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/*
 * Copyright 2014-2015 Objectos, Fábrica de Software LTDA.
 *
 * 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 br.com.objectos.metainf;

import java.nio.file.Path;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;

import javax.annotation.processing.ProcessingEnvironment;
import javax.annotation.processing.RoundEnvironment;
import javax.lang.model.element.TypeElement;

import br.com.objectos.code.AbstractAnnotationProcessor;
import br.com.objectos.code.Artifact;
import br.com.objectos.code.Configuration;
import br.com.objectos.code.ProcessorListener;
import br.com.objectos.code.SimpleTypeInfo;
import br.com.objectos.code.TypeInfo;

/**
 * @author [email protected] (Marcio Endo)
 */
public class ServicesCompiler extends AbstractAnnotationProcessor implements ProcessorListener {

  private final Set artifactSet = new LinkedHashSet<>();

  @Override
  public void onFinish(Set typeElements, RoundEnvironment roundEnv) {
    if (roundEnv.processingOver()) {
      artifactSet.stream()
          .collect(Collectors.groupingBy(ThisArtifact::service))
          .forEach(this::write);
    }
  }

  @Override
  protected Configuration configuration() {
    return Configuration.builder()
        .addAnnotationType(Services.class)
        .addTypeInfoArtifactGenerator(this::generate)
        .listener(this)
        .build();
  }

  private Artifact generate(TypeInfo typeInfo) {
    SimpleTypeInfo serviceTypeInfo = typeInfo.annotationInfo(Services.class)
        .flatMap(ann -> ann.simpleTypeInfoValue("value"))
        .get();
    return new ThisArtifact(serviceTypeInfo.qualifiedName(), typeInfo.qualifiedName());
  }

  private void write(String service, List artifactList) {
    Artifact artifact = Artifact.resourceNamed("META-INF/services/" + service)
        .addAll(artifactList.stream().map(ThisArtifact::implementation))
        .build();
    execute(artifact);
  }

  private class ThisArtifact extends Artifact {

    private final String service;
    private final String implementation;

    public ThisArtifact(String service, String implementation) {
      this.service = service;
      this.implementation = implementation;
    }

    @Override
    public int hashCode() {
      return Objects.hash(service, implementation);
    }

    @Override
    public boolean equals(Object obj) {
      ThisArtifact that = (ThisArtifact) obj;
      return service.equals(that.service)
          && implementation.equals(that.implementation);
    }

    @Override
    protected void execute(ProcessingEnvironment processingEnv) {
      artifactSet.add(this);
    }

    @Override
    public void writeTo(Path path) {
      throw new UnsupportedOperationException();
    }

    String implementation() {
      return implementation;
    }

    String service() {
      return service;
    }

  }

}