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package net.zerobuilder.compiler;

import com.squareup.javapoet.AnnotationSpec;
import com.squareup.javapoet.ClassName;
import com.squareup.javapoet.JavaFile;
import com.squareup.javapoet.TypeSpec;
import net.zerobuilder.BeanBuilder;
import net.zerobuilder.Builder;
import net.zerobuilder.Updater;
import net.zerobuilder.compiler.analyse.Analyser;
import net.zerobuilder.compiler.analyse.ValidationException;
import net.zerobuilder.compiler.common.LessTypes;
import net.zerobuilder.compiler.generate.DtoGeneratorInput.AbstractGoalInput;
import net.zerobuilder.compiler.generate.DtoGeneratorOutput.GeneratorOutput;
import net.zerobuilder.compiler.generate.Generator;

import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.RoundEnvironment;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.TypeElement;
import javax.lang.model.util.Elements;
import javax.tools.JavaFileObject;
import java.io.IOException;
import java.io.Writer;
import java.lang.annotation.Annotation;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.Stream;

import static java.util.Arrays.asList;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toSet;
import static javax.lang.model.util.ElementFilter.constructorsIn;
import static javax.lang.model.util.ElementFilter.methodsIn;
import static javax.lang.model.util.ElementFilter.typesIn;
import static javax.tools.Diagnostic.Kind.ERROR;
import static net.zerobuilder.compiler.Messages.JavadocMessages.generatedAnnotations;

public final class ZeroProcessor extends AbstractProcessor {

  private final Set done = new HashSet<>();

  @Override
  public Set getSupportedAnnotationTypes() {
    return Stream.of(Builder.class, Updater.class, BeanBuilder.class)
        .map(Class::getName)
        .collect(toSet());
  }

  @Override
  public SourceVersion getSupportedSourceVersion() {
    return SourceVersion.latestSupported();
  }

  @Override
  public boolean process(Set annotations, RoundEnvironment env) {
    Elements elements = processingEnv.getElementUtils();
    List generatedAnnotations = generatedAnnotations(elements);
    Set types = new HashSet<>();
    for (Class c : asList(Builder.class, Updater.class)) {
      types.addAll(Stream.concat(
          methodsIn(env.getElementsAnnotatedWith(c)).stream(),
          constructorsIn(env.getElementsAnnotatedWith(c)).stream())
          .map(ExecutableElement::getEnclosingElement)
          .map(Element::asType)
          .map(LessTypes::asTypeElement)
          .collect(toList()));
    }
    types.addAll(typesIn(env.getElementsAnnotatedWith(BeanBuilder.class)));
    for (TypeElement enclosingElement : types) {
      try {
        if (!done.add(enclosingElement)) {
          continue;
        }
        List generatorInput = Analyser.analyse(enclosingElement);
        GeneratorOutput generatorOutput = Generator.generate(generatorInput);
        TypeSpec typeSpec = generatorOutput.typeSpec(generatedAnnotations);
        try {
          write(generatorOutput.generatedType(), typeSpec);
        } catch (IOException e) {
          String message = "Error processing "
              + ClassName.get(enclosingElement) + ": " + e.getMessage();
          processingEnv.getMessager().printMessage(ERROR, message, enclosingElement);
          return false;
        }
      } catch (ValidationException e) {
        processingEnv.getMessager().printMessage(e.kind, e.getMessage(), e.about);
      } catch (RuntimeException e) {
        e.printStackTrace();
        String message = "Error processing "
            + ClassName.get(enclosingElement) + ": " + e.getMessage();
        processingEnv.getMessager().printMessage(ERROR, message, enclosingElement);
        return false;
      }
    }
    return false;
  }

  private void write(ClassName generatedType, TypeSpec typeSpec) throws IOException {
    JavaFile javaFile = JavaFile.builder(generatedType.packageName(), typeSpec)
        .skipJavaLangImports(true)
        .build();
    JavaFileObject sourceFile = processingEnv.getFiler()
        .createSourceFile(generatedType.toString(),
            javaFile.typeSpec.originatingElements.toArray(new Element[0]));
    try (Writer writer = sourceFile.openWriter()) {
      writer.write(javaFile.toString());
    }
  }
}