// Copyright (c) 2020 Google LLC
//
// 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.

#ifndef SOURCE_FUZZ_REPEATED_PASS_MANAGER_H_
#define SOURCE_FUZZ_REPEATED_PASS_MANAGER_H_

#include "source/fuzz/fuzzer_context.h"
#include "source/fuzz/fuzzer_pass.h"
#include "source/fuzz/pass_management/repeated_pass_instances.h"
#include "source/fuzz/pass_management/repeated_pass_recommender.h"
#include "source/fuzz/protobufs/spirvfuzz_protobufs.h"

namespace spvtools {
namespace fuzz {

// Each field of this enum corresponds to an available repeated pass
// strategy, and is used to decide which kind of RepeatedPassManager object
// to create.
enum class RepeatedPassStrategy {
  kSimple,
  kRandomWithRecommendations,
  kLoopedWithRecommendations
};

// An interface to encapsulate the manner in which the sequence of repeated
// passes that are applied during fuzzing is chosen.  An implementation of this
// interface could, for example, keep track of the history of passes that have
// been run and bias the selection of future passes according to this history.
class RepeatedPassManager {
 public:
  RepeatedPassManager(FuzzerContext* fuzzer_context,
                      RepeatedPassInstances* pass_instances);

  virtual ~RepeatedPassManager();

  // Returns the fuzzer pass instance that should be run next.  The
  // transformations that have been applied so far are provided via
  // |applied_transformations| and can be used to influence the decision.
  virtual FuzzerPass* ChoosePass(
      const protobufs::TransformationSequence& applied_transformations) = 0;

  // Creates a corresponding RepeatedPassManager based on the |strategy|.
  static std::unique_ptr<RepeatedPassManager> Create(
      RepeatedPassStrategy strategy, FuzzerContext* fuzzer_context,
      RepeatedPassInstances* pass_instances,
      RepeatedPassRecommender* pass_recommender);

 protected:
  FuzzerContext* GetFuzzerContext() { return fuzzer_context_; }

  RepeatedPassInstances* GetPassInstances() { return pass_instances_; }

 private:
  // Provided in order to allow the pass manager to make random decisions.
  FuzzerContext* fuzzer_context_;

  // The repeated fuzzer passes that are enabled.
  RepeatedPassInstances* pass_instances_;
};

}  // namespace fuzz
}  // namespace spvtools

#endif  // SOURCE_FUZZ_REPEATED_PASS_MANAGER_H_