// Copyright 2024 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

//

//     https://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 THIRD_PARTY_CEL_CPP_EVAL_EVAL_TRACE_STEP_H_

#define THIRD_PARTY_CEL_CPP_EVAL_EVAL_TRACE_STEP_H_

#include <memory>

#include <utility>

#include <vector>

#include "absl/status/status.h"

#include "absl/types/optional.h"

#include "common/native_type.h"

#include "common/value.h"

#include "eval/eval/attribute_trail.h"

#include "eval/eval/direct_expression_step.h"

#include "eval/eval/evaluator_core.h"

#include "internal/status_macros.h"

namespace google::api::expr::runtime {

// A decorator that implements tracing for recursively evaluated CEL

// expressions.

//

// Allows inspection for extensions to extract the wrapped expression.

class TraceStep : public DirectExpressionStep {

 public:

  explicit TraceStep(std::unique_ptr<DirectExpressionStep> expression)

      : DirectExpressionStep(-1), expression_(std::move(expression)) {}

  absl::Status Evaluate(ExecutionFrameBase& frame, cel::Value& result,

                        AttributeTrail& trail) const override {

    CEL_RETURN_IF_ERROR(expression_->Evaluate(frame, result, trail));

    if (!frame.callback()) {

      return absl::OkStatus();

    }

    return frame.callback()(expression_->expr_id(), result,

                            frame.descriptor_pool(), frame.message_factory(),

                            frame.arena());

  }

  cel::NativeTypeId GetNativeTypeId() const override {

    return cel::NativeTypeId::For<TraceStep>();

  }

  absl::optional<std::vector<const DirectExpressionStep*>> GetDependencies()

      const override {

    return {{expression_.get()}};

  }

  absl::optional<std::vector<std::unique_ptr<DirectExpressionStep>>>

  ExtractDependencies() override {

    std::vector<std::unique_ptr<DirectExpressionStep>> dependencies;

    dependencies.push_back(std::move(expression_));

    return dependencies;

  };

 private:

  std::unique_ptr<DirectExpressionStep> expression_;

};

}  // namespace google::api::expr::runtime

#endif  // THIRD_PARTY_CEL_CPP_EVAL_EVAL_TRACE_STEP_H_