#ifndef _QTL_COMMON_H_
#define _QTL_COMMON_H_

#if __cplusplus < 201103L && _MSC_VER < 1800
#error QTL need C++11 compiler
#endif // C++11

#if _MSC_VER >= 1800 && _MSC_VER < 1900
#define NOEXCEPT throw()
#else
#define NOEXCEPT noexcept
#endif // NOEXCEPT

#include <stdint.h>
#include <string.h>
#include <type_traits>
#include <tuple>
#include <memory>
#include <string>
#include <vector>
#include <functional>
#include <algorithm>
#include "apply_tuple.h"

#if ((defined(_MSVC_LANG) && _MSVC_LANG >= 201703L) || __cplusplus >= 201703L)
#define _QTL_ENABLE_CPP17
#include <optional>
#include <any>
#endif // C++17

namespace qtl
{

	struct null
	{
	};

	struct blob_data
	{
		void *data;
		size_t size;

		blob_data() : data(NULL), size(0) {}
		blob_data(void *d, size_t n) : data(d), size(n) {}
	};

	struct const_blob_data
	{
		const void *data;
		size_t size;

		const_blob_data() : data(NULL), size(0) {}
		const_blob_data(const void *d, size_t n) : data(d), size(n) {}
	};

	const size_t blob_buffer_size = 64 * 1024;

	inline std::string &trim_string(std::string &str, const char *target)
	{
		str.erase(0, str.find_first_not_of(target));
		str.erase(str.find_last_not_of(target) + 1);
		return str;
	}

	template <typename T>
	struct indicator
	{
		typedef T data_type;

		data_type data;
		size_t length;
		bool is_null;
		bool is_truncated;

		indicator()
			: is_null(false), is_truncated(false), length(0) {}
		explicit indicator(const data_type &src)
			: is_null(false), is_truncated(false), length(0), data(src) {}
		explicit indicator(data_type &&src)
			: is_null(false), is_truncated(false), length(0), data(std::move(src)) {}

		operator bool() const { return is_null; }
		operator data_type &() { return data; }
		operator const data_type &() const { return data; }
	};

	template <typename StringT>
	struct bind_string_helper
	{
		typedef StringT string_type;
		typedef typename string_type::value_type char_type;
		bind_string_helper(string_type &&value) : m_value(std::forward<string_type>(value)) {}
		bind_string_helper(const bind_string_helper &src)
			: m_value(std::forward<StringT>(src.m_value))
		{
		}
		bind_string_helper(bind_string_helper &&src)
			: m_value(std::forward<StringT>(src.m_value))
		{
		}
		bind_string_helper &operator=(const bind_string_helper &src)
		{
			if (this != &src)
			{
				m_value = std::forward<StringT>(src.m_value);
			}
			return *this;
		}
		bind_string_helper &operator=(bind_string_helper &&src)
		{
			if (this != &src)
			{
				m_value = std::forward<StringT>(src.m_value);
			}
			return *this;
		}

		void clear() { m_value.clear(); }
		char_type *alloc(size_t n)
		{
			m_value.resize(n);
			return (char_type *)m_value.data();
		}
		void truncate(size_t n) { m_value.resize(n); }
		void assign(const char_type *str, size_t n) { m_value.assign(str, n); }
		const char_type *data() const { return m_value.data(); }
		size_t size() const { return m_value.size(); }

	private:
		string_type &&m_value;
	};

	template <typename StringT>
	inline bind_string_helper<typename std::decay<StringT>::type> bind_string(StringT &&value)
	{
		typedef typename std::decay<StringT>::type string_type;
		return bind_string_helper<string_type>(std::forward<string_type>(value));
	}

	template <typename Command>
	inline void bind_param(Command &command, size_t index, const std::string &param)
	{
		command.bind_param(index, param.data(), param.size());
	}

	template <typename Command>
	inline void bind_param(Command &command, size_t index, std::istream &param)
	{
		command.bind_param(index, param);
	}

	template <typename Command, typename T>
	inline void bind_param(Command &command, size_t index, const T &param)
	{
		command.bind_param(index, param);
	}

#ifdef _QTL_ENABLE_CPP17

	template <typename Command, typename T>
	inline void bind_param(Command &command, size_t index, const std::optional<T> &param)
	{
		if (param)
			command.bind_param(index, *param);
		else
			command.bind_param(index, nullptr);
	}

#endif // C++17

	// The order of the overloaded functions 'bind_field' is very important
	// The version with the most generic parameters is at the end

	template <typename Command, size_t N>
	inline void bind_field(Command &command, size_t index, char (&value)[N])
	{
		command.bind_field(index, value, N);
	}

	template <typename Command, size_t N>
	inline void bind_field(Command &command, size_t index, wchar_t (&value)[N])
	{
		command.bind_field(index, value, N);
	}

	template <typename Command>
	inline void bind_field(Command &command, size_t index, char *value, size_t length)
	{
		command.bind_field(index, value, length);
	}

	template <typename Command>
	inline void bind_field(Command &command, size_t index, wchar_t *value, size_t length)
	{
		command.bind_field(index, value, length);
	}

	template <typename Command>
	inline void bind_field(Command &command, size_t index, std::string &&value)
	{
		command.bind_field(index, bind_string(std::forward<std::string>(value)));
	}

	template <typename Command>
	inline void bind_field(Command &command, size_t index, std::wstring &&value)
	{
		command.bind_field(index, bind_string(std::forward<std::wstring>(value)));
	}

