/*
 * X11 GUI for slide puzzle game
 * Copyright © 2022 Nick Bowler
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <assert.h>

#include <X11/Intrinsic.h>
#include <X11/StringDefs.h>
#include <X11/Xatom.h>
#include <X11/Shell.h>
#include "motif.h"

/* Size of the traditional icon pixmap (multiple of 3) */
#define ICON_SIZE 48

/* Define to 1 to add highlights and delays for visually debugging redraws */
#if X11_RENDER_DEBUG
#  include <unistd.h>
#endif

enum {
	NUM_TILE_COLOURS = COLOUR_MAX*(TILE_MAX-1),
	COLOUR_UI_GAMEBG = NUM_TILE_COLOURS,
	COLOUR_UI_MAX
};
typedef Pixel colour_tab[COLOUR_UI_MAX];

#define COLOURRES(name, index, def) { \
	(name), (NULL), XtRPixel, sizeof (String), \
	offsetof(struct { colour_tab t; }, t[index]), \
	XtRString, (def) }

static XtResource colour_resources[] = {
	COLOURRES("colour0", 0, COLOUR0_PRIMARY),
	COLOURRES("colour1", 1, COLOUR1_PRIMARY),
	COLOURRES("colour2", 2, COLOUR2_PRIMARY),
	COLOURRES("colour3", 3, COLOUR3_PRIMARY),
	COLOURRES("colour4", 4, COLOUR4_PRIMARY),
	COLOURRES("colour5", 5, COLOUR5_PRIMARY),

	COLOURRES("colourDark0",  6, COLOUR0_DARK),
	COLOURRES("colourDark1",  7, COLOUR1_DARK),
	COLOURRES("colourDark2",  8, COLOUR2_DARK),
	COLOURRES("colourDark3",  9, COLOUR3_DARK),
	COLOURRES("colourDark4", 10, COLOUR4_DARK),
	COLOURRES("colourDark5", 11, COLOUR5_DARK),

	COLOURRES("colourLight0", 12, COLOUR0_LIGHT),
	COLOURRES("colourLight1", 13, COLOUR1_LIGHT),
	COLOURRES("colourLight2", 14, COLOUR2_LIGHT),
	COLOURRES("colourLight3", 15, COLOUR3_LIGHT),
	COLOURRES("colourLight4", 16, COLOUR4_LIGHT),
	COLOURRES("colourLight5", 17, COLOUR5_LIGHT),

	COLOURRES("gameBackground", COLOUR_UI_GAMEBG, "#181818")
};

static void init_colours(struct app_state *state, Widget shell)
{
	unsigned i;

	colour_tab colours;
	XtGetApplicationResources(shell, &colours, colour_resources,
	                          XtNumber(colour_resources), NULL, 0);

	for (i = 0; i < NUM_TILE_COLOURS; i++) {
		unsigned tile = i % (TILE_MAX-1), shade = i / (TILE_MAX-1);

		state->tile_colour[tile][shade] = colours[i];
	}

	XtVaSetValues(state->game, XtNbackground, colours[COLOUR_UI_GAMEBG],
	                           (char *)NULL);
}

void x11_initialize(struct app_state *state, Widget shell)
{
	Display *display = XtDisplay(shell);
	Screen *screen = XtScreen(shell);
	Window root = RootWindowOfScreen(screen);
	XGCValues gcv;

	init_colours(state, shell);

	gcv.line_width = 1;
	state->tile_gc = XCreateGC(display, root, GCLineWidth, &gcv);

	state->icon_pixmap = XCreatePixmap(display, root, ICON_SIZE, ICON_SIZE,
	                                   DefaultDepthOfScreen(screen));
}

static void draw_tile(struct app_state *state, Display *display, Drawable d,
                      int tile, int gx, int gy, Dimension tw, Dimension th)
{
	int tx = gx * tw, ty = gy * th;

	XSegment topshadow[] = {
		{ tx,      ty,      tx,      ty+th   },
		{ tx+1,    ty,      tx+tw,   ty      },

		{ tx+1,    ty+1,    tx+1,    ty+th-1 },
		{ tx+2,    ty+1,    tx+tw-1, ty+1    }
	};

	XSegment bottomshadow[] = {
		{ tx+1,    ty+th-1, tx+tw,   ty+th-1 },
		{ tx+tw-1, ty+th-1, tx+tw-1, ty+1    },

