/*
 * 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 the copyright holders not be used in
 * advertising or publicity pertaining to distribution of the software
 * without specific, written prior permission.  The copyright holders make
 * no representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
 * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS 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.
 */

#include "config.h"

#include <assert.h>
#include <math.h>
#include <stdbool.h>
#include <limits.h>

#include "evdev-mt-touchpad.h"

#define DEFAULT_ACCEL_NUMERATOR 1200.0
#define DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR 700.0

static inline int
tp_hysteresis(int in, int center, int margin)
{
	int diff = in - center;
	if (abs(diff) <= margin)
		return center;

	if (diff > margin)
		return center + diff - margin;
	else
		return center + diff + margin;
}

static inline struct tp_motion *
tp_motion_history_offset(struct tp_touch *t, int offset)
{
	int offset_index =
		(t->history.index - offset + TOUCHPAD_HISTORY_LENGTH) %
		TOUCHPAD_HISTORY_LENGTH;

	return &t->history.samples[offset_index];
}

static void
tp_filter_motion(struct tp_dispatch *tp,
	         double *dx, double *dy, uint64_t time)
{
	struct motion_params motion;

	motion.dx = *dx * tp->accel.x_scale_coeff;
	motion.dy = *dy * tp->accel.y_scale_coeff;

	if (motion.dx != 0.0 || motion.dy != 0.0)
		filter_dispatch(tp->filter, &motion, tp, time);

	*dx = motion.dx;
	*dy = motion.dy;
}

static inline void
tp_motion_history_push(struct tp_touch *t)
{
	int motion_index = (t->history.index + 1) % TOUCHPAD_HISTORY_LENGTH;

	if (t->history.count < TOUCHPAD_HISTORY_LENGTH)
		t->history.count++;

	t->history.samples[motion_index].x = t->x;
	t->history.samples[motion_index].y = t->y;
	t->history.index = motion_index;
}

static inline void
tp_motion_hysteresis(struct tp_dispatch *tp,
		     struct tp_touch *t)
{
	int x = t->x,
	    y = t->y;

	if (t->history.count == 0) {
		t->hysteresis.center_x = t->x;
		t->hysteresis.center_y = t->y;
	} else {
		x = tp_hysteresis(x,
				  t->hysteresis.center_x,
				  tp->hysteresis.margin_x);
		y = tp_hysteresis(y,
				  t->hysteresis.center_y,
				  tp->hysteresis.margin_y);
		t->hysteresis.center_x = x;
		t->hysteresis.center_y = y;
		t->x = x;
		t->y = y;
	}
}

static inline void
tp_motion_history_reset(struct tp_touch *t)
{
	t->history.count = 0;
}

static inline struct tp_touch *
tp_current_touch(struct tp_dispatch *tp)
{
	return &tp->touches[min(tp->slot, tp->ntouches - 1)];
}

static inline struct tp_touch *
tp_get_touch(struct tp_dispatch *tp, unsigned int slot)
{
	assert(slot < tp->ntouches);
	return &tp->touches[slot];
}

static inline void
tp_begin_touch(struct tp_dispatch *tp, struct tp_touch *t)
{
	if (t->state != TOUCH_UPDATE) {
		tp_motion_history_reset(t);
		t->dirty = true;
		t->state = TOUCH_BEGIN;
		t->pinned.is_pinned = false;
		tp->nfingers_down++;
		assert(tp->nfingers_down >= 1);
		tp->queued |= TOUCHPAD_EVENT_MOTION;
	}
}

static inline void
tp_end_touch(struct tp_dispatch *tp, struct tp_touch *t)
{
	if (t->state == TOUCH_NONE)
		return;

	t->dirty = true;
	t->is_pointer = false;
	t->palm.is_palm = false;
	t->state = TOUCH_END;
	t->pinned.is_pinned = false;
	assert(tp->nfingers_down >= 1);
	tp->nfingers_down--;
	tp->queued |= TOUCHPAD_EVENT_MOTION;
}

static double
tp_estimate_delta(int x0, int x1, int x2, int x3)
{
	return (x0 + x1 - x2 - x3) / 4;
}

void
tp_get_delta(struct tp_touch *t, double *dx, double *dy)
{
	if (t->history.count < 4) {
		*dx = 0;
		*dy = 0;
		return;
	}

