idataaccess.h

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/*! @brief This file have the interface for IDataAccess class.
    @file idataaccess.h
    @author Alvaro Denis <denisacostaq@gmail.com>
    @date 6/23/2019

    @copyright
    @attention <h1><center><strong>COPYRIGHT &copy; 2019 </strong>
    [<strong>denisacostaq</strong>][denisacostaq-URL].
    All rights reserved.</center></h1>
    @attention This file is part of [<strong>DAQs</strong>][DAQs-URL].

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    [denisacostaq-URL]: https://about.me/denisacostaq "Alvaro Denis Acosta"
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 */
#ifndef DATABASESERVER_IDATAACCESS_H
#define DATABASESERVER_IDATAACCESS_H

#include <chrono>
#include <functional>
#include <string>
#include <tuple>
#include <vector>

#include "src/database-server/data-model/variable.h"
#include "src/database-server/data-model/varvalue.h"

/**
 * @brief The IDataAccess interface is like a proxy for the data layer
 * @details This class can filter request or data, for example check for
 * authorization or data compression.
 */
class IDataAccess {
 public:
  enum class Err { Ok, Failed, InvalidArgument };

  IDataAccess() noexcept = default;
  virtual ~IDataAccess() = default;
  IDataAccess(const IDataAccess&) = delete;
  IDataAccess& operator=(const IDataAccess&) = delete;
  IDataAccess(IDataAccess&&) = default;
  IDataAccess& operator=(IDataAccess&&) = default;

  /**
   * @brief add_variable add a new variable.
   * @param var variable info.
   * @return Ok on success.
   * @sa IDataSource::add_variable
   */
  virtual Err add_variable(const Variable& var) noexcept = 0;

  /**
   * @brief add_variable_value add a new variable value related to a variable.
   * @param var add a variable value.
   * @return Ok on success.
   * @sa IDataSource::add_variable_value
   */
  virtual Err add_variable_value(const VarValue& var) noexcept = 0;

  /**
   * @brief fetch_variables get all variables.
   * @return a vector with the variables.
   * @sa IDataSource::add_variable
   */
  virtual std::tuple<std::vector<Variable>, Err> fetch_variables() noexcept = 0;

  /**
   * @brief fetch_variable_values get values for a variable.
   * @param var_name variable name.
   * @param max_len max result len (for data compression for example).
   * @return a vector with the variable values.
   * @sa IDataSource::fetch_variable_values
   */
  virtual std::tuple<std::vector<VarValue>, Err> fetch_variable_values(
      const std::string& var_name,
      size_t max_len = std::numeric_limits<size_t>::infinity()) noexcept = 0;

  /**
   * @brief fetch_variable_values get values for a variable in a date range.
   * @param var_name variable name.
   * @param start_date start date of the period.
   * @param end_date end date of the period.
   * @param max_len max result len (for data compression for example).
   * @return a vector with the variable values.
   * @sa IDataSource::fetch_variable_values
   */
  virtual std::tuple<std::vector<VarValue>, Err> fetch_variable_values(
      const std::string& var_name,
      const std::chrono::system_clock::time_point& start_date,
      const std::chrono::system_clock::time_point& end_date,
      size_t max_len = std::numeric_limits<size_t>::infinity()) noexcept = 0;
};

#endif  // DATABASESERVER_IDATAACCESS_H