/*
 * Copyright © 2015 Red Hat, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include "config.h"

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

#include "evdev-mt-touchpad.h"

#define DEFAULT_GESTURE_SWITCH_TIMEOUT ms2us(100)
#define DEFAULT_GESTURE_2FG_SCROLL_TIMEOUT ms2us(150)

static inline const char*
gesture_state_to_str(enum tp_gesture_state state)
{
	switch (state) {
	CASE_RETURN_STRING(GESTURE_STATE_NONE);
	CASE_RETURN_STRING(GESTURE_STATE_UNKNOWN);
	CASE_RETURN_STRING(GESTURE_STATE_SCROLL);
	CASE_RETURN_STRING(GESTURE_STATE_PINCH);
	CASE_RETURN_STRING(GESTURE_STATE_SWIPE);
	}
	return NULL;
}

static struct normalized_coords
tp_get_touches_delta(struct tp_dispatch *tp, bool average)
{
	struct tp_touch *t;
	unsigned int i, nactive = 0;
	struct normalized_coords normalized;
	struct normalized_coords delta = {0.0, 0.0};

	for (i = 0; i < tp->num_slots; i++) {
		t = &tp->touches[i];

		if (!tp_touch_active(tp, t))
			continue;

		nactive++;

		if (t->dirty) {
			normalized = tp_get_delta(t);

			delta.x += normalized.x;
			delta.y += normalized.y;
		}
	}

	if (!average || nactive == 0)
		return delta;

	delta.x /= nactive;
	delta.y /= nactive;

	return delta;
}

static inline struct normalized_coords
tp_get_combined_touches_delta(struct tp_dispatch *tp)
{
	return tp_get_touches_delta(tp, false);
}

static inline struct normalized_coords
tp_get_average_touches_delta(struct tp_dispatch *tp)
{
	return tp_get_touches_delta(tp, true);
}

static void
tp_gesture_start(struct tp_dispatch *tp, uint64_t time)
{
	const struct normalized_coords zero = { 0.0, 0.0 };

	if (tp->gesture.started)
		return;

	switch (tp->gesture.state) {
	case GESTURE_STATE_NONE:
	case GESTURE_STATE_UNKNOWN:
		evdev_log_bug_libinput(tp->device,
				       "%s in unknown gesture mode\n",
				       __func__);
		break;
	case GESTURE_STATE_SCROLL:
		/* NOP */
		break;
	case GESTURE_STATE_PINCH:
		gesture_notify_pinch(&tp->device->base, time,
				    LIBINPUT_EVENT_GESTURE_PINCH_BEGIN,
				    tp->gesture.finger_count,
				    &zero, &zero, 1.0, 0.0);
		break;
	case GESTURE_STATE_SWIPE:
		gesture_notify_swipe(&tp->device->base, time,
				     LIBINPUT_EVENT_GESTURE_SWIPE_BEGIN,
				     tp->gesture.finger_count,
				     &zero, &zero);
		break;
	}

	tp->gesture.started = true;
}

static void
tp_gesture_post_pointer_motion(struct tp_dispatch *tp, uint64_t time)
{
	struct normalized_coords delta, unaccel;
	struct device_float_coords raw;

	/* When a clickpad is clicked, combine motion of all active touches */
	if (tp->buttons.is_clickpad && tp->buttons.state)
		unaccel = tp_get_combined_touches_delta(tp);
	else
		unaccel = tp_get_average_touches_delta(tp);

	delta = tp_filter_motion(tp, &unaccel, time);

	if (!normalized_is_zero(delta) || !normalized_is_zero(unaccel)) {
		raw = tp_unnormalize_for_xaxis(tp, unaccel);
		pointer_notify_motion(&tp->device->base,
				      time,
				      &delta,
				      &raw);
	}
}

static unsigned int
tp_gesture_get_active_touches(const struct tp_dispatch *tp,
			      struct tp_touch **touches,
			      unsigned int count)
{
	unsigned int n = 0;
	struct tp_touch *t;

	memset(touches, 0, count * sizeof(struct tp_touch *));

	tp_for_each_touch(tp, t) {
		if (tp_touch_active(tp, t)) {
			touches[n++] = t;
			if (n == count)
				return count;
		}
	}