	template <typename Command>
	inline void bind_field(Command &command, size_t index, std::vector<char> &&value)
	{
		command.bind_field(index, bind_string(std::forward<std::vector<char>>(value)));
	}

	template <typename Command>
	inline void bind_field(Command &command, size_t index, std::vector<wchar_t> &&value)
	{
		command.bind_field(index, bind_string(std::forward<std::vector<wchar_t>>(value)));
	}

	template <typename Command, typename T, typename = typename std::enable_if<!std::is_reference<T>::value>::type>
	inline void bind_field(Command &command, size_t index, T &&value)
	{
		command.bind_field(index, std::forward<T>(value));
	}

	template <typename Command, typename T>
	inline void bind_field(Command &command, size_t index, T &value)
	{
		bind_field(command, index, std::forward<T>(value));
	}

	template <typename Command, typename T, typename = typename std::enable_if<!std::is_reference<T>::value>::type>
	inline void bind_field(Command &command, const char *name, T &&value)
	{
		size_t index = command.find_field(name);
		if (index == -1)
			value = T();
		else
			command.bind_field(index, std::forward<T>(value));
	}

	template <typename Command, typename T>
	inline void bind_field(Command &command, const char *name, T &value)
	{
		size_t index = command.find_field(name);
		if (index == -1)
			value = T();
		else
			bind_field(command, index, std::forward<T>(value));
	}

	template <typename Command>
	inline void bind_field(Command &command, const char *name, char *value, size_t length)
	{
		size_t index = command.find_field(name);
		if (index == -1)
		{
			if (length > 0)
				value[0] = '\0';
		}
		else
			command.bind_field(index, value, length);
	}

	template <typename Command>
	inline void bind_field(Command &command, const char *name, wchar_t *value, size_t length)
	{
		size_t index = command.find_field(name);
		if (index == -1)
		{
			if (length > 0)
				value[0] = '\0';
		}
		else
			command.bind_field(index, value, length);
	}

	template <typename Command, typename T>
	inline void bind_field(Command &command, const char *name, std::reference_wrapper<T> &&value)
	{
		return bind_field(command, value.get());
	}

#ifdef _QTL_ENABLE_CPP17

	template <typename Command, typename T>
	inline void bind_field(Command &command, size_t index, std::optional<T> &value)
	{
		value.emplace();
		command.bind_field(index, std::forward<T>(value));
	}

	template <typename Command, typename T>
	inline void bind_field(Command &command, const char *name, std::optional<T> &value)
	{
		size_t index = command.find_field(name);
		if (index == -1)
			value.reset();
		else
			bind_field(command, index, value);
	}

#endif // C++17

	template <typename Command, typename T>
	inline size_t bind_fields(Command &command, size_t index, T &&value)
	{
		bind_field(command, index, std::forward<T>(value));
		return index + 1;
	}

	template <typename Command, typename T, typename... Other>
	inline size_t bind_fields(Command &command, size_t start, T &&value, Other &&...other)
	{
		bind_field(command, start, std::forward<T>(value));
		return bind_fields(command, start + 1, std::forward<Other>(other)...);
	}

	template <typename Command, typename... Fields>
	inline size_t bind_fields(Command &command, Fields &&...fields)
	{
		return bind_fields(command, (size_t)0, std::forward<Fields>(fields)...);
	}

	namespace detail
	{

		template <typename F, typename T>
		struct apply_impl
		{
		private:
#if __cplusplus >= 202002L || _MSVC_LANG >= 202002L
			typedef typename std::invoke_result<F, T>::type raw_result_type;
#else
			typedef typename std::result_of<F(T)>::type raw_result_type;
#endif
			template <typename Ret, bool>
			struct impl
			{
			};
			template <typename Ret>
			struct impl<Ret, true>
			{
				typedef bool result_type;
				result_type operator()(F &&f, T &&v)
				{
					f(std::forward<T>(v));
					return true;
				}
			};
			template <typename Ret>
			struct impl<Ret, false>
			{
				typedef Ret result_type;
				result_type operator()(F &&f, T &&v)
				{
					return f(std::forward<T>(v));
				}
			};

		public:
			typedef typename impl<raw_result_type, std::is_void<raw_result_type>::value>::result_type result_type;
			result_type operator()(F &&f, T &&v)
			{
				return impl<raw_result_type, std::is_void<raw_result_type>::value>()(std::forward<F>(f), std::forward<T>(v));
			}
		};

		template <typename F, typename... Types>
		struct apply_impl<F, std::tuple<Types...>>
		{
		private:
			typedef typename std::remove_reference<F>::type fun_type;
			typedef std::tuple<Types...> arg_type;
#if __cplusplus >= 202002L || _MSVC_LANG >= 202002L
			typedef typename std::invoke_result<F, Types...>::type raw_result_type;
#else
			typedef typename std::result_of<F(Types...)>::type raw_result_type;
#endif
			template <typename Ret, bool>
			struct impl
			{
			};
			template <typename Ret>
			struct impl<Ret, true>
			{
				typedef bool result_type;
				result_type operator()(F &&f, arg_type &&v)
				{
					qtl::detail::apply_tuple(std::forward<F>(f), std::forward<arg_type>(v));
					return true;
				}
			};
			template <typename Ret>
			struct impl<Ret, false>
			{
				typedef Ret result_type;
				result_type operator()(F &&f, arg_type &&v)
				{
					return qtl::detail::apply_tuple(std::forward<F>(f), std::forward<arg_type>(v));
				}
			};

