InlineEdit: Add GET /changes/{id}/edit/{path}/type endpoint

Change-Id: I3b5bb2fab294e5ba560ac2db32dcc80055bdc6a8

Documentation/rest-api-changes.txt

@@ -1369,6 +1369,29 @@ specified file was deleted in the change edit "`204 No Content`" is returned.
   RnJvbSA3ZGFkY2MxNTNmZGVhMTdhYTg0ZmYzMmE2ZTI0NWRiYjY...
 ----
 
+[[get-edit-file-mime-type]]
+=== Retrieve file content MIME type from Change Edit
+--
+'GET /changes/link:#change-id[\{change-id\}]/edit/path%2fto%2ffile/type
+--
+
+Retrieves content MIME type of a file from a change edit.
+
+.Request
+----
+  GET /changes/myProject~master~I8473b95934b5732ac55d26311a706c9c2bde9940/edit/foo%2fbar%2fbaz%2fqux.txt/type HTTP/1.0
+----
+
+.Response
+----
+  HTTP/1.1 200 OK
+  Content-Disposition: attachment
+  Content-Type: application/json;charset=UTF-8
+
+  )]}'
+  "text/plain"
+----
+
 [[get-edit-message]]
 === Retrieve commit message from Change Edit or current patch set of the change
 --

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/edit/ChangeEditIT.java

@@ -484,6 +484,18 @@ public class ChangeEditIT extends AbstractDaemonTest {
         .isEqualTo(StringUtils.newStringUtf8(CONTENT_NEW2));
   }
 
+  @Test
+  public void getFileContentTypeRest() throws Exception {
+    Put.Input in = new Put.Input();
+    in.content = RestSession.newRawInput(CONTENT_NEW);
+    assertThat(adminSession.putRaw(urlEditFile(), in.content).getStatusCode())
+        .isEqualTo(SC_NO_CONTENT);
+    RestResponse r = adminSession.get(urlEditFileContentType());
+    assertThat(r.getStatusCode()).isEqualTo(SC_OK);
+    String res = newGson().fromJson(r.getReader(), String.class);
+    assertThat(res).isEqualTo("application/octet-stream");
+  }
+
   @Test
   public void getFileNotFoundRest() throws Exception {
     assertThat(modifier.createEdit(change, ps)).isEqualTo(RefUpdate.Result.NEW);
@@ -606,6 +618,13 @@ public class ChangeEditIT extends AbstractDaemonTest {
         + FILE_NAME;
   }
 
+  private String urlEditFileContentType() {
+    return urlEdit()
+        + "/"
+        + FILE_NAME
+        + "/type";
+  }
+
   private String urlGetFiles() {
     return urlEdit()
         + "?list";

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeEdits.java

@@ -516,4 +516,23 @@ public class ChangeEdits implements
       return BinaryResult.create(m).base64();
     }
   }
+
+  @Singleton
+  public static class GetType implements RestReadView<ChangeEditResource> {
+    private final FileContentUtil fileContentUtil;
+
+    @Inject
+    GetType(FileContentUtil fileContentUtil) {
+      this.fileContentUtil = fileContentUtil;
+    }
+
+    @Override
+    public String apply(ChangeEditResource rsrc)
+        throws ResourceNotFoundException, IOException {
+      return fileContentUtil.getContentType(
+          rsrc.getChangeEdit().getChange().getProject(),
+          rsrc.getChangeEdit().getRevision().get(),
+          rsrc.getPath());
+    }
+  }
 }

gerrit-server/src/main/java/com/google/gerrit/server/change/FileContentUtil.java

@@ -14,14 +14,18 @@
 
 package com.google.gerrit.server.change;
 
+import static org.eclipse.jgit.lib.Constants.OBJ_BLOB;
+
 import com.google.gerrit.extensions.restapi.BinaryResult;
 import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
 import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.FileTypeRegistry;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 
 import org.eclipse.jgit.lib.ObjectLoader;
+import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;
@@ -33,10 +37,13 @@ import java.io.OutputStream;
 @Singleton
 public class FileContentUtil {
   private final GitRepositoryManager repoManager;
+  private final FileTypeRegistry registry;
 
   @Inject
-  FileContentUtil(GitRepositoryManager repoManager) {
+  FileContentUtil(GitRepositoryManager repoManager,
+      FileTypeRegistry ftr) {
     this.repoManager = repoManager;
+    this.registry = ftr;
   }
 
   public BinaryResult getContent(Project.NameKey project, String revstr,
@@ -68,4 +75,32 @@ public class FileContentUtil {
       repo.close();
     }
   }
+
+  public String getContentType(Project.NameKey project, String revstr,
+      String path) throws ResourceNotFoundException, IOException {
+    Repository repo = repoManager.openRepository(project);
+    try {
+      RevWalk rw = new RevWalk(repo);
+      ObjectReader reader = repo.newObjectReader();
+      try {
+        RevCommit commit = rw.parseCommit(repo.resolve(revstr));
+        TreeWalk tw =
+            TreeWalk.forPath(rw.getObjectReader(), path,
+                commit.getTree().getId());
+        if (tw == null) {
+          throw new ResourceNotFoundException();
+        }
+        ObjectLoader blobLoader = reader.open(tw.getObjectId(0), OBJ_BLOB);
+        byte[] raw = blobLoader.isLarge()
+            ? null
+            : blobLoader.getCachedBytes();
+        return registry.getMimeType(path, raw).toString();
+      } finally {
+        reader.release();
+        rw.release();
+      }
+    } finally {
+      repo.close();
+    }
+  }
 }

gerrit-server/src/main/java/com/google/gerrit/server/change/Module.java

@@ -113,6 +113,7 @@ public class Module extends RestApiModule {
     put(CHANGE_EDIT_KIND, "/").to(ChangeEdits.Put.class);
     delete(CHANGE_EDIT_KIND).to(ChangeEdits.DeleteContent.class);
     get(CHANGE_EDIT_KIND, "/").to(ChangeEdits.Get.class);
+    get(CHANGE_EDIT_KIND, "type").to(ChangeEdits.GetType.class);
 
     install(new FactoryModule() {
       @Override