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package edu.isi.nlp;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.inject.Module;
import edu.isi.nlp.parameters.Parameters;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;

/**
 * Installs specifies module(s) if a specified parameter is present.
 *
 * @author Ryan Gabbard
 */
public final class ModuleIfPresent {

  private final List> classes;

  private ModuleIfPresent(final String parameter, final List> classes) {
    this.classes = Lists.newArrayList(classes);
  }

  public static ModuleIfPresent module(Class clazz) {
    return new ModuleIfPresent(null, ImmutableList.>of(clazz));
  }

  public static ModuleIfPresent modules(Class clazz1, Class... clazzes) {
    final List> ret = new ArrayList<>();
    ret.add(clazz1);
    for (final Class clazz : clazzes) {
      ret.add(clazz);
    }

    return new ModuleIfPresent(null, ret);
  }

  public Stage2 ifPresent(String param) {
    return new Stage2(param);
  }

  public class Stage2 {

    private String parameter;

    Stage2(final String parameter) {
      this.parameter = checkNotNull(parameter);
    }

    public Module in(Parameters params) {
      if (params.isPresent(parameter)) {
        final ImmutableList.Builder ret = ImmutableList.builder();
        for (final Class clazz : classes) {
          try {
            ret.add(ModuleUtils.classNameToModule(params, clazz));
          } catch (IllegalAccessException | InvocationTargetException | InstantiationException e) {
            throw new RuntimeException(
                "Error instantiating " + clazz.getName() + " for parameter " + parameter);
          }
        }
        return new ModuleUtils.MultiModule(ret.build());
      } else {
        return new NoOpModule();
      }
    }
  }
}