// gKeyMapper daemon - watches the mappings file for changes (inotify).
#ifndef GKEYMAPPER_DAEMON_CONFIG_WATCH_H
#define GKEYMAPPER_DAEMON_CONFIG_WATCH_H

#include <string>

namespace gkeymapper::daemon {

// Watches mappings.conf so a save in the GUI is picked up without a signal.
//
// The *directory* is watched, not the file: that also catches an atomic save
// (write a temporary file, rename it over the config) and the config appearing
// after it was deleted.
//
// poll_events() collects whatever happened since the last call and take_change()
// reports it once. Because the daemon evaluates this once per loop iteration
// (at least every read timeout, i.e. 500 ms), all events a single save produces
// collapse into one reload, and the file is complete by the time it is read
// (that is what the atomic save in shared/mapping.cpp guarantees).
//
// The daemon still accepts SIGHUP/SIGUSR1 as a fallback when inotify is
// unavailable.
class ConfigWatcher {
public:
    ConfigWatcher() = default;
    ~ConfigWatcher();

    ConfigWatcher(const ConfigWatcher&) = delete;
    ConfigWatcher& operator=(const ConfigWatcher&) = delete;

    // Watches the directory holding `path` (creating it if it does not exist
    // yet). Returns false if inotify cannot be set up; the daemon then relies
    // on signals only.
    bool init(const std::string& path);

    bool is_watching() const { return fd_ >= 0; }

    // Consumes queued inotify events. Non-blocking and cheap; call it once per
    // event-loop iteration.
    void poll_events();

    // True if the mappings file changed since the last call; clears the mark so
    // every change is reported exactly once.
    bool take_change();

private:
    int fd_ = -1;
    std::string directory_;
    std::string name_;
    bool pending_ = false;
};

} // namespace gkeymapper::daemon

#endif // GKEYMAPPER_DAEMON_CONFIG_WATCH_H