		public:
			typedef typename impl<raw_result_type, std::is_void<raw_result_type>::value>::result_type result_type;
			result_type operator()(F &&f, arg_type &&v)
			{
				return impl<raw_result_type, std::is_void<raw_result_type>::value>()(std::forward<F>(f), std::forward<arg_type>(v));
			}
		};

		template <typename Type, typename R>
		struct apply_impl<R (Type::*)(), Type>
		{
		private:
			typedef R (Type::*fun_type)();
			typedef R raw_result_type;
			template <typename Ret, bool>
			struct impl
			{
			};
			template <typename Ret>
			struct impl<Ret, true>
			{
				typedef bool result_type;
				result_type operator()(fun_type f, Type &&v)
				{
					(v.*f)();
					return true;
				}
			};
			template <typename Ret>
			struct impl<Ret, false>
			{
				typedef Ret result_type;
				result_type operator()(fun_type f, Type &&v)
				{
					return (v.*f)();
				}
			};

		public:
			typedef typename impl<raw_result_type, std::is_void<raw_result_type>::value>::result_type result_type;
			result_type operator()(R (Type::*f)(), Type &&v)
			{
				return impl<raw_result_type, std::is_void<raw_result_type>::value>()(f, std::forward<Type>(v));
			}
		};

		template <typename Type, typename R>
		struct apply_impl<R (Type::*)() const, Type>
		{
		private:
			typedef R (Type::*fun_type)() const;
			typedef R raw_result_type;
			template <typename Ret, bool>
			struct impl
			{
			};
			template <typename Ret>
			struct impl<Ret, true>
			{
				typedef bool result_type;
				result_type operator()(fun_type f, Type &&v)
				{
					(v.*f)();
					return true;
				}
			};
			template <typename Ret>
			struct impl<Ret, false>
			{
				typedef Ret result_type;
				result_type operator()(fun_type f, Type &&v)
				{
					return (v.*f)();
				}
			};

		public:
			typedef typename impl<raw_result_type, std::is_void<raw_result_type>::value>::result_type result_type;
			result_type operator()(fun_type f, Type &&v)
			{
				return impl<raw_result_type, std::is_void<raw_result_type>::value>()(f, std::forward<Type>(v));
			}
		};

		template <typename F, typename T>
		typename apply_impl<F, T>::result_type apply(F &&f, T &&v)
		{
			return apply_impl<F, T>()(std::forward<F>(f), std::forward<T>(v));
		}

		template <typename Command, size_t N, typename... Types>
		struct bind_helper
		{
		public:
			explicit bind_helper(Command &command) : m_command(command) {}
			void operator()(const std::tuple<Types...> &params) const
			{
				bind_param(m_command, N - 1, std::get<N - 1>(params));
				(bind_helper<Command, N - 1, Types...>(m_command))(params);
			}
			void operator()(std::tuple<Types...> &&params) const
			{
				typedef typename std::remove_reference<typename std::tuple_element<N - 1, tuple_type>::type>::type param_type;
				bind_field(m_command, N - 1, std::forward<param_type>(std::get<N - 1>(std::forward<tuple_type>(params))));
				(bind_helper<Command, N - 1, Types...>(m_command))(std::forward<tuple_type>(params));
			}

		private:
			typedef std::tuple<Types...> tuple_type;
			Command &m_command;
		};

		template <typename Command, typename... Types>
		struct bind_helper<Command, 1, Types...>
		{
		public:
			explicit bind_helper(Command &command) : m_command(command) {}
			void operator()(const std::tuple<Types...> &params) const
			{
				bind_param(m_command, 0, std::get<0>(params));
			}
			void operator()(std::tuple<Types...> &&params) const
			{
				typedef typename std::remove_reference<typename std::tuple_element<0, tuple_type>::type>::type param_type;
				bind_field(m_command, static_cast<size_t>(0), std::forward<param_type>(std::get<0>(std::forward<tuple_type>(params))));
			}

		private:
			typedef std::tuple<Types...> tuple_type;
			Command &m_command;
		};

		template <typename Command, typename... Types>
		struct bind_helper<Command, 0, Types...>
		{
		public:
			explicit bind_helper(Command &command) {}
			void operator()(const std::tuple<Types...> &params) const
			{
			}
			void operator()(std::tuple<Types...> &&params) const
			{
			}
		};

#define QTL_ARGS_TUPLE(Arg, Others) \
	typename std::tuple<typename std::decay<Arg>::type, typename std::decay<Others>::type...>

		template <typename Ret, typename Arg>
		inline typename std::decay<Arg>::type make_values(Ret (*)(Arg))
		{
			return typename std::decay<Arg>::type();
		};

		template <typename Ret, typename Arg, typename... Others>
		inline auto make_values(Ret (*)(Arg, Others...)) -> QTL_ARGS_TUPLE(Arg, Others)
		{
			return QTL_ARGS_TUPLE(Arg, Others)();
		};

		template <typename Type, typename Ret>
		inline Type make_values(Ret (Type::*)())
		{
			return Type();
		};
		template <typename Type, typename Ret>
		inline Type make_values(Ret (Type::*)() const)
		{
			return Type();
		};

		template <typename Type, typename Ret, typename... Args>
		inline auto make_values(Ret (Type::*)(Args...)) -> QTL_ARGS_TUPLE(Type, Args)
		{
			return QTL_ARGS_TUPLE(Type, Args)();
		};
		template <typename Type, typename Ret, typename... Args>
		inline auto make_values(Ret (Type::*)(Args...) const) -> QTL_ARGS_TUPLE(Type, Args)
		{
			return QTL_ARGS_TUPLE(Type, Args)();
		};

