cppscripts/statusweather.cpp

// Print weather information for i3 status bar.
/* i3blocks config:
 * [weather]
 * command=statusweather
 * interval=persist
 * markup=pango
 */
/* ~/.config/statusweather.cfg:
 * api_key = abc123
 * city = Hamburd,de
 */

#include "helpers.hpp"

#include <boost/program_options/options_description.hpp>
#include <boost/program_options/parsers.hpp>
#include <boost/program_options/variables_map.hpp>
#include <fmt/core.h>
#include <nlohmann/json.hpp>
#include <restclient-cpp/connection.h>
#include <restclient-cpp/restclient.h>

#include <atomic>
#include <chrono>
#include <cstdint>
#include <fstream>
#include <functional>
#include <future>
#include <iostream>
#include <map>
#include <mutex>
#include <stdexcept>
#include <string>
#include <string_view>
#include <thread>
#include <tuple>

struct weather
{
    float temperature{-273.15};
    std::string icon{"❗"};
    bool old{true};
} __attribute__((aligned(64))) weather; // NOLINT(cert-err58-cpp)
std::mutex mutex_weather;

std::string map_icon(const std::string_view icon_id)
{
    // <https://openweathermap.org/weather-conditions>
    const std::map<std::uint8_t, std::string> icons{{{1, "🌞"},
                                                     {2, "⛅"},
                                                     {3, "☁"},
                                                     {4, "☁"},
                                                     {9, "🌧"},
                                                     {10, "🌧"},
                                                     {10, "⛈"},
                                                     {13, "🌨"},
                                                     {50, "🌫"}}};
    // TODO: Differenciate between day and night.
    auto icon{icons.find(std::stoul(icon_id.data()))};
    if (icon != icons.end())
    {
        return icon->second;
    }
    return {};
}

std::tuple<std::string, std::string> get_options()
{
    namespace po = boost::program_options;

    po::options_description options("Options");
    // clang-format off
    options.add_options()
        ("api_key", po::value<std::string>()->required()->value_name("API key"),
         "API key for openweathermap.org.")
        ("city", po::value<std::string>()->required()->value_name("City"),
         "City you want the weather data for.")
        ;
    // clang-format on

    po::variables_map vm;
    const auto path{[]()
                    {
                        auto path{helpers::get_env("XDG_CONFIG_HOME")};
                        if (path.empty())
                        {
                            path = helpers::get_env("HOME");
                            if (!path.empty())
                            {
                                path += "/.config";
                            }
                        }
                        return path += "/statusweather.cfg";
                    }()};
    std::ifstream configfile(path);
    po::store(po::parse_config_file(configfile, options, true), vm);
    configfile.close();
    if ((vm.count("api_key") == 0) || (vm.count("city") == 0))
    {
        throw std::runtime_error{"api_key or city not configured."};
    }

    return std::make_tuple(vm["api_key"].as<std::string>(),
                           vm["city"].as<std::string>());
}

bool fetch_weather()
{
    using fmt::format;

    std::string api_key;
    std::string city;
    try
    {
        std::tie(api_key, city) = get_options();
    }
    catch (std::runtime_error &e)
    {
        std::cout << R"(<span color="red">)" << e.what() << "</span>"
                  << std::endl;
        return false;
    }

    RestClient::init();
    RestClient::Connection conn(
        "http://api.openweathermap.org/data/2.5/weather");
    conn.FollowRedirects(true, 5);
    conn.SetTimeout(10);
    // <https://openweathermap.org/current>
    auto response{
        conn.get(format("?appid={0:s}&q={1:s}&units=metric", api_key, city))};
    RestClient::disable();

    if (response.code == 200)
    {
        std::lock_guard<std::mutex> guard(mutex_weather);
        const auto json{nlohmann::json::parse(response.body)};
        weather.temperature = json[0]["main"]["temp"].get<float>();
        weather.icon = map_icon(
            json[0]["weather"][0]["icon"].get<std::string_view>());
        weather.old = false;
    }
    else
    {
        weather.old = true;
    }

    return true;
}

void print_weather()
{
    using fmt::format;

    std::lock_guard<std::mutex> guard(mutex_weather);
    const std::string color{[]
                            {
                                if (weather.temperature > 25.0)
                                {
                                    return "#ff2200";
                                }
                                if (weather.temperature < 0.0)
                                {
                                    return "#aaffff";
                                }
                                if (weather.temperature < 10.0)
                                {
                                    return "#44ddff";
                                }
                                return "#66ff66";
                            }()};

    std::cout << format(R"({0:s} <span color="{1:s}">{2:.1f}°C</span>{3:s})",
                        weather.icon, color, weather.temperature,
                        weather.old ? R"( <span color="red">⏳</span>)" : "")
              << std::endl;
}

void update(std::atomic<bool> &cancelled)
{
    using clock = std::chrono::system_clock;
    using namespace std::chrono_literals;

    while (!cancelled)
    {
        if (fetch_weather())
        {
            print_weather();
        }
        std::this_thread::sleep_until(clock::now() + 30min);
    }
}

int main()
{
    // TODO: Implement clean shutdown.
    std::atomic<bool> cancelled{false};
    auto future{std::async(std::launch::async, update, std::ref(cancelled))};

    std::string line;
    while (std::getline(std::cin, line)) // Button click is sent to stdin.
    {
        if (line == "1") // Left mouse button.
        {
            if (fetch_weather())
            {
                print_weather();
            }
        }
    }
}