// Copyright (c) 2022, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
package com.android.tools.r8.experimental.keepanno.ast;

import java.util.Collections;
import java.util.List;
import java.util.function.Function;
import java.util.function.Supplier;

public abstract class KeepMethodParametersPattern {

  public static KeepMethodParametersPattern any() {
    return Any.getInstance();
  }

  public static KeepMethodParametersPattern none() {
    return None.getInstance();
  }

  private KeepMethodParametersPattern() {}

  public abstract <T> T match(Supplier<T> onAny, Function<List<KeepTypePattern>, T> onList);

  public boolean isAny() {
    return match(() -> true, params -> false);
  }

  private static class None extends KeepMethodParametersPattern {
    private static None INSTANCE = null;

    public static None getInstance() {
      if (INSTANCE == null) {
        INSTANCE = new None();
      }
      return INSTANCE;
    }

    @Override
    public <T> T match(Supplier<T> onAny, Function<List<KeepTypePattern>, T> onList) {
      return onList.apply(Collections.emptyList());
    }

    @Override
    public boolean equals(Object obj) {
      return this == obj;
    }

    @Override
    public int hashCode() {
      return System.identityHashCode(this);
    }

    @Override
    public String toString() {
      return "()";
    }
  }

  private static class Any extends KeepMethodParametersPattern {
    private static Any INSTANCE = null;

    public static Any getInstance() {
      if (INSTANCE == null) {
        INSTANCE = new Any();
      }
      return INSTANCE;
    }

    @Override
    public <T> T match(Supplier<T> onAny, Function<List<KeepTypePattern>, T> onList) {
      return onAny.get();
    }

    @Override
    public boolean equals(Object obj) {
      return this == obj;
    }

    @Override
    public int hashCode() {
      return System.identityHashCode(this);
    }

    @Override
    public String toString() {
      return "(...)";
    }
  }
}