/**
 * Relational pipes
 * Copyright © 2020 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 <cstdlib>
#include <iostream>
#include <memory>
#include <vector>

#include <yaml.h>

#include <relpipe/writer/RelationalWriter.h>
#include <relpipe/writer/typedefs.h>

namespace relpipe {
namespace in {
namespace yaml {

class YAMLCommand {
private:
	std::wstring_convert<codecvt_utf8<wchar_t>> convertor; // TODO: support also other encodings.

	class YAMLEvent {
	private:
		yaml_event_t event;
	public:

		YAMLEvent(yaml_event_t event) : event(event) {
		}

		virtual ~YAMLEvent() {
			yaml_event_delete(&event);
		}

		const yaml_event_type_t getType() const {
			return event.type;
		}

		const yaml_event_t* getEvent() const {
			return &event;
		}

		YAMLEvent(const YAMLEvent&) = delete;
		YAMLEvent& operator=(const YAMLEvent&) = delete;
	};

	class YAMLParser {
	private:
		yaml_parser_t yamlParser;
		std::istream* input = nullptr;

		static int readFromInput(void* instance, unsigned char* buffer, size_t size, size_t* length) {
			std::istream* input = ((YAMLParser*) instance)->input;
			input->read((char*) buffer, size);
			*length = input->gcount();
			return (input->good() || input->eof()) ? 1 : 0;
		}
	public:

		YAMLParser() {
			yaml_parser_initialize(&yamlParser);
		}

		virtual ~YAMLParser() {
			yaml_parser_delete(&yamlParser);
		}

		YAMLParser(const YAMLParser&) = delete;
		YAMLParser& operator=(const YAMLParser&) = delete;

		void setInput(std::istream* input) {
			this->input = input;
			yaml_parser_set_input(&yamlParser, readFromInput, (void*) this);
		}

		YAMLEvent* next() {
			yaml_event_t event;
			int result = yaml_parser_parse(&yamlParser, &event);
			return result == 1 && event.type != yaml_event_type_e::YAML_NO_EVENT ? new YAMLEvent(event) : nullptr; // 1 = OK in yaml.h; YAML_NO_EVENT = end
		}
	};

	YAMLParser parser;

	using YAMLEvent_p = std::shared_ptr<YAMLEvent>;

	enum class Mode {
		ROOT,
		RELATIONS_SEQUENCE,
		MAPPING,
		MAP_KEY
	};

	std::vector<Mode> mode;

	/**
	 * Both YAML and XML strings are in UTF-8.
	 */
	const char* y2x(yaml_char_t* value) {
		return value ? (const char*) value : "";
	}

public:

	YAMLCommand() {
	}

	virtual ~YAMLCommand() {
	}

	void process(std::istream& input, std::shared_ptr<relpipe::writer::RelationalWriter> writer) {
		parser.setInput(&input);

		std::vector<relpipe::writer::AttributeMetadata> attributesMetadata;
		attributesMetadata.push_back(relpipe::writer::AttributeMetadata{L"todo", relpipe::writer::TypeId::STRING});
		writer->startRelation(L"YAML", attributesMetadata, true);

		mode.push_back(Mode::ROOT);
		std::string itemName;

		writer->writeAttribute(L"before cycle");
		for (YAMLEvent_p event = YAMLEvent_p(parser.next()); event; event = YAMLEvent_p(parser.next())) {

			if (event->getType() == YAML_NO_EVENT) { writer->writeAttribute(L"YAML_NO_EVENT");
			} else if (event->getType() == YAML_STREAM_START_EVENT) { writer->writeAttribute(L"YAML_STREAM_START_EVENT");
			} else if (event->getType() == YAML_STREAM_END_EVENT) { writer->writeAttribute(L"YAML_STREAM_END_EVENT");
			} else if (event->getType() == YAML_DOCUMENT_START_EVENT) { writer->writeAttribute(L"YAML_DOCUMENT_START_EVENT");
			} else if (event->getType() == YAML_DOCUMENT_END_EVENT) { writer->writeAttribute(L"YAML_DOCUMENT_END_EVENT");
			} else if (event->getType() == YAML_ALIAS_EVENT) { writer->writeAttribute(L"YAML_ALIAS_EVENT");
			} else if (event->getType() == YAML_SCALAR_EVENT) { writer->writeAttribute(L"YAML_SCALAR_EVENT");
			} else if (event->getType() == YAML_SEQUENCE_START_EVENT) { writer->writeAttribute(L"YAML_SEQUENCE_START_EVENT");
			} else if (event->getType() == YAML_SEQUENCE_END_EVENT) { writer->writeAttribute(L"YAML_SEQUENCE_END_EVENT");
			} else if (event->getType() == YAML_MAPPING_START_EVENT) { writer->writeAttribute(L"YAML_MAPPING_START_EVENT");
			} else if (event->getType() == YAML_MAPPING_END_EVENT) { writer->writeAttribute(L"YAML_MAPPING_END_EVENT");
			} else { writer->writeAttribute(L"else???");
				// TODO: unsupported type?
			}
		}
		writer->writeAttribute(L"after cycle");
	}
};

}
}
}