/* spellathon.c -- Spellathon

Copyright (C) 2011 Stephen D. Cofer.  Released under the GPL version 2 ONLY.
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 2
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, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

Usage: 
spellathon [spellathon-grid]

Spellathon grid is the thirteen letters in the puzzle organized from left to right and
top to bottom and passed as a single argument with no spaces.
EXAMPLE:
spellathon HTCYNLAILGBUR

for

  H   T
    C
