Fix to show project creators correctly (line#909)

Motivation:
The current creator of a project is the creator of the internal `dogma` repository, consistently set as `System`. We should show the correct creator which is stored in the `metadata.json` file.

A noteworthy observation is that only the email of the creator is stored in `metadata.json` instead of the complete `Author` information. A temporary solution involves restoring the `Author` using the email, with plans to revisit this approach if issues arise.

Modifications:
- Fix to show project creators correctly using information stored in the `metadata.json` file.

Result:
- Close line#908 
- The project creator is now correctly retrieved based on the information stored in the `metadata.json` file.

benchmarks/jmh/src/jmh/java/com/linecorp/centraldogma/server/internal/storage/repository/git/GitRepositoryBenchmark.java

@@ -41,7 +41,7 @@
 @State(Scope.Benchmark)
 public class GitRepositoryBenchmark {
 
-    private static final Author AUTHOR = new Author("[email protected]");
+    private static final Author AUTHOR = Author.ofEmail("[email protected]");
 
     @Param({ "0", "2000", "4000", "6000", "8000" })
     private int previousCommits;

common/src/main/java/com/linecorp/centraldogma/common/Author.java

@@ -16,6 +16,7 @@
 
 package com.linecorp.centraldogma.common;
 
+import static com.linecorp.centraldogma.internal.Util.emailToUsername;
 import static java.util.Objects.requireNonNull;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
@@ -43,12 +44,23 @@ public class Author {
      */
     public static final Author UNKNOWN = new Author("Unknown", "[email protected]");
 
+    /**
+     * Create a new {@link Author} with the {@code email}.
+     * The {@link #name()} will be set to the username of the {@code email}.
+     */
+    public static Author ofEmail(String email) {
+        return new Author(emailToUsername(email, "email"), email);
+    }
+
     private final String name;
     private final String email;
 
     /**
      * Creates a new instance with the specified e-mail address.
+     *
+     * @deprecated Use {@link #ofEmail(String)}.
      */
+    @Deprecated
     public Author(String email) {
         this(email, email);
     }

common/src/test/java/com/linecorp/centraldogma/common/AuthorTest.java

@@ -42,9 +42,9 @@ void testJsonConversion() {
                              "  \"email\": \"[email protected]\"" +
                              '}');
 
-        TestUtil.assertJsonConversion(new Author("[email protected]"),
+        TestUtil.assertJsonConversion(Author.ofEmail("[email protected]"),
                              '{' +
-                             "  \"name\": \"bart@simpsonsworld.com\"," +
+                             "  \"name\": \"bart\"," +
                              "  \"email\": \"[email protected]\"" +
                              '}');
     }

server/src/main/java/com/linecorp/centraldogma/server/internal/storage/project/DefaultProject.java

@@ -29,14 +29,19 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.fasterxml.jackson.core.JsonParseException;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.JsonNode;
 import com.google.common.collect.ImmutableMap;
 
 import com.linecorp.centraldogma.common.Author;
 import com.linecorp.centraldogma.common.CentralDogmaException;
 import com.linecorp.centraldogma.common.Change;
+import com.linecorp.centraldogma.common.Entry;
 import com.linecorp.centraldogma.common.Markup;
 import com.linecorp.centraldogma.common.ProjectExistsException;
 import com.linecorp.centraldogma.common.ProjectNotFoundException;
+import com.linecorp.centraldogma.common.Query;
 import com.linecorp.centraldogma.common.RepositoryExistsException;
 import com.linecorp.centraldogma.common.Revision;
 import com.linecorp.centraldogma.internal.Jackson;
@@ -61,6 +66,8 @@ public class DefaultProject implements Project {
     private static final Logger logger = LoggerFactory.getLogger(DefaultProject.class);
 
     private final String name;
+    private final long creationTimeMillis;
+    private final Author author;
     final RepositoryManager repos;
     private final AtomicReference<MetaRepository> metaRepo = new AtomicReference<>();
 
@@ -82,6 +89,14 @@ public class DefaultProject implements Project {
         boolean success = false;
         try {
             createReservedRepos(System.currentTimeMillis());
+            final UserAndTimestamp creation = metadataCreation();
+            if (creation != null) {
+                creationTimeMillis = creation.timestampMillis();
+                author = Author.ofEmail(creation.user());
+            } else {
+                creationTimeMillis = repos.get(REPO_DOGMA).creationTimeMillis();
+                author = repos.get(REPO_DOGMA).author();
+            }
             success = true;
         } finally {
             if (!success) {
@@ -109,6 +124,8 @@ public class DefaultProject implements Project {
         try {
             createReservedRepos(creationTimeMillis);
             initializeMetadata(creationTimeMillis, author);
+            this.creationTimeMillis = creationTimeMillis;
+            this.author = author;
             success = true;
         } finally {
             if (!success) {
@@ -117,6 +134,23 @@ public class DefaultProject implements Project {
         }
     }
 
