#include "DataImporter.h"
#include <DataId.h>
#include <Logging.h>
#include <MySQLClient.h>
#include <SQLiteClient.h>
#include <StringAlgorithm.h>
#include <sstream>


namespace DataStorageInterface {
namespace DataInterface {

DataImporter::DataImporter(MySQL::MySQLClient* pMySQLClient, SQLite::SQLiteClient* pSQLiteClient) :
	m_pMySQLClient(pMySQLClient),
	m_pSQLiteClient(pSQLiteClient)
{
}

void DataImporter::ImportData()
{
	auto tables = GetTables();
	for (auto& table : tables)
	{
		auto devices = GetDevices(table);
		for (auto& device : devices)
			ImportData(table, device);
	}
}

std::vector<std::string> DataImporter::GetTables()
{
	std::stringstream query;
	query << "SELECT name FROM sqlite_master WHERE type ='table' AND name NOT LIKE 'sqlite_%';";
	auto resultSet = m_pSQLiteClient->ExecuteQuery(query.str());

	std::vector<std::string> tables;
	while (resultSet.Next())
		tables.push_back(resultSet.String("name"));

	return tables;
}

std::vector<int> DataImporter::GetDevices(const std::string& table)
{
	std::stringstream query;
	query << "SELECT DISTINCT device_id FROM " << table << ";";
	auto resultSet = m_pSQLiteClient->ExecuteQuery(query.str());

	std::vector<int> devices;
	while (resultSet.Next())
		devices.push_back(resultSet.Int("device_id"));

	return devices;
}

void DataImporter::ImportData(const std::string& table, int device)
{
	std::stringstream ss;
	ss << "Table: " << table << " #" << device;
	Logging::Log(Logging::Severity::Info, ss.str());

	int maxMySQLPacketSize = GetMaximumMySQLPacketSize() - 2;
	int maxTimestamp = GetMaximumTimestamp(table, device);
	int dataId = DataStorage::DataId(table).Id();

	std::stringstream queryPart;

	std::stringstream query;
	query << "SELECT timestamp, value FROM " << table << " WHERE device_id = '" << device << "' AND timestamp > '" << maxTimestamp << "' ORDER BY timestamp ASC;";
	auto resultSet = m_pSQLiteClient->ExecuteQuery(query.str());

	int writeCount = 0;
	InitializeInsertQuery(query);
	while (resultSet.Next())
	{
		queryPart.str("");
		queryPart << "('" << device << "', '" << dataId << "', FROM_UNIXTIME(" << resultSet.Int("timestamp") << "), '" << resultSet.String("value") << "'),";
		++writeCount;

		int packetSize = StringStreamSize(query) + StringStreamSize(queryPart);
		if (packetSize > maxMySQLPacketSize)
		{
			ExecuteInsertQuery(query);
			writeCount = 0;
			InitializeInsertQuery(query);
		}

		query << queryPart.str();
	}

	if (writeCount > 0)
		ExecuteInsertQuery(query);
}

int DataImporter::GetMaximumMySQLPacketSize()
{
	std::stringstream query;
	query << "show variables like 'max_allowed_packet';";
	MySQL::MySQLResultSet resultSet = m_pMySQLClient->ExecuteQuery(query.str());

	if (resultSet.RowsCount() != 1)
		throw std::runtime_error("Unexpected reply when retrieving max_allowed_packet.");

	resultSet.Next();
	return resultSet.Int("Value");
}

int DataImporter::StringStreamSize(std::stringstream& ss)
{
	ss.seekp(0, std::ios_base::end);
	return ss.tellp();
}

void DataImporter::InitializeInsertQuery(std::stringstream& query)
{
	query.str("");
	query << "INSERT INTO `datalog` (`device_id`, `data_id`, `timestamp`, `value`) VALUES ";
}

void DataImporter::ExecuteInsertQuery(std::stringstream& query)
{
	query.seekp(-1, std::ios_base::end);
	query << ";";
	m_pMySQLClient->Execute(query.str());
}

int DataImporter::GetMaximumTimestamp(const std::string& table, int device)
{
	std::stringstream query;
	query << "SELECT MAX(UNIX_TIMESTAMP(`timestamp`)) AS timestamp FROM `datalog` WHERE `device_id` = '" << device <<"' AND `data_id` = '" << DataStorage::DataId(table).Id() << "';";
	auto resultSet = m_pMySQLClient->ExecuteQuery(query.str());
	if (resultSet.Next())
		return resultSet.Int("timestamp");

	return 0;
}

} // namespace DataInterface
} // namespace DataStorageInterface