#include <stdbool.h>
#include <stdint.h>

#include <app_event_manager.h>

#define MODULE mode_switch_module
#include <caf/events/module_state_event.h>
#include <caf/events/power_event.h>

#include <zephyr/device.h>
#include <zephyr/devicetree.h>
#include <zephyr/drivers/sensor.h>
#include <zephyr/kernel.h>
#include <zephyr/logging/log.h>
#include <zephyr/pm/device.h>

#include "mode_switch_event.h"

LOG_MODULE_REGISTER(MODULE, LOG_LEVEL_INF);

#define MODE_SWITCH_ADC_NODE DT_NODELABEL(mode_switch_adc)
#define MODE_SWITCH_SAMPLE_INTERVAL K_MSEC(500)
#define MODE_SWITCH_USB_MAX_MV 825
#define MODE_SWITCH_24G_MAX_MV 2475

BUILD_ASSERT(DT_NODE_EXISTS(MODE_SWITCH_ADC_NODE),
	     "Missing mode_switch_adc node in devicetree");

static const struct device *const mode_switch_adc_dev =
	DEVICE_DT_GET(MODE_SWITCH_ADC_NODE);

static struct k_work_delayable mode_switch_sample_work;
static bool initialized;
static bool running;
static bool force_report;
static bool mode_valid;
static enum mode_switch_mode last_mode;

static enum mode_switch_mode detect_mode(uint16_t voltage_mv)
{
	if (voltage_mv < MODE_SWITCH_USB_MAX_MV) {
		return MODE_SWITCH_USB;
	}

	if (voltage_mv < MODE_SWITCH_24G_MAX_MV) {
		return MODE_SWITCH_24G;
	}

	return MODE_SWITCH_BLE;
}

static int mode_switch_enable(bool enable)
{
	enum pm_device_action action = enable ? PM_DEVICE_ACTION_RESUME
					      : PM_DEVICE_ACTION_SUSPEND;
	int err = pm_device_action_run(mode_switch_adc_dev, action);

	if (err && (err != -EALREADY) && (err != -ENOTSUP)) {
		LOG_ERR("Cannot %s mode switch ADC (%d)",
			enable ? "resume" : "suspend", err);
		return err;
	}

	return 0;
}

static void mode_switch_sample_fn(struct k_work *work)
{
	struct sensor_value voltage;
	int err;

	ARG_UNUSED(work);

	if (!running) {
		return;
	}

	err = sensor_sample_fetch(mode_switch_adc_dev);
	if (err) {
		LOG_WRN("Mode switch ADC sample fetch failed (%d)", err);
		goto reschedule;
	}

	err = sensor_channel_get(mode_switch_adc_dev, SENSOR_CHAN_VOLTAGE, &voltage);
	if (err) {
		LOG_WRN("Mode switch ADC channel get failed (%d)", err);
		goto reschedule;
	}

	uint16_t sample_mv = (uint16_t)((voltage.val1 * 1000) + (voltage.val2 / 1000));
	enum mode_switch_mode mode = detect_mode(sample_mv);

	if (force_report || !mode_valid || (mode != last_mode)) {
		submit_mode_switch_event(mode, sample_mv);

		last_mode = mode;
		mode_valid = true;
		force_report = false;
	}

reschedule:
	if (running) {
		k_work_reschedule(&mode_switch_sample_work, MODE_SWITCH_SAMPLE_INTERVAL);
	}
}

static int module_init(void)
{
	if (!device_is_ready(mode_switch_adc_dev)) {
		LOG_ERR("Mode switch ADC device not ready");
		return -ENODEV;
	}

	k_work_init_delayable(&mode_switch_sample_work, mode_switch_sample_fn);
	mode_valid = false;
	force_report = false;

	return 0;
}

static int module_start(void)
{
	int err;

	if (running) {
		return 0;
	}

	err = mode_switch_enable(true);
	if (err) {
		return err;
	}

	running = true;
	force_report = true;
	k_work_reschedule(&mode_switch_sample_work, K_NO_WAIT);

	return 0;
}

static void module_pause(void)
{
	if (!running) {
		return;
	}

	(void)k_work_cancel_delayable(&mode_switch_sample_work);
	(void)mode_switch_enable(false);
	running = false;
}

static bool app_event_handler(const struct app_event_header *aeh)
{
	if (is_module_state_event(aeh)) {
		const struct module_state_event *event = cast_module_state_event(aeh);

		if (check_state(event, MODULE_ID(main), MODULE_STATE_READY)) {
			int err;

			if (!initialized) {
				err = module_init();
				if (err) {
					module_set_state(MODULE_STATE_ERROR);
					return false;
				}

				initialized = true;
			}

			err = module_start();
			if (err) {
				module_set_state(MODULE_STATE_ERROR);
			} else {
				module_set_state(MODULE_STATE_READY);
			}
		}

		return false;
	}

	if (is_power_down_event(aeh)) {
		if (initialized) {
			module_pause();
			module_set_state(MODULE_STATE_STANDBY);
		}

		return false;
	}

	if (is_wake_up_event(aeh)) {
		if (initialized) {
			int err = module_start();

			if (err) {
				module_set_state(MODULE_STATE_ERROR);
			} else {
				module_set_state(MODULE_STATE_READY);
			}
		}

		return false;
	}

	__ASSERT_NO_MSG(false);
	return false;
}

APP_EVENT_LISTENER(MODULE, app_event_handler);
APP_EVENT_SUBSCRIBE(MODULE, module_state_event);
APP_EVENT_SUBSCRIBE_EARLY(MODULE, power_down_event);
APP_EVENT_SUBSCRIBE(MODULE, wake_up_event);