	*dx = tp_estimate_delta(tp_motion_history_offset(t, 0)->x,
				tp_motion_history_offset(t, 1)->x,
				tp_motion_history_offset(t, 2)->x,
				tp_motion_history_offset(t, 3)->x);
	*dy = tp_estimate_delta(tp_motion_history_offset(t, 0)->y,
				tp_motion_history_offset(t, 1)->y,
				tp_motion_history_offset(t, 2)->y,
				tp_motion_history_offset(t, 3)->y);
}

static void
tp_process_absolute(struct tp_dispatch *tp,
		    const struct input_event *e,
		    uint64_t time)
{
	struct tp_touch *t = tp_current_touch(tp);

	switch(e->code) {
	case ABS_MT_POSITION_X:
		t->x = e->value;
		t->millis = time;
		t->dirty = true;
		tp->queued |= TOUCHPAD_EVENT_MOTION;
		break;
	case ABS_MT_POSITION_Y:
		t->y = e->value;
		t->millis = time;
		t->dirty = true;
		tp->queued |= TOUCHPAD_EVENT_MOTION;
		break;
	case ABS_MT_SLOT:
		tp->slot = e->value;
		break;
	case ABS_MT_TRACKING_ID:
		t->millis = time;
		if (e->value != -1)
			tp_begin_touch(tp, t);
		else
			tp_end_touch(tp, t);
	}
}

static void
tp_process_absolute_st(struct tp_dispatch *tp,
		       const struct input_event *e,
		       uint64_t time)
{
	struct tp_touch *t = tp_current_touch(tp);

	switch(e->code) {
	case ABS_X:
		t->x = e->value;
		t->millis = time;
		t->dirty = true;
		tp->queued |= TOUCHPAD_EVENT_MOTION;
		break;
	case ABS_Y:
		t->y = e->value;
		t->millis = time;
		t->dirty = true;
		tp->queued |= TOUCHPAD_EVENT_MOTION;
		break;
	}
}

static void
tp_process_fake_touch(struct tp_dispatch *tp,
		      const struct input_event *e,
		      uint64_t time)
{
	struct tp_touch *t;
	unsigned int fake_touches;
	unsigned int nfake_touches;
	unsigned int i;
	unsigned int shift;

	if (e->code != BTN_TOUCH &&
	    (e->code < BTN_TOOL_DOUBLETAP || e->code > BTN_TOOL_QUADTAP))
		return;

	shift = e->code == BTN_TOUCH ? 0 : (e->code - BTN_TOOL_DOUBLETAP + 1);

	if (e->value)
		tp->fake_touches |= 1 << shift;
	else
		tp->fake_touches &= ~(0x1 << shift);

	fake_touches = tp->fake_touches;
	nfake_touches = 0;
	while (fake_touches) {
		nfake_touches++;
		fake_touches >>= 1;
	}

	for (i = 0; i < tp->ntouches; i++) {
		t = tp_get_touch(tp, i);
		if (i >= nfake_touches) {
			if (t->state != TOUCH_NONE) {
				tp_end_touch(tp, t);
				t->millis = time;
			}
		} else if (t->state != TOUCH_UPDATE &&
			   t->state != TOUCH_BEGIN) {
			t->state = TOUCH_NONE;
			tp_begin_touch(tp, t);
			t->millis = time;
			t->fake =true;
		}
	}

	assert(tp->nfingers_down == nfake_touches);
}

static void
tp_process_key(struct tp_dispatch *tp,
	       const struct input_event *e,
	       uint64_t time)
{
	switch (e->code) {
		case BTN_LEFT:
		case BTN_MIDDLE:
		case BTN_RIGHT:
			tp_process_button(tp, e, time);
			break;
		case BTN_TOUCH:
		case BTN_TOOL_DOUBLETAP:
		case BTN_TOOL_TRIPLETAP:
		case BTN_TOOL_QUADTAP:
			if (!tp->has_mt)
				tp_process_fake_touch(tp, e, time);
			break;
	}
}

static void
tp_unpin_finger(struct tp_dispatch *tp, struct tp_touch *t)
{
	unsigned int xdist, ydist;

	if (!t->pinned.is_pinned)
		return;

	xdist = abs(t->x - t->pinned.center_x);
	ydist = abs(t->y - t->pinned.center_y);

	if (xdist * xdist + ydist * ydist >=
			tp->buttons.motion_dist * tp->buttons.motion_dist) {
		t->pinned.is_pinned = false;
		tp_set_pointer(tp, t);
	}
}

static void
tp_pin_fingers(struct tp_dispatch *tp)
{
	struct tp_touch *t;

	tp_for_each_touch(tp, t) {
		t->is_pointer = false;
		t->pinned.is_pinned = true;
		t->pinned.center_x = t->x;
		t->pinned.center_y = t->y;
	}
}

static int
tp_touch_active(struct tp_dispatch *tp, struct tp_touch *t)
{
	return (t->state == TOUCH_BEGIN || t->state == TOUCH_UPDATE) &&
		!t->palm.is_palm &&
		!t->pinned.is_pinned && tp_button_touch_active(tp, t);
}

void
tp_set_pointer(struct tp_dispatch *tp, struct tp_touch *t)
{
	struct tp_touch *tmp = NULL;

