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

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>

#include <linux/ioctl.h>
#include <linux/hiddev.h>

static int devfd;

static char *get_device_name()
{
	static char buf[1024];

	if (ioctl(devfd, HIDIOCGNAME(sizeof(buf)), buf) >= 0) {
		return buf;
	}

	return NULL;
}

static void process_event(struct hiddev_usage_ref *ev)
{
	printf("0x%x (0x%x): %d\n", ev->usage_code, ev->report_id, ev->value);
}

static bool send_report(unsigned int report_type, unsigned int report_id)
{
	struct hiddev_report_info rinfo;
	rinfo.report_type = report_type;
	rinfo.report_id = report_id;
	rinfo.num_fields = 0;

	if (ioctl(devfd, HIDIOCSREPORT, &rinfo) < 0) {
		perror("HIDIOCSREPORT");
		return false;
	}

	printf("Report 0x%x sent\n", rinfo.report_id);

	return true;
}

static __s32 read_usage(unsigned int report_type, unsigned int usage_code)
{
	struct hiddev_usage_ref uref;
	uref.report_type = report_type;
	uref.report_id = HID_REPORT_ID_UNKNOWN;
	uref.usage_code = usage_code;

	if (ioctl(devfd, HIDIOCGUSAGE, &uref) < 0) {
		perror("HIDIOCGUSAGE");
		return -1;
	}

	printf("0x%x: %d\n", uref.usage_code, uref.value);

	return uref.value;
}

static void write_usage(unsigned int report_type, unsigned int usage_code, __s32 value)
{
	struct hiddev_usage_ref uref;
	uref.report_type = report_type;
	uref.report_id = HID_REPORT_ID_UNKNOWN;
	uref.usage_code = usage_code;

	if (ioctl(devfd, HIDIOCGUSAGE, &uref) < 0) {
		perror("HIDIOCGUSAGE");
		return;
	}

	uref.value = value;
	if (ioctl(devfd, HIDIOCSUSAGE, &uref) < 0)
	{
		perror("HIDIOCSUSAGE");
		return;
	}

	printf("0x%x := %d\n", uref.usage_code, uref.value);

	send_report(uref.report_type, uref.report_id);
}

int main(int argc, const char *argv[])
{
	if (argc != 3) {
		fprintf(stderr, "Usage: %s <device> <0|1>\n", argv[0]);
		return EXIT_FAILURE;
	}

	const char *device = argv[1];
	const bool enable_ptp = strtol(argv[2], NULL, 10);

	printf("Opening %s...\n", device);
	devfd = open(device, O_RDONLY);

	if (devfd == -1) {
		perror("Could not open device");
		return EXIT_FAILURE;
	}

	printf("Found '%s'\n", get_device_name());

	// Setup flags
	int flags = HIDDEV_FLAG_UREF | HIDDEV_FLAG_REPORT;
	if (ioctl(devfd, HIDIOCSFLAG, &flags) < 0) {
		perror("HIDIOCSFLAG");
		return EXIT_FAILURE;
	}

	write_usage(HID_REPORT_TYPE_FEATURE, 0x0d0052, enable_ptp ? 3 : 0);

	int rc;
	do {
		struct hiddev_usage_ref ev;
		rc = read(devfd, &ev, sizeof(ev));
		if (rc < 0) {
			perror("Could not read events from device");
			return EXIT_FAILURE;
		} else if (rc == 0) {
		}

		process_event(&ev);
	} while (rc > 0);

	return EXIT_SUCCESS;
}