/*
 * Copyright (c) 2019 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup display
 * @{
 */
/**
 * @file Display server seat
 */

#include <adt/list.h>
#include <errno.h>
#include <gfx/color.h>
#include <gfx/render.h>
#include <stdlib.h>
#include "client.h"
#include "cursor.h"
#include "display.h"
#include "seat.h"
#include "window.h"

static void ds_seat_get_pointer_rect(ds_seat_t *, gfx_rect_t *);
static errno_t ds_seat_repaint_pointer(ds_seat_t *, gfx_rect_t *);

/** Create seat.
 *
 * @param display Parent display
 * @param rseat Place to store pointer to new seat.
 * @return EOK on success, ENOMEM if out of memory
 */
errno_t ds_seat_create(ds_display_t *display, ds_seat_t **rseat)
{
	ds_seat_t *seat;

	seat = calloc(1, sizeof(ds_seat_t));
	if (seat == NULL)
		return ENOMEM;

	ds_display_add_seat(display, seat);
	seat->pntpos.x = 0;
	seat->pntpos.y = 0;

	seat->client_cursor = display->cursor[dcurs_arrow];
	seat->wm_cursor = NULL;

	*rseat = seat;
	return EOK;
}

/** Destroy seat.
 *
 * @param seat Seat
 */
void ds_seat_destroy(ds_seat_t *seat)
{
	ds_display_remove_seat(seat);
	free(seat);
}

/** Set seat focus to a window.
 *
 * @param seat Seat
 * @param wnd Window to focus
 */
void ds_seat_set_focus(ds_seat_t *seat, ds_window_t *wnd)
{
	if (wnd == seat->focus) {
		/* Focus is not changing */
		return;
	}

	if (seat->focus != NULL)
		ds_window_post_unfocus_event(seat->focus);

	seat->focus = wnd;

	if (wnd != NULL) {
		ds_window_post_focus_event(wnd);
		ds_window_bring_to_top(wnd);
	}
}

/** Evacuate focus from window.
 *
 * If seat's focus is @a wnd, it will be set to a different window.
 *
 * @param seat Seat
 * @param wnd Window to evacuate focus from
 */
void ds_seat_evac_focus(ds_seat_t *seat, ds_window_t *wnd)
{
	ds_window_t *nwnd;

	if (seat->focus == wnd) {
		nwnd = ds_display_prev_window(wnd);
		if (nwnd == NULL)
			nwnd = ds_display_last_window(wnd->display);
		if (nwnd == wnd)
			nwnd = NULL;

		ds_seat_set_focus(seat, nwnd);
	}
}

/** Switch focus to another window.
 *
 * @param seat Seat
 * @param wnd Window to evacuate focus from
 */
void ds_seat_switch_focus(ds_seat_t *seat)
{
	ds_window_t *nwnd;

	if (seat->focus != NULL)
		nwnd = ds_display_prev_window(seat->focus);
	else
		nwnd = NULL;

	if (nwnd == NULL)
		nwnd = ds_display_last_window(seat->display);

	if (nwnd != NULL)
		ds_seat_set_focus(seat, nwnd);
}

/** Post keyboard event to the seat's focused window.
 *
 * @param seat Seat
 * @param event Event
 *
 * @return EOK on success or an error code
 */
errno_t ds_seat_post_kbd_event(ds_seat_t *seat, kbd_event_t *event)
{
	ds_window_t *dwindow;
	bool alt_or_shift;

	alt_or_shift = event->mods & (KM_SHIFT | KM_ALT);
	if (event->type == KEY_PRESS && alt_or_shift && event->key == KC_TAB) {
		/* On Alt-Tab or Shift-Tab, switch focus to next window */
		ds_seat_switch_focus(seat);
		return EOK;
	}

	dwindow = seat->focus;
	if (dwindow == NULL)
		return EOK;

	return ds_window_post_kbd_event(dwindow, event);
}

/** Get current cursor used by seat.
 *
 * @param wmcurs WM curor
 * @param ccurs Client cursor
 * @return
 */
static ds_cursor_t *ds_seat_compute_cursor(ds_cursor_t *wmcurs, ds_cursor_t *ccurs)
{
	if (wmcurs != NULL)
		return wmcurs;

	return ccurs;
}

/** Get current cursor used by seat.
 *
 * @param seat Seat
 * @return Current cursor
 */
static ds_cursor_t *ds_seat_get_cursor(ds_seat_t *seat)
{
	return ds_seat_compute_cursor(seat->wm_cursor, seat->client_cursor);
}