+    @Nullable
+    private UserAndTimestamp metadataCreation() {
+        if (name.equals(INTERNAL_PROJECT_DOGMA)) {
+            return null;
+        }
+        final Entry<JsonNode> metadata = repos.get(REPO_DOGMA)
+                                              .get(Revision.HEAD, Query.ofJson(METADATA_JSON))
+                                              .join();
+        try {
+            return Jackson.treeToValue(metadata.content(), ProjectMetadata.class)
+                          .creation();
+        } catch (JsonParseException | JsonMappingException e) {
+            logger.warn("Failed to retrieve creation in {} file. project: {}", METADATA_JSON, name);
+            return null;
+        }
+    }
+
     private RepositoryManager newRepoManager(File rootDir, Executor repositoryWorker, Executor purgeWorker,
                                              @Nullable RepositoryCache cache) {
         // Enable caching if 'cache' is not null.
@@ -174,6 +208,16 @@ public String name() {
         return name;
     }
 
+    @Override
+    public long creationTimeMillis() {
+        return creationTimeMillis;
+    }
+
+    @Override
+    public Author author() {
+        return author;
+    }
+
     @Override
     public MetaRepository metaRepo() {
         MetaRepository metaRepo = this.metaRepo.get();

server/src/main/java/com/linecorp/centraldogma/server/metadata/UserAndTimestamp.java

@@ -89,6 +89,13 @@ public String timestamp() {
         return timestampAsText;
     }
 
+    /**
+     * Returns the epoch milliseconds of the {@link #timestamp()}.
+     */
+    public long timestampMillis() {
+        return timestamp.toEpochMilli();
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) {

server/src/main/java/com/linecorp/centraldogma/server/storage/project/Project.java

@@ -51,16 +51,12 @@ public interface Project {
     /**
      * Returns the creation time of this project, in milliseconds.
      */
-    default long creationTimeMillis() {
-        return repos().get(REPO_DOGMA).creationTimeMillis();
-    }
+    long creationTimeMillis();
 
     /**
      * Returns the author who initially created this project.
      */
-    default Author author() {
-        return repos().get(REPO_DOGMA).author();
-    }
+    Author author();
 
     /**
      * Returns the {@link MetaRepository} of this project.

server/src/test/java/com/linecorp/centraldogma/server/internal/api/ProjectServiceV1Test.java

@@ -135,8 +135,8 @@ void unremoveProject() {
                 '{' +
                 "   \"name\": \"bar\"," +
                 "   \"creator\": {" +
-                "       \"name\": \"System\"," +
-                "       \"email\": \"system@localhost.localdomain\"" +
+                "       \"name\": \"admin\"," +
+                "       \"email\": \"admin@localhost.localdomain\"" +
                 "   }," +
                 "   \"url\": \"/api/v1/projects/bar\"," +
                 "   \"createdAt\": \"${json-unit.ignore}\"" +
@@ -187,26 +187,26 @@ void listProjects() {
                     "   {" +
                     "       \"name\": \"hyangtack\"," +
                     "       \"creator\": {" +
-                    "           \"name\": \"System\"," +
-                    "           \"email\": \"system@localhost.localdomain\"" +
+                    "           \"name\": \"admin\"," +
+                    "           \"email\": \"admin@localhost.localdomain\"" +
                     "       }," +
                     "       \"url\": \"/api/v1/projects/hyangtack\"," +
                     "       \"createdAt\": \"${json-unit.ignore}\"" +
                     "   }," +
                     "   {" +
                     "       \"name\": \"minwoox\"," +
                     "       \"creator\": {" +
-                    "           \"name\": \"System\"," +
-                    "           \"email\": \"system@localhost.localdomain\"" +
+                    "           \"name\": \"admin\"," +
+                    "           \"email\": \"admin@localhost.localdomain\"" +
                     "       }," +
                     "       \"url\": \"/api/v1/projects/minwoox\"," +
                     "       \"createdAt\": \"${json-unit.ignore}\"" +
                     "   }," +
                     "   {" +
                     "       \"name\": \"trustin\"," +
                     "       \"creator\": {" +
-                    "           \"name\": \"System\"," +
-                    "           \"email\": \"system@localhost.localdomain\"" +
+                    "           \"name\": \"admin\"," +
+                    "           \"email\": \"admin@localhost.localdomain\"" +
                     "       }," +
                     "       \"url\": \"/api/v1/projects/trustin\"," +
                     "       \"createdAt\": \"${json-unit.ignore}\"" +

server/src/test/java/com/linecorp/centraldogma/server/internal/api/TokenServiceTest.java

@@ -52,8 +52,8 @@ class TokenServiceTest {
     @RegisterExtension
     static final ProjectManagerExtension manager = new ProjectManagerExtension();
 
-    private static final Author adminAuthor = new Author("[email protected]");
-    private static final Author guestAuthor = new Author("[email protected]");
+    private static final Author adminAuthor = Author.ofEmail("[email protected]");
+    private static final Author guestAuthor = Author.ofEmail("[email protected]");
     private static final User admin = new User("[email protected]", User.LEVEL_ADMIN);
     private static final User guest = new User("[email protected]");
     private static final JsonNode activation = Jackson.valueToTree(