		template <typename Type, typename Ret, typename Arg>
		inline typename std::decay<Arg>::type make_values_noclass(Ret (Type::*)(Arg))
		{
			return typename std::decay<Arg>::type();
		};
		template <typename Type, typename Ret, typename Arg>
		inline typename std::decay<Arg>::type make_values_noclass(Ret (Type::*)(Arg) const)
		{
			return typename std::decay<Arg>::type();
		};

		template <typename Type, typename Ret, typename Arg, typename... Others>
		inline auto make_values_noclass(Ret (Type::*)(Arg, Others...)) -> QTL_ARGS_TUPLE(Arg, Others)
		{
			return QTL_ARGS_TUPLE(Arg, Others)();
		};
		template <typename Type, typename Ret, typename Arg, typename... Others>
		inline auto make_values_noclass(Ret (Type::*)(Arg, Others...) const) -> QTL_ARGS_TUPLE(Arg, Others)
		{
			return QTL_ARGS_TUPLE(Arg, Others)();
		};

		template <typename Functor, typename = typename std::enable_if<std::is_member_function_pointer<decltype(&Functor::operator())>::value>::type>
		inline auto make_values(const Functor &)
			-> decltype(make_values_noclass(&Functor::operator()))
		{
			return make_values_noclass(&Functor::operator());
		}

		template <typename Command, typename ValueProc>
		inline void fetch_command(Command &command, ValueProc &&proc)
		{
			auto values = make_values(proc);
			typedef decltype(values) values_type;
			while (command.fetch(std::forward<values_type>(values)))
			{
				if (!apply(std::forward<ValueProc>(proc), std::forward<values_type>(values)))
					break;
			}
		}

		template <typename Command, typename ValueProc, typename... OtherProc>
		inline void fetch_command(Command &command, ValueProc &&proc, OtherProc &&...other)
		{
			fetch_command(command, std::forward<ValueProc>(proc));
			if (command.next_result())
			{
				fetch_command(command, std::forward<OtherProc>(other)...);
			}
		}

	}

	template <typename Command, typename T>
	struct params_binder
	{
		enum
		{
			size = 1
		};
		inline void operator()(Command &command, const T &param) const
		{
			qtl::bind_param(command, 0, param);
		}
	};

	template <typename Command, typename... Types>
	struct params_binder<Command, std::tuple<Types...>>
	{
		enum
		{
			size = sizeof...(Types)
		};
		void operator()(Command &command, const std::tuple<Types...> &params) const
		{
			(detail::bind_helper<Command, std::tuple_size<std::tuple<Types...>>::value, Types...>(command))(params);
		}
	};

	template <typename Command, typename Type1, typename Type2>
	struct params_binder<Command, std::pair<Type1, Type2>>
	{
		enum
		{
			size = 2
		};
		void operator()(Command &command, std::pair<Type1, Type2> &&values) const
		{
			qtl::bind_param(command, 0, std::forward<Type1>(values.first));
			qtl::bind_param(command, 1, std::forward<Type2>(values.second));
		}
	};

	template <typename Command, typename T>
	inline void bind_params(Command &command, const T &param)
	{
		params_binder<Command, T> binder;
		binder(command, param);
	}

	template <typename Command, typename T>
	struct record_binder
	{
		inline void operator()(Command &command, T &&value) const
		{
			bind_field(command, static_cast<size_t>(0), std::forward<typename std::remove_reference<T>::type>(value));
		}
	};

	template <typename Command, typename T>
	struct record_binder<Command, std::reference_wrapper<T>>
	{
		inline void operator()(Command &command, std::reference_wrapper<T> &&value) const
		{
			bind_field(command, static_cast<size_t>(0), std::forward<typename std::remove_reference<T>::type>(value.get()));
		}
	};

	template <typename Command, typename... Types>
	struct record_binder<Command, std::tuple<Types...>>
	{
		void operator()(Command &command, std::tuple<Types...> &&values) const
		{
			(detail::bind_helper<Command, std::tuple_size<std::tuple<Types...>>::value, Types...>(command))(std::forward<std::tuple<Types...>>(values));
		}
	};

	template <typename Command, typename Type1, typename Type2>
	struct record_binder<Command, std::pair<Type1, Type2>>
	{
		void operator()(Command &command, std::pair<Type1, Type2> &&values) const
		{
			bind_field(command, static_cast<size_t>(0), std::forward<Type1>(values.first));
			bind_field(command, static_cast<size_t>(1), std::forward<Type2>(values.second));
		}
	};

	template <typename T, typename Tag>
	struct record_with_tag : public T
	{
	};

	template <typename T, typename Pred>
	struct custom_binder_type : public T
	{
		typedef T value_type;

		explicit custom_binder_type(Pred pred) : m_pred(pred) {}
		custom_binder_type(value_type &&v, Pred pred)
			: value_type(std::forward<value_type>(v)), m_pred(pred)
		{
		}
		template <typename... Args>
		custom_binder_type(Pred pred, Args &&...args)
			: value_type(std::forward<Args>(args)...), m_pred(pred)
		{
		}

		template <typename Command>
		void bind(Command &command)
		{
			m_pred(std::forward<T>(*this), command); // Pred maybe member function
		}

	private:
		Pred m_pred;
	};

	template <typename T, typename Pred>
	struct custom_binder_type<std::reference_wrapper<T>, Pred> : public std::reference_wrapper<T>
	{
		typedef std::reference_wrapper<T> value_type;