/** Set client cursor.
 *
 * Set cursor selected by client. This may update the actual cursor
 * if WM is not overriding the cursor.
 *
 * @param seat Seat
 * @param cursor Client cursor
 */
static void ds_seat_set_client_cursor(ds_seat_t *seat, ds_cursor_t *cursor)
{
	ds_cursor_t *old_cursor;
	ds_cursor_t *new_cursor;
	gfx_rect_t old_rect;

	old_cursor = ds_seat_get_cursor(seat);
	new_cursor = ds_seat_compute_cursor(seat->wm_cursor, cursor);

	if (new_cursor != old_cursor) {
		ds_seat_get_pointer_rect(seat, &old_rect);
		seat->client_cursor = cursor;
		ds_seat_repaint_pointer(seat, &old_rect);
	} else {
		seat->client_cursor = cursor;
	}
}

/** Set WM cursor.
 *
 * Set cursor override for window management.
 *
 * @param seat Seat
 * @param cursor WM cursor override or @c NULL not to override the cursor
 */
void ds_seat_set_wm_cursor(ds_seat_t *seat, ds_cursor_t *cursor)
{
	ds_cursor_t *old_cursor;
	ds_cursor_t *new_cursor;
	gfx_rect_t old_rect;

	old_cursor = ds_seat_get_cursor(seat);
	new_cursor = ds_seat_compute_cursor(cursor, seat->client_cursor);

	if (new_cursor != old_cursor) {
		ds_seat_get_pointer_rect(seat, &old_rect);
		seat->wm_cursor = cursor;
		ds_seat_repaint_pointer(seat, &old_rect);
	} else {
		seat->wm_cursor = cursor;
	}
}

/** Get rectangle covered by pointer.
 *
 * @param seat Seat
 * @param rect Place to store rectangle
 */
void ds_seat_get_pointer_rect(ds_seat_t *seat, gfx_rect_t *rect)
{
	ds_cursor_t *cursor;

	cursor = ds_seat_get_cursor(seat);
	ds_cursor_get_rect(cursor, &seat->pntpos, rect);
}

/** Repaint seat pointer
 *
 * Repaint the pointer after it has moved or changed. This is done by
 * repainting the area of the display previously (@a old_rect) and currently
 * covered by the pointer.
 *
 * @param seat Seat
 * @param old_rect Rectangle previously covered by pointer
 *
 * @return EOK on success or an error code
 */
static errno_t ds_seat_repaint_pointer(ds_seat_t *seat, gfx_rect_t *old_rect)
{
	gfx_rect_t new_rect;
	gfx_rect_t envelope;
	errno_t rc;

	ds_seat_get_pointer_rect(seat, &new_rect);

	if (gfx_rect_is_incident(old_rect, &new_rect)) {
		/* Rectangles do not intersect. Repaint them separately. */
		rc = ds_display_paint(seat->display, &new_rect);
		if (rc != EOK)
			return rc;

		rc = ds_display_paint(seat->display, old_rect);
		if (rc != EOK)
			return rc;
	} else {
		/*
		 * Rectangles intersect. As an optimization, repaint them
		 * in a single operation.
		 */
		gfx_rect_envelope(old_rect, &new_rect, &envelope);

		rc = ds_display_paint(seat->display, &envelope);
		if (rc != EOK)
			return rc;
	}

	return EOK;
}

/** Post pointing device event to the seat
 *
 * Update pointer position and generate position event.
 *
 * @param seat Seat
 * @param event Event
 *
 * @return EOK on success or an error code
 */
errno_t ds_seat_post_ptd_event(ds_seat_t *seat, ptd_event_t *event)
{
	ds_display_t *disp = seat->display;
	gfx_coord2_t npos;
	gfx_rect_t old_rect;
	ds_window_t *wnd;
	pos_event_t pevent;
	errno_t rc;

	wnd = ds_display_window_by_pos(seat->display, &seat->pntpos);

