#include "driver/gpio.h"
#include "esp_log.h"
#include "esp_sleep.h"

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

#include "back_button.h"

static const char *TAG = "back_button";

#if CONFIG_FRAME_BACK_BUTTON_GPIO >= 0

#define BACK_BUTTON_GPIO ((gpio_num_t)CONFIG_FRAME_BACK_BUTTON_GPIO)
#define BACK_BUTTON_DEBOUNCE_MS 20
#define BACK_BUTTON_DEBOUNCE_CHECKS 3

void back_button_init(void)
{
    /* See next_button.c's next_button_init() for why this has to run
     * before gpio_config() -- a deep sleep with this pin armed as a
     * wakeup source leaves it "held," and nothing un-holds it on wake
     * except explicitly asking. */
    gpio_hold_dis(BACK_BUTTON_GPIO);

    gpio_config_t io_conf = {
        .pin_bit_mask = 1ULL << BACK_BUTTON_GPIO,
        .mode = GPIO_MODE_INPUT,
        .pull_up_en = GPIO_PULLUP_ENABLE,
    };
    gpio_config(&io_conf);

    /* See next_button.c for why this API (not ext1) -- it manages the
     * pull resistor across the sleep transition itself, so the pin
     * doesn't float and wake the device spuriously. */
    esp_sleep_enable_gpio_wakeup_on_hp_periph_powerdown(1ULL << BACK_BUTTON_GPIO, ESP_GPIO_WAKEUP_GPIO_LOW);
}

bool back_button_check(void)
{
    /* A quick tap can easily release before this runs (~0.4-0.5s into
     * boot, confirmed on hardware -- a live gpio_get_level() check here
     * missed real presses that had already woken the device). The wakeup
     * status register is latched at the moment of waking and isn't
     * cleared until the next sleep entry, so it reliably reflects a tap
     * regardless of how quickly it was released. */
    if (esp_sleep_get_gpio_wakeup_status() & (1ULL << BACK_BUTTON_GPIO)) {
        ESP_LOGI(TAG, "Back-photo button caused this wake, going back");
        return true;
    }

    /* Not a GPIO-wakeup-from-this-pin boot (normal timer wake, or a fresh
     * power-on/reflash) -- fall back to a live, debounced level check so
     * holding the button down while powering on also works. */
    if (gpio_get_level(BACK_BUTTON_GPIO) != 0) {
        return false;
    }

    for (int i = 0; i < BACK_BUTTON_DEBOUNCE_CHECKS; i++) {
        vTaskDelay(pdMS_TO_TICKS(BACK_BUTTON_DEBOUNCE_MS));
        if (gpio_get_level(BACK_BUTTON_GPIO) != 0) {
            return false; /* noise, not a real press */
        }
    }

    ESP_LOGI(TAG, "Back-photo button held during power-on, going back");
    return true;
}

#else

void back_button_init(void) {}
bool back_button_check(void) { return false; }

#endif
