#include <stdbool.h>
#include <string.h>

#include <app_event_manager.h>

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

#include <zephyr/kernel.h>
#include <zephyr/logging/log.h>

#include "usb_cdc_tx_event.h"
#include "usb_device_state_event.h"

LOG_MODULE_REGISTER(MODULE, LOG_LEVEL_INF);

#define USB_CDC_TEST_PERIOD K_SECONDS(1)

static const uint8_t hello_message[] = "hello\r\n";

static struct k_work_delayable hello_work;
static bool initialized;
static bool running;
static bool usb_active;

static void submit_hello_message(void)
{
	struct usb_cdc_tx_event *event =
		new_usb_cdc_tx_event(sizeof(hello_message) - 1U);

	memcpy(event->dyndata.data, hello_message, sizeof(hello_message) - 1U);
	APP_EVENT_SUBMIT(event);
}

static void hello_work_handler(struct k_work *work)
{
	ARG_UNUSED(work);

	if (!running || !usb_active) {
		return;
	}

	submit_hello_message();
	k_work_reschedule(&hello_work, USB_CDC_TEST_PERIOD);
}

static int module_init(void)
{
	k_work_init_delayable(&hello_work, hello_work_handler);
	return 0;
}

static int module_start(void)
{
	if (running) {
		return 0;
	}

	running = true;
	if (usb_active) {
		k_work_reschedule(&hello_work, USB_CDC_TEST_PERIOD);
	}

	return 0;
}

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

	k_work_cancel_delayable(&hello_work);
	running = false;
}

static bool handle_usb_device_state_event(const struct usb_device_state_event *event)
{
	bool new_usb_active = (event->state == USB_DEVICE_STATE_ACTIVE);

	if (new_usb_active == usb_active) {
		return false;
	}

	usb_active = new_usb_active;

	if (!running) {
		return false;
	}

	if (usb_active) {
		k_work_reschedule(&hello_work, USB_CDC_TEST_PERIOD);
	} else {
		k_work_cancel_delayable(&hello_work);
	}

	return false;
}

static bool app_event_handler(const struct app_event_header *aeh)
{
	if (is_usb_device_state_event(aeh)) {
		return handle_usb_device_state_event(cast_usb_device_state_event(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;
	}

	return false;
}

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