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// Copyright 2022 Huawei Cloud Computing Technology Co., Ltd.
//
// 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 INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_EXPRESSION_EVALUATOR_HPP
#define INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_EXPRESSION_EVALUATOR_HPP

#include <exception>
#include <string>

#include "src/buildtool/build_engine/expression/expression.hpp"
#include "src/buildtool/build_engine/expression/function_map.hpp"

class Configuration;

class Evaluator {
    struct ConfigData {
        std::size_t expression_log_limit{kDefaultExpressionLogLimit};
    };

  public:
    /// \brief Set the limit for the size of logging a single expression
    /// in an error message.
    static void SetExpressionLogLimit(std::size_t width) {
        Config().expression_log_limit = width;
    }

    class EvaluationError : public std::exception {
      public:
        explicit EvaluationError(std::string const& msg,
                                 bool while_eval = false,
                                 bool user_context = false) noexcept
            : msg_{(while_eval ? ""
                               : (user_context ? "UserError: "
                                               : "EvaluationError: ")) +
                   msg},
              while_eval_{while_eval},
              user_context_{user_context} {}
        [[nodiscard]] auto what() const noexcept -> char const* final {
            return msg_.c_str();
        }

        [[nodiscard]] auto WhileEvaluation() const -> bool {
            return while_eval_;
        }

        [[nodiscard]] auto UserContext() const -> bool { return user_context_; }

        [[nodiscard]] static auto WhileEvaluating(ExpressionPtr const& expr,
                                                  Configuration const& env,
                                                  std::exception const& ex)
            -> EvaluationError;

        [[nodiscard]] static auto WhileEval(ExpressionPtr const& expr,
                                            Configuration const& env,
                                            EvaluationError const& ex)
            -> EvaluationError;

        [[nodiscard]] static auto WhileEvaluating(const std::string& where,
                                                  std::exception const& ex)
            -> Evaluator::EvaluationError;

        [[nodiscard]] static auto WhileEval(const std::string& where,
                                            EvaluationError const& ex)
            -> Evaluator::EvaluationError;

      private:
        std::string msg_;
        bool while_eval_;
        bool user_context_;
    };

    // Exception-free evaluation of expression
    [[nodiscard]] static auto EvaluateExpression(
        ExpressionPtr const& expr,
        Configuration const& env,
        FunctionMapPtr const& provider_functions,
        std::function<void(std::string const&)> const& logger,
        std::function<void(void)> const& note_user_context = []() {}) noexcept
        -> ExpressionPtr;

    constexpr static std::size_t kDefaultExpressionLogLimit = 320;

  private:
    [[nodiscard]] static auto Evaluate(ExpressionPtr const& expr,
                                       Configuration const& env,
                                       FunctionMapPtr const& functions)
        -> ExpressionPtr;
    [[nodiscard]] static auto Config() noexcept -> ConfigData& {
        static ConfigData instance{};
        return instance;
    }
};

#endif  // INCLUDED_SRC_BUILDTOOL_BUILD_ENGINE_EXPRESSION_EVALUATOR_HPP