trmnl_server_cpp/main.cpp

#include <iostream>
#include <list>
#include <map>
#include <memory>
#include <random>
#include <string>
#include <vector>

#include <stdint.h>

#include "httplib.h"
#include "json.hpp"

#include "helpers.h"

using nlohmann::json;

using namespace std;

struct device
{
	string id;
	string api_key;
	string friendly_id;
	int refresh_rate;

	// Default constructor
	device()
	: id(""),
	api_key(""),
	friendly_id(""),
	refresh_rate(600)
	{}
};

void to_json(json& j, const device& d)
{
	j = json{
		{"ID", d.id},
		{"api_key", d.api_key},
		{"friendly_id", d.friendly_id},
		{"refresh_rate", d.refresh_rate}
	};
}

bool json_extract(const json& j, const string& key, device& out)
{
	bool result = false;

	if (!key.empty())
	{
		if (j.contains(key) && j[key].is_object())
		{
			result |= json_extract(j[key], "ID", out.id);
			result |= json_extract(j[key], "api_key", out.api_key);
			result |= json_extract(j[key], "friendly_id", out.friendly_id);
			result |= json_extract(j[key], "refresh_rate", out.refresh_rate);
		}
	}
	else
	{
		result |= json_extract(j, "ID", out.id);
		result |= json_extract(j, "api_key", out.api_key);
		result |= json_extract(j, "friendly_id", out.friendly_id);
		result |= json_extract(j, "refresh_rate", out.refresh_rate);
	}

	return result;
}

string device_id_to_friendly(string id)
{
	size_t pos = id.find(':');
	while (pos != string::npos)
	{
		id.erase(pos, 1);
		pos = id.find(':');
	}

	if (id.size() <= 6)
	{
		return id;
	}
	else
	{
		return id.substr(id.size() - 6);
	}
}

class DeviceContainer
{
private:
	list<device> m_devices;
	map<string, list<device>::iterator> m_by_id;
	map<string, list<device>::iterator> m_by_friendly;

public:
	DeviceContainer() = default;

	void add_device(const device& d)
	{
		if (d.id.empty())
		{
			return;
		}

		auto it = m_devices.insert(m_devices.end(), d);
		m_by_id.insert(make_pair(it->id, it));

		if (!it->friendly_id.empty())
		{
			m_by_friendly.insert(make_pair(it->friendly_id, it));
		}
	}

	const device* get_device_by_id(const string& id)
	{
		if (0 == m_by_id.count(id))
		{
			return nullptr;
		}
		else
		{
			return &(*(*(m_by_id.find(id))).second);
		}
	}

	const device* get_device_by_friendly(const string& friendly)
	{
		if (0 == m_by_friendly.count(friendly))
		{
			return nullptr;
		}
		else
		{
			return &(*(*(m_by_friendly.find(friendly))).second);
		}
	}

	void set_device_friendly(const string& id, const string& friendly)
	{
		if (0 == m_by_id.count(id))
		{
			return;
		}

		auto it = m_by_id[id];
		it->friendly_id = friendly;
		m_by_friendly.insert(make_pair(it->friendly_id, it));
	}
};

int main(int argc, char **argv)
{
	string config_filename = "config.json";
	string devices_filename = "devices.json";
	string host = "";
	string cert_file = "";
	string key_file = "";
	uint16_t port = 0;
	shared_ptr<httplib::Server> server = nullptr;

	bool ok;
	json cfg;
	json devs;
	vector<device> devices;
	DeviceContainer container;

	if (argc > 2)
	{
		config_filename = argv[1];
	}

	ok = read_file_json(cfg, config_filename, &cout);
	if (!ok)
	{
		return -1;
	}

	json_extract(cfg, "devices_filename", devices_filename);
	json_extract(cfg, "host", host);
	json_extract(cfg, "port", port);
	// json_extract(cfg, "cert_file", cert_file);
	// json_extract(cfg, "key_file", cert_file);

	if (host.empty())
	{
		cout << "host not provided" << endl;
		return -1;
	}

	if (0 == port)
	{
		cout << "port number not provided" << endl;
		return -1;
	}

	if (!cert_file.empty() && !key_file.empty())
	{
		// TODO: Implement SSL Server Properly
	}
	else
	{
		server = make_shared<httplib::Server>();
	}

	ok = read_file_json(devs, devices_filename, &cout);
	if (!ok)
	{
		return -1;
	}

	if (devs.is_array())
	{
		for (int i = 0; i < devs.size(); ++i)
		{
			device d;
			json_extract(devs[i], "", d);
			devices.push_back(d);
		}
	}

	for (auto device : devices)
	{
		container.add_device(device);
	}


	auto setup_handler = [&container](const httplib::Request& req, httplib::Response& res)
	{
		if (req.has_header("ID"))
		{
			json response;
			string id = req.get_header_value("ID");
			const device* dev = container.get_device_by_id(id);
			if (nullptr == dev)
			{
				res.status = 404;

				response["status"] = 404;
				response["api_key"] = nullptr;
				response["friendly_id"] = nullptr;
				response["image_url"] = nullptr;
				response["filename"] = nullptr;

				res.body = response.dump();
			}
			else
			{
				res.status = 200;
				if (dev->friendly_id.empty())
				{
					container.set_device_friendly(id, device_id_to_friendly(id));
				}

				device* dev_mut = const_cast<device*>(dev);

				response["status"] = 200;
				response["api_key"] = "nullptr";
				response["friendly_id"] = dev->friendly_id;
				response["image_url"] = "https://trmnl.com/images/setup/setup-logo.bmp";
				response["filename"] = "welcome";

				res.body = response.dump();

				json test = *dev_mut;
				cout << test.dump(4) << endl;
			}
		}
		else
		{
			res.status = 500;
		}
	};

	auto log_handler = [](const httplib::Request& req, httplib::Response& res)
	{
		try
		{
			json j = json::parse(req.body);
			cout << j.dump(4) << endl;
		}
		catch (const exception& e)
		{
			cout << req.body << endl;
		}
		res.status = 200;
	};

	server->Get("/api/setup/", setup_handler);
	server->Get("/api/setup", setup_handler);

	server->Post("/api/log/", log_handler);
	server->Post("/api/log", log_handler);

	server->listen(host, port);

	return 0;
}