dataaccess.h

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/*! @brief This file have the interface for DataAccess class.
    @file dataaccess.h
    @author Alvaro Denis <denisacostaq@gmail.com>
    @date 6/22/2019

    @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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      notice, this list of conditions and the following disclaimer.
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    [denisacostaq-URL]: https://about.me/denisacostaq "Alvaro Denis Acosta"
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 */
#ifndef DATABASESERVER_DATAACCESS_H
#define DATABASESERVER_DATAACCESS_H

#include "src/database-server/data-access/idataaccess.h"
#include "src/database-server/data-source/idatasource.h"

class DataAccess : public IDataAccess {
 public:
  explicit DataAccess(IDataSource* ds) noexcept;

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

  /**
   * @brief add_variable_value add a new value for a given variable.
   * @param var variable value.
   * @return Ok on success.
   * @sa IDataAccess::add_variable_value
   */
  Err add_variable_value(const VarValue& var) noexcept override;

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

  /**
   * @brief fetch_variable_values get values for a given variable.
   * @param var_name variable name.
   * @param max_len TODO(denisacostaq@gmail.com): not implemented yet
   * @return a vector of values if any and an error code.
   * @sa IDataAccess::fetch_variable_values
   */
  std::tuple<std::vector<VarValue>, Err> fetch_variable_values(
      const std::string& var_name, size_t max_len) noexcept override;

  /**
   * @brief fetch_variable_values get values for a given variable in a period.
   * @param var variable value.
   * @param start_date start date.
   * @param end_date end date
   * @param max_len TODO(denisacostaq@gmail.com): not implemented yet
   * @return a vector of values if any and an error code.
   * @sa IDataAccess::fetch_variable_values
   */
  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) noexcept override;

  /**
   * @brief compress a dumy compression algorithm
   * @param in_vals input values.
   * @param out_vals output(compressed) values.
   * @param max_len len of the compressed values.
   * @return Err::Ok on success.
   */
  Err compress(const std::vector<VarValue>& in_vals,
               std::vector<VarValue>* out_vals, size_t max_len) noexcept;

 private:
  IDataSource* ds_;
};
#endif  // DATABASESERVER_DATAACCESS_H