ClickHouse/dbms/include/DB/Dictionaries/MongoDBBlockInputStream.h

#pragma once

#include <DB/Core/Block.h>
#include <DB/DataStreams/IProfilingBlockInputStream.h>
#include <DB/Dictionaries/ExternalResultDescription.h>


namespace Poco
{
	namespace MongoDB
	{
		class Connection;
		class Cursor;
	}
}


namespace DB
{

/// Converts MongoDB Cursor to a stream of Blocks
class MongoDBBlockInputStream final : public IProfilingBlockInputStream
{
public:
	MongoDBBlockInputStream(
		std::shared_ptr<Poco::MongoDB::Connection> & connection_,
		std::unique_ptr<Poco::MongoDB::Cursor> cursor_,
		const Block & sample_block,
		const size_t max_block_size);

	~MongoDBBlockInputStream() override;

	String getName() const override { return "MongoDB"; }

	String getID() const override;

private:
	Block readImpl() override;

	static void insertDefaultValue(IColumn * column, const IColumn & sample_column)
	{
		column->insertFrom(sample_column, 0);
	}

	std::shared_ptr<Poco::MongoDB::Connection> connection;
	std::unique_ptr<Poco::MongoDB::Cursor> cursor;
	const size_t max_block_size;
	ExternalResultDescription description;
	bool all_read = false;
};

}