/*
 * 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 <inttypes.h>
#include <assert.h>
#include <Xm/XmAll.h>

#include "motif.h"
#include "motifstr.h"
#include "motifgui.h"

#define SPLIT_NUMERATOR    75
#define SPLIT_DENOMINATOR 100

#define MIN(a, b) ((a) < (b) ? (a) : (b))

/* XXX generate this list? */
enum {
	widgetMainWindow,
	widgetForm,
	widgetFrame,
	widgetDrawingArea,
	widgetCascadeButton,
	widgetPushButton,
	widgetMax,

	/* Pseudo-widgets */
	widgetMenuBar = widgetMax
};

static WidgetClass * const widgets[widgetMax] = {
	&xmMainWindowWidgetClass,
	&xmFormWidgetClass,
	&xmFrameWidgetClass,
	&xmDrawingAreaWidgetClass,
	&xmCascadeButtonWidgetClass,
	&xmPushButtonWidgetClass
};

static const struct ui_widget {
	uint_least16_t name;
	uint_least8_t subtree;
	uint_least8_t widget_type;
} mainwin[] = { MAINWIN_INITIALIZER };

static const struct ui_menuitem {
	struct ui_widget w;
	uint_least16_t label;
} mainmenu[] = { MAINMENU_INITIALIZER };

static void
ResizeGameArea(Widget form, XEvent *e, String *args, Cardinal *num_args)
{
	Widget game = XtNameToWidget(form, &tree_strtab[gameArea]);
	Widget goal = XtNameToWidget(form, &tree_strtab[goalArea]);
	Dimension w, h, gamesz, gameborder, goalsz, goalborder;
	int x, y, gap;

	XtVaGetValues(form, XmNwidth, &w, XmNheight, &h, (char *)NULL);
	XtVaGetValues(game, XmNshadowThickness, &gameborder, (char *)NULL);
	XtVaGetValues(goal, XmNshadowThickness, &goalborder,
	                    XmNleftOffset, &gap,
	                    (char *)NULL);

	gamesz = MIN(h, w * SPLIT_NUMERATOR / SPLIT_DENOMINATOR);
	gamesz = 5*( (gamesz - 2*gameborder)/5 ) + 2*gameborder;

	goalsz = MIN(gamesz*3/5, w - gamesz - gap);
	goalsz = 3*( (goalsz - 2*goalborder)/3 ) + 2*goalborder;

	x = (w - gamesz - goalsz - gap) / 2;
	if (x < 2) x = 0;

	y = (h - gamesz) / 2;
	if (y < 3) y = 0;

	XtVaSetValues(game, XmNleftOffset, x, XmNtopOffset, y, (char *)NULL);
	XtVaSetValues(game, XmNwidth, gamesz, XmNheight, gamesz, (char *)NULL);
	XtVaSetValues(goal, XmNwidth, goalsz, XmNheight, goalsz, (char *)NULL);
}

static void game_configure(Widget form)
{
	Widget gamearea = XtNameToWidget(form, &tree_strtab[gameArea]);
	Widget goalarea = XtNameToWidget(form, &tree_strtab[goalArea]);
	XtActionsRec resize_rec;

	assert(gamearea && goalarea);
	XtVaSetValues(form, XmNfractionBase, SPLIT_DENOMINATOR, (char *)NULL);

	XtVaSetValues(gamearea, XmNleftAttachment, XmATTACH_FORM,
	                        XmNtopAttachment, XmATTACH_FORM,
	                        (char *)NULL);

	XtVaSetValues(goalarea, XmNleftAttachment, XmATTACH_WIDGET,
	                        XmNleftWidget, gamearea,
	                        XmNtopAttachment, XmATTACH_OPPOSITE_WIDGET,
	                        XmNtopWidget, gamearea,
	                        (char *)NULL);

	resize_rec.string = "ResizeGameArea";
	resize_rec.proc = ResizeGameArea;
	XtAppAddActions(XtWidgetToApplicationContext(form), &resize_rec, 1);
	XtOverrideTranslations(form, XtParseTranslationTable(
		"<Configure>: ResizeGameArea()\n"
		"<Map>: ResizeGameArea()\n"
	));
}

static Widget create_widget(const struct ui_widget *item, Widget parent,
                            ArgList args, Cardinal num_args)
{
	String name = (void *)&tree_strtab[item->name];
	WidgetClass class;

	if (item->widget_type == widgetMenuBar)
		return XmCreateMenuBar(parent, name, args, num_args);

	assert(item->widget_type < widgetMax);
	class = *widgets[item->widget_type];
	return XtCreateWidget(name, class, parent, args, num_args);
}

static void
construct_widgets(const struct ui_widget *root, Widget parent, unsigned i)
{
	const struct ui_widget *item;

	for (item = &root[i]; item->name; item++) {
		Widget w = create_widget(item, parent, NULL, 0);

		if (item->subtree)
			construct_widgets(root, w, item->subtree);