		explicit custom_binder_type(Pred pred) : m_pred(pred) {}
		custom_binder_type(value_type &&v, Pred pred)
			: value_type(std::forward<value_type>(v)), m_pred(pred)
		{
		}
		template <typename... Args>
		custom_binder_type(Pred pred, Args &&...args)
			: T(std::forward<Args>(args)...), m_pred(pred)
		{
		}

		template <typename Command>
		void bind(Command &command)
		{
			m_pred(std::forward<T>(*this), command); // Pred maybe member function
		}

	private:
		Pred m_pred;
	};

	template <typename T, typename Pred>
	inline custom_binder_type<T, Pred> custom_bind(T &&v, Pred pred)
	{
		return custom_binder_type<T, Pred>(std::forward<T>(v), pred);
	}

	template <typename Command, typename T, typename Pred>
	struct record_binder<Command, custom_binder_type<T, Pred>>
	{
		void operator()(Command &command, custom_binder_type<T, Pred> &&values) const
		{
			values.bind(command);
		}
	};

	template <typename Command, typename T>
	inline void bind_record(Command &command, T &&value)
	{
		record_binder<Command, T> binder;
		binder(command, std::forward<T>(value));
	}

	template <typename Command, typename Record>
	class query_iterator final
	{
	public:
		using iterator_category = std::forward_iterator_tag;
		using value_type = Record;
		using difference_type = ptrdiff_t;
		using pointer = Record *;
		using reference = Record &;

		explicit query_iterator(Command &command)
			: m_command(command) {}
		Record *operator->() const { return m_record.get(); }
		Record &operator*() const { return *m_record; }

		query_iterator &operator++()
		{
			if (!m_record)
				m_record = std::make_shared<Record>();
			if (m_record.use_count() == 1)
			{
				if (!m_command.fetch(std::forward<Record>(*m_record)))
					m_record.reset();
			}
			else
			{
				std::shared_ptr<Record> record = std::make_shared<Record>();
				if (m_command.fetch(std::forward<Record>(*record)))
					m_record = record;
				else
					m_record.reset();
			}
			return *this;
		}
		query_iterator operator++(int)
		{
			query_iterator temp = *this;
			m_record = std::make_shared<Record>();
			if (!m_command.fetch(std::forward<Record>(*m_record)))
				m_record.reset();
			return temp;
		}

		bool operator==(const query_iterator &rhs)
		{
			return &this->m_command == &rhs.m_command &&
				   this->m_record == rhs.m_record;
		}
		bool operator!=(const query_iterator &rhs)
		{
			return !(*this == rhs);
		}

	private:
		Command &m_command;
		std::shared_ptr<Record> m_record;
	};

	template <typename Command, typename Record>
	class query_result final
	{
	public:
		typedef typename query_iterator<Command, Record>::value_type value_type;
		typedef typename query_iterator<Command, Record>::pointer pointer;
		typedef typename query_iterator<Command, Record>::reference reference;
		typedef query_iterator<Command, Record> iterator;

		explicit query_result(Command &&command) : m_command(std::move(command)) {}
		query_result(query_result &&src) : m_command(std::move(src.m_command)) {}
		query_result &operator=(query_result &&src)
		{
			if (this != &src)
				m_command = std::move(src.m_command);
			return *this;
		}

		template <typename Params>
		iterator begin(const Params &params)
		{
			query_iterator<Command, Record> it(m_command);
			++it;
			return it;
		}
		iterator begin()
		{
			return begin(std::make_tuple());
		}

		iterator end()
		{
			return query_iterator<Command, Record>(m_command);
		}

	private:
		Command m_command;
	};

	template <typename T, class Command>
	class base_database
	{
	public:
		template <typename Params>
		base_database &execute(const char *query_text, size_t text_length, const Params &params, uint64_t *affected = NULL)
		{
			T *pThis = static_cast<T *>(this);
			Command command = pThis->open_command(query_text, text_length);
			command.execute(params);
			if (affected)
				*affected = command.affetced_rows();
			command.close();
			return *this;
		}
		template <typename Params>
		base_database &execute(const char *query_text, const Params &params, uint64_t *affected = NULL)
		{
			return execute(query_text, strlen(query_text), params, affected);
		}
		template <typename Params>
		base_database &execute(const std::string &query_text, const Params &params, uint64_t *affected = NULL)
		{
			return execute(query_text.data(), query_text.length(), params, affected);
		}

		template <typename... Params>
		base_database &execute_direct(const char *query_text, size_t text_length, uint64_t *affected, const Params &...params)
		{
			return execute(query_text, text_length, std::forward_as_tuple(params...), affected);
		}
		template <typename... Params>
		base_database &execute_direct(const char *query_text, uint64_t *affected, const Params &...params)
		{
			return execute(query_text, std::forward_as_tuple(params...), affected);
		}
		template <typename... Params>
		base_database &execute_direct(const std::string &query_text, uint64_t *affected, const Params &...params)
		{
			return execute(query_text, std::forward_as_tuple(params...), affected);
		}

		template <typename Params>
		uint64_t insert(const char *query_text, size_t text_length, const Params &params)
		{
			uint64_t id = 0;
			T *pThis = static_cast<T *>(this);
			Command command = pThis->open_command(query_text, text_length);
			command.execute(params);
			if (command.affetced_rows() > 0)
				id = command.insert_id();
			return id;
		}

		template <typename Params>
		uint64_t insert(const char *query_text, const Params &params)
		{
			return insert(query_text, strlen(query_text), params);
		}