		{ tx+2,    ty+th-2, tx+tw-1, ty+th-2 },
		{ tx+tw-2, ty+th-2, tx+tw-2, ty+2    }
	};

	XSetForeground(display, state->tile_gc, state->tile_colour[tile-1][COLOUR_LIGHT]);
	XDrawSegments(display, d, state->tile_gc, topshadow, XtNumber(topshadow));

	XSetForeground(display, state->tile_gc, state->tile_colour[tile-1][COLOUR_DARK]);
	XDrawSegments(display, d, state->tile_gc, bottomshadow, XtNumber(bottomshadow));

	XSetForeground(display, state->tile_gc, state->tile_colour[tile-1][COLOUR_PRIMARY]);
	XFillRectangle(display, d, state->tile_gc, tx+2, ty+2, tw-4, th-4);
}

/*
 * Clear a contiguous rectangle of tiles from top-left (x0, y0) to
 * bottom-right (x1, y1).
 */
static void
clear_tiles(struct app_state *state, Display *display, Drawable d,
            int x0, int y0, int x1, int y1, Dimension w, Dimension h)
{
	XRectangle r = { x0*w, y0*h, (x1+1)*w, (y1+1)*h };

#if X11_RENDER_DEBUG
	XSetForeground(display, state->tile_gc, 0xff0000);
	XFillRectangles(display, d, state->tile_gc, &r, 1);
	XFlush(display);
	usleep(70000);
#endif

	XClearArea(display, d, r.x, r.y, r.width, r.height, 0);
}

/*
 * Efficiently clear all the border tiles in the game area.  The mask indicates
 * which tiles need clearing, but for the border clear it is safe to wipe an
 * entire row or column of the border using a single XClearArea.
 *
 * The idea is to pick whichever row or column has the most tiles to clear,
 * clear them, and then repeat until none are left (repeats at most 4 times).
 */
static void clear_border(struct app_state *state, Display *display, Drawable d,
                         Dimension w, Dimension h, uint_fast32_t mask)
{
	uint_fast32_t best_mask = 0;
	int best_count = -1;
	int i, best = -1;

	if (!(mask &= ~GOAL_MASK & 0x1ffffff))
		return;

	for (i = 0; i < 4; i++) {
		uint_fast32_t this_mask, tmp;
		int this_count = 0;

		if (i & 2)
			this_mask = board_column(4*(i & 1));
		else
			this_mask = board_row(4*(i & 1));

		/* Count set bits */
		for (tmp = mask & this_mask; tmp; this_count++)
			tmp &= tmp - 1;

		if (this_count > best_count) {
			best_count = this_count;
			best_mask = this_mask;
			best = i;
		}
	}

	switch (best) {
	case 0: clear_tiles(state, display, d, 0, 0, 4, 0, w, h); break;
	case 1: clear_tiles(state, display, d, 0, 4, 4, 4, w, h); break;
	case 2: clear_tiles(state, display, d, 0, 0, 0, 4, w, h); break;
	case 3: clear_tiles(state, display, d, 4, 0, 4, 4, w, h); break;
	}

	clear_border(state, display, d, w, h, mask & ~best_mask);
}

static int
redraw_tile(struct app_state *state, Display *display, Drawable d,
            uint_fast32_t bit0, uint_fast32_t bit1, uint_fast32_t bit2,
            int x, int y, Dimension w, Dimension h)
{
	uint_fast32_t pos = board_position(x, y);
	unsigned char tile = 0;

#if X11_RENDER_DEBUG
	if (d == XtWindow(state->game) || d == XtWindow(state->goal)) {
		XRectangle r = { x*w, y*h, w, h };
		XSetForeground(display, state->tile_gc, 0xff0000);
		XFillRectangles(display, d, state->tile_gc, &r, 1);
		XFlush(display);
		usleep(70000);
	}
#endif

	if (bit0 & pos) tile |= 1;
	if (bit1 & pos) tile |= 2;
	if (bit2 & pos) tile |= 4;
	assert(tile < TILE_MAX);

	if (tile == TILE_EMPTY) {
		XClearArea(display, d, x*w, y*h, w, h, 0);
	} else {
		draw_tile(state, display, d, tile, x, y, w, h);
	}

	return tile;
}

static int
redraw_goal_tile(struct app_state *state, Display *display, Drawable d,
                 int x, int y, Dimension w, Dimension h)
{
	uint_least16_t *gp = state->board.goal;

	return redraw_tile(state, display, d, gp[0], gp[1], gp[2], x, y, w, h);
}

void x11_redraw_goal(struct app_state *state, uint_fast32_t mask)
{
	Display *display = XtDisplay(state->goal);
	Window goal = XtWindow(state->goal);
	Dimension w, h;
	int i;

