/*
 * Copyright © 2014 Red Hat, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software
 * and its documentation for any purpose is hereby granted without
 * fee, provided that the above copyright notice appear in all copies
 * and that both that copyright notice and this permission notice
 * appear in supporting documentation, and that the name of Red Hat
 * not be used in advertising or publicity pertaining to distribution
 * of the software without specific, written prior permission.  Red
 * Hat makes no representations about the suitability of this software
 * for any purpose.  It is provided "as is" without express or implied
 * warranty.
 *
 * THE AUTHORS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
 * NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
 * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <libevdev/libevdev.h>
#include <sys/signalfd.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <poll.h>
#include <signal.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#define min(a, b) (((a) < (b)) ? (a) : (b))
#define max(a, b) (((a) > (b)) ? (a) : (b))

struct measurements {
	int distance;
	double max_frequency;
	double *frequencies;
	size_t frequencies_sz;
	size_t nfrequencies;
	uint64_t us;
};

static int
usage(void) {
	printf("Usage: %s /dev/input/event0\n", program_invocation_short_name);
	printf("\n");
	printf("This tool reads relative events from the kernel and calculates\n"
	       "the distance covered and maximum frequency of the incoming events.\n"
	       "Some mouse devices provide dynamic frequencies, it is\n"
	       "recommended to measure multiple times to obtain the highest value.\n");
	return 1;
}

static inline double
get_frequency(uint64_t last, uint64_t current)
{
	return 1000000.0/(current - last);
}

static inline void
push_frequency(struct measurements *m, double freq)
{
	if (m->nfrequencies == m->frequencies_sz) {
		m->frequencies_sz += 100;
		m->frequencies = realloc(m->frequencies,
					 m->frequencies_sz * sizeof *m->frequencies);
		if (!m->frequencies)
			abort();
	}

	m->frequencies[m->nfrequencies] = freq;
	m->nfrequencies++;
}

static int
print_current_values(const struct measurements *m)
{
	static int progress = 0;
	char status = 0;

	switch (progress) {
		case 0: status = '|'; break;
		case 1: status = '/'; break;
		case 2: status = '-'; break;
		case 3: status = '\\'; break;
		default:
			status = '?';
			break;
	}

	progress = (progress + 1) % 4;

	printf("\rCovered distance in device units: %8d at frequency %3.1fHz 	%c",
	       abs(m->distance), m->max_frequency, status);

	return 0;
}

static int
handle_event(struct measurements *m, const struct input_event *ev)
{
	if (ev->type == EV_SYN) {
		const int idle_reset = 3000000; /* us */
		uint64_t last_us = m->us;

		m->us = ev->input_event_sec * 1000000 + ev->input_event_usec;

		/* reset after pause */
		if (last_us + idle_reset < m->us) {
			m->max_frequency = 0.0;
			m->distance = 0;
		} else {
			double freq = get_frequency(last_us, m->us);
			push_frequency(m, freq);
			m->max_frequency = max(freq, m->max_frequency);
			return print_current_values(m);
		}

		return 0;
	} else if (ev->type != EV_REL)
		return 0;

	switch(ev->code) {
		case REL_X:
			m->distance += ev->value;
			break;
	}

	return 0;
}

static int
mainloop(struct libevdev *dev, struct measurements *m) {
	struct pollfd fds[2];
	sigset_t mask;

	fds[0].fd = libevdev_get_fd(dev);
	fds[0].events = POLLIN;

	sigemptyset(&mask);
	sigaddset(&mask, SIGINT);
	fds[1].fd = signalfd(-1, &mask, SFD_NONBLOCK);
	fds[1].events = POLLIN;

	sigprocmask(SIG_BLOCK, &mask, NULL);

	while (poll(fds, 2, -1)) {
		struct input_event ev;
		int rc;

		if (fds[1].revents)
			break;

		do {
			rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
			if (rc == LIBEVDEV_READ_STATUS_SYNC) {
				fprintf(stderr, "Error: cannot keep up\n");
				return 1;
			} else if (rc != -EAGAIN && rc < 0) {
				fprintf(stderr, "Error: %s\n", strerror(-rc));
				return 1;
			} else if (rc == LIBEVDEV_READ_STATUS_SUCCESS) {
				handle_event(m, &ev);
			}
		} while (rc != -EAGAIN);
	}

