ChangeScreen2: Show inline comments in history

When a history comment is expanded include the inline comments written
on that revision by the author at the same timestamp.  This makes it
easier to follow a change's evolution over time, especially if the
reader is new to the change and does not have the entire email thread
in their inbox.

Bug: issue 93
Change-Id: I57fe29fea2b3651306ff0a58746cefcfe1669267

gerrit-gwtui/src/main/java/com/google/gerrit/client/change/History.java

@@ -0,0 +1,172 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// Licensed 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 com.google.gerrit.client.change;
+
+import com.google.gerrit.client.account.AccountInfo;
+import com.google.gerrit.client.changes.ChangeApi;
+import com.google.gerrit.client.changes.ChangeInfo;
+import com.google.gerrit.client.changes.ChangeInfo.MessageInfo;
+import com.google.gerrit.client.changes.CommentInfo;
+import com.google.gerrit.client.rpc.NativeMap;
+import com.google.gerrit.client.rpc.Natives;
+import com.google.gerrit.client.ui.CommentLinkProcessor;
+import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.PatchSet;
+import com.google.gwt.core.client.JsArray;
+import com.google.gwt.user.client.rpc.AsyncCallback;
+import com.google.gwt.user.client.ui.FlowPanel;
+import com.google.gwt.user.client.ui.Widget;
+
+import java.sql.Timestamp;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+class History extends FlowPanel {
+  private CommentLinkProcessor clp;
+  private Change.Id changeId;
+
+  private final Set<Integer> loaded = new HashSet<Integer>();
+  private final Map<AuthorRevision, List<CommentInfo>> byAuthor =
+      new HashMap<AuthorRevision, List<CommentInfo>>();
+
+  void set(CommentLinkProcessor clp, Change.Id id, ChangeInfo info) {
+    this.clp = clp;
+    this.changeId = id;
+
+    JsArray<MessageInfo> messages = info.messages();
+    if (messages != null) {
+      for (MessageInfo msg : Natives.asList(messages)) {
+        Message ui = new Message(this, msg);
+        if (loaded.contains(msg._revisionNumber())) {
+          ui.addComments(comments(msg));
+        }
+        add(ui);
+      }
+    }
+  }
+
+  CommentLinkProcessor getCommentLinkProcessor() {
+    return clp;
+  }
+
+  Change.Id getChangeId() {
+    return changeId;
+  }
+
+  void addComments(int id, NativeMap<JsArray<CommentInfo>> map) {
+    loaded.add(id);
+
+    for (String path : map.keySet()) {
+      for (CommentInfo c : Natives.asList(map.get(path))) {
+        c.setPath(path);
+        if (c.author() != null) {
+          AuthorRevision k = new AuthorRevision(c.author(), id);
+          List<CommentInfo> l = byAuthor.get(k);
+          if (l == null) {
+            l = new ArrayList<CommentInfo>();
+            byAuthor.put(k, l);
+          }
+          l.add(c);
+        }
+      }
+    }
+  }
+
+  void load(final int revisionNumber) {
+    if (revisionNumber > 0 && loaded.add(revisionNumber)) {
+      ChangeApi.revision(new PatchSet.Id(changeId, revisionNumber))
+        .view("comments")
+        .get(new AsyncCallback<NativeMap<JsArray<CommentInfo>>>() {
+          @Override
+          public void onSuccess(NativeMap<JsArray<CommentInfo>> result) {
+            addComments(revisionNumber, result);
+            update(revisionNumber);
+          }
+
+          @Override
+          public void onFailure(Throwable caught) {
+          }
+        });
+    }
+  }
+
+  private void update(int revisionNumber) {
+    for (Widget child : getChildren()) {
+      Message ui = (Message) child;
+      MessageInfo info = ui.getMessageInfo();
+      if (info._revisionNumber() == revisionNumber) {
+        ui.addComments(comments(info));
+      }
+    }
+  }
+
+  private List<CommentInfo> comments(MessageInfo msg) {
+    if (msg.author() == null) {
+      return Collections.emptyList();
+    }
+
+    AuthorRevision k = new AuthorRevision(msg.author(), msg._revisionNumber());
+    List<CommentInfo> list = byAuthor.get(k);
+    if (list == null) {
+      return Collections.emptyList();
+    }
+
+    Timestamp when = msg.date();
+    List<CommentInfo> match = new ArrayList<CommentInfo>();
+    List<CommentInfo> other = new ArrayList<CommentInfo>();
+    for (int i = 0; i < list.size(); i++) {
+      CommentInfo c = list.get(i);
+      if (c.updated().compareTo(when) <= 0) {
+        match.add(c);
+      } else {
+        other.add(c);
+      }
+    }
+    if (match.isEmpty()) {
+      return Collections.emptyList();
+    } else if (other.isEmpty()) {
+      byAuthor.remove(k);
+    } else {
+      byAuthor.put(k, other);
+    }
+    return match;
+  }
+
+  private static final class AuthorRevision {
+    final int author;
+    final int revision;
+
+    AuthorRevision(AccountInfo author, int revision) {
+      this.author = author._account_id();
+      this.revision = revision;
+    }
+
+    @Override
+    public int hashCode() {
+      return author * 31 + revision;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      AuthorRevision b = (AuthorRevision) o;
+      return author == b.author && revision == b.revision;
+    }
+  }
+}