/*
 * Copyright 2019 Google LLC.
 *
 * 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.cloud;

import com.google.cloud.tools.opensource.classpath.ClassFile;
import com.google.cloud.tools.opensource.classpath.LinkageChecker;
import com.google.cloud.tools.opensource.classpath.SymbolProblem;
import com.google.cloud.tools.opensource.dependencies.Bom;
import com.google.cloud.tools.opensource.dependencies.MavenRepositoryException;
import com.google.cloud.tools.opensource.dependencies.RepositoryUtility;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ImmutableSetMultimap;
import com.google.common.collect.Sets;
import com.google.common.collect.Sets.SetView;
import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;
import org.eclipse.aether.RepositoryException;
import org.junit.Assert;
import org.junit.Test;

public class MaximumLinkageErrorsTest {

  @Test
  public void textMaximumLinkageErrors() 
      throws IOException, MavenRepositoryException, RepositoryException {

    Bom baseline = RepositoryUtility.readBom("com.google.cloud:libraries-bom:2.2.0");

    Path bomFile = Paths.get("../cloud-oss-bom/pom.xml");
    Bom bom = RepositoryUtility.readBom(bomFile);

    ImmutableSetMultimap<SymbolProblem, ClassFile> oldProblems =
        LinkageChecker.create(baseline).findSymbolProblems();
    ImmutableSetMultimap<SymbolProblem, ClassFile> currentProblems =
        LinkageChecker.create(bom).findSymbolProblems();

    // This only tests for newly missing methods, not new references to
    // previously missing methods.
    SetView<SymbolProblem> newProblems =
        Sets.difference(currentProblems.keySet(), oldProblems.keySet());

    // Check that no new linkage errors have been introduced since 1.2.0
    if (!newProblems.isEmpty()) {
      StringBuilder message = new StringBuilder("Newly introduced problems:\n");
      for (SymbolProblem problem : newProblems) {
        message.append(problem + "\n");
      }
      Assert.fail(message.toString());
    }
    
    // If that passes, check whether there are any new references to missing methods:
    for (SymbolProblem problem : currentProblems.keySet()) {
      ImmutableSet<ClassFile> oldReferences = oldProblems.get(problem);
      ImmutableSet<ClassFile> currentReferences = currentProblems.get(problem);
      SetView<ClassFile> newReferences = Sets.difference(currentReferences, oldReferences);
      if (!newReferences.isEmpty()) {
        StringBuilder message =
            new StringBuilder("Newly introduced classes linking to " + problem + ":\n");
        for (ClassFile classFile : newReferences) {
          message.append("Link from " + classFile + "\n");
        }
        Assert.fail(message.toString());
      }
    }
  }
}