	/* Only set the touch as pointer if we don't have one yet */
	tp_for_each_touch(tp, tmp) {
		if (tmp->is_pointer)
			return;
	}

	if (tp_touch_active(tp, t))
		t->is_pointer = true;
}

static void
tp_palm_detect(struct tp_dispatch *tp, struct tp_touch *t, uint64_t time)
{
	const int PALM_TIMEOUT = 200; /* ms */
	const int DIRECTIONS = NE|E|SE|SW|W|NW;

	/* If labelled a touch as palm, we unlabel as palm when
	   we move out of the palm edge zone within the timeout, provided
	   the direction is within 45 degrees of the horizontal.
	 */
	if (t->palm.is_palm) {
		if (time < t->palm.time + PALM_TIMEOUT &&
		    (t->x > tp->palm.left_edge && t->x < tp->palm.right_edge)) {
			int dirs = vector_get_direction(t->x - t->palm.x, t->y - t->palm.y);
			if ((dirs & DIRECTIONS) && !(dirs & ~DIRECTIONS)) {
				t->palm.is_palm = false;
				tp_set_pointer(tp, t);
			}
		}
		return;
	}

	/* palm must start in exclusion zone, it's ok to move into
	   the zone without being a palm */
	if (t->state != TOUCH_BEGIN ||
	    (t->x > tp->palm.left_edge && t->x < tp->palm.right_edge))
		return;

	/* don't detect palm in software button areas, it's
	   likely that legitimate touches start in the area
	   covered by the exclusion zone */
	if (tp->buttons.is_clickpad &&
	    tp_button_is_inside_softbutton_area(tp, t))
		return;

	t->palm.is_palm = true;
	t->palm.time = time;
	t->palm.x = t->x;
	t->palm.y = t->y;
}

static void
tp_process_state(struct tp_dispatch *tp, uint64_t time)
{
	struct tp_touch *t;
	struct tp_touch *first = tp_get_touch(tp, 0);

	tp_for_each_touch(tp, t) {
		if (!tp->has_mt && t != first && first->fake) {
			t->x = first->x;
			t->y = first->y;
			if (!t->dirty)
				t->dirty = first->dirty;
		} else if (!t->dirty) {
			continue;
		}

		tp_palm_detect(tp, t, time);

		tp_motion_hysteresis(tp, t);
		tp_motion_history_push(t);

		tp_unpin_finger(tp, t);
	}

	tp_button_handle_state(tp, time);

	/*
	 * We have a physical button down event on a clickpad. To avoid
	 * spurious pointer moves by the clicking finger we pin all fingers.
	 * We unpin fingers when they move more then a certain threshold to
	 * to allow drag and drop.
	 */
	if ((tp->queued & TOUCHPAD_EVENT_BUTTON_PRESS) &&
	    tp->buttons.is_clickpad)
		tp_pin_fingers(tp);
}

static void
tp_post_process_state(struct tp_dispatch *tp, uint64_t time)
{
	struct tp_touch *t;

	tp_for_each_touch(tp, t) {
		if (!t->dirty)
			continue;

		if (t->state == TOUCH_END) {
			t->state = TOUCH_NONE;
			t->fake = false;
		} else if (t->state == TOUCH_BEGIN)
			t->state = TOUCH_UPDATE;

		t->dirty = false;
	}

	tp->buttons.old_state = tp->buttons.state;

	tp->queued = TOUCHPAD_EVENT_NONE;
}

static void
tp_post_twofinger_scroll(struct tp_dispatch *tp, uint64_t time)
{
	struct tp_touch *t;
	int nchanged = 0;
	double dx = 0, dy =0;
	double tmpx, tmpy;

	tp_for_each_touch(tp, t) {
		if (tp_touch_active(tp, t) && t->dirty) {
			nchanged++;
			tp_get_delta(t, &tmpx, &tmpy);

			dx += tmpx;
			dy += tmpy;
		}
		/* Stop spurious MOTION events at the end of scrolling */
		t->is_pointer = false;
	}

	if (nchanged == 0)
		return;

	dx /= nchanged;
	dy /= nchanged;

	tp_filter_motion(tp, &dx, &dy, time);

