/*
 * Copyright 2000-2009 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.ide.util.treeView;

import com.intellij.openapi.fileTypes.FileTypeManager;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.Key;
import com.intellij.openapi.util.UserDataHolderEx;
import com.intellij.openapi.vfs.VirtualFile;
import com.intellij.psi.JavaDirectoryService;
import com.intellij.psi.PsiDirectory;
import com.intellij.psi.PsiManager;
import com.intellij.psi.PsiPackage;
import com.intellij.psi.impl.PsiManagerEx;
import com.intellij.util.containers.ConcurrentWeakHashMap;
import org.jetbrains.annotations.NotNull;

import java.util.concurrent.ConcurrentMap;

/**
 * @author Eugene Zhuravlev
 *         Date: Oct 6, 2004
 */
public class TreeViewUtil {
  private static final int SUBPACKAGE_LIMIT = 2;
  private static final Key<ConcurrentMap<PsiPackage,Boolean>> SHOULD_ABBREV_PACK_KEY = Key.create("PACK_ABBREV_CACHE");

  private static boolean shouldAbbreviateName(PsiPackage aPackage) {
    final Project project = aPackage.getProject();
    ConcurrentMap<PsiPackage, Boolean> map = project.getUserData(SHOULD_ABBREV_PACK_KEY);
    if (map == null) {
      final ConcurrentWeakHashMap<PsiPackage, Boolean> newMap = new ConcurrentWeakHashMap<PsiPackage, Boolean>();
      map = ((UserDataHolderEx)project).putUserDataIfAbsent(SHOULD_ABBREV_PACK_KEY, newMap);
      if (map == newMap) {
        ((PsiManagerEx)PsiManager.getInstance(project)).registerRunnableToRunOnChange(new Runnable() {
          @Override
          public void run() {
            newMap.clear();
          }
        });
      }
    }

    Boolean ret = map.get(aPackage);
    if (ret != null) return ret;
    ret = scanPackages(aPackage, 1);
    map.put(aPackage, ret);
    return ret;
  }

  private static boolean scanPackages(@NotNull PsiPackage p, int packageNameOccurrencesFound) {
    final PsiPackage[] subPackages = p.getSubPackages();
    packageNameOccurrencesFound += subPackages.length;
    if (packageNameOccurrencesFound > SUBPACKAGE_LIMIT) {
      return true;
    }
    for (PsiPackage subPackage : subPackages) {
      if (scanPackages(subPackage, packageNameOccurrencesFound)) {
        return true;
      }
    }
    return false;
  }

  @NotNull
  public static String calcAbbreviatedPackageFQName(@NotNull PsiPackage aPackage) {
    final StringBuilder name = new StringBuilder(aPackage.getName());
    for (PsiPackage parentPackage = aPackage.getParentPackage(); parentPackage != null; parentPackage = parentPackage.getParentPackage()) {
      final String packageName = parentPackage.getName();
      if (packageName == null || packageName.isEmpty()) {
        break; // reached default package
      }
      name.insert(0, ".");
      if (packageName.length() > 2 && shouldAbbreviateName(parentPackage)) {
        name.insert(0, packageName.substring(0, 1));
      }
      else {
        name.insert(0, packageName);
      }
    }
    return name.toString();
  }

  /**
   * a directory is considered "empty" if it has at least one child and all its children are only directories
   *
   * @param strictlyEmpty if true, the package is considered empty if it has only 1 child and this child  is a directory
   *                      otherwise the package is considered as empty if all direct children that it has are directories
   */
  public static boolean isEmptyMiddlePackage(@NotNull PsiDirectory dir, boolean strictlyEmpty) {
    final VirtualFile[] files = dir.getVirtualFile().getChildren();
    if (files.length == 0) {
      return false;
    }
    PsiManager manager = dir.getManager();
    int subpackagesCount = 0;
    int directoriesCount = 0;
    for (VirtualFile file : files) {
      if (FileTypeManager.getInstance().isFileIgnored(file)) continue;
      if (!file.isDirectory()) return false;
      PsiDirectory childDir = manager.findDirectory(file);
      if (childDir != null) {
        directoriesCount++;
        if (strictlyEmpty && directoriesCount > 1) return false;
        if (JavaDirectoryService.getInstance().getPackage(childDir) != null) {
          subpackagesCount++;
        }
      }
    }
    if (strictlyEmpty) {
      return directoriesCount == subpackagesCount && directoriesCount == 1;
    }
    return directoriesCount == subpackagesCount && directoriesCount > 0;
  }
}