// Copyright 2021 The Tint Authors.
//
// 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 FUZZERS_TINT_SPIRV_TOOLS_FUZZER_SPIRV_OPT_MUTATOR_H_
#define FUZZERS_TINT_SPIRV_TOOLS_FUZZER_SPIRV_OPT_MUTATOR_H_

#include <random>
#include <sstream>
#include <string>
#include <vector>

#include "fuzzers/tint_spirv_tools_fuzzer/mutator.h"
#include "spirv-tools/libspirv.h"

namespace tint {
namespace fuzzers {
namespace spvtools_fuzzer {

/// Mutates the SPIR-V module using the spirv-opt tool.
///
/// The initial `binary` must be valid according to `target_env`. On each call
/// to the `Mutate` method the mutator selects `opt_batch_size` random
/// optimization passes (with substitutions) and applies them to the binary.
class SpirvOptMutator : public Mutator {
 public:
  /// Constructor.
  /// @param target_env - target environment for the `binary`.
  /// @param seed - seed for the RNG.
  /// @param binary - SPIR-V binary. Must be valid.
  /// @param validate_after_each_opt - whether to validate the binary after each
  ///     optimization pass.
  /// @param opt_batch_size - the maximum number of optimization passes that
  ///     will be applied in a single call to `Mutate`. If it's equal to 0 then
  ///     all available optimization passes are applied.
  SpirvOptMutator(spv_target_env target_env,
                  uint32_t seed,
                  std::vector<uint32_t> binary,
                  bool validate_after_each_opt,
                  uint32_t opt_batch_size);

  Result Mutate() override;
  std::vector<uint32_t> GetBinary() const override;
  void LogErrors(const std::string* path, uint32_t count) const override;
  std::string GetErrors() const override;

 private:
  // Number of times this mutator was executed.
  uint32_t num_executions_;

  // Whether the last execution left it in a valid state.
  bool is_valid_;

  // Target environment for the SPIR-V binary.
  const spv_target_env target_env_;

  // The original SPIR-V binary. Useful for debugging.
  const std::vector<uint32_t> original_binary_;

  // The seed for the RNG. Useful for debugging.
  const uint32_t seed_;

  // All the optimization passes available.
  const std::vector<std::string> opt_passes_;

  // The result of the optimization.
  std::vector<uint32_t> optimized_binary_;

  // Whether we need to validate the binary after each optimization pass.
  const bool validate_after_each_opt_;

  // The number of optimization passes to apply at once.
  const uint32_t opt_batch_size_;

  // All the errors produced by the optimizer.
  std::stringstream errors_;

  // The random number generator initialized with `seed_`.
  std::mt19937 rng_;
};

}  // namespace spvtools_fuzzer
}  // namespace fuzzers
}  // namespace tint

#endif  // FUZZERS_TINT_SPIRV_TOOLS_FUZZER_SPIRV_OPT_MUTATOR_H_