#ifndef ROTARY_ENCODER_DRIVER_H
#define ROTARY_ENCODER_DRIVER_H

#include <stdint.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/kernel.h>

#include "digital_in.h"
#include "timer_usec.h"

class RotaryEncoderDriver {
public:
    static constexpr uint16_t SAMPLE_PERIOD_US = 4000;   // Ts = 4 ms
    static constexpr float COUNTS_PER_REV = 1050.0f;

    RotaryEncoderDriver();

    // Returns 0 on success, or a negative Zephyr error code.
    int begin();

    void update();
    int32_t position();
    void update_delta();
    float count_per_sec();
    float rpm();
    bool new_speed_available();
    void reset_speed_measurement();

    // Blocks until the next speed sample, or until the timeout expires.
    // Lets the main loop run in step with the 4 ms sampling.
    void wait_for_sample(k_timeout_t timeout);

private:
    static const uint8_t HIST_LEN = 4;   // 4 x Ts = 16 ms gluggi fyrir rpm-utreikning

    volatile int32_t count;
    volatile int16_t delta;
    volatile bool speed_ready;

    volatile int32_t history[HIST_LEN];
    volatile uint8_t hist_idx;

    Digital_in eA;
    Digital_in eB;

    struct gpio_callback encoder_c1_callback;
    struct k_sem sample_sem;
    Timer_usec timer;

    static void gpio_edge_handler(
        const struct device *dev,
        struct gpio_callback *callback,
        uint32_t pins);

    static void timer_expired(void *context);
};

#endif