[MNG-8385] Introduce proto session

api/maven-api-core/src/main/java/org/apache/maven/api/ProtoSession.java

@@ -0,0 +1,212 @@
+/*
+ * 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.api;
+
+import java.nio.file.Path;
+import java.time.Instant;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.annotations.Nonnull;
+import org.apache.maven.api.annotations.Nullable;
+import org.apache.maven.api.annotations.ThreadSafe;
+
+import static java.util.Objects.requireNonNull;
+
+/**
+ * The proto session, material used to create {@link Session}.
+ *
+ * @since 4.0.0
+ */
+@Experimental
+@ThreadSafe
+public interface ProtoSession {
+
+    /**
+     * Returns immutable user properties to use for interpolation. The user properties have been configured directly
+     * by the user, e.g. via the {@code -Dkey=value} parameter on the command line.
+     *
+     * @return the user properties, never {@code null}
+     */
+    @Nonnull
+    Map<String, String> getUserProperties();
+
+    /**
+     * Returns immutable system properties to use for interpolation. The system properties are collected from the
+     * runtime environment such as {@link System#getProperties()} and environment variables
+     * (prefixed with {@code env.}).
+     *
+     * @return the system properties, never {@code null}
+     */
+    @Nonnull
+    Map<String, String> getSystemProperties();
+
+    /**
+     * Returns the start time of the session.
+     *
+     * @return the start time as an Instant object, never {@code null}
+     */
+    @Nonnull
+    Instant getStartTime();
+
+    /**
+     * Gets the directory of the topmost project being built, usually the current directory or the
+     * directory pointed at by the {@code -f/--file} command line argument.
+     *
+     * @return the directory of the topmost project, never {@code null}
+     * @see Project#isTopProject()
+     * @see #getRootDirectory()
+     */
+    @Nonnull
+    Path getTopDirectory();
+
+    /**
+     * Gets the root directory of the session, which is the root directory for the top directory project.
+     *
+     * @return the root directory, never {@code null}
+     * @throws IllegalStateException if the root directory could not be found
+     * @see #getTopDirectory()
+     * @see Project#getRootDirectory()
+     * @see Project#isRootProject()
+     */
+    @Nonnull
+    Path getRootDirectory();
+
+    /**
+     * Returns a proto session builder of this instance.
+     */
+    @Nonnull
+    default Builder toBuilder() {
+        try {
+            return new Builder(
+                    getUserProperties(), getSystemProperties(), getStartTime(), getTopDirectory(), getRootDirectory());
+        } catch (IllegalStateException e) {
+            return new Builder(getUserProperties(), getSystemProperties(), getStartTime(), getTopDirectory(), null);
+        }
+    }
+
+    /**
+     * Returns new builder from scratch.
+     */
+    static Builder newBuilder() {
+        return new Builder().withStartTime(Instant.now());
+    }
+
+    class Builder {
+        private Map<String, String> userProperties;
+        private Map<String, String> systemProperties;
+        private Instant startTime;
+        private Path topDirectory;
+        private Path rootDirectory;
+
+        private Builder() {}
+
+        private Builder(
+                Map<String, String> userProperties,
+                Map<String, String> systemProperties,
+                Instant startTime,
+                Path topDirectory,
+                Path rootDirectory) {
+            this.userProperties = userProperties;
+            this.systemProperties = systemProperties;
+            this.startTime = startTime;
+            this.topDirectory = topDirectory;
+            this.rootDirectory = rootDirectory;
+        }
+
+        public Builder withUserProperties(@Nonnull Map<String, String> userProperties) {
+            this.userProperties = new HashMap<>(userProperties);
+            return this;
+        }
+
+        public Builder withSystemProperties(@Nonnull Map<String, String> systemProperties) {
+            this.systemProperties = new HashMap<>(systemProperties);
+            return this;
+        }
+
+        public Builder withStartTime(@Nonnull Instant startTime) {
+            this.startTime = requireNonNull(startTime, "startTime");
+            return this;
+        }
+
+        public Builder withTopDirectory(@Nonnull Path topDirectory) {
+            this.topDirectory = requireNonNull(topDirectory, "topDirectory");
+            return this;
+        }
+
+        public Builder withRootDirectory(@Nullable Path rootDirectory) {
+            this.rootDirectory = rootDirectory;
+            return this;
+        }
+
+        public ProtoSession build() {
+            return new Impl(userProperties, systemProperties, startTime, topDirectory, rootDirectory);
+        }
+
+        private static class Impl implements ProtoSession {
+            private final Map<String, String> userProperties;
+            private final Map<String, String> systemProperties;
+            private final Instant startTime;
+            private final Path topDirectory;
+            private final Path rootDirectory;
+
+            private Impl(
+                    Map<String, String> userProperties,
+                    Map<String, String> systemProperties,
+                    Instant startTime,
+                    Path topDirectory,
+                    Path rootDirectory) {
+                this.userProperties = requireNonNull(userProperties);
+                this.systemProperties = requireNonNull(systemProperties);
+                this.startTime = requireNonNull(startTime);
+                this.topDirectory = requireNonNull(topDirectory);
+                this.rootDirectory = rootDirectory;
+            }
+
+            @Override
+            public Map<String, String> getUserProperties() {
+                return userProperties;
+            }
+
+            @Override
+            public Map<String, String> getSystemProperties() {
+                return systemProperties;
+            }
+
+            @Override
+            public Instant getStartTime() {
+                return startTime;
+            }
+
+            @Override
+            public Path getTopDirectory() {
+                return topDirectory;
+            }
+
+            @Override
+            public Path getRootDirectory() {
+                if (rootDirectory == null) {
+                    throw new IllegalStateException("root directory not set");
+                }
+                return rootDirectory;
+            }
+        }
+    }
+}