		template <typename Params>
		uint64_t insert(const std::string &query_text, const Params &params)
		{
			return insert(query_text.data(), query_text.length(), params);
		}

		template <typename... Params>
		uint64_t insert_direct(const char *query_text, size_t text_length, const Params &...params)
		{
			return insert(query_text, text_length, std::forward_as_tuple(params...));
		}

		template <typename... Params>
		uint64_t insert_direct(const char *query_text, const Params &...params)
		{
			return insert(query_text, strlen(query_text), std::forward_as_tuple(params...));
		}

		template <typename... Params>
		uint64_t insert_direct(const std::string &query_text, const Params &...params)
		{
			return insert(query_text.data(), query_text.length(), std::forward_as_tuple(params...));
		}

		template <typename Record, typename Params>
		query_result<Command, Record> result(const char *query_text, size_t text_length, const Params &params)
		{
			T *pThis = static_cast<T *>(this);
			Command command = pThis->open_command(query_text, text_length);
			command.execute(params);
			return query_result<Command, Record>(std::move(command));
		}
		template <typename Record, typename Params>
		query_result<Command, Record> result(const char *query_text, const Params &params)
		{
			return result<Record, Params>(query_text, strlen(query_text), params);
		}
		template <typename Record, typename Params>
		query_result<Command, Record> result(const std::string &query_text, const Params &params)
		{
			return result<Record, Params>(query_text.data(), query_text.length(), params);
		}
		template <typename Record>
		query_result<Command, Record> result(const char *query_text, size_t text_length)
		{
			return result<Record>(query_text, text_length, std::make_tuple());
		}
		template <typename Record>
		query_result<Command, Record> result(const char *query_text)
		{
			return result<Record>(query_text, strlen(query_text), std::make_tuple());
		}
		template <typename Record>
		query_result<Command, Record> result(const std::string &query_text)
		{
			return result<Record>(query_text.data(), query_text.length(), std::make_tuple());
		}

		template <typename Params, typename Values, typename ValueProc>
		base_database &query_explicit(const char *query_text, size_t text_length, const Params &params, Values &&values, ValueProc &&proc)
		{
			T *pThis = static_cast<T *>(this);
			Command command = pThis->open_command(query_text, text_length);
			command.execute(params);
			while (command.fetch(std::forward<Values>(values)))
			{
				if (!detail::apply(std::forward<ValueProc>(proc), std::forward<Values>(values)))
					break;
			}
			command.close();
			return *this;
		}

		template <typename Params, typename Values, typename ValueProc>
		base_database &query_explicit(const char *query_text, const Params &params, Values &&values, ValueProc &&proc)
		{
			return query_explicit(query_text, strlen(query_text), params, std::forward<Values>(values), std::forward<ValueProc>(proc));
		}
		template <typename Params, typename Values, typename ValueProc>
		base_database &query_explicit(const std::string &query_text, const Params &params, Values &&values, ValueProc &&proc)
		{
			return query_explicit(query_text.data(), query_text.size(), params, std::forward<Values>(values), std::forward<ValueProc>(proc));
		}
		template <typename Values, typename ValueProc>
		base_database &query_explicit(const char *query_text, size_t text_length, Values &&values, ValueProc &&proc)
		{
			return query_explicit(query_text, text_length, std::make_tuple(), std::forward<Values>(values), std::forward<ValueProc>(proc));
		}
		template <typename Values, typename ValueProc>
		base_database &query_explicit(const char *query_text, Values &&values, ValueProc &&proc)
		{
			return query_explicit(query_text, strlen(query_text), std::make_tuple(), std::forward<Values>(values), std::forward<ValueProc>(proc));
		}
		template <typename Values, typename ValueProc>
		base_database &query_explicit(const std::string &query_text, Values &&values, ValueProc &&proc)
		{
			return query_explicit(query_text, std::make_tuple(), std::forward<Values>(values), std::forward<ValueProc>(proc));
		}

		template <typename Params, typename ValueProc>
		base_database &query(const char *query_text, size_t text_length, const Params &params, ValueProc &&proc)
		{
			return query_explicit(query_text, text_length, params, detail::make_values(proc), std::forward<ValueProc>(proc));
		}
		template <typename Params, typename ValueProc>
		base_database &query(const char *query_text, const Params &params, ValueProc &&proc)
		{
			return query_explicit(query_text, params, detail::make_values(proc), std::forward<ValueProc>(proc));
		}
		template <typename Params, typename ValueProc>
		base_database &query(const std::string &query_text, const Params &params, ValueProc &&proc)
		{
			return query_explicit(query_text, params, detail::make_values(proc), std::forward<ValueProc>(proc));
		}
		template <typename ValueProc>
		base_database &query(const char *query_text, size_t text_length, ValueProc &&proc)
		{
			return query_explicit(query_text, text_length, detail::make_values(proc), std::forward<ValueProc>(proc));
		}
		template <typename ValueProc>
		base_database &query(const char *query_text, ValueProc &&proc)
		{
			return query_explicit(query_text, detail::make_values(proc), std::forward<ValueProc>(proc));
		}
		template <typename ValueProc>
		base_database &query(const std::string &query_text, ValueProc &&proc)
		{
			return query_explicit(query_text, detail::make_values(proc), std::forward<ValueProc>(proc));
		}

