/*
 * Linux mouse driver for Twin
 *
 * Copyright 2006 Benjamin Herrenschmidt <benh@kernel.crashing.org>
 *
 * This Library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This Library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with the Twin Library; see the file COPYING.  If not,
 * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <math.h>

#include "twin_linux_mouse.h"

#define QUADRATIC_ACCELERATION		1
#define DEFAULT_ACC_NUMERATOR   	2
#define DEFAULT_ACC_DENOMINATOR 	1
#define DEFAULT_ACC_THRESHOLD   	4

static void twin_linux_mouse_check_bounds(twin_linux_mouse_t *tm)
{
	if (tm->x < 0)
		tm->x = 0;
	if (tm->x > tm->screen->width)
		tm->x = tm->screen->width;
	if (tm->y < 0)
		tm->y = 0;
	if (tm->y > tm->screen->height)
		tm->y = tm->screen->height;
}

/* This is directly copied from kdrive */
static void twin_linux_mouse_accel(twin_linux_mouse_t *tm, int *dx, int *dy)
{
	double  speed = sqrt (*dx * *dx + *dy * *dy);
	double  accel;
#ifdef QUADRATIC_ACCELERATION
	double  m;

	/*
	 * Ok, so we want it moving num/den times faster at threshold*2
	 *
	 * accel = m *threshold + b
	 * 1 = m * 0 + b	-> b = 1
	 *
	 * num/den = m * (threshold * 2) + 1
	 *
	 * num / den - 1 = m * threshold * 2
	 * (num / den - 1) / threshold * 2 = m
	 */
	m = (((double) tm->acc_num / (double) tm->acc_den - 1.0) / 
	     ((double) tm->acc_threshold * 2.0));
	accel = m * speed + 1;
#else
	accel = 1.0;
	if (speed > tm->acc_threshold)
		accel = (double) tm->acc_num / tm->acc_den;
#endif
	*dx = accel * *dx;
	*dy = accel * *dy;
}

static twin_bool_t twin_linux_mouse_events(int file, twin_file_op_t ops,
					   void *closure)
{
	twin_linux_mouse_t *tm = closure;
	char evts[34];
	char *ep;
	int n = tm->res_cnt;
	twin_event_t tev;

	if (n)
		memcpy(evts, tm->residual, n);
	n += read(file, evts + n, 32);

	for(ep = evts; n >= 3; n -= 3, ep += 3) {
		int dx, dy, btn;
		dx = ep[1];
		if (ep[0] & 0x10)
			dx -= 256;
		dy = ep[2];
		if (ep[0] & 0x20)
			dy -= 256;
		dy = -dy;
		/* we handle only one btn for now */
		btn = ep[0] & 0x1;
		if (dx || dy) {
			twin_linux_mouse_accel(tm, &dx, &dy);
			tm->x += dx;
			tm->y += dy;
			twin_linux_mouse_check_bounds(tm);
			tev.kind = TwinEventMotion;
			tev.u.pointer.screen_x = tm->x;
			tev.u.pointer.screen_y = tm->y;
			tev.u.pointer.button = tm->btns;
			twin_screen_dispatch (tm->screen, &tev);
		}
		if (btn != tm->btns) {
			tm->btns = btn;
			tev.kind = (btn & 0x1) ?
				TwinEventButtonDown : TwinEventButtonUp;
			tev.u.pointer.screen_x = tm->x;
			tev.u.pointer.screen_y = tm->y;
			tev.u.pointer.button = tm->btns;
			twin_screen_dispatch(tm->screen, &tev);
		}
	}
	tm->res_cnt = n;
	if (n)
		memcpy(tm->residual, ep, n);

	return 1;
}

twin_linux_mouse_t *twin_linux_mouse_create(const char *file,
					    twin_screen_t *screen)
{
	twin_linux_mouse_t *tm;

	tm = calloc(1, sizeof(twin_linux_mouse_t));
	if (tm == NULL)
		return NULL;

	if (file == NULL)
		file = "/dev/input/mice";

	tm->screen = screen;
	tm->acc_num = DEFAULT_ACC_NUMERATOR;
	tm->acc_den = DEFAULT_ACC_DENOMINATOR;
	tm->acc_threshold =DEFAULT_ACC_THRESHOLD;
	tm->x = screen->width / 2; 
	tm->y = screen->height / 2; 
	tm->fd = open(file, O_RDONLY);
	if (tm->fd < 0) {
		free(tm);
		return NULL;
	}

	twin_set_file(twin_linux_mouse_events, tm->fd, TWIN_READ, tm);

	return tm;
}

void twin_linux_mouse_destroy(twin_linux_mouse_t *tm)
{
	close(tm->fd);
	free(tm);
}

void twin_linux_mouse_screen_changed(twin_linux_mouse_t *tm)
{
	int oldx, oldy;

	oldx = tm->x;
	oldy = tm->y;
	twin_linux_mouse_check_bounds(tm);
	if (tm->x != oldx || tm->y != oldy) {
		twin_event_t tev;

		tev.kind = TwinEventMotion;
		tev.u.pointer.screen_x = tm->x;
		tev.u.pointer.screen_y = tm->y;
		tev.u.pointer.button = tm->btns;
		twin_screen_dispatch (tm->screen, &tev);
	}
}

void twin_linux_mouse_set_accel(twin_linux_mouse_t *tm,
				int num, int den, int threshold)
{
	tm->acc_num = num;
	tm->acc_den = den;
	tm->acc_threshold = threshold;
}