/**
 * @file mix_cc/sql/select.h
 * @brief 查询语句
 * @author Cat (null.null.null@qq.com)
 * @version 0.1
 * @date 2021-09-17
 * 
 * Copyright: Baosight Co. Ltd.
 * DO NOT COPY/USE WITHOUT PERMISSION
 * 
 */
#pragma once
#include <mix_cc/sql/public.h>
#include <mix_cc/sql/from.h>
#include <mix_cc/sql/column.h>
#include <mix_cc/sql/statement.h>
#include <algorithm>

namespace mix_cc {
namespace sql {
template <typename... Columns>
struct select_t : public prev_statement_t<void>, public statement_t {
  static constexpr auto s_text = op::cmd_t::select;
  constexpr explicit select_t(Columns... columns)
      : prev_statement_t<void>(), cols_(hana::make_tuple(columns...)) {}

  template <typename Tab>
  constexpr auto from(Tab tab) {
    return from_t(*this, tab);
  }

  constexpr auto get_command() {
    auto sel_str_c = s_text + " "_s;
    auto col_names =
        hana::transform(cols_, [](auto col) { return col.col_name; });
    auto r_str_c = hana::fold_left(
        col_names, [](auto col1, auto col2) { return col1 + ","_s + col2; });
    return sel_str_c + r_str_c;
  }

 public:
  hana::tuple<Columns...> cols_;
};

template <typename... Columns>
auto select(Columns... columns) {
  return select_t<Columns...>(columns...);
}
}  // namespace sql
}  // namespace mix_cc