	/* Focus window on button press */
	if (event->type == PTD_PRESS && event->btn_num == 1) {
		if (wnd != NULL) {
			ds_seat_set_focus(seat, wnd);
		}
	}

	if (event->type == PTD_PRESS || event->type == PTD_RELEASE) {
		pevent.pos_id = 0;
		pevent.type = (event->type == PTD_PRESS) ?
		    POS_PRESS : POS_RELEASE;
		pevent.btn_num = event->btn_num;
		pevent.hpos = seat->pntpos.x;
		pevent.vpos = seat->pntpos.y;

		rc = ds_seat_post_pos_event(seat, &pevent);
		if (rc != EOK)
			return rc;
	}

	if (event->type == PTD_MOVE) {
		gfx_coord2_add(&seat->pntpos, &event->dmove, &npos);
		gfx_coord2_clip(&npos, &disp->rect, &npos);

		ds_seat_get_pointer_rect(seat, &old_rect);
		seat->pntpos = npos;

		pevent.pos_id = 0;
		pevent.type = POS_UPDATE;
		pevent.btn_num = 0;
		pevent.hpos = seat->pntpos.x;
		pevent.vpos = seat->pntpos.y;

		rc = ds_seat_post_pos_event(seat, &pevent);
		if (rc != EOK)
			return rc;

		ds_seat_repaint_pointer(seat, &old_rect);
	}

	if (event->type == PTD_ABS_MOVE) {
		/*
		 * Project input device area onto display area. Technically
		 * we probably want to project onto the area of a particular
		 * display device. The tricky part is figuring out which
		 * display device the input device is associated with.
		 */
		gfx_coord2_project(&event->apos, &event->abounds,
		    &disp->rect, &npos);

		gfx_coord2_clip(&npos, &disp->rect, &npos);

		ds_seat_get_pointer_rect(seat, &old_rect);
		seat->pntpos = npos;

		pevent.pos_id = 0;
		pevent.type = POS_UPDATE;
		pevent.btn_num = 0;
		pevent.hpos = seat->pntpos.x;
		pevent.vpos = seat->pntpos.y;

		rc = ds_seat_post_pos_event(seat, &pevent);
		if (rc != EOK)
			return rc;

		ds_seat_repaint_pointer(seat, &old_rect);
	}

	return EOK;
}

/** Post position event to seat.
 *
 * Deliver event to relevant windows.
 *
 * @param seat Seat
 * @param event Position event
 */
errno_t ds_seat_post_pos_event(ds_seat_t *seat, pos_event_t *event)
{
	ds_window_t *wnd;
	errno_t rc;

	wnd = ds_display_window_by_pos(seat->display, &seat->pntpos);
	if (seat->focus != wnd && seat->focus != NULL) {
		rc = ds_window_post_pos_event(seat->focus, event);
		if (rc != EOK)
			return rc;

		/* Only deliver release events to the focused window */
		if (event->type == POS_RELEASE)
			return EOK;
	}

	if (wnd != NULL) {
		/* Moving over a window */
		ds_seat_set_client_cursor(seat, wnd->cursor);

		rc = ds_window_post_pos_event(wnd, event);
		if (rc != EOK)
			return rc;
	} else {
		/* Not over a window */
		ds_seat_set_client_cursor(seat, seat->display->cursor[dcurs_arrow]);
	}

	return EOK;
}

/** Paint seat pointer.
 *
 * @param seat Seat whose pointer to paint
 * @param rect Clipping rectangle
 */
errno_t ds_seat_paint_pointer(ds_seat_t *seat, gfx_rect_t *rect)
{
	ds_cursor_t *cursor;

	cursor = ds_seat_get_cursor(seat);
	return ds_cursor_paint(cursor, &seat->pntpos, rect);
}

/** @}
 */