/*
 * Copyright 2000-2012 JetBrains s.r.o.
 *
 * 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.intellij.openapi.diff.impl.external;

import com.intellij.openapi.diff.DiffContent;
import com.intellij.openapi.diff.DiffRequest;
import com.intellij.openapi.diff.impl.DiffUtil;
import com.intellij.openapi.vfs.VirtualFile;
import org.jetbrains.annotations.NotNull;

/**
 * @author Konstantin Bulenkov
 */
class ExtCompareFiles extends BaseExternalTool {
  public static final BaseExternalTool INSTANCE = new ExtCompareFiles();

  private ExtCompareFiles() {
    super(DiffManagerImpl.ENABLE_FILES, DiffManagerImpl.FILES_TOOL);
  }

  public boolean isAvailable(@NotNull DiffRequest request) {
    final DiffContent[] contents = request.getContents();
    for (DiffContent content : contents) {
      final VirtualFile file = getLocalFile(content.getFile());
      if (file != null && file.isDirectory()) {
        return false;
      }

      if (LocalFileExternalizer.canExternalizeAsFile(file)) {
        continue;
      }

      if (DiffUtil.isWritable(content)) {
        return false;
      }
    }
    if (contents.length != 2) return false;
    if (externalize(request, 0) == null) return false;
    if (externalize(request, 1) == null) return false;
    return true;
  }
}