#pragma once

#include <cstdint>
#include <optional>
#include <string>

namespace hidpp {

/// Battery state of a wireless Logitech device.
struct BatteryStatus {
    enum class Level : uint8_t { UNKNOWN,
                                 CRITICAL,
                                 LOW,
                                 GOOD,
                                 FULL };

    bool connected     = false;
    int percentage     = -1; // 0..100, or -1 when the device only reports a level
    Level level        = Level::UNKNOWN;
    bool charging      = false;
    bool externalPower = false;
};

/// Reads the battery level of a Logitech HID++ 2.0 device.
///
/// Prefers the power_supply entry that hid-logitech-hidpp exports, and falls
/// back to speaking HID++ 2.0 over /dev/hidraw* when that driver is not bound
/// (the receiver then sits on hid-generic and exports no battery at all).
///
/// read() blocks on wireless round-trips that can take seconds when the device
/// is asleep, so it must be called off the GTK main thread.
class BatteryReader {
  public:
    explicit BatteryReader(std::string deviceName);
    ~BatteryReader();

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

    BatteryStatus read();

  private:
    /// A resolved HID++ endpoint: which hidraw node, which device slot on it,
    /// and the feature index the battery lives behind.
    struct Endpoint {
        int fd              = -1;
        uint8_t deviceIndex = 0;
        uint8_t featureIdx  = 0;
        uint16_t featureId  = 0; // kFeatureUnifiedBattery or kFeatureBatteryStatus
    };

    std::string deviceName;
    Endpoint endpoint{};

    std::optional<BatteryStatus> readFromSysfs() const;
    std::optional<BatteryStatus> readFromHidpp();

    /// Finds the hidraw node and device slot our device answers on. Expensive:
    /// only called on first use and after the cached endpoint stops replying.
    bool resolveEndpoint();
    void closeEndpoint();
};

} // namespace hidpp