Show old file paths on renamed files

In the side-by-side view its hard to know that a file was actually
a rename from somewhere else.  Make it clear by showing the old
path in the column header when its not the same location.

Change-Id: I1d0e2fd370d34f9d4da481f7034380de0099a6af
Signed-off-by: Shawn O. Pearce <sop@google.com>

gerrit-common/src/main/java/com/google/gerrit/common/data/PatchScript.java

@@ -23,6 +23,7 @@ import com.google.gerrit.prettify.common.SparseFileContent;
 import com.google.gerrit.prettify.common.SparseHtmlFile;
 import com.google.gerrit.reviewdb.Change;
 import com.google.gerrit.reviewdb.Patch;
+import com.google.gerrit.reviewdb.Patch.ChangeType;
 
 import org.eclipse.jgit.diff.Edit;
 
@@ -34,6 +35,9 @@ public class PatchScript {
   }
 
   protected Change.Key changeId;
+  protected ChangeType changeType;
+  protected String oldName;
+  protected String newName;
   protected List<String> header;
   protected PatchScriptSettings settings;
   protected SparseFileContent a;
@@ -44,11 +48,15 @@ public class PatchScript {
   protected CommentDetail comments;
   protected List<Patch> history;
 
-  public PatchScript(final Change.Key ck, final List<String> h,
-      final PatchScriptSettings s, final SparseFileContent ca,
-      final SparseFileContent cb, final List<Edit> e, final DisplayMethod ma,
-      final DisplayMethod mb, final CommentDetail cd, final List<Patch> hist) {
+  public PatchScript(final Change.Key ck, final ChangeType ct, final String on,
+      final String nn, final List<String> h, final PatchScriptSettings s,
+      final SparseFileContent ca, final SparseFileContent cb,
+      final List<Edit> e, final DisplayMethod ma, final DisplayMethod mb,
+      final CommentDetail cd, final List<Patch> hist) {
     changeId = ck;
+    changeType = ct;
+    oldName = on;
+    newName = nn;
     header = h;
     settings = s;
     a = ca;
@@ -79,6 +87,18 @@ public class PatchScript {
     return header;
   }
 
+  public ChangeType getChangeType() {
+    return changeType;
+  }
+
+  public String getOldName() {
+    return oldName;
+  }
+
+  public String getNewName() {
+    return newName;
+  }
+
   public CommentDetail getCommentDetail() {
     return comments;
   }

gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/SideBySideTable.java

@@ -26,6 +26,7 @@ import com.google.gerrit.prettify.common.EditList;
 import com.google.gerrit.prettify.common.SparseHtmlFile;
 import com.google.gerrit.reviewdb.Patch;
 import com.google.gerrit.reviewdb.PatchLineComment;
+import com.google.gerrit.reviewdb.Patch.ChangeType;
 import com.google.gwt.core.client.GWT;
 import com.google.gwt.user.client.ui.HTMLTable.CellFormatter;
 import com.google.gwtexpui.safehtml.client.SafeHtml;
@@ -209,7 +210,12 @@ public class SideBySideTable extends AbstractPatchContentTable {
     m.openTd();
     m.setStyleName(Gerrit.RESOURCES.css().fileColumnHeader());
     m.setAttribute("width", "50%");
-    m.append(PatchUtil.C.patchHeaderOld());
+    if (script.getChangeType() == ChangeType.RENAMED
+        || script.getChangeType() == ChangeType.COPIED) {
+      m.append(script.getOldName());
+    } else {
+      m.append(PatchUtil.C.patchHeaderOld());
+    }
     m.br();
     if (0 < script.getA().size()) {
       if (idSideA == null) {

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/patch/PatchScriptBuilder.java

@@ -63,7 +63,6 @@ class PatchScriptBuilder {
     }
   };
 
-  private final List<String> header;
   private Repository db;
   private Change change;
   private PatchScriptSettings settings;
@@ -79,7 +78,6 @@ class PatchScriptBuilder {
 
   @Inject
   PatchScriptBuilder(final FileTypeRegistry ftr) {
-    header = new ArrayList<String>();
     a = new Side();
     b = new Side();
     registry = ftr;
@@ -110,7 +108,8 @@ class PatchScriptBuilder {
       // For a diff --cc format we don't support converting it into
       // a patch script. Instead treat everything as a file header.
       //
-      return new PatchScript(change.getKey(), content.getHeaderLines(),
+      return new PatchScript(change.getKey(), content.getChangeType(), content
+          .getOldName(), content.getNewName(), content.getHeaderLines(),
           settings, a.dst, b.dst, Collections.<Edit> emptyList(),
           a.displayMethod, b.displayMethod, comments, history);
     }
@@ -123,7 +122,6 @@ class PatchScriptBuilder {
 
     edits = new ArrayList<Edit>(content.getEdits());
     ensureCommentsVisible(comments);
-    header.addAll(content.getHeaderLines());
 
     if (a.mode == FileMode.GITLINK || b.mode == FileMode.GITLINK) {
 
@@ -158,8 +156,10 @@ class PatchScriptBuilder {
       packContent(settings.getWhitespace() != Whitespace.IGNORE_NONE);
     }
 
-    return new PatchScript(change.getKey(), header, settings, a.dst, b.dst,
-        edits, a.displayMethod, b.displayMethod, comments, history);
+    return new PatchScript(change.getKey(), content.getChangeType(), content
+        .getOldName(), content.getNewName(), content.getHeaderLines(),
+        settings, a.dst, b.dst, edits, a.displayMethod, b.displayMethod,
+        comments, history);
   }
 
   private static String oldName(final PatchListEntry entry) {