api/maven-api-core/src/main/java/org/apache/maven/api/Session.java

@@ -19,7 +19,6 @@
 package org.apache.maven.api;
 
 import java.nio.file.Path;
-import java.time.Instant;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
@@ -46,7 +45,15 @@
  */
 @Experimental
 @ThreadSafe
-public interface Session {
+public interface Session extends ProtoSession {
+
+    /**
+     * Returns the current maven version.
+     *
+     * @return the maven version, never {@code null}
+     */
+    @Nonnull
+    Version getMavenVersion();
 
     /**
      * Retrieves the settings for the current session.
@@ -80,25 +87,6 @@ public interface Session {
     @Nonnull
     SessionData getData();
 
-    /**
-     * Returns immutable user properties to use for interpolation. The user properties have been configured directly
-     * by the user, e.g. via the {@code -Dkey=value} parameter on the command line.
-     *
-     * @return the user properties, never {@code null}
-     */
-    @Nonnull
-    Map<String, String> getUserProperties();
-
-    /**
-     * Returns immutable system properties to use for interpolation. The system properties are collected from the
-     * runtime environment such as {@link System#getProperties()} and environment variables
-     * (prefixed with {@code env.}).
-     *
-     * @return the system properties, never {@code null}
-     */
-    @Nonnull
-    Map<String, String> getSystemProperties();
-
     /**
      * Each invocation computes a new map of effective properties. To be used in interpolation.
      * <p>
@@ -121,52 +109,13 @@ public interface Session {
     @Nonnull
     Map<String, String> getEffectiveProperties(@Nullable Project project);
 
-    /**
-     * Returns the current maven version.
-     *
-     * @return the maven version, never {@code null}
-     */
-    @Nonnull
-    Version getMavenVersion();
-
     /**
      * Returns the degree of concurrency for the build.
      *
      * @return  the degree of concurrency
      */
     int getDegreeOfConcurrency();
 
-    /**
-     * Returns the start time of the session.
-     *
-     * @return the start time as an Instant object, never {@code null}
-     */
-    @Nonnull
-    Instant getStartTime();
-
-    /**
-     * Gets the directory of the topmost project being built, usually the current directory or the
-     * directory pointed at by the {@code -f/--file} command line argument.
-     *
-     * @return the directory of the topmost project, never {@code null}
-     * @see Project#isTopProject()
-     * @see #getRootDirectory()
-     */
-    @Nonnull
-    Path getTopDirectory();
-
-    /**
-     * Gets the root directory of the session, which is the root directory for the top directory project.
-     *
-     * @return the root directory, never {@code null}
-     * @throws IllegalStateException if the root directory could not be found
-     * @see #getTopDirectory()
-     * @see Project#getRootDirectory()
-     * @see Project#isRootProject()
-     */
-    @Nonnull
-    Path getRootDirectory();
-
     /**
      * Retrieves a list of projects associated with the session.
      *

api/maven-api-core/src/main/java/org/apache/maven/api/services/ArtifactCoordinatesFactoryRequest.java

