package org.checkerframework.framework.source;

import com.sun.source.util.TreePath;
import com.sun.tools.javac.processing.JavacProcessingEnvironment;
import com.sun.tools.javac.util.Context;
import com.sun.tools.javac.util.Log;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.TypeElement;
import javax.tools.Diagnostic.Kind;

/**
 * An aggregate checker that packages multiple checkers together. The resulting checker invokes the
 * component checkers in turn on the processed files.
 *
 * <p>There is no communication, interaction, or cooperation between the component checkers, even to
 * the extent of being able to read one another's qualifiers. An aggregate checker is merely
 * shorthand to invoke a sequence of checkers.
 *
 * <p>This class delegates {@code AbstractTypeProcessor} responsibilities to each component checker.
 *
 * <p>Checker writers need to subclass this class and only override {@link #getSupportedCheckers()}
 * to indicate the classes of the checkers to be bundled.
 */
public abstract class AggregateChecker extends SourceChecker {

  protected final List<SourceChecker> checkers;

  /**
   * Returns the list of supported checkers to be run together. Subclasses need to override this
   * method.
   */
  protected abstract Collection<Class<? extends SourceChecker>> getSupportedCheckers();

  /** Create a new AggregateChecker. */
  protected AggregateChecker() {
    Collection<Class<? extends SourceChecker>> checkerClasses = getSupportedCheckers();

    checkers = new ArrayList<>(checkerClasses.size());
    for (Class<? extends SourceChecker> checkerClass : checkerClasses) {
      try {
        SourceChecker instance = checkerClass.getDeclaredConstructor().newInstance();
        instance.setParentChecker(this);
        checkers.add(instance);
      } catch (Exception e) {
        message(Kind.ERROR, "Couldn't instantiate an instance of " + checkerClass);
      }
    }
  }

  /**
   * processingEnv needs to be set on each checker since we are not calling init on the checker,
   * which leaves it null. If one of checkers is an AggregateChecker, its visitors will try use
   * checker's processing env which should not be null.
   */
  @Override
  protected void setProcessingEnvironment(ProcessingEnvironment env) {
    super.setProcessingEnvironment(env);
    for (SourceChecker checker : checkers) {
      checker.setProcessingEnvironment(env);
    }
  }

  @Override
  public void initChecker() {
    // No need to call super, it might result in reflective instantiations
    // of visitor/factory classes.
    // super.initChecker();
    // To prevent the warning that initChecker wasn't called.
    messager = processingEnv.getMessager();

    // first initialize all checkers
    for (SourceChecker checker : checkers) {
      checker.initChecker();
    }
    // then share options as necessary
    for (SourceChecker checker : checkers) {
      // We need to add all options that are activated for the aggregate to
      // the individual checkers.
      checker.addOptions(super.getOptions());
      // Each checker should "support" all possible lint options - otherwise
      // subchecker A would complain about a lint option for subchecker B.
      checker.setSupportedLintOptions(this.getSupportedLintOptions());
    }
    allCheckersInited = true;
  }

  // Whether all checkers were successfully initialized.
  private boolean allCheckersInited = false;

  // AbstractTypeProcessor delegation
  @Override
  public final void typeProcess(TypeElement element, TreePath tree) {
    Context context = ((JavacProcessingEnvironment) processingEnv).getContext();
    Log log = Log.instance(context);
    if (log.nerrors > this.errsOnLastExit) {
      // If there is a Java error, do not perform any of the component type checks, but come back
      // for the next compilation unit.
      this.errsOnLastExit = log.nerrors;
      return;
    }
    if (!allCheckersInited) {
      // If there was an initialization problem, an
      // error was already output. Just quit.
      return;
    }
    for (SourceChecker checker : checkers) {
      checker.errsOnLastExit = this.errsOnLastExit;
      checker.typeProcess(element, tree);
      if (checker.javacErrored) {
        this.javacErrored = true;
        return;
      }
      this.errsOnLastExit = checker.errsOnLastExit;
    }
  }

  @Override
  public void typeProcessingOver() {
    for (SourceChecker checker : checkers) {
      checker.typeProcessingOver();
    }
    super.typeProcessingOver();
  }

  @Override
  public final Set<String> getSupportedOptions() {
    Set<String> options = new HashSet<>();
    for (SourceChecker checker : checkers) {
      options.addAll(checker.getSupportedOptions());
    }
    options.addAll(expandCFOptions(Arrays.asList(this.getClass()), options.toArray(new String[0])));
    return options;
  }

  @Override
  public final Map<String, String> getOptions() {
    Map<String, String> options = new HashMap<>(super.getOptions());
    for (SourceChecker checker : checkers) {
      options.putAll(checker.getOptions());
    }
    return options;
  }

  @Override
  public final Set<String> getSupportedLintOptions() {
    Set<String> lints = new HashSet<>();
    for (SourceChecker checker : checkers) {
      lints.addAll(checker.getSupportedLintOptions());
    }
    return lints;
  }

  @Override
  protected SourceVisitor<?, ?> createSourceVisitor() {
    return new SourceVisitor<Void, Void>(this) {
      // Aggregate checkers do not visit source,
      // the checkers in the aggregate checker do.
    };
  }

  // TODO some methods in a component checker should behave differently if they
  // are part of an aggregate, e.g. getSuppressWarningKeys should additionally
  // return the name of the aggregate checker.
  // We could add a query method in SourceChecker that refers to the aggregate, if present.
  // At the moment, all the component checkers manually need to add the name of the aggregate.
}