#pragma once

#include <functional>
#include <string>
#include <pgsql/libpq-fe.h>
#include <cassert>
#include <QString>

#include <memory>

namespace Pgsql {

	class Connection;
	/*
	This library has multiple layers.

	Layer 1 delivers lowlevel C++ wrappers for the basic libpq functionality. Adding
	automatic resource management.

	*/

	class ConnectionParams {
	public:
		std::string host;
		std::string hostaddr;
		unsigned short port = 5432;
		std::string dbname;
		std::string user;
		std::string password;
		int connect_timeout = -1; ///< -1 omit (ie uses default)
		std::string application_name;

	};

	class ErrorDetails {
	public:
		static ErrorDetails createErrorDetailsFromPGresult(const PGresult *res);

		std::string state; ///< PG_DIAG_SQLSTATE Error code as listed in	https://www.postgresql.org/docs/9.5/static/errcodes-appendix.html
		std::string severity;
		std::string messagePrimary;
		std::string messageDetail;
		std::string messageHint;
		int statementPosition; ///< First character is one, measured in characters not bytes!
		int internalPosition;
		std::string internalQuery;
		std::string context;
		std::string schemaName;
		std::string tableName;
		std::string columnName;
		std::string datatypeName;
		std::string constraintName;
		std::string sourceFile;
		std::string sourceLine;
		std::string sourceFunction;
	};

	/** Non-copyable but movable wrapper for a postgresql result. */
	class Result {
	public:
//		class iterator {
//		public:
//			iterator(Result &r, int rw)
//				: result(r), row(rw)
//			{}

//			iterator operator++()
//			{
//				iterator t(*this);
//				++row;
//				return t;
//			}

//			iterator& operator++(int)
//			{
//				++row;
//				return *this;
//			}

//			bool operator!=(const iterator &rhs)
//			{
//				assert()
//			}

//		private:
//			Result &result;
//			int row;
//		};

		Result() = default;
		Result(PGresult *result);
		~Result();

		Result(const Result &rhs) = delete;
		Result& operator=(const Result &rhs) = delete;

		Result(Result &&rhs);
		Result& operator=(Result &&rhs);

		operator bool() const;

		ExecStatusType resultStatus();

		std::string getResStatus();

		/** Use this to retrieve an error code when this is an error result
		 *
		 * The possible code are listed in https://www.postgresql.org/docs/9.5/static/errcodes-appendix.html
		 */
		std::string diagSqlState();
		/** Retrieves all the error fields. */
		ErrorDetails diagDetails();




		int getRows() const;
		int getCols() const;

		const char* const getColName(int idx) const;

		const char * getVal(int col, int row) const;

//		iterator begin();
	private:
		PGresult *result = nullptr;
	};


	class Canceller {
	public:
		Canceller(PGcancel *c);
		Canceller(const Canceller&) = delete;
		Canceller& operator=(const Canceller&) = delete;
		Canceller(Canceller&& rhs);
		Canceller& operator=(Canceller&& rhs);
		~Canceller();
		void cancel();
	private:
		PGcancel *m_cancel;
	};


	class Connection {
	public:
		Connection();
		~Connection();

		Connection(const Connection &rhs) = delete;
		Connection& operator=(const Connection &rhs) = delete;

		Connection(Connection &&rhs);
		Connection& operator=(Connection &&rhs);

//		void connect(const ConnectionParams &params);
		bool connect(const char *params);
		bool connect(const QString &params)
		{
			return connect(params.toUtf8().data());
		}

		bool connectStart(const char *params);
		bool connectStart(const QString &params)
		{
			return connectStart(params.toUtf8().data());
		}

		PostgresPollingStatusType connectPoll();
		ConnStatusType status();
		int socket();

		void close();
		Canceller getCancel();

		std::string getErrorMessage() const;

		Result query(const char * command);
		Result query(const QString &command)
		{
			return query(command.toUtf8().data());
		}

		bool sendQuery(const char * query);
		bool sendQuery(const QString &command)
		{
			return sendQuery(command.toUtf8().data());
		}

		std::unique_ptr<Result> getResult();

		bool consumeInput();
		bool isBusy();

		void setNoticeReceiver(std::function<void(const PGresult *)> callback);
	private:
		PGconn *conn = nullptr;
		std::function<void(const PGresult *)> notifyReceiver;

		static void notifyReceiveFunc(void *arg, const PGresult *result);
	};




	class Field {
	public:

		std::string getName() const;

	private:
		//Tuples tuples;
		int field;
		//

	};

	class Tuples {
	public:
		int getRowCount() const;
		int getColCount() const;

		Field getField(const std::string &fname);
		Field getField(const int idx);

		class const_iterator {
		public:
            const_iterator& operator++();
		};

		void rewind();


	};

	class OkResult: public Result {
	public:
		/** If the result is a data result then returns an interface for processing this data.

		The returned interface remains valid as long as this OkResult exists.
		*/
		Tuples* hasTuples();
	};

//	class ErrorResult: public Result {
//
//	};

//	class ITransaction {
//	public:
//
//		Canceller Query(std::string query,
//			std::function<void(OkResult)> on_success,
//			std::function<void()> on_cancelled,
//			std::function<void(ErrorResult)> on_error);
//
//		Canceller Query(std::string query,
//			std::function<void(OkResult)> on_success,
//			std::function<void()> on_cancelled,
//			std::function<void(ErrorResult)> on_error);
//
//
//		void Rollback(
//			std::function<void(OkResult)> on_success,
//			std::function<void(ErrorResult)> on_error);
//		void Commit(
//			std::function<void(OkResult)> on_success,
//			std::function<void()> on_cancelled,
//			std::function<void(ErrorResult)> on_error);
//
//	};
}