/**

 * Relational pipes

 * Copyright © 2021 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 <codecvt>

#include <vector>

#include <libxml++-2.6/libxml++/libxml++.h>

#include <vmime/vmime.hpp>

#include "XMLNameCodec.h"

namespace relpipe {

namespace in {

namespace xmltable {

class XMLDocumentConstructor {

private:

	std::istream* input = nullptr;

	xmlpp::DomParser* parser = nullptr;

	XMLNameCodec nameCodec;

	std::string rootName = "mime-message";

	std::string format(std::shared_ptr<vmime::datetime> value) {

		std::stringstream timestamp;

		int tz = value->getZone();

		timestamp << value->getYear() << "-";

		timestamp << std::setw(2) << std::setfill('0') << value->getMonth() << "-";

		timestamp << std::setw(2) << std::setfill('0') << value->getDay() << "T";

		timestamp << std::setw(2) << std::setfill('0') << value->getHour() << ":";

		timestamp << std::setw(2) << std::setfill('0') << value->getMinute() << ":";

		timestamp << std::setw(2) << std::setfill('0') << value->getSecond() << (tz >= 0 ? "+" : "-");

		timestamp << std::setw(2) << std::setfill('0') << std::abs(tz / 60) << ":";

		timestamp << std::setw(2) << std::setfill('0') << std::abs(tz % 60);

		return timestamp.str();

	}

	std::string format(const vmime::mediaType& contentType) {

		return contentType.getType() + "/" + contentType.getSubType();

	}

	std::string toLowerCase(const std::string& value) {

		std::string result = value;

		std::transform(result.begin(), result.end(), result.begin(), ::tolower);

		return result;

	}

	std::string toHex(const std::string& value) {

		static const char* const hexSymbols = "0123456789abcdef";

		size_t length = value.length();

		std::string result;

		result.reserve(3 * length - 1);

		for (size_t i = 0; i < length; i++) {

			const unsigned char ch = value[i];

			result.push_back(hexSymbols[ch >> 4]);

			result.push_back(hexSymbols[ch & 15]);

			if (i < length - 1) result.push_back(' ');

		}

		return result;

	}

	std::string fetchBodyText(std::shared_ptr<vmime::body> body) {

		std::stringstream result;

		vmime::utility::outputStreamAdapter resultAdapter(result);

		const vmime::charset targetEncoding = vmime::charset("utf-8");

		const vmime::charset sourceEncoding = body->getCharset();

		vmime::shared_ptr <vmime::charsetConverter> charsetConverter = vmime::charsetConverter::create(sourceEncoding, targetEncoding);

		vmime::shared_ptr <vmime::utility::charsetFilteredOutputStream> resultConverter = charsetConverter->getFilteredOutputStream(resultAdapter);

		body->getContents()->extract(*resultConverter);

		resultConverter->flush();

		return result.str();

	}

	std::string fetchBodyBinary(std::shared_ptr<vmime::body> body) {

		std::stringstream result;

		return toHex(result.str());

	}

	void appendBody(xmlpp::Element* element, std::shared_ptr<vmime::body> body) {

		element->set_attribute("content-type", format(body->getContentType()));

		// element->set_attribute("content-type-charset", body->getCharset().getName());

		// element->set_attribute("content-transfer-encoding", body->getEncoding().getName());

		if (body->getPartCount() == 0) {

			if (body->getContentType().getType() == "text") element->add_child_cdata(fetchBodyText(body));

			else element->add_child_text(fetchBodyBinary(body));

			// TODO: if content is valid XML, import it in the DOM tree instead of pasting as a nested text/cdata

			// TODO: optional trim of long data

		} else {

			for (auto part : body->getPartList()) {

				xmlpp::Element* partElement = element->add_child("part");

				appendBody(partElement, part->getBody());

			}

		}

	}

public:

	XMLDocumentConstructor(std::istream* input, xmlpp::DomParser* parser) : input(input), parser(parser) {

	}

	virtual ~XMLDocumentConstructor() {

	}

	void setOption(const std::string& uri, const std::string& value) {

		if (uri == "root-name") rootName = value;

		else throw std::invalid_argument(std::string("Invalid parser option: „") + uri + "“ with value: „" + value + "“");

	}

	void process() {

		vmime::utility::inputStreamAdapter is(*input);

		vmime::string data;

		vmime::utility::outputStreamStringAdapter os(data);

		vmime::utility::bufferedStreamCopy(is, os);

		vmime::message m;

		m.parse(data);