	return 0;
}

static inline double
mean_frequency(struct measurements *m)
{
	int idx;

	idx = m->nfrequencies/2;
	return m->frequencies[idx];
}

static inline const char*
bustype(int bustype)
{
	const char *bus;

	switch(bustype) {
		case BUS_PCI: bus = "pci"; break;
		case BUS_ISAPNP: bus = "isapnp"; break;
		case BUS_USB: bus = "usb"; break;
		case BUS_HIL: bus = "hil"; break;
		case BUS_BLUETOOTH: bus = "bluetooth"; break;
		case BUS_VIRTUAL: bus = "virtual"; break;
		default: bus = "unknown bus type"; break;
	}

	return bus;
}

static void
print_summary(struct libevdev *dev, struct measurements *m)
{
	int res;
	int max_freq, mean_freq;

	if (m->nfrequencies == 0) {
		fprintf(stderr, "Error: no matching events received.\n");
		return;
	}

	max_freq = (int)m->max_frequency;
	mean_freq = (int)mean_frequency(m);

	printf("Estimated sampling frequency: %dHz (mean %dHz)\n",
	       max_freq, mean_freq);

	if (max_freq > mean_freq * 1.3)
		printf("WARNING: Max frequency is more than 30%% higher "
		       "than mean frequency. Manual verification required!\n");

	printf("To calculate resolution, measure physical distance covered\n"
	       "and look up the matching resolution in the table below\n");

	m->distance = abs(m->distance);

	/* If the mouse has more than 2500dpi, the manufacturer usually
	   shows off on their website anyway */
	for (res = 400; res <= 2500; res += 200) {
		double inch = m->distance/(double)res;
		printf("%8dmm	%8.2fin	%8ddpi\n",
		       (int)(inch * 25.4), inch, res);
	}
	printf("If your resolution is not in the list, calculate it with:\n"
	       "\tresolution=%d/inches, or\n"
	       "\tresolution=%d * 25.4/mm\n", m->distance, m->distance);

	printf("\n");
	printf("Entry for hwdb match (replace XXX with the resolution in DPI):\n"
	       "mouse:%s:v%04xp%04x:name:%s:\n"
	       " MOUSE_DPI=XXX@%d\n",
	       bustype(libevdev_get_id_bustype(dev)),
	       libevdev_get_id_vendor(dev),
	       libevdev_get_id_product(dev),
	       libevdev_get_name(dev),
	       (int)m->max_frequency);
}

int
main (int argc, char **argv) {
	int rc;
	int fd;
	const char *path;
	struct libevdev *dev;
	struct measurements measurements = {0};

	if (argc < 2)
		return usage();

	path = argv[1];
	if (path[0] == '-')
		return usage();

	fd = open(path, O_RDONLY|O_NONBLOCK);
	if (fd < 0) {
		fprintf(stderr, "Error opening the device: %s\n", strerror(errno));
		return 1;
	}

	rc = libevdev_new_from_fd(fd, &dev);
	if (rc != 0) {
		fprintf(stderr, "Error fetching the device info: %s\n", strerror(-rc));
		return 1;
	}

	if (libevdev_grab(dev, LIBEVDEV_GRAB) != 0) {
		fprintf(stderr, "Error: cannot grab the device, something else is grabbing it.\n");
		fprintf(stderr, "Use 'fuser -v %s' to find processes with an open fd\n", path);
		return 1;
	}
	libevdev_grab(dev, LIBEVDEV_UNGRAB);

	printf("Mouse %s on %s\n", libevdev_get_name(dev), path);
	printf("Move the device 250mm/10in or more along the x-axis.\n");
	printf("Pause 3 seconds before movement to reset, Ctrl+C to exit.\n");
	setbuf(stdout, NULL);

	rc = mainloop(dev, &measurements);

	printf("\n");

	print_summary(dev, &measurements);

	libevdev_free(dev);
	close(fd);

	return rc;
}