	/*
	 * This can happen when the user does .e.g:
	 * 1) Put down 1st finger in center (so active)
	 * 2) Put down 2nd finger in a button area (so inactive)
	 * 3) Put down 3th finger somewhere, gets reported as a fake finger,
	 *    so gets same coordinates as 1st -> active
	 *
	 * We could avoid this by looking at all touches, be we really only
	 * want to look at real touches.
	 */
	return n;
}

static uint32_t
tp_gesture_get_direction(struct tp_dispatch *tp, struct tp_touch *touch,
			 unsigned int nfingers)
{
	struct phys_coords mm;
	struct device_float_coords delta;
	double move_threshold = 1.0; /* mm */

	move_threshold *= (nfingers - 1);

	delta = device_delta(touch->point, touch->gesture.initial);
	mm = tp_phys_delta(tp, delta);

	if (length_in_mm(mm) < move_threshold)
		return UNDEFINED_DIRECTION;

	return phys_get_direction(mm);
}

static void
tp_gesture_get_pinch_info(struct tp_dispatch *tp,
			  double *distance,
			  double *angle,
			  struct device_float_coords *center)
{
	struct normalized_coords normalized;
	struct device_float_coords delta;
	struct tp_touch *first = tp->gesture.touches[0],
			*second = tp->gesture.touches[1];

	delta = device_delta(first->point, second->point);
	normalized = tp_normalize_delta(tp, delta);
	*distance = normalized_length(normalized);
	*angle = atan2(normalized.y, normalized.x) * 180.0 / M_PI;

	*center = device_average(first->point, second->point);
}

static void
tp_gesture_set_scroll_buildup(struct tp_dispatch *tp)
{
	struct device_float_coords d0, d1;
	struct device_float_coords average;
	struct tp_touch *first = tp->gesture.touches[0],
			*second = tp->gesture.touches[1];

	d0 = device_delta(first->point, first->gesture.initial);
	d1 = device_delta(second->point, second->gesture.initial);

	average = device_float_average(d0, d1);
	tp->device->scroll.buildup = tp_normalize_delta(tp, average);
}

static enum tp_gesture_state
tp_gesture_handle_state_none(struct tp_dispatch *tp, uint64_t time)
{
	struct tp_touch *first, *second;
	struct tp_touch *touches[4];
	unsigned int ntouches;
	unsigned int i;

	ntouches = tp_gesture_get_active_touches(tp, touches, 4);
	if (ntouches < 2)
		return GESTURE_STATE_NONE;

	if (!tp->gesture.enabled) {
		if (ntouches == 2)
			return GESTURE_STATE_SCROLL;
		else
			return GESTURE_STATE_NONE;
	}

	first = touches[0];
	second = touches[1];

	/* For 3+ finger gestures we cheat. A human hand's finger
	 * arrangement means that for a 3 or 4 finger swipe gesture, the
	 * fingers are roughly arranged in a horizontal line.
	 * They will all move in the same direction, so we can simply look
	 * at the left and right-most ones only. If we have fake touches, we
	 * just take the left/right-most real touch position, since the fake
	 * touch has the same location as one of those.
	 *
	 * For a 3 or 4 finger pinch gesture, 2 or 3 fingers are roughly in
	 * a horizontal line, with the thumb below and left (right-handed
	 * users) or right (left-handed users). Again, the row of non-thumb
	 * fingers moves identically so we can look at the left and
	 * right-most only and then treat it like a two-finger
	 * gesture.
	 */
	if (ntouches > 2) {
		second = touches[0];

		for (i = 1; i < ntouches && i < tp->num_slots; i++) {
			if (touches[i]->point.x < first->point.x)
				first = touches[i];
			else if (touches[i]->point.x > second->point.x)
				second = touches[i];
		}

		if (first == second)
			return GESTURE_STATE_NONE;

