/**

 * Relational pipes

 * Copyright © 2022 František Kučera (Frantovo.cz, GlobalCode.info)

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, version 3 of the License.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program. If not, see <http://www.gnu.org/licenses/>.

 */

#pragma once

#include <regex>

#include <stdexcept>

#include <sstream>

#include <codecvt>

#include <iomanip>

#include <relpipe/common/type/typedefs.h>

#include <relpipe/reader/TypeId.h>

#include <relpipe/reader/handlers/RelationalReaderStringHandler.h>

#include <relpipe/reader/handlers/AttributeMetadata.h>

#include <relpipe/writer/Factory.h>

#include <relpipe/cli/RelpipeCLIException.h>

#include "Configuration.h"

namespace relpipe {

namespace tr {

namespace deserialize {

/**

 * Forwards all attributes to given writer.

 * If an relation has same name and attributes as the previous one, records are just appended to it.

 * If name or attributes differ, new relation is started and records are written to it.

 * 

 * So it does something like UNION ALL in SQL for sequences of relations that have same name and attributes.

 */

class UnionAllHandler : public relpipe::reader::handlers::RelationalReaderValueHandler {

private:

	Configuration configuration;

	shared_ptr<relpipe::writer::RelationalWriter> writer;

	class RelationContext {

	public:

		relpipe::common::type::StringX name;

		std::vector<relpipe::reader::handlers::AttributeMetadata> readerMetadata;

		std::vector<relpipe::writer::AttributeMetadata> writerMetadata;

	} relationContext;

	void convert(const std::vector<relpipe::reader::handlers::AttributeMetadata>& r, std::vector<relpipe::writer::AttributeMetadata>& w) {

		w.clear();

		for (const relpipe::reader::handlers::AttributeMetadata& a : r) {

			w.push_back({a.getAttributeName(), writer->toTypeId(a.getTypeName())});

		}

	}

	bool equals(const std::vector<relpipe::reader::handlers::AttributeMetadata>& a, const std::vector<relpipe::reader::handlers::AttributeMetadata>& b) {

		if (a.size() != b.size()) return false;

		for (size_t i = 0, limit = a.size(); i < limit; i++) {

			if (a[i].getAttributeName() != b[i].getAttributeName()) return false;

			if (a[i].getTypeId() != b[i].getTypeId()) return false;

		}

		return true;

	}

public:

	UnionAllHandler(shared_ptr<relpipe::writer::RelationalWriter> writer, Configuration configuration) : writer(writer), configuration(configuration) {

	}

	virtual ~UnionAllHandler() = default;

	void startRelation(relpipe::common::type::StringX name, std::vector<relpipe::reader::handlers::AttributeMetadata> attributes) override {

		bool continuation = name == relationContext.name && equals(attributes, relationContext.readerMetadata);

		relationContext = RelationContext();

		relationContext.name = name;

		relationContext.readerMetadata = attributes;

		if (continuation) {

			// same relation → just append records

		} else {

			convert(attributes, relationContext.writerMetadata);

			writer->startRelation(name, relationContext.writerMetadata, true);

		}

	}

	void attribute(const void* value, const std::type_info& type) override {

		writer->writeAttribute(value, type);

	}

	void endOfPipe() {

	}

};

}

}

}