/*
 * Copyright 2012 Google Inc. All Rights Reserved.
 *
 * 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.errorprone.matchers;

import com.google.errorprone.VisitorState;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.ExpressionTree;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.tree.JCTree.JCFieldAccess;
import com.sun.tools.javac.tree.JCTree.JCIdent;

/**
 * Matches an instance method expression.
 *
 * @author eaftan@google.com (Eddie Aftandilian)
 */
public class InstanceMethod implements Matcher<ExpressionTree> {

  private final Matcher<? super ExpressionTree> receiverMatcher;
  private final String methodName;
  private final boolean isWildCard;

  public InstanceMethod(Matcher<? super ExpressionTree> receiverMatcher, String methodName) {
    this(receiverMatcher, methodName, false);
  }

  private InstanceMethod(
      Matcher<? super ExpressionTree> receiverMatcher, String methodName, boolean isWildCard) {
    this.receiverMatcher = receiverMatcher;
    this.methodName = methodName;
    this.isWildCard = isWildCard;
  }

  /**
   * @return an InstanceMethod matcher that only matches the method receiver.
   */
  public static InstanceMethod methodReceiverMatcher(
      Matcher<? super ExpressionTree> receiverMatcher) {
    return new InstanceMethod(receiverMatcher, "", true);
  }

  @Override
  public boolean matches(ExpressionTree item, VisitorState state) {
    Symbol sym = ASTHelpers.getSymbol(item);
    // Don't match if:
    // 1) symbol is null (item is of the wrong type),
    // 2) symbol is static (not an instance method), or
    // 3) the method names don't match.
    if (sym == null || sym.isStatic() ||
        (!isWildCard && !sym.getQualifiedName().equals(state.getName(methodName)))) {  // methodName doesn't match
      return false;
    }

    if (item instanceof JCFieldAccess) {
      JCFieldAccess fieldAccess = (JCFieldAccess) item;
      return receiverMatcher.matches(fieldAccess.getExpression(), state);
    } else if (item instanceof JCIdent) {
      // There's no explicit receiver in this case, so try the receiverMatcher against null. If it
      // throws a NullPointerException (i.e., it cares about the input), then return false.
      try {
        return receiverMatcher.matches(null, state);
      } catch (NullPointerException e) {
        return false;
      }
    } else {
      throw new IllegalStateException("Unexpected type in InstanceMethod matcher: "
          + item.getClass().getName());
    }
  }
}