ClickHouse/dbms/include/DB/Interpreters/InterpreterShowCreateQuery.h

#pragma once

#include <DB/Storages/IStorage.h>
#include <DB/Parsers/TablePropertiesQueriesASTs.h>
#include <DB/Parsers/formatAST.h>
#include <DB/Interpreters/Context.h>
#include <DB/Interpreters/IInterpreter.h>
#include <DB/DataStreams/OneBlockInputStream.h>
#include <DB/DataStreams/BlockIO.h>
#include <DB/DataStreams/copyData.h>
#include <DB/DataTypes/DataTypesNumberFixed.h>
#include <DB/DataTypes/DataTypeString.h>


namespace DB
{


/** Вернуть одну строку с одним столбцом statement типа String с текстом запроса, создающего указанную таблицу.
	*/
class InterpreterShowCreateQuery : public IInterpreter
{
public:
	InterpreterShowCreateQuery(ASTPtr query_ptr_, Context & context_)
		: query_ptr(query_ptr_), context(context_) {}

	BlockIO execute() override
	{
		BlockIO res;
		res.in = executeImpl();
		res.in_sample = getSampleBlock();

		return res;
	}

private:
	ASTPtr query_ptr;
	Context context;

	Block getSampleBlock()
	{
		ColumnWithTypeAndName col;
		col.name = "statement";
		col.type = std::make_shared<DataTypeString>();
		col.column = col.type->createColumn();

		Block block;
		block.insert(col);

		return block;
	}

	BlockInputStreamPtr executeImpl()
	{
		const ASTShowCreateQuery & ast = typeid_cast<const ASTShowCreateQuery &>(*query_ptr);

		std::stringstream stream;
		formatAST(*context.getCreateQuery(ast.database, ast.table), stream, 0, false, true);
		String res = stream.str();

		ColumnWithTypeAndName col;
		col.name = "statement";
		col.type = std::make_shared<DataTypeString>();
		col.column = std::make_shared<ColumnConstString>(1, res);

		Block block;
		block.insert(col);

		return std::make_shared<OneBlockInputStream>(block);
	}
};


}