/*-
 * Copyright (c) 2013 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by David A. Holland.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``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 FOUNDATION OR CONTRIBUTORS
 * 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.
 */

#include <assert.h>
#include <ctype.h>
#include <err.h>
#include <curses.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "pathnames.h"

////////////////////////////////////////////////////////////

static char *
xstrdup(const char *s)
{
	char *ret;

	ret = malloc(strlen(s) + 1);
	if (ret == NULL)
		errx(1, "Out of memory");

	strcpy(ret, s);
	return ret;
}

////////////////////////////////////////////////////////////

struct stringarray {
	char	**v;
	int	num;
};

static void
stringarray_init(struct stringarray *a)
{
	a->v = NULL;
	a->num = 0;
}

static void
stringarray_cleanup(struct stringarray *a)
{
	free(a->v);
}

static void
stringarray_add(struct stringarray *a, const char *s)
{
	a->v = realloc(a->v, (a->num + 1) * sizeof(a->v[0]));
	if (a->v == NULL)
		errx(1, "Out of memory");

	a->v[a->num] = xstrdup(s);
	a->num++;
}

////////////////////////////////////////////////////////////

static struct stringarray lines;
static struct stringarray sollines;
static bool	hinting;
static int	scrolldown;
static unsigned	curx;
static int	cury;

static void
readquote(void)
{
	FILE *f = popen(_PATH_FORTUNE, "r");
	if (!f)
		err(1, "%s", _PATH_FORTUNE);

	char buf[128], buf2[8 * sizeof(buf)];
	while (fgets(buf, sizeof(buf), f)) {
		char *s = strrchr(buf, '\n');
		assert(s && strlen(s) == 1);
		*s = '\0';

		int i, j;
		for (i = j = 0; buf[i]; i++) {
			if (buf[i] == '\t') {
				buf2[j++] = ' ';
				while (j % 8)
					buf2[j++] = ' ';
			} else if (buf[i] == '\b') {
				if (j > 0)
					j--;
			} else {
				buf2[j++] = buf[i];
			}
		}
		buf2[j] = 0;

		stringarray_add(&lines, buf2);
		stringarray_add(&sollines, buf2);
	}

	pclose(f);
}

static void
encode(void)
{
	int key[26];

	for (int i = 0; i < 26; i++)
		key[i] = i;
	for (int i = 26; i > 1; i--) {
		int c = random() % i;
		int t = key[i - 1];
		key[i - 1] = key[c];
		key[c] = t;
	}

	for (int y = 0; y < lines.num; y++) {
		for (int x = 0; lines.v[y][x]; x++) {
			if (islower((unsigned char)lines.v[y][x])) {
				int q = lines.v[y][x] - 'a';
				lines.v[y][x] = 'a' + key[q];
			}
			if (isupper((unsigned char)lines.v[y][x])) {
				int q = lines.v[y][x] - 'A';
				lines.v[y][x] = 'A' + key[q];
			}
		}
	}
}

static int
substitute(int ch)
{
	assert(cury >= 0 && cury < lines.num);
	if (curx >= strlen(lines.v[cury])) {
		beep();
		return -1;
	}

	int och = (unsigned char)lines.v[cury][curx];
	if (!isalpha(och)) {
		beep();
		return -1;
	}

	int loch = tolower(och);
	int uoch = toupper(och);
	int lch = tolower(ch);
	int uch = toupper(ch);

	for (int y = 0; y < lines.num; y++) {
		for (int x = 0; lines.v[y][x]; x++) {
			if (lines.v[y][x] == loch)
				lines.v[y][x] = lch;
			else if (lines.v[y][x] == uoch)
				lines.v[y][x] = uch;
			else if (lines.v[y][x] == lch)
				lines.v[y][x] = loch;
			else if (lines.v[y][x] == uch)
				lines.v[y][x] = uoch;
		}
	}

	return 0;
}

////////////////////////////////////////////////////////////

static void
redraw(void)
{
	erase();

	bool won = true;

	for (int i = 0; i < LINES - 1; i++) {
		move(i, 0);
		int ln = i + scrolldown;
		if (ln < lines.num) {
			for (int j = 0; lines.v[i][j]; j++) {
				int ch = (unsigned char)lines.v[i][j];
				int solch = (unsigned char)sollines.v[i][j];
				if (ch != solch && isalpha(ch))
					won = false;

				int attr = 0;
				if (hinting && ch == solch && isalpha(ch))
					attr = A_BOLD;
				addch(ch | attr);
			}
		}
		clrtoeol();
	}

	move(LINES - 1, 0);
	if (won)
		addstr("*solved* ");
	addstr("~ to quit, * to cheat, ^pnfb to move");

	move(cury - scrolldown, curx);

	refresh();
}

static void
opencurses(void)
{
	initscr();
	cbreak();
	noecho();
	keypad(stdscr, TRUE);
}

static void
closecurses(void)
{
	endwin();
}

////////////////////////////////////////////////////////////

static void
loop(void)
{
	bool done = false;

	while (!done) {
		redraw();

		int ch = getch();
		switch (ch) {
		case 1:		/* ^A */
		case KEY_HOME:
			curx = 0;
			break;
		case 2:		/* ^B */
		case KEY_LEFT:
			if (curx > 0) {
				curx--;
			} else if (cury > 0) {
				cury--;
				curx = strlen(lines.v[cury]);
			}
			break;
		case 5:		/* ^E */
		case KEY_END:
			curx = strlen(lines.v[cury]);
			break;
		case 6:		/* ^F */
		case KEY_RIGHT:
			if (curx < strlen(lines.v[cury])) {
				curx++;
			} else if (cury < lines.num - 1) {
				cury++;
				curx = 0;
			}
			break;
		case 12:	/* ^L */
			clear();
			break;
		case 14:	/* ^N */
		case KEY_DOWN:
			if (cury < lines.num - 1)
				cury++;
			if (curx > strlen(lines.v[cury]))
				curx = strlen(lines.v[cury]);
			if (scrolldown < cury - (LINES - 2))
				scrolldown = cury - (LINES - 2);
			break;
		case 16:	/* ^P */
		case KEY_UP:
			if (cury > 0)
				cury--;
			if (curx > strlen(lines.v[cury]))
				curx = strlen(lines.v[cury]);
			if (scrolldown > cury)
				scrolldown = cury;
			break;
		case '*':
			hinting = !hinting;
			break;
		case '~':
			done = true;
			break;
		default:
			if (isalpha(ch)) {
				if (!substitute(ch)) {
					if (curx < strlen(lines.v[cury]))
						curx++;
					if (curx == strlen(lines.v[cury]) &&
					    cury < lines.num - 1) {
						curx = 0;
						cury++;
					}
				}
			} else if (curx < strlen(lines.v[cury]) &&
				   ch == lines.v[cury][curx]) {
				curx++;
				if (curx == strlen(lines.v[cury]) &&
				    cury < lines.num - 1) {
					curx = 0;
					cury++;
				}
			} else {
				beep();
			}
			break;
		}
	}
}

////////////////////////////////////////////////////////////

int
main(void)
{
	stringarray_init(&lines);
	stringarray_init(&sollines);
	srandom(time(NULL));
	readquote();
	encode();

	opencurses();
	loop();
	closecurses();

	stringarray_cleanup(&sollines);
	stringarray_cleanup(&lines);

	return 0;
}