	/* Require at least five px scrolling to start */
	if (dy <= -5.0 || dy >= 5.0)
		tp->scroll.direction |= (1 << LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL);

	if (dx <= -5.0 || dx >= 5.0)
		tp->scroll.direction |= (1 << LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL);

	if (dy != 0.0 &&
	    (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL))) {
		pointer_notify_axis(&tp->device->base,
				    time,
				    LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL,
				    dy);
	}

	if (dx != 0.0 &&
	    (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL))) {
		pointer_notify_axis(&tp->device->base,
				    time,
				    LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL,
				    dx);
	}
}

static void
tp_stop_scroll_events(struct tp_dispatch *tp, uint64_t time)
{
	/* terminate scrolling with a zero scroll event */
	if (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL))
		pointer_notify_axis(&tp->device->base,
				    time,
				    LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL,
				    0);
	if (tp->scroll.direction & (1 << LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL))
		pointer_notify_axis(&tp->device->base,
				    time,
				    LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL,
				    0);

	tp->scroll.direction = 0;
}

static int
tp_post_scroll_events(struct tp_dispatch *tp, uint64_t time)
{
	struct tp_touch *t;
	int nfingers_down = 0;

	/* Only count active touches for 2 finger scrolling */
	tp_for_each_touch(tp, t) {
		if (tp_touch_active(tp, t))
			nfingers_down++;
	}

	if (nfingers_down != 2) {
		tp_stop_scroll_events(tp, time);
		return 0;
	}

	tp_post_twofinger_scroll(tp, time);
	return 1;
}

static void
tp_post_events(struct tp_dispatch *tp, uint64_t time)
{
	struct tp_touch *t = tp_current_touch(tp);
	double dx, dy;
	int consumed = 0;

	consumed |= tp_tap_handle_state(tp, time);
	consumed |= tp_post_button_events(tp, time);

	if (consumed) {
		tp_stop_scroll_events(tp, time);
		return;
	}

	if (tp_post_scroll_events(tp, time) != 0)
		return;

	if (!t->is_pointer) {
		tp_for_each_touch(tp, t) {
			if (t->is_pointer)
				break;
		}
	}

	if (!t->is_pointer ||
	    !t->dirty ||
	    t->history.count < TOUCHPAD_MIN_SAMPLES)
		return;

	tp_get_delta(t, &dx, &dy);
	tp_filter_motion(tp, &dx, &dy, time);

	if (dx != 0.0 || dy != 0.0)
		pointer_notify_motion(&tp->device->base, time, dx, dy);
}

static void
tp_process(struct evdev_dispatch *dispatch,
	   struct evdev_device *device,
	   struct input_event *e,
	   uint64_t time)
{
	struct tp_dispatch *tp =
		(struct tp_dispatch *)dispatch;

	switch (e->type) {
	case EV_ABS:
		if (tp->has_mt)
			tp_process_absolute(tp, e, time);
		else
			tp_process_absolute_st(tp, e, time);
		break;
	case EV_KEY:
		tp_process_key(tp, e, time);
		break;
	case EV_SYN:
		tp_process_state(tp, time);
		tp_post_events(tp, time);
		tp_post_process_state(tp, time);
		break;
	}
}

static void
tp_destroy(struct evdev_dispatch *dispatch)
{
	struct tp_dispatch *tp =
		(struct tp_dispatch*)dispatch;

	tp_destroy_tap(tp);
	tp_destroy_buttons(tp);

	filter_destroy(tp->filter);
	free(tp->touches);
	free(tp);
}

static struct evdev_dispatch_interface tp_interface = {
	tp_process,
	tp_destroy
};

static void
tp_init_touch(struct tp_dispatch *tp,
	      struct tp_touch *t)
{
	t->tp = tp;
}

static int
tp_init_slots(struct tp_dispatch *tp,
	      struct evdev_device *device)
{
	size_t i;
	const struct input_absinfo *absinfo;

	absinfo = libevdev_get_abs_info(device->evdev, ABS_MT_SLOT);
	if (absinfo) {
		tp->ntouches = absinfo->maximum + 1;
		tp->slot = absinfo->value;
		tp->has_mt = true;
	} else {
		struct map {
			unsigned int code;
			int ntouches;
		} max_touches[] = {
			{ BTN_TOOL_QUINTTAP, 5 },
			{ BTN_TOOL_QUADTAP, 4 },
			{ BTN_TOOL_TRIPLETAP, 3 },
			{ BTN_TOOL_DOUBLETAP, 2 },
		};
		struct map *m;

		tp->slot = 0;
		tp->has_mt = false;
		tp->ntouches = 1;