	XtVaGetValues(state->goal, XtNwidth, &w, XtNheight, &h, (char *)NULL);
	w /= 3; h /= 3;

	for (i = 0; i < 9; i++) {
		int x = i%3, y = i/3;

		if (mask & 1) {
			redraw_goal_tile(state, display, goal, x, y, w, h);
		}

		/*
		 * Goal bitmaps have a gap of 2 tiles between each row.
		 * This funny shift will accomodate that.
		 */
		mask >>= 1|x;
	}
}

/* Render the goal area as the window's icon */
void x11_redraw_icon(struct app_state *state, Widget shell)
{
	Display *display = XtDisplay(shell);
	Dimension tilesz = ICON_SIZE/3;
	int i, j, tile;

	XColor colours[(TILE_MAX-1)*COLOUR_MAX];
	unsigned long *icons[ICON_MAX];
	void *wm_icon = NULL;

	if (state->use_ewmh_icons && (wm_icon = ewmh_icon_alloc(icons))) {
		Colormap cmap = DefaultColormapOfScreen(XtScreen(shell));

		for (i = 0; i < TILE_MAX-1; i++) {
			for (j = 0; j < COLOUR_MAX; j++) {
				XColor *c = &colours[i*COLOUR_MAX+j];
				c->pixel = state->tile_colour[i][j];
			}
		}

		XQueryColors(display, cmap, colours, i*j);
	}

	for (i = 0; i < 9; i++) {
		tile = redraw_goal_tile(state, display, state->icon_pixmap,
		                        i%3, i/3, tilesz, tilesz);

		if (wm_icon) {
			XColor *c = &colours[(tile-1)*COLOUR_MAX];
			ewmh_tile16(icons[ICON_16x16], c, i%3, i/3);
			ewmh_tile24(icons[ICON_24x24], c, i%3, i/3);
			ewmh_tile32(icons[ICON_32x32], c, i%3, i/3);
			ewmh_tile48(icons[ICON_48x48], c, i%3, i/3);
		}
	}

	/*
	 * Clear and reset XtNiconPixmap otherwise it seems dtwm will not
	 * notice the changed icon.
	 */
	XtVaSetValues(shell, XtNiconPixmap, None, (char *)NULL);
	XtVaSetValues(shell, XtNiconPixmap, state->icon_pixmap, (char *)NULL);

	if (wm_icon) {
		Atom net_wm_icon = XInternAtom(display, "_NET_WM_ICON", FALSE);

		XChangeProperty(display, XtWindow(shell), net_wm_icon,
		                XA_CARDINAL, 32, PropModeReplace,
		                wm_icon, EWMH_ICON_NELEM);

		free(wm_icon);
	}
}

void x11_redraw_game(struct app_state *state, uint_fast32_t mask)
{
	Display *display = XtDisplay(state->goal);
	Window game = XtWindow(state->game);
	uint_least32_t buf[3], *gp = state->board.game;
	Dimension w, h;
	int i;

	XtVaGetValues(state->game, XtNwidth, &w, XtNheight, &h, (char *)NULL);
	w /= 5; h /= 5;

	if (state->view_goal_on_game) {
		for (i = 0; i < 3; i++) {
			buf[i] = state->board.goal[i];
			buf[i] = (gp[i] & ~GOAL_MASK) | (buf[i] << GOAL_SHIFT);
		}
		gp = buf;
	}

	/* Optimize the game end case where the outer frame is cleared */
	if (((gp[0] | gp[1] | gp[2]) & ~GOAL_MASK) == 0) {
		clear_border(state, display, game, w, h, mask);
		mask &= GOAL_MASK;
	}

	for (i = 0; i < 25; i++) {
		if (mask & 1) {
			redraw_tile(state, display, game,
			            gp[0], gp[1], gp[2],
			            i%5, i/5, w, h);
		}
		mask >>= 1;
	}
}