/*
 * Copyright (C) 2019 Emeric Poupon
 *
 * This file is part of LMS.
 *
 * LMS 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * LMS 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 LMS.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "SubsonicResponse.hpp"

#include <Wt/Json/Array.h>
#include <Wt/Json/Object.h>
#include <Wt/Json/Value.h>
#include <Wt/Json/Serializer.h>

#include <boost/property_tree/json_parser.hpp>
#include <boost/property_tree/xml_parser.hpp>

#include "utils/Exception.hpp"
#include "utils/String.hpp"
#include "ProtocolVersion.hpp"

namespace API::Subsonic
{

std::string
ResponseFormatToMimeType(ResponseFormat format)
{
	switch (format)
	{
		case ResponseFormat::xml: return "text/xml";
		case ResponseFormat::json: return "application/json";
	}

	return "";
}

void
Response::Node::setValue(std::string_view value)
{
	if (!_children.empty() || !_childrenArrays.empty())
		throw LmsException {"Node already has children"};

	_value = std::string {value};
}

void
Response::Node::setValue(long long value)
{
	if (!_children.empty() || !_childrenArrays.empty())
		throw LmsException {"Node already has children"};

	_value = value;
}

void
Response::Node::setAttribute(std::string_view key, std::string_view value)
{
	_attributes[std::string {key}] = std::string {value};
}

void
Response::Node::addChild(const std::string& key, Node node)
{
	if (_value)
		throw LmsException {"Node already has a value"};

	_children[key].emplace_back(std::move(node));
}

void
Response::Node::addArrayChild(const std::string& key, Node node)
{
	if (_value)
		throw LmsException {"Node already has a value"};

	_childrenArrays[key].emplace_back(std::move(node));
}


Response::Node&
Response::Node::createChild(const std::string& key)
{
	_children[key].emplace_back();
	return _children[key].back();
}

Response::Node&
Response::Node::createArrayChild(const std::string& key)
{
	_childrenArrays[key].emplace_back();
	return _childrenArrays[key].back();
}

void
Response::Node::setVersionAttribute(ProtocolVersion protocolVersion)
{
	setAttribute("version", std::to_string(protocolVersion.major) + "." + std::to_string(protocolVersion.minor) + "." + std::to_string(protocolVersion.patch));
}

Response
Response::createOkResponse(ProtocolVersion protocolVersion)
{
	Response response;
	Node& responseNode {response._root.createChild("subsonic-response")};

	responseNode.setAttribute("status", "ok");
	responseNode.setVersionAttribute(protocolVersion);
	responseNode.setAttribute("type", "lms"); // non standard field to ease client hacks

	return response;
}

Response
Response::createFailedResponse(ProtocolVersion protocolVersion, const Error& error)
{
	Response response;
	Node& responseNode {response._root.createChild("subsonic-response")};

	responseNode.setAttribute("status", "failed");
	responseNode.setVersionAttribute(protocolVersion);
	responseNode.setAttribute("type", "lms"); // non standard field to ease client hacks

	Node& errorNode {responseNode.createChild("error")};
	errorNode.setAttribute("code", std::to_string(static_cast<int>(error.getCode())));
	errorNode.setAttribute("message", error.getMessage());

	return response;
}

void
Response::addNode(const std::string& key, Node node)
{
	return _root._children["subsonic-response"].front().addChild(key, std::move(node));
}

Response::Node&
Response::createNode(const std::string& key)
{
	return _root._children["subsonic-response"].front().createChild(key);
}

Response::Node&
Response::createArrayNode(const std::string& key)
{
	return _root._children["subsonic-response"].front().createArrayChild(key);
}

void
Response::write(std::ostream& os, ResponseFormat format)
{
	switch (format)
	{
		case ResponseFormat::xml:
			writeXML(os);
			break;
		case ResponseFormat::json:
			writeJSON(os);
			break;
	}
}

void
Response::writeXML(std::ostream& os)
{
	std::function<boost::property_tree::ptree(const Response::Node&)> nodeToPropertyTree = [&] (const Response::Node& node)
	{
		boost::property_tree::ptree res;

		for (auto itAttribute : node._attributes)
		{
			if (std::holds_alternative<std::string>(itAttribute.second))
				res.put("<xmlattr>." + itAttribute.first, std::get<std::string>(itAttribute.second));
			else if (std::holds_alternative<bool>(itAttribute.second))
				res.put("<xmlattr>." + itAttribute.first, std::get<bool>(itAttribute.second));
			else if (std::holds_alternative<long long>(itAttribute.second))
				res.put("<xmlattr>." + itAttribute.first, std::get<long long>(itAttribute.second));
		}

		if (node._value)
		{
			const auto& value {*node._value};

			if (std::holds_alternative<std::string>(value))
				res.put_value(std::get<std::string>(value));
			else if (std::holds_alternative<bool>(value))
				res.put_value(std::get<bool>(value));
			else if (std::holds_alternative<long long>(value))
				res.put_value(std::get<long long>(value));
		}
		else
		{
			for (auto itChildNode : node._children)
			{
				for (const Response::Node& childNode : itChildNode.second)
					res.add_child(itChildNode.first, nodeToPropertyTree(childNode));
			}

			for (auto itChildArrayNode : node._childrenArrays)
			{
				const std::vector<Response::Node>& childArrayNodes {itChildArrayNode.second};

				for (const Response::Node& childNode : childArrayNodes )
					res.add_child(itChildArrayNode.first, nodeToPropertyTree(childNode));
			}
		}

		return res;
	};

	boost::property_tree::ptree root {nodeToPropertyTree(_root)};
	boost::property_tree::write_xml(os, root);
}

void
Response::writeJSON(std::ostream& os)
{
	namespace Json = Wt::Json;

	std::function<Json::Object(const Response::Node&)> nodeToJsonObject = [&] (const Response::Node& node)
	{
		Json::Object res;

		auto valueToJsonValue {[](const Node::ValueType& value) -> Json::Value
		{
			if (std::holds_alternative<std::string>(value))
				return Json::Value {std::get<std::string>(value)};
			else if (std::holds_alternative<bool>(value))
				return Json::Value {std::get<bool>(value)};
			else if (std::holds_alternative<long long>(value))
				return Json::Value {std::get<long long>(value)};

			throw LmsException("Unexpected value type");
		}};

		for (auto itAttribute : node._attributes)
			res[itAttribute.first] = valueToJsonValue(itAttribute.second);

		if (node._value)
		{
			res["value"] = valueToJsonValue(*node._value);
		}
		else
		{
			for (auto itChildNode : node._children)
			{
				for (const Response::Node& childNode : itChildNode.second)
					res[itChildNode.first] = nodeToJsonObject(childNode);
			}

			for (auto itChildArrayNode : node._childrenArrays)
			{
				const std::vector<Response::Node>& childArrayNodes {itChildArrayNode .second};

				Json::Array array;
				for (const Response::Node& childNode : childArrayNodes )
					array.emplace_back(nodeToJsonObject(childNode));

				res[itChildArrayNode.first] = std::move(array);
			}
		}

		return res;
	};

	Json::Object root {nodeToJsonObject(_root)};
	os << Json::serialize(root);
}

} // namespace