InlineEdit: Add change content file API for change edits

Change-Id: Ica531d8080b5d9fe03a3064abc383fc367dcdc0d

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ChangeFileApi.java

diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ChangeFileApi.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ChangeFileApi.java
new file mode 100644
index 0000000..fc15017
--- /dev/null
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ChangeFileApi.java
@@ -0,0 +1,102 @@
+// Copyright (C) 2014 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.changes;
+
+import com.google.gerrit.client.VoidResult;
+import com.google.gerrit.client.rpc.NativeString;
+import com.google.gerrit.client.rpc.RestApi;
+import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.PatchSet;
+import com.google.gwt.core.client.JavaScriptObject;
+import com.google.gwt.user.client.rpc.AsyncCallback;
+
+/**
+ * A collection of static methods which work on the Gerrit REST API for specific
+ * files in a change.
+ */
+public class ChangeFileApi {
+  static abstract class CallbackWrapper<I, O> implements AsyncCallback<I> {
+    protected AsyncCallback<O> wrapped;
+
+    public CallbackWrapper(AsyncCallback<O> callback) {
+      wrapped = callback;
+    }
+
+    @Override
+    public abstract void onSuccess(I result);
+
+    @Override
+    public void onFailure(Throwable caught) {
+      wrapped.onFailure(caught);
+    }
+  }
+
+  /** Get the contents of a File in a PatchSet or cange edit. */
+  public static void getContent(PatchSet.Id id, String filename,
+      AsyncCallback<String> cb) {
+    contentEditOrPs(id, filename).get(
+        new CallbackWrapper<NativeString, String>(cb) {
+            @Override
+            public void onSuccess(NativeString b64) {
+              wrapped.onSuccess(b64decode(b64.asString()));
+            }
+          });
+  }
+
+  /** Put contents into a File in a change edit. */
+  public static void putContent(PatchSet.Id id, String filename,
+      String content, AsyncCallback<VoidResult> result) {
+    contentEdit(id.getParentKey(), filename).put(content, result);
+  }
+
+  /** Restore contents of a File in a change edit. */
+  public static void restoreContent(PatchSet.Id id, String filename,
+      AsyncCallback<VoidResult> result) {
+    Input in = Input.create();
+    in.path(filename);
+    in.restore(true);
+    ChangeApi.edit(id.getParentKey().get()).post(in, result);
+  }
+
+  /** Delete a file from a change edit. */
+  public static void deleteContent(PatchSet.Id id, String filename,
+      AsyncCallback<VoidResult> result) {
+    contentEdit(id.getParentKey(), filename).delete(result);
+  }
+
+  private static RestApi contentEditOrPs(PatchSet.Id id, String filename) {
+    return id.get() == 0
+        ? contentEdit(id.getParentKey(), filename)
+        : ChangeApi.revision(id).view("files").id(filename).view("content");
+  }
+
+  private static RestApi contentEdit(Change.Id id, String filename) {
+    return ChangeApi.edit(id.get()).id(filename);
+  }
+
+  private static native String b64decode(String a) /*-{ return window.atob(a); }-*/;
+
+  private static class Input extends JavaScriptObject {
+    final native void path(String p) /*-{ if(p)this.path=p; }-*/;
+    final native void restore(boolean r) /*-{ if(r)this.restore=r; }-*/;
+
+    static Input create() {
+      return (Input) createObject();
+    }
+
+    protected Input() {
+    }
+  }
+}
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