		XtManageChild(w);
	}
}

static void menu_cb(Widget w, void *data, void *cb_data)
{
	XmRowColumnCallbackStruct *cbs = cb_data;
	XtCallActionProc(cbs->widget, XtName(cbs->widget), cbs->event, NULL, 0);
}

static Widget create_pulldown(Widget parent)
{
	Widget w;

	w = XmCreatePulldownMenu(parent, XtName(parent), NULL, 0);
	XtVaSetValues(parent, XmNsubMenuId, w, (char *)NULL);
	XtAddCallback(w, XmNentryCallback, menu_cb, NULL);

	return w;
}

static void
construct_menu(const struct ui_menuitem *root, Widget parent, unsigned i)
{
	const struct ui_menuitem *item;

	for (item = &root[i]; item->w.name; item++) {
		const char *label = &strtab[item->label];
		unsigned n = 0;
		Arg args[2];
		XmString s;
		Widget w;

		if (XtClass(parent) == *widgets[widgetCascadeButton])
			parent = create_pulldown(parent);

		if (label[0] && label[1] == '|') {
			XtSetArg(args[n], XmNmnemonic, label[0]); n++;
			label += 2;
		}

		s = XmStringCreateLocalized((void *)label);
		XtSetArg(args[n], XmNlabelString, s); n++;

		w = create_widget(&item->w, parent, args, n);

		XmStringFree(s);

		if (item->w.subtree)
			construct_menu(root, w, item->w.subtree);

		XtManageChild(w);
	}
}

static void game_resize(Widget w, void *data, void *cb_data)
{
	if (XtIsRealized(w))
		x11_redraw_game(data, -1);
}

static void goal_resize(Widget w, void *data, void *cb_data)
{
	if (XtIsRealized(w))
		x11_redraw_goal(data, -1);
}

static void do_input_move(struct app_state *state, int x, int y)
{
	uint_least32_t *gp = state->board.game, prev[4];

	memcpy(prev, gp, sizeof prev);
	if (game_do_move(&state->board, x, y) == 0) {
		uint_least32_t mask;

		if (game_check_goal(&state->board)) {
			printf("You win!\n");
			game_finish(&state->board);
		}

		/* Figure out which tiles changed */
		prev[0] ^= gp[0];
		prev[1] ^= gp[1];
		prev[2] ^= gp[2];
		mask = prev[0] | prev[1] | prev[2];

		x11_redraw_game(state, mask);
	}
}

static void game_input(Widget w, void *data, void *cb_data)
{
	XmDrawingAreaCallbackStruct *cbs = cb_data;
	XButtonEvent *click = &cbs->event->xbutton;
	struct app_state *state = data;
	Dimension width, height;
	unsigned x = -1, y = -1;

	switch (cbs->event->type) {
	case ButtonPress:
		XtVaGetValues(w, XmNwidth, &width,
		                 XmNheight, &height,
		                 (char *)NULL);
		x = click->x / (width/5);
		y = click->y / (height/5);
	}

	if (x > 4 || y > 4)
		return;

	do_input_move(state, x, y);
}

/* Figure out which tiles intersect a rectangle. */
static uint_fast32_t
expose_mask(int rect_x, int rect_y, int rect_w, int rect_h,
                                    int tile_w, int tile_h)
{
	return board_right(rect_x / tile_w)
	     & board_below(rect_y / tile_h)
	     & board_above((rect_y + rect_h - 1) / tile_h)
	     & board_left((rect_x + rect_w - 1) / tile_w);
}

static void game_expose(Widget w, void *data, void *cb_data)
{
	XmDrawingAreaCallbackStruct *cbs = cb_data;
	XExposeEvent *e = &cbs->event->xexpose;
	Dimension width, height;
	uint_fast32_t mask;

	XtVaGetValues(w, XmNwidth, &width, XmNheight, &height, (char *)NULL);
	if (!(width /= 5) || !(height /= 5))
		return;

	mask = expose_mask(e->x, e->y, e->width, e->height, width, height);
	x11_redraw_game(data, mask);
}

static void goal_expose(Widget w, void *data, void *cb_data)
{
	XmDrawingAreaCallbackStruct *cbs = cb_data;
	XExposeEvent *e = &cbs->event->xexpose;
	Dimension width, height;
	uint_fast32_t mask;

	XtVaGetValues(w, XmNwidth, &width, XmNheight, &height, (char *)NULL);
	if (!(width /= 3) || !(height /= 3))
		return;

	mask = expose_mask(e->x, e->y, e->width, e->height, width, height);
	x11_redraw_goal(data, mask);
}

void ui_initialize(struct app_state *state, Widget shell)
{
	Widget menubar, help;

	construct_widgets(mainwin, shell, 0);

	menubar = XtNameToWidget(shell, "*menuBar");
	construct_menu(mainmenu, menubar, 0);

	help = XtNameToWidget(menubar, "helpMenu");
	XtVaSetValues(menubar, XmNmenuHelpWidget, help, (char *)NULL);

	game_configure(XtNameToWidget(shell, "*game"));

	state->game = XtNameToWidget(shell, "*gameCanvas");
	XtAddCallback(state->game, XmNresizeCallback, game_resize, state);
	XtAddCallback(state->game, XmNexposeCallback, game_expose, state);
	XtAddCallback(state->game, XmNinputCallback,  game_input,  state);

	state->goal = XtNameToWidget(shell, "*goalCanvas");
	XtAddCallback(state->goal, XmNresizeCallback, goal_resize, state);
	XtAddCallback(state->goal, XmNexposeCallback, goal_expose, state);
}