/*
 * Copyright 2014 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.bugpatterns.threadsafety;

import com.google.auto.value.AutoValue;
import com.google.common.base.Optional;
import com.google.errorprone.VisitorState;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.Tree;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.parser.JavacParser;
import com.sun.tools.javac.parser.ParserFactory;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.util.Context;

/**
 * @author cushon@google.com (Liam Miller-Cushon)
 */
public class GuardedByUtils {
  static String getGuardValue(Tree tree) {
    {
      net.jcip.annotations.GuardedBy guardedBy =
          ASTHelpers.getAnnotation(tree, net.jcip.annotations.GuardedBy.class);
      if (guardedBy != null) {
        return guardedBy.value();
      }
    }

    {
      javax.annotation.concurrent.GuardedBy guardedBy =
          ASTHelpers.getAnnotation(tree, javax.annotation.concurrent.GuardedBy.class);
      if (guardedBy != null) {
        return guardedBy.value();
      }
    }

    return null;
  }

  public static JCTree.JCExpression parseString(String guardedByString, Context context) {
    JavacParser parser =
        ParserFactory.instance(context).newParser(guardedByString, false, true, false);
    JCTree.JCExpression exp;
    try {
      exp = parser.parseExpression();
    } catch (Throwable e) {
      throw new IllegalGuardedBy(e.getMessage());
    }
    int len = (parser.getEndPos(exp) - exp.getStartPosition());
    if (len != guardedByString.length()) {
      throw new IllegalGuardedBy("Didn't parse entire string.");
    }
    return exp;
  }
  

  @AutoValue
  abstract static class GuardedByValidationResult {
    abstract String message();
    abstract Boolean isValid();
    
    static GuardedByValidationResult invalid(String message) {
      return new AutoValue_GuardedByUtils_GuardedByValidationResult(message, false);
    }
    
    static GuardedByValidationResult ok() {
      return new AutoValue_GuardedByUtils_GuardedByValidationResult("", true);
    }
  }

  public static GuardedByValidationResult isGuardedByValid(Tree tree, VisitorState state) {
    String guard = GuardedByUtils.getGuardValue(tree);
    if (guard == null) {
      return GuardedByValidationResult.ok();
    }

    Optional<GuardedByExpression> boundGuard =
        GuardedByBinder.bindString(guard, GuardedBySymbolResolver.from(tree, state));
    if (!boundGuard.isPresent()) {
      return GuardedByValidationResult.invalid("could not resolve guard");
    }

    Symbol treeSym = ASTHelpers.getSymbol(tree);
    if (treeSym == null) {
      // this shouldn't happen unless the compilation had already failed.
      return GuardedByValidationResult.ok();
    }

    boolean staticGuard = boundGuard.get().kind() == GuardedByExpression.Kind.CLASS_LITERAL
        || (boundGuard.get().sym() != null && boundGuard.get().sym().isStatic());
    if (treeSym.isStatic() && !staticGuard) {
      return GuardedByValidationResult.invalid(
          "static member guarded by instance");
    }

    return GuardedByValidationResult.ok();
  }

  public static Symbol bindGuardedByString(Tree tree, String guard, VisitorState visitorState) {
    Optional<GuardedByExpression> bound =
        GuardedByBinder.bindString(guard, GuardedBySymbolResolver.from(tree, visitorState));
    if (!bound.isPresent()) {
      return null;
    }
    return bound.get().sym();
  }
}