	}

	tp->gesture.initial_time = time;
	first->gesture.initial = first->point;
	second->gesture.initial = second->point;
	tp->gesture.touches[0] = first;
	tp->gesture.touches[1] = second;

	return GESTURE_STATE_UNKNOWN;
}

static inline int
tp_gesture_same_directions(int dir1, int dir2)
{
	/*
	 * In some cases (semi-mt touchpads) we may seen one finger move
	 * e.g. N/NE and the other W/NW so we not only check for overlapping
	 * directions, but also for neighboring bits being set.
	 * The ((dira & 0x80) && (dirb & 0x01)) checks are to check for bit 0
	 * and 7 being set as they also represent neighboring directions.
	 */
	return ((dir1 | (dir1 >> 1)) & dir2) ||
		((dir2 | (dir2 >> 1)) & dir1) ||
		((dir1 & 0x80) && (dir2 & 0x01)) ||
		((dir2 & 0x80) && (dir1 & 0x01));
}

static inline void
tp_gesture_init_pinch(struct tp_dispatch *tp)
{
	tp_gesture_get_pinch_info(tp,
				  &tp->gesture.initial_distance,
				  &tp->gesture.angle,
				  &tp->gesture.center);
	tp->gesture.prev_scale = 1.0;
}

static enum tp_gesture_state
tp_gesture_handle_state_unknown(struct tp_dispatch *tp, uint64_t time)
{
	struct tp_touch *first = tp->gesture.touches[0],
			*second = tp->gesture.touches[1];
	uint32_t dir1, dir2;
	int yres = tp->device->abs.absinfo_y->resolution;
	int vert_distance;

	if (time > (tp->gesture.initial_time + DEFAULT_GESTURE_2FG_SCROLL_TIMEOUT)) {
		/* for two-finger gestures, if the fingers stay unmoving for a
		 * while, assume (slow) scroll */
		if (tp->gesture.finger_count == 2) {
			tp_gesture_set_scroll_buildup(tp);
			return GESTURE_STATE_SCROLL;
		}

		/* for 3+ finger gestures, check if one finger is > 20mm
		   below the others */
		vert_distance = abs(first->point.y - second->point.y);
		if (vert_distance > 20 * yres &&
		    tp->gesture.enabled) {
			tp_gesture_init_pinch(tp);
			return GESTURE_STATE_PINCH;
		} else {
			return GESTURE_STATE_SWIPE;
		}
	}

	/* Else wait for both fingers to have moved */
	dir1 = tp_gesture_get_direction(tp, first, tp->gesture.finger_count);
	dir2 = tp_gesture_get_direction(tp, second, tp->gesture.finger_count);
	if (dir1 == UNDEFINED_DIRECTION || dir2 == UNDEFINED_DIRECTION)
		return GESTURE_STATE_UNKNOWN;

	/* If both touches are moving in the same direction assume
	 * scroll or swipe */
	if (tp_gesture_same_directions(dir1, dir2)) {
		if (tp->gesture.finger_count == 2) {
			tp_gesture_set_scroll_buildup(tp);
			return GESTURE_STATE_SCROLL;
		} else if (tp->gesture.enabled) {
			return GESTURE_STATE_SWIPE;
		}
	} else {
		tp_gesture_init_pinch(tp);
		return GESTURE_STATE_PINCH;
	}

	return GESTURE_STATE_UNKNOWN;
}

static enum tp_gesture_state
tp_gesture_handle_state_scroll(struct tp_dispatch *tp, uint64_t time)
{
	struct normalized_coords delta;

	if (tp->scroll.method != LIBINPUT_CONFIG_SCROLL_2FG)
		return GESTURE_STATE_SCROLL;

	delta = tp_get_average_touches_delta(tp);

