation to given repository layout used checksums, returned by method {@link
+     * Returns immutable collection of all supported algorithms. This set represents ALL the algorithms supported by
+     * Resolver, and is NOT in any relation to given repository layout used checksums, returned by method {@link
      * org.eclipse.aether.spi.connector.layout.RepositoryLayout#getChecksumAlgorithmFactories()} (in fact, is super set
      * of it).
      */
     Collection<ChecksumAlgorithmFactory> getChecksumAlgorithmFactories();
+
+    /**
+     * Returns {@code true} if passed in extension matches any known checksum extension. The extension string may
+     * start or contain dot ("."), but does not have to. In former case "ends with" is checked (i.e. "jar.sha1" -> true;
+     * ".sha1" -> true) while in latter equality (i.e. "sha1" -> true).
+     *
+     * @since 1.9.3
+     */
+    boolean isChecksumExtension( String extension );
 }