		// vmime::shared_ptr<vmime::utility::inputStreamAdapter> is = vmime::make_shared<vmime::utility::inputStreamAdapter>(*input);

		// m.parse(is, 0);

		vmime::charset ch(vmime::charsets::UTF_8);

		//std::cerr << "Subject:" << m.getHeader()->Subject()->getValue<vmime::text>()->getConvertedText(ch) << std::endl;

		xmlpp::Element* root = parser->get_document()->create_root_node(rootName);

		xmlpp::Element* headers = root->add_child("headers");

		for (std::shared_ptr<vmime::headerField> mimeField : m.getHeader()->getFieldList()) {

			// TODO: Are names always ASCII and subset of UTF-8?

			xmlpp::Element* field = headers->add_child(toLowerCase(nameCodec.encode(mimeField->getName())));

			if (auto value = mimeField->getValue<vmime::text>()) {

				field->add_child_text(value->getConvertedText(ch));

			} else if (auto value = mimeField->getValue<vmime::mailbox>()) {

				std::string name = value->getName().getConvertedText(ch);

				std::string email = value->getEmail().toString();

				if (name.size()) field->set_attribute("name", name);

				if (email.size()) field->add_child_text(email);

			} else if (auto value = mimeField->getValue<vmime::addressList>()) {

				for (auto address : value->getAddressList()) {

					xmlpp::Element* addressField = field->add_child("address");

					if (std::shared_ptr<vmime::mailbox> mailbox = std::dynamic_pointer_cast<vmime::mailbox> (address)) {

						std::string name = mailbox->getName().getConvertedText(ch);

						std::string email = mailbox->getEmail().toString();

						if (name.size()) addressField->set_attribute("name", name);

						if (email.size()) addressField->add_child_text(email);

					} else if (std::shared_ptr<vmime::mailboxGroup> mailbox = std::dynamic_pointer_cast<vmime::mailboxGroup> (address)) {

						// TODO: mailboxGroup?

					}

				}

			} else if (auto value = mimeField->getValue<vmime::datetime>()) {

				// TODO: keep particular timestamp bits attributes or not?

				field->set_attribute("year", std::to_string(value->getYear()));

				field->set_attribute("month", std::to_string(value->getMonth()));

				field->set_attribute("day", std::to_string(value->getDay()));

				field->set_attribute("hour", std::to_string(value->getHour()));

				field->set_attribute("minute", std::to_string(value->getMinute()));

				field->set_attribute("second", std::to_string(value->getSecond()));

				field->set_attribute("zone", std::to_string(value->getZone())); // timezone is in minutes

				field->add_child_text(format(value));

			} else if (auto value = mimeField->getValue<vmime::mediaType>()) {

				if (value) field->add_child_text(format(*value));

				// TODO: encoding from the "Content-Type: text/plain; charset=us-ascii" type header?

			} else if (auto value = mimeField->getValue<vmime::messageId>()) {

				field->add_child_text(value->getId());

			} else if (auto value = mimeField->getValue<vmime::messageIdSequence>()) {

				for (auto messageId : value->getMessageIdList()) {

					messageIdField->add_child_text(messageId->getId());

				}

			} else if (auto value = mimeField->getValue<vmime::contentDisposition>()) {

				field->add_child_text(value->getName());

			} else if (auto value = mimeField->getValue<vmime::relay>()) {

				field->set_attribute("from", value->getFrom());

				field->set_attribute("via", value->getVia());

				field->set_attribute("by", value->getBy());

				field->set_attribute("id", value->getId());

				field->set_attribute("for", value->getFor());

				// TODO: date of Received/relay

				// TODO: missing values or incomplete parsing of Received/relay in vmime

			} else if (auto value = mimeField->getValue<vmime::path>()) {

				std::string local = value->getLocalPart();

				std::string domain = value->getDomain();

				if (local.size() && domain.size()) field->add_child_text(local + "@" + domain);

				else field->add_child_text(local + domain);

			} else if (auto value = mimeField->getValue<vmime::encoding>()) {

				field->add_child_text(value->getName());

			} else {

				field->add_child_text("TODO: unknown header type"); // TODO: generic conversion as fallback?

			}

		}

		// TODO: check null pointers

		xmlpp::Element* body = root->add_child("body");

		appendBody(body, m.getBody());

	}

};

}

}

}