/**
 * 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() {
	}

};

}
}
}