@@ -167,7 +167,7 @@ public ArtifactCoordinatesFactoryRequest build() {
                     session, groupId, artifactId, version, classifier, extension, type, coordinateString);
         }
 
-        private static class DefaultArtifactFactoryRequestArtifact extends BaseRequest
+        private static class DefaultArtifactFactoryRequestArtifact extends BaseRequest<Session>
                 implements ArtifactCoordinatesFactoryRequest {
             private final String groupId;
             private final String artifactId;

api/maven-api-core/src/main/java/org/apache/maven/api/services/ArtifactDeployerRequest.java

@@ -101,7 +101,8 @@ public ArtifactDeployerRequest build() {
             return new DefaultArtifactDeployerRequest(session, repository, artifacts, retryFailedDeploymentCount);
         }
 
-        private static class DefaultArtifactDeployerRequest extends BaseRequest implements ArtifactDeployerRequest {
+        private static class DefaultArtifactDeployerRequest extends BaseRequest<Session>
+                implements ArtifactDeployerRequest {
 
             private final RemoteRepository repository;
             private final Collection<ProducedArtifact> artifacts;

api/maven-api-core/src/main/java/org/apache/maven/api/services/ArtifactFactoryRequest.java

@@ -136,7 +136,8 @@ public ArtifactFactoryRequest build() {
                     session, groupId, artifactId, version, classifier, extension, type);
         }
 
-        private static class DefaultArtifactFactoryRequest extends BaseRequest implements ArtifactFactoryRequest {
+        private static class DefaultArtifactFactoryRequest extends BaseRequest<Session>
+                implements ArtifactFactoryRequest {
             private final String groupId;
             private final String artifactId;
             private final String version;

api/maven-api-core/src/main/java/org/apache/maven/api/services/ArtifactInstallerRequest.java

@@ -83,7 +83,7 @@ public ArtifactInstallerRequest build() {
             return new DefaultArtifactInstallerRequest(session, artifacts);
         }
 
-        static class DefaultArtifactInstallerRequest extends BaseRequest implements ArtifactInstallerRequest {
+        static class DefaultArtifactInstallerRequest extends BaseRequest<Session> implements ArtifactInstallerRequest {
 
             private final Collection<ProducedArtifact> artifacts;
 

api/maven-api-core/src/main/java/org/apache/maven/api/services/ArtifactResolverRequest.java

@@ -106,7 +106,8 @@ public ArtifactResolverRequest build() {
             return new DefaultArtifactResolverRequest(session, coordinates, repositories);
         }
 
-        private static class DefaultArtifactResolverRequest extends BaseRequest implements ArtifactResolverRequest {
+        private static class DefaultArtifactResolverRequest extends BaseRequest<Session>
+                implements ArtifactResolverRequest {
             @Nonnull
             private final Collection<? extends ArtifactCoordinates> coordinates;
 

api/maven-api-core/src/main/java/org/apache/maven/api/services/BaseRequest.java

@@ -22,7 +22,7 @@
 import java.util.Collection;
 import java.util.Collections;
 
-import org.apache.maven.api.Session;
+import org.apache.maven.api.ProtoSession;
 import org.apache.maven.api.annotations.Experimental;
 import org.apache.maven.api.annotations.Nonnull;
 
@@ -32,16 +32,16 @@
  * @since 4.0.0
  */
 @Experimental
-abstract class BaseRequest {
+abstract class BaseRequest<S extends ProtoSession> {
 
-    private final Session session;
+    private final S session;
 
-    protected BaseRequest(@Nonnull Session session) {
+    protected BaseRequest(@Nonnull S session) {
         this.session = nonNull(session, "session cannot be null");
     }
 
     @Nonnull
-    public Session getSession() {
+    public S getSession() {
         return session;
     }