#include "usb_device_detection.h"

#include <stdio.h>
#include <stdlib.h>

int hotplug_callback(struct libusb_context*,
                     struct libusb_device*,
                     libusb_hotplug_event event,
                     void*                user_data)
{
	struct usb_detector* detector = user_data;

	if (event == LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED) {
		detector->is_connected = true;
		if (detector->has_hotplug_callbacks) detector->on_connected();
	} else if (event == LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT) {
		detector->is_connected = false;
		if (detector->has_hotplug_callbacks) detector->on_disconnected();
	} else
		printf("Unexpected USB device event %d\n", event);

	return 0;
}

static int libusb_event_handler(void* data)
{
	struct usb_detector* detector = data;

	while (!detector->event_handler_should_exit) {
		thrd_sleep(&(struct timespec){.tv_sec = 1}, NULL);
		libusb_handle_events_completed(detector->usb_context, NULL);
	}

	return 0;
}

struct usb_detector* create_detector(uint16_t vendor_id, uint16_t product_id)
{

	struct libusb_context* usb_context;
	libusb_init(&usb_context);

	if (!usb_context) {
		fprintf(stderr,
		        "Couldn't get USB contexxt. Device detection will not work\n");
		return 0;
	}

	struct usb_detector* detector = calloc(1, sizeof(struct usb_detector));
	detector->usb_context         = usb_context;
	detector->is_connected        = false;
	detector->event_handler_should_exit = false;

	detector->has_hotplug_callbacks = false;

	if (libusb_hotplug_register_callback(detector->usb_context,
	                                     LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED |
	                                         LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT,
	                                     LIBUSB_HOTPLUG_ENUMERATE,
	                                     vendor_id,
	                                     product_id,
	                                     LIBUSB_HOTPLUG_MATCH_ANY,
	                                     hotplug_callback,
	                                     detector,
	                                     &detector->hotplug_handle) !=
	    LIBUSB_SUCCESS) {

		fprintf(stderr,
		        "Couldn't register usb hotplug listener. Device detection "
		        "will not work.\n");
		free(detector);
		return 0;
	}

	if (thrd_create(&detector->event_handler_thread,
	                &libusb_event_handler,
	                detector) != thrd_success) {
		fprintf(stderr,
		        "Couldn't start event handler. Device detection will not "
		        "work.\n");
		free(detector);
		return 0;
	}

	return detector;
}

void destroy_detector(struct usb_detector* detector)
{
	libusb_hotplug_deregister_callback(detector->usb_context,
	                                   detector->hotplug_handle);

	detector->event_handler_should_exit = true;
	if (thrd_join(detector->event_handler_thread, 0) != thrd_success)
		fprintf(stderr,
		        "Couldn't join with usb event handler thread, something went "
		        "really wrong, we likely won't exit cleanly\n");

	libusb_exit(detector->usb_context);

	free(detector);
}