		ARRAY_FOR_EACH(max_touches, m) {
			if (libevdev_has_event_code(device->evdev,
						    EV_KEY,
						    m->code)) {
				tp->ntouches = m->ntouches;
				break;
			}
		}
	}
	tp->touches = calloc(tp->ntouches,
			     sizeof(struct tp_touch));
	if (!tp->touches)
		return -1;

	for (i = 0; i < tp->ntouches; i++)
		tp_init_touch(tp, &tp->touches[i]);

	return 0;
}

static int
tp_init_accel(struct tp_dispatch *tp, double diagonal)
{
	struct motion_filter *accel;
	int res_x, res_y;

	if (tp->has_mt) {
		res_x = libevdev_get_abs_resolution(tp->device->evdev,
						    ABS_MT_POSITION_X);
		res_y = libevdev_get_abs_resolution(tp->device->evdev,
						    ABS_MT_POSITION_Y);
	} else {
		res_x = libevdev_get_abs_resolution(tp->device->evdev,
						    ABS_X);
		res_y = libevdev_get_abs_resolution(tp->device->evdev,
						    ABS_Y);
	}

	/*
	 * Not all touchpads report the same amount of units/mm (resolution).
	 * Normalize motion events to a resolution of 15.74 units/mm
	 * (== 400 dpi) as base (unaccelerated) speed. This also evens out any
	 * differences in x and y resolution, so that a circle on the
	 * touchpad does not turn into an elipse on the screen.
	 *
	 * We pick 400dpi as thats one of the many default resolutions
	 * for USB mice, so we end up with a similar base speed on the device.
	 */
	if (res_x > 1 && res_y > 1) {
		tp->accel.x_scale_coeff = (400/25.4) / res_x;
		tp->accel.y_scale_coeff = (400/25.4) / res_y;
	} else {
	/*
	 * For touchpads where the driver does not provide resolution, fall
	 * back to scaling motion events based on the diagonal size in units.
	 */
		tp->accel.x_scale_coeff = DEFAULT_ACCEL_NUMERATOR / diagonal;
		tp->accel.y_scale_coeff = DEFAULT_ACCEL_NUMERATOR / diagonal;
	}

	accel = create_pointer_accelator_filter(
			pointer_accel_profile_smooth_simple);
	if (accel == NULL)
		return -1;

	tp->filter = accel;

	return 0;
}

static int
tp_init_scroll(struct tp_dispatch *tp)
{
	tp->scroll.direction = 0;

	return 0;
}

static int
tp_init_palmdetect(struct tp_dispatch *tp,
		   struct evdev_device *device)
{
	int width;

	/* We don't know how big the touchpad is */
	if (device->abs.absinfo_x->resolution == 1)
		return 0;

	width = abs(device->abs.absinfo_x->maximum -
		    device->abs.absinfo_x->minimum);

	/* Enable palm detection on touchpads >= 80 mm. Anything smaller
	   probably won't need it, until we find out it does */
	if (width/device->abs.absinfo_x->resolution < 80) {
		tp->palm.right_edge = INT_MAX;
		tp->palm.left_edge = INT_MIN;
		return 0;
	}

	/* palm edges are 5% of the width on each side */
	tp->palm.right_edge = device->abs.absinfo_x->maximum - width * 0.05;
	tp->palm.left_edge = device->abs.absinfo_x->minimum + width * 0.05;

	return 0;
}


static int
tp_init(struct tp_dispatch *tp,
	struct evdev_device *device)
{
	int width, height;
	double diagonal;

	tp->base.interface = &tp_interface;
	tp->device = device;

	if (tp_init_slots(tp, device) != 0)
		return -1;

	width = abs(device->abs.absinfo_x->maximum -
		    device->abs.absinfo_x->minimum);
	height = abs(device->abs.absinfo_y->maximum -
		     device->abs.absinfo_y->minimum);
	diagonal = sqrt(width*width + height*height);

	tp->hysteresis.margin_x =
		diagonal / DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR;
	tp->hysteresis.margin_y =
		diagonal / DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR;

	if (tp_init_scroll(tp) != 0)
		return -1;

	if (tp_init_accel(tp, diagonal) != 0)
		return -1;

	if (tp_init_tap(tp) != 0)
		return -1;

	if (tp_init_buttons(tp, device) != 0)
		return -1;

	if (tp_init_palmdetect(tp, device) != 0)
		return -1;

	return 0;
}

struct evdev_dispatch *
evdev_mt_touchpad_create(struct evdev_device *device)
{
	struct tp_dispatch *tp;

	tp = zalloc(sizeof *tp);
	if (!tp)
		return NULL;

	if (tp_init(tp, device) != 0) {
		tp_destroy(&tp->base);
		return NULL;
	}

	return  &tp->base;
}