/*
 * 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.psi.util.proximity;

import com.intellij.openapi.extensions.Extensions;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.text.StringUtil;
import com.intellij.psi.*;
import com.intellij.psi.util.ProximityLocation;
import org.jetbrains.annotations.NonNls;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/**
 * @author peter
*/
public class KnownElementWeigher extends ProximityWeigher {

  @Override
  public Comparable weigh(@NotNull final PsiElement element, @NotNull final ProximityLocation location) {
    for (ForcedElementWeigher weigher : Extensions.getExtensions(ForcedElementWeigher.EP_NAME)) {
      final Comparable weigh = weigher.getForcedWeigh(element);
      if (weigh != null) return weigh;
    }

    Project project = location.getProject();
    if (project == null || !SdkOrLibraryWeigher.isJdkElement(element, project)) {
      return 0;
    }

    if (element instanceof PsiClass) {
      return getJdkClassProximity((PsiClass)element);
    }
    if (element instanceof PsiMethod) {
      final PsiMethod method = (PsiMethod)element;
      final PsiClass containingClass = method.getContainingClass();
      if (containingClass != null) {
        String methodName = method.getName();
        if ("finalize".equals(methodName) || "registerNatives".equals(methodName) || methodName.startsWith("wait") || methodName.startsWith("notify")) {
          if (CommonClassNames.JAVA_LANG_OBJECT.equals(containingClass.getQualifiedName())) {
            return -1;
          }
        }
        if (isGetClass(method)) {
          return -1;
        }
        if ("subSequence".equals(methodName)) {
          if (CommonClassNames.JAVA_LANG_STRING.equals(containingClass.getQualifiedName())) {
            return -1;
          }
        }
        if (CommonClassNames.JAVA_LANG_OBJECT.equals(containingClass.getQualifiedName())) {
          return 0;
        }
        return getJdkClassProximity(method.getContainingClass());
      }
    }
    if (element instanceof PsiField) {
      return getJdkClassProximity(((PsiField)element).getContainingClass());
    }
    return 0;
  }

  public static boolean isGetClass(PsiMethod method) {
    return "getClass".equals(method.getName()) && method.getParameterList().getParametersCount() <= 0;
  }

  private static Comparable getJdkClassProximity(@Nullable PsiClass element) {
    if (element == null || element.getContainingClass() != null) {
      return 0;
    }

    @NonNls final String qname = element.getQualifiedName();
    if (qname != null) {
      String pkg = StringUtil.getPackageName(qname);
      if (qname.equals(CommonClassNames.JAVA_LANG_OBJECT)) return 5;
      if (isPopularJdkClass(qname)) return 8;
      if (pkg.equals("java.lang")) return 6;
      if (pkg.equals("java.util")) return 7;

      if (qname.startsWith("java.lang")) return 5;
      if (qname.startsWith("java.util")) return 4;

      if (pkg.equals("javax.swing")) return 3;
      if (qname.startsWith("java.")) return 2;
      if (qname.startsWith("javax.")) return 1;
      if (qname.startsWith("com.")) return -1;
      if (qname.startsWith("net.")) return -1;
    }
    return 0;
  }

  private static boolean isPopularJdkClass(String qname) {
    return qname.equals(CommonClassNames.JAVA_LANG_STRING) || 
           qname.equals(System.class.getName()) || 
           qname.equals(CommonClassNames.JAVA_LANG_EXCEPTION) || 
           qname.equals(CommonClassNames.JAVA_LANG_THROWABLE) || 
           qname.equals(CommonClassNames.JAVA_LANG_RUNTIME_EXCEPTION) || 
           qname.equals(CommonClassNames.JAVA_LANG_RUNNABLE) || 
           qname.equals(CommonClassNames.JAVA_LANG_CLASS);
  }
}