		template <typename Params, typename... ValueProc>
		base_database &query_multi_with_params(const char *query_text, size_t text_length, const Params &params, ValueProc &&...proc)
		{
			T *pThis = static_cast<T *>(this);
			Command command = pThis->open_command(query_text, text_length);
			command.execute(params);
			detail::fetch_command(command, std::forward<ValueProc>(proc)...);
			command.close();
			return *this;
		}
		template <typename Params, typename... ValueProc>
		base_database &query_multi_with_params(const char *query_text, const Params &params, ValueProc &&...proc)
		{
			return query_multi_with_params(query_text, strlen(query_text), params, std::forward<ValueProc>(proc)...);
		}
		template <typename Params, typename... ValueProc>
		base_database &query_multi_with_params(const std::string &query_text, const Params &params, ValueProc &&...proc)
		{
			return query_multi_with_params(query_text.data(), query_text.size(), params, std::forward<ValueProc>(proc)...);
		}
		template <typename... ValueProc>
		base_database &query_multi(const char *query_text, size_t text_length, ValueProc &&...proc)
		{
			return query_multi_with_params<std::tuple<>, ValueProc...>(query_text, text_length, std::make_tuple(), std::forward<ValueProc>(proc)...);
		}
		template <typename... ValueProc>
		base_database &query_multi(const char *query_text, ValueProc &&...proc)
		{
			return query_multi_with_params<std::tuple<>, ValueProc...>(query_text, strlen(query_text), std::make_tuple(), std::forward<ValueProc>(proc)...);
		}
		template <typename... ValueProc>
		base_database &query_multi(const std::string &query_text, ValueProc &&...proc)
		{
			return query_multi_with_params<std::tuple<>, ValueProc...>(query_text.data(), query_text.size(), std::make_tuple(), std::forward<ValueProc>(proc)...);
		}

		template <typename Params, typename Values>
		bool query_first(const char *query_text, size_t text_length, const Params &params, Values &&values)
		{
			first_record fetcher;
			query_explicit(query_text, text_length, params, std::forward<Values>(values), std::ref(fetcher));
			return fetcher;
		}

		template <typename Params, typename Values>
		bool query_first(const char *query_text, const Params &params, Values &&values)
		{
			first_record fetcher;
			query_explicit(query_text, strlen(query_text), params, std::forward<Values>(values), std::ref(fetcher));
			return fetcher;
		}

		template <typename Params, typename Values>
		bool query_first(const std::string &query_text, const Params &params, Values &&values)
		{
			first_record fetcher;
			return query_explicit(query_text, params, values, std::ref(fetcher));
			return fetcher;
		}

		template <typename Values>
		bool query_first(const char *query_text, size_t text_length, Values &&values)
		{
			first_record fetcher;
			return query_explicit(query_text, text_length, std::make_tuple(), std::forward<Values>(values), std::ref(fetcher));
			return fetcher;
		}

		template <typename Values>
		bool query_first(const char *query_text, Values &&values)
		{
			first_record fetcher;
			query_explicit(query_text, strlen(query_text), std::make_tuple(), std::forward<Values>(values), std::ref(fetcher));
			return fetcher;
		}

		template <typename Values>
		bool query_first(const std::string &query_text, Values &&values)
		{
			first_record fetcher;
			return query_explicit(query_text, std::make_tuple(), std::forward<Values>(values), std::ref(fetcher));
			return fetcher;
		}

		template <typename... Values>
		bool query_first_direct(const char *query_text, size_t text_length, Values &...values)
		{
			return query_first(query_text, text_length, std::tie(values...));
		}

		template <typename... Values>
		bool query_first_direct(const char *query_text, Values &...values)
		{
			return query_first(query_text, std::tie(values...));
		}

		template <typename... Values>
		bool query_first_direct(const std::string &query_text, Values &...values)
		{
			return query_first(query_text, std::tie(values...));
		}

	protected:
		struct nothing
		{
			template <typename... Values>
			bool operator()(Values &&...) const { return true; }
		};
		struct first_record
		{
			first_record() : _found(false) {}
			template <typename... Values>
			bool operator()(Values &&...)
			{
				_found = true;
				return false;
			}
			operator bool() const { return _found; }

		private:
			bool _found;
		};
	};

	class blobbuf : public std::streambuf
	{
	public:
		blobbuf() = default;
		blobbuf(const blobbuf &) = default;
		blobbuf &operator=(const blobbuf &) = default;
		virtual ~blobbuf()
		{
			overflow();
		}

		void swap(blobbuf &other)
		{
			std::swap(m_buf, other.m_buf);
			std::swap(m_size, other.m_size);
			std::swap(m_pos, other.m_pos);

			std::streambuf::swap(other);
		}

	protected:
		virtual pos_type seekoff(off_type off, std::ios_base::seekdir dir,
								 std::ios_base::openmode which = std::ios_base::in | std::ios_base::out) override
		{
			if (which & std::ios_base::in)
			{
				pos_type pos = 0;
				pos = seekoff(m_pos, off, dir);
				return seekpos(pos, which);
			}
			return std::streambuf::seekoff(off, dir, which);
		}

		virtual pos_type seekpos(pos_type pos,
								 std::ios_base::openmode which = std::ios_base::in | std::ios_base::out) override
		{
			if (pos >= m_size)
				return pos_type(off_type(-1));

			if (which & std::ios_base::out)
			{
				if (pos < m_pos || pos >= m_pos + off_type(egptr() - pbase()))
				{
					overflow();
					m_pos = pos;
					setp(m_buf.data(), m_buf.data() + m_buf.size());
				}
				else
				{
					pbump(off_type(pos - pabs()));
				}
			}
			else if (which & std::ios_base::in)
			{
				if (pos < m_pos || pos >= m_pos + off_type(epptr() - eback()))
				{
					m_pos = pos;
					setg(m_buf.data(), m_buf.data(), m_buf.data());
				}
				else
				{
					gbump(off_type(pos - gabs()));
				}
			}
			return pos;
		}

