#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 "module_lifecycle.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");

struct mode_switch_module_ctx {
	struct module_lifecycle_ctx lc;
	const struct device *mode_switch_adc_dev;
	struct k_work_delayable mode_switch_sample_work;
	enum mode_switch_mode last_mode;
};

static int do_init(void);
static int do_start(void);
static int do_stop(void);

static const struct module_lifecycle_cfg lifecycle_cfg = {
	.mode = ML_MODE_POWER,
	.stopped_state = MODULE_STATE_STANDBY,
};

static const struct module_lifecycle_ops lifecycle_ops = {
	.do_init = do_init,
	.do_start = do_start,
	.do_stop = do_stop,
};

static struct mode_switch_module_ctx ctx = {
	.lc = {
		.state = LC_UNINIT,
		.cfg = &lifecycle_cfg,
		.ops = &lifecycle_ops,
	},
	.mode_switch_adc_dev = DEVICE_DT_GET(MODE_SWITCH_ADC_NODE),
};

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(ctx.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 (!module_lifecycle_is_running(&ctx.lc)) {
		return;
	}

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

	err = sensor_channel_get(ctx.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 ((ctx.last_mode == MODE_SWITCH_INVALID) || (mode != ctx.last_mode)) {
		submit_mode_switch_event(mode, sample_mv);

		ctx.last_mode = mode;
	}

reschedule:
	if (module_lifecycle_is_running(&ctx.lc)) {
		k_work_reschedule(&ctx.mode_switch_sample_work,
				  MODE_SWITCH_SAMPLE_INTERVAL);
	}
}

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

	k_work_init_delayable(&ctx.mode_switch_sample_work, mode_switch_sample_fn);
	ctx.last_mode = MODE_SWITCH_INVALID;

	return 0;
}

static int do_start(void)
{
	int err;

	if (module_lifecycle_is_running(&ctx.lc)) {
		return 0;
	}

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

	k_work_reschedule(&ctx.mode_switch_sample_work, K_NO_WAIT);

	return 0;
}

static int do_stop(void)
{
	if (!module_lifecycle_is_running(&ctx.lc)) {
		return 0;
	}

	(void)k_work_cancel_delayable(&ctx.mode_switch_sample_work);
	(void)mode_switch_enable(false);

	return 0;
}

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)) {
			(void)module_set_lifecycle(&ctx.lc, LC_RUNNING);
			return false;
		}

		if (check_state(event, MODULE_ID(mode_policy_module),
				MODULE_STATE_READY)) {
			if (ctx.last_mode != MODE_SWITCH_INVALID) {
				submit_mode_switch_event(ctx.last_mode, 0U);
			} 
			return false;
		}

		return false;
	}

	if (is_power_down_event(aeh)) {
		if (module_lifecycle_is_initialized(&ctx.lc)) {
			(void)module_set_lifecycle(&ctx.lc, LC_STOPPED);
		}

		return false;
	}

	if (is_wake_up_event(aeh)) {
		if (module_lifecycle_is_initialized(&ctx.lc)) {
			(void)module_set_lifecycle(&ctx.lc, LC_RUNNING);
		}

		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);