	/* scroll is not accelerated */
	delta = tp_filter_motion_unaccelerated(tp, &delta, time);

	if (normalized_is_zero(delta))
		return GESTURE_STATE_SCROLL;

	tp_gesture_start(tp, time);
	evdev_post_scroll(tp->device,
			  time,
			  LIBINPUT_POINTER_AXIS_SOURCE_FINGER,
			  &delta);

	return GESTURE_STATE_SCROLL;
}

static enum tp_gesture_state
tp_gesture_handle_state_swipe(struct tp_dispatch *tp, uint64_t time)
{
	struct normalized_coords delta, unaccel;

	unaccel = tp_get_average_touches_delta(tp);
	delta = tp_filter_motion(tp, &unaccel, time);

	if (!normalized_is_zero(delta) || !normalized_is_zero(unaccel)) {
		tp_gesture_start(tp, time);
		gesture_notify_swipe(&tp->device->base, time,
				     LIBINPUT_EVENT_GESTURE_SWIPE_UPDATE,
				     tp->gesture.finger_count,
				     &delta, &unaccel);
	}

	return GESTURE_STATE_SWIPE;
}

static enum tp_gesture_state
tp_gesture_handle_state_pinch(struct tp_dispatch *tp, uint64_t time)
{
	double angle, angle_delta, distance, scale;
	struct device_float_coords center, fdelta;
	struct normalized_coords delta, unaccel;

	tp_gesture_get_pinch_info(tp, &distance, &angle, &center);

	scale = distance / tp->gesture.initial_distance;

	angle_delta = angle - tp->gesture.angle;
	tp->gesture.angle = angle;
	if (angle_delta > 180.0)
		angle_delta -= 360.0;
	else if (angle_delta < -180.0)
		angle_delta += 360.0;

	fdelta = device_float_delta(center, tp->gesture.center);
	tp->gesture.center = center;
	unaccel = tp_normalize_delta(tp, fdelta);
	delta = tp_filter_motion(tp, &unaccel, time);

	if (normalized_is_zero(delta) && normalized_is_zero(unaccel) &&
	    scale == tp->gesture.prev_scale && angle_delta == 0.0)
		return GESTURE_STATE_PINCH;

	tp_gesture_start(tp, time);
	gesture_notify_pinch(&tp->device->base, time,
			     LIBINPUT_EVENT_GESTURE_PINCH_UPDATE,
			     tp->gesture.finger_count,
			     &delta, &unaccel, scale, angle_delta);

	tp->gesture.prev_scale = scale;

	return GESTURE_STATE_PINCH;
}

static void
tp_gesture_post_gesture(struct tp_dispatch *tp, uint64_t time)
{
	enum tp_gesture_state oldstate = tp->gesture.state;

	if (tp->gesture.state == GESTURE_STATE_NONE)
		tp->gesture.state =
			tp_gesture_handle_state_none(tp, time);

	if (tp->gesture.state == GESTURE_STATE_UNKNOWN)
		tp->gesture.state =
			tp_gesture_handle_state_unknown(tp, time);

	if (tp->gesture.state == GESTURE_STATE_SCROLL)
		tp->gesture.state =
			tp_gesture_handle_state_scroll(tp, time);

	if (tp->gesture.state == GESTURE_STATE_SWIPE)
		tp->gesture.state =
			tp_gesture_handle_state_swipe(tp, time);

	if (tp->gesture.state == GESTURE_STATE_PINCH)
		tp->gesture.state =
			tp_gesture_handle_state_pinch(tp, time);

	evdev_log_debug(tp->device,
			"gesture state: %s → %s\n",
			gesture_state_to_str(oldstate),
			gesture_state_to_str(tp->gesture.state));
}

void
tp_gesture_post_events(struct tp_dispatch *tp, uint64_t time)
{
	if (tp->gesture.finger_count == 0)
		return;

	/* When tap-and-dragging, or a clickpad is clicked force 1fg mode */
	if (tp_tap_dragging(tp) || (tp->buttons.is_clickpad && tp->buttons.state)) {
		tp_gesture_cancel(tp, time);
		tp->gesture.finger_count = 1;
		tp->gesture.finger_count_pending = 0;
	}

