#pragma once

#include <cstdint>

/**
 * @brief Button gesture detector, ported from OneButton 2.6.1.
 *
 * Only the parts the firmware actually uses are kept (single click and long
 * press start); the state machine, the debounce rule and the default timings
 * are a line-by-line port of `OneButton::_fsm()` from
 * https://github.com/mathertel/OneButton (BSD-3-Clause) so gesture behaviour
 * matches the original Arduino build exactly.
 *
 * The unused OneButton features (double click, multi click, press, long press
 * stop/during, idle) were never attached in the original firmware and are
 * therefore not reproduced here.
 */
class Button {
  public:
    using callback_t = void (*)();

    /**
     * @param gpio       GPIO the button is attached to.
     * @param active_low true when pressing connects the pin to GND
     *                   (the original used `OneButton button(9, true)`).
     */
    Button(int gpio, bool active_low);

    void attachClick(callback_t cb);
    void attachLongPressStart(callback_t cb);

    /** Milliseconds before a click is considered stable (OneButton setClickMs). */
    void setClickMs(uint32_t ms);

    /** Milliseconds before the press counts as a long press (setPressMs). */
    void setPressMs(uint32_t ms);

    /** Poll the pin and advance the state machine. Call periodically (10 ms). */
    void tick();

  private:
    enum state_t {
        OCS_INIT = 0,
        OCS_DOWN = 1,
        OCS_UP = 2,
        OCS_COUNT = 3,
        OCS_PRESS = 6,
        OCS_PRESSEND = 7,
    };

    bool debounce(bool value);
    void fsm(bool active_level);
    void reset();

    int _pin;
    bool _active_low;

    state_t _state = OCS_INIT;
    int _nClicks = 0;

    // Debounce state (OneButton: _debounce_ms defaults to 50 ms).
    int _debounce_ms = 50;
    bool debouncedLevel = false;
    bool _lastDebounceLevel = false;
    unsigned long _lastDebounceTime = 0;
    unsigned long now = 0;

    unsigned long _startTime = 0;

    // `setClickMs(50)` / `setPressMs(500)` are applied by the application;
    // these are the OneButton defaults.
    unsigned int _click_ms = 400;
    unsigned int _press_ms = 800;
    int _maxClicks = 1;

    callback_t _clickFunc = nullptr;
    callback_t _longPressStartFunc = nullptr;
};