lms/src/api/subsonic/SubsonicResponse.cpp

/*
 * 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"

#define API_VERSION	"1.12.0"

namespace API::Subsonic
{

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

	return "";
}

static
const char*
ErrorCodeToString(Error::Code error)
{
	switch (error)
	{
		case Error::Code::RequiredParameterMissing:
			return "Required parameter is missing.";
		case Error::Code::ClientMustUpgrade:
			return "Incompatible Subsonic REST protocol version. Client must upgrade.";
		case Error::Code::ServerMustUpgrade:
			return "Incompatible Subsonic REST protocol version. Server must upgrade.";
		case Error::Code::WrongUsernameOrPassword:
			return "Wrong username or password.";
		case Error::Code::UserNotAuthorized:
			return "User is not authorized for the given operation.";
		case Error::Code::RequestedDataNotFound:
			return "The requested data was not found.";
		default:
			return "Unknown error";
	}
}

static
const char*
CustomTypeToString(Error::CustomType type)
{
	switch (type)
	{
		case Error::CustomType::BadId:
			return "Bad id";
		case Error::CustomType::NotImplemented:
			return "Not implemented";
		case Error::CustomType::InternalError:
			return "Internal error";
		default:
			return "Unknown custom error";
	}
}

Error::Error(Code code)
: _code {code},
_message {ErrorCodeToString(code)}
{
}

Error::Error(Error::CustomType type)
: _code {Code::Generic},
_message {CustomTypeToString(type)}
{
}

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

	_value = value;
}

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

void
Response::Node::addChild(const std::string& key, Node node)
{
	if (!_value.empty())
		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.empty())
		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();
}

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

	responseNode.setAttribute("status", "ok");
	responseNode.setAttribute("version", API_VERSION);

	return response;
}

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

	responseNode.setAttribute("status", "failed");
	responseNode.setAttribute("version", API_VERSION);

	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)
			res.put("<xmlattr>." + itAttribute.first, itAttribute.second);

		if (!node._value.empty())
		{
			res.put_value(node._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;

		for (auto itAttribute : node._attributes)
			res[itAttribute.first] = Json::Value {itAttribute.second};

		if (!node._value.empty())
		{
			res["value"] = Json::Value {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