Gerrit API: Allow to get file diff with options

Change-Id: Ia743166df6bc5f7bcaf88d426eba3a4bd1d02379
Signed-off-by: Edwin Kempin <ekempin@google.com>

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/changes/FileApi.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.extensions.api.changes;
 
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.extensions.common.DiffInfo;
 import com.google.gerrit.extensions.restapi.BinaryResult;
 import com.google.gerrit.extensions.restapi.NotImplementedException;
@@ -33,6 +34,57 @@ public interface FileApi {
    */
   DiffInfo diff(String base) throws RestApiException;
 
+  /**
+   * Creates a request to retrieve the diff. On the returned request formatting
+   * options for the diff can be set.
+   */
+  DiffRequest diffRequest() throws RestApiException;
+
+  public abstract class DiffRequest {
+    private String base;
+    private Integer context;
+    private Boolean intraline;
+    private Whitespace whitespace;
+
+    public abstract DiffInfo get() throws RestApiException;
+
+    public DiffRequest withBase(String base) {
+      this.base = base;
+      return this;
+    }
+
+    public DiffRequest withContext(int context) {
+      this.context = context;
+      return this;
+    }
+
+    public DiffRequest withIntraline(boolean intraline) {
+      this.intraline = intraline;
+      return this;
+    }
+
+    public DiffRequest withWhitespace(Whitespace whitespace) {
+      this.whitespace = whitespace;
+      return this;
+    }
+
+    public String getBase() {
+      return base;
+    }
+
+    public Integer getContext() {
+      return context;
+    }
+
+    public Boolean getIntraline() {
+      return intraline;
+    }
+
+    public Whitespace getWhitespace() {
+      return whitespace;
+    }
+  }
+
   /**
    * A default implementation which allows source compatibility
    * when adding new methods to the interface.
@@ -52,5 +104,10 @@ public interface FileApi {
     public DiffInfo diff(String base) throws RestApiException {
       throw new NotImplementedException();
     }
+
+    @Override
+    public DiffRequest diffRequest() throws RestApiException {
+      throw new NotImplementedException();
+    }
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/api/changes/FileApiImpl.java

@@ -74,4 +74,35 @@ class FileApiImpl implements FileApi {
       throw new RestApiException("Cannot retrieve diff", e);
     }
   }
+
+  @Override
+  public DiffRequest diffRequest() {
+    return new DiffRequest() {
+      @Override
+      public DiffInfo get() throws RestApiException {
+        return FileApiImpl.this.get(this);
+      }
+    };
+  }
+
+  private DiffInfo get(DiffRequest r) throws RestApiException {
+    GetDiff diff = getDiff.get();
+    if (r.getBase() != null) {
+      diff.setBase(r.getBase());
+    }
+    if (r.getContext() != null) {
+      diff.setContext(r.getContext());
+    }
+    if (r.getIntraline() != null) {
+      diff.setIntraline(r.getIntraline());
+    }
+    if (r.getWhitespace() != null) {
+      diff.setWhitespace(r.getWhitespace());
+    }
+    try {
+      return diff.apply(file).value();
+    } catch (IOException | InvalidChangeOperationException | OrmException e) {
+      throw new RestApiException("Cannot retrieve diff", e);
+    }
+  }
 }

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

@@ -272,6 +272,21 @@ public class GetDiff implements RestReadView<FileResource> {
     return this;
   }
 
+  public GetDiff setContext(int context) {
+    this.context = context;
+    return this;
+  }
+
+  public GetDiff setIntraline(boolean intraline) {
+    this.intraline = intraline;
+    return this;
+  }
+
+  public GetDiff setWhitespace(Whitespace whitespace) {
+    this.whitespace = whitespace;
+    return this;
+  }
+
   private static class Content {
     final List<ContentEntry> lines;
     final SparseFileContent fileA;