	/* Don't send events when we're unsure in which mode we are */
	if (tp->gesture.finger_count_pending)
		return;

	switch (tp->gesture.finger_count) {
	case 1:
		if (tp->queued & TOUCHPAD_EVENT_MOTION)
			tp_gesture_post_pointer_motion(tp, time);
		break;
	case 2:
	case 3:
	case 4:
		tp_gesture_post_gesture(tp, time);
		break;
	}
}

void
tp_gesture_stop_twofinger_scroll(struct tp_dispatch *tp, uint64_t time)
{
	if (tp->scroll.method != LIBINPUT_CONFIG_SCROLL_2FG)
		return;

	evdev_stop_scroll(tp->device,
			  time,
			  LIBINPUT_POINTER_AXIS_SOURCE_FINGER);
}

static void
tp_gesture_end(struct tp_dispatch *tp, uint64_t time, bool cancelled)
{
	enum tp_gesture_state state = tp->gesture.state;

	tp->gesture.state = GESTURE_STATE_NONE;

	if (!tp->gesture.started)
		return;

	switch (state) {
	case GESTURE_STATE_NONE:
	case GESTURE_STATE_UNKNOWN:
		evdev_log_bug_libinput(tp->device,
				       "%s in unknown gesture mode\n",
				       __func__);
		break;
	case GESTURE_STATE_SCROLL:
		tp_gesture_stop_twofinger_scroll(tp, time);
		break;
	case GESTURE_STATE_PINCH:
		gesture_notify_pinch_end(&tp->device->base, time,
					 tp->gesture.finger_count,
					 tp->gesture.prev_scale,
					 cancelled);
		break;
	case GESTURE_STATE_SWIPE:
		gesture_notify_swipe_end(&tp->device->base,
					 time,
					 tp->gesture.finger_count,
					 cancelled);
		break;
	}

	tp->gesture.started = false;
}

void
tp_gesture_cancel(struct tp_dispatch *tp, uint64_t time)
{
	tp_gesture_end(tp, time, true);
}

void
tp_gesture_stop(struct tp_dispatch *tp, uint64_t time)
{
	tp_gesture_end(tp, time, false);
}

static void
tp_gesture_finger_count_switch_timeout(uint64_t now, void *data)
{
	struct tp_dispatch *tp = data;

	if (!tp->gesture.finger_count_pending)
		return;

	tp_gesture_cancel(tp, now); /* End current gesture */
	tp->gesture.finger_count = tp->gesture.finger_count_pending;
	tp->gesture.finger_count_pending = 0;
}

void
tp_gesture_handle_state(struct tp_dispatch *tp, uint64_t time)
{
	unsigned int active_touches = 0;
	struct tp_touch *t;

	tp_for_each_touch(tp, t) {
		if (tp_touch_active(tp, t))
			active_touches++;
	}

	if (active_touches != tp->gesture.finger_count) {
		/* If all fingers are lifted immediately end the gesture */
		if (active_touches == 0) {
			tp_gesture_stop(tp, time);
			tp->gesture.finger_count = 0;
			tp->gesture.finger_count_pending = 0;
		/* Immediately switch to new mode to avoid initial latency */
		} else if (!tp->gesture.started) {
			tp->gesture.finger_count = active_touches;
			tp->gesture.finger_count_pending = 0;
		/* Else debounce finger changes */
		} else if (active_touches != tp->gesture.finger_count_pending) {
			tp->gesture.finger_count_pending = active_touches;
			libinput_timer_set(&tp->gesture.finger_count_switch_timer,
				time + DEFAULT_GESTURE_SWITCH_TIMEOUT);
		}
	} else {
		 tp->gesture.finger_count_pending = 0;
	}
}

void
tp_init_gesture(struct tp_dispatch *tp)
{
	/* two-finger scrolling is always enabled, this flag just
	 * decides whether we detect pinch. semi-mt devices are too
	 * unreliable to do pinch gestures. */
	tp->gesture.enabled = !tp->semi_mt && tp->num_slots > 1;

	tp->gesture.state = GESTURE_STATE_NONE;

	libinput_timer_init(&tp->gesture.finger_count_switch_timer,
			    tp_libinput_context(tp),
			    tp_gesture_finger_count_switch_timeout, tp);
}

void
tp_remove_gesture(struct tp_dispatch *tp)
{
	libinput_timer_cancel(&tp->gesture.finger_count_switch_timer);
}