azerothcore-wotlk/src/server/database/Database/Field.h

/*
 * This file is part of the AzerothCore Project. See AUTHORS file for Copyright information
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Affero General Public License as published by the
 * Free Software Foundation; either version 3 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef _FIELD_H
#define _FIELD_H

#include "DatabaseEnvFwd.h"
#include "Define.h"
#include "Duration.h"
#include <array>
#include <string_view>
#include <vector>

namespace Acore::Types
{
    template <typename T>
    using is_chrono_v = std::enable_if_t<std::is_same_v<Milliseconds, T>
        || std::is_same_v<Seconds, T>
        || std::is_same_v<Minutes, T>
        || std::is_same_v<Hours, T>
        || std::is_same_v<Days, T>
        || std::is_same_v<Weeks, T>
        || std::is_same_v<Years, T>
        || std::is_same_v<Months, T>, T>;
}

using Binary = std::vector<uint8>;

enum class DatabaseFieldTypes : uint8
{
    Null,
    Int8,
    Int16,
    Int32,
    Int64,
    Float,
    Double,
    Decimal,
    Date,
    Binary
};

struct QueryResultFieldMetadata
{
    std::string TableName{};
    std::string TableAlias{};
    std::string Name{};
    std::string Alias{};
    std::string TypeName{};
    uint32 Index = 0;
    DatabaseFieldTypes Type = DatabaseFieldTypes::Null;
};

/**
    @class Field

    @brief Class used to access individual fields of database query result

    Guideline on field type matching:

    |   MySQL type           |  method to use                          |
    |------------------------|-----------------------------------------|
    | TINYINT                | Get<bool>, Get<int8>, Get<uint8>        |
    | SMALLINT               | Get<int16>, Get<uint16>                 |
    | MEDIUMINT, INT         | Get<int32>, Get<uint32>                 |
    | BIGINT                 | Get<int64>, Get<uint64>                 |
    | FLOAT                  | Get<float>                              |
    | DOUBLE, DECIMAL        | Get<double>                             |
    | CHAR, VARCHAR,         | Get<std::string>, Get<std::string_view> |
    | TINYTEXT, MEDIUMTEXT,  | Get<std::string>, Get<std::string_view> |
    | TEXT, LONGTEXT         | Get<std::string>, Get<std::string_view> |
    | TINYBLOB, MEDIUMBLOB,  | Get<Binary>, Get<std::string>           |
    | BLOB, LONGBLOB         | Get<Binary>, Get<std::string>           |
    | BINARY, VARBINARY      | Get<Binary>                             |

    Return types of aggregate functions:

    | Function |       Type        |
    |----------|-------------------|
    | MIN, MAX | Same as the field |
    | SUM, AVG | DECIMAL           |
    | COUNT    | BIGINT            |
*/
class AC_DATABASE_API Field
{
friend class ResultSet;
friend class PreparedResultSet;

public:
    Field();
    ~Field() = default;

    [[nodiscard]] inline bool IsNull() const
    {
        return data.value == nullptr;
    }

    template<typename T>
    inline std::enable_if_t<std::is_arithmetic_v<T>, T> Get() const
    {
        return GetData<T>();
    }

    template<typename T>
    inline std::enable_if_t<std::is_same_v<std::string, T>, T> Get() const
    {
        return GetDataString();
    }

    template<typename T>
    inline std::enable_if_t<std::is_same_v<std::string_view, T>, T> Get() const
    {
        return GetDataStringView();
    }

    template<typename T>
    inline std::enable_if_t<std::is_same_v<Binary, T>, T> Get() const
    {
        return GetDataBinary();
    }

    template <typename T, std::size_t S>
    inline std::enable_if_t<std::is_same_v<Binary, T>, std::array<uint8, S>> Get() const
    {
        std::array<uint8, S> buf = {};
        GetBinarySizeChecked(buf.data(), S);
        return buf;
    }

    template<typename T>
    inline Acore::Types::is_chrono_v<T> Get(bool convertToUin32 = true) const
    {
        return convertToUin32 ? T(GetData<uint32>()) : T(GetData<uint64>());
    }

    DatabaseFieldTypes GetType() { return meta->Type; }

protected:
    struct
    {
        char const* value;      // Actual data in memory
        uint32 length;          // Length
        bool raw;               // Raw bytes? (Prepared statement or ad hoc)
    } data;

    void SetByteValue(char const* newValue, uint32 length);
    void SetStructuredValue(char const* newValue, uint32 length);
    [[nodiscard]] bool IsType(DatabaseFieldTypes type) const;
    [[nodiscard]] bool IsNumeric() const;

private:
    template<typename T>
    T GetData() const;

    std::string GetDataString() const;
    std::string_view GetDataStringView() const;
    Binary GetDataBinary() const;

    QueryResultFieldMetadata const* meta;
    void LogWrongType(std::string_view getter, std::string_view typeName) const;
    void SetMetadata(QueryResultFieldMetadata const* fieldMeta);
    void GetBinarySizeChecked(uint8* buf, std::size_t size) const;
};

#endif