		virtual std::streamsize showmanyc() override
		{
			return m_size - pabs();
		}

		virtual int_type underflow() override
		{
			if (pptr() > pbase())
				overflow();

			off_type count = egptr() - eback();
			pos_type next_pos = 0;
			if (count == 0 && eback() == m_buf.data())
			{
				setg(m_buf.data(), m_buf.data(), m_buf.data() + m_buf.size());
				count = m_buf.size();
			}
			else
			{
				next_pos = m_pos + pos_type(count);
			}
			if (next_pos >= m_size)
				return traits_type::eof();

			count = std::min(count, m_size - next_pos);
			m_pos = next_pos;
			if (read_blob(m_buf.data(), count, m_pos))
			{
				setg(eback(), eback(), eback() + count);
				return traits_type::to_int_type(*gptr());
			}
			else
			{
				return traits_type::eof();
			}
		}

		virtual int_type overflow(int_type ch = traits_type::eof()) override
		{
			if (pptr() != pbase())
			{
				size_t count = pptr() - pbase();
				write_blob(pbase(), count);

				// auto intersection = interval_intersection(m_pos, egptr() - eback(), m_pos, epptr() - pbase());
				// if (intersection.first != intersection.second)
				//{
				//	commit(intersection.first, intersection.second);
				// }

				m_pos += count;
				setp(pbase(), epptr());
			}
			if (!traits_type::eq_int_type(ch, traits_type::eof()))
			{
				char_type c = traits_type::to_char_type(ch);
				if (m_pos >= m_size)
					return traits_type::eof();
				write_blob(&c, 1);

				// auto intersection = interval_intersection(m_pos, egptr() - eback(), m_pos, 1);
				// if (intersection.first != intersection.second)
				//{
				//	eback()[intersection.first - m_pos] = c;
				// }
				m_pos += 1;
			}
			return ch;
		}

		virtual int_type pbackfail(int_type c = traits_type::eof()) override
		{
			if (gptr() == 0 || gptr() <= eback() || (!traits_type::eq_int_type(traits_type::eof(), c) && !traits_type::eq(traits_type::to_char_type(c), gptr()[-1])))
			{
				return (traits_type::eof()); // can't put back, fail
			}
			else
			{ // back up one position and store put-back character
				gbump(-1);
				if (!traits_type::eq_int_type(traits_type::eof(), c))
					*gptr() = traits_type::to_char_type(c);
				return (traits_type::not_eof(c));
			}
		}

	private:
		off_type seekoff(off_type position, off_type off, std::ios_base::seekdir dir)
		{
			off_type result = 0;
			switch (dir)
			{
			case std::ios_base::beg:
				result = off;
				break;
			case std::ios_base::cur:
				result = position + off;
				break;
			case std::ios_base::end:
				result = m_size - off;
			}
			if (result > m_size)
				result = m_size;
			return result;
		}

		pos_type gabs() const // absolute offset of input pointer in blob field
		{
			return m_pos + off_type(gptr() - eback());
		}

		pos_type pabs() const // absolute offset of output pointer in blob field
		{
			return m_pos + off_type(pptr() - pbase());
		}

	protected:
		std::vector<char> m_buf;
		pos_type m_size;
		pos_type m_pos; // position in the input sequence

		virtual bool read_blob(char *buffer, off_type &count, pos_type position) = 0;
		virtual void write_blob(const char *buffer, size_t count) = 0;

		void init_buffer(std::ios_base::openmode mode)
		{
			size_t bufsize;
			if (m_size > 0)
				bufsize = std::min<size_t>(blob_buffer_size, m_size);
			else
				bufsize = blob_buffer_size;
			if (mode & std::ios_base::in)
			{
				m_buf.resize(bufsize);
				m_pos = 0;
				setg(m_buf.data(), m_buf.data(), m_buf.data());
			}
			else if (mode & std::ios_base::out)
			{
				m_buf.resize(bufsize);
				m_pos = 0;
				setp(m_buf.data(), m_buf.data() + bufsize);
			}
		}
	};

	typedef std::function<void(std::ostream &)> blob_writer;

	template <typename Database>
	struct transaction
	{
		transaction(Database &db) : m_db(db), m_commited(true)
		{
			begin();
		}
		~transaction()
		{
			rollback();
		}
		void begin()
		{
			if (m_commited)
			{
				m_db.begin_transaction();
				m_commited = false;
			}
		}
		void rollback()
		{
			if (!m_commited)
			{
				m_db.rollback();
				m_commited = true;
			}
		}
		void commit()
		{
			if (!m_commited)
			{
				m_db.commit();
				m_commited = true;
			}
		}

	private:
		bool m_commited;
		Database &m_db;
	};

	template <typename Command, typename Params, typename... Others>
	inline void execute(Command &command, uint64_t *affected, const Params &params)
	{
		command.reset();
		command.execute(params);
		if (affected)
			*affected += command.affetced_rows();
	}

	template <typename Command, typename Params, typename... Others>
	inline void execute(Command &command, uint64_t *affected, const Params &params, const Others &...others)
	{
		execute(command, affected, params);
		execute(command, affected, others...);
	}

}

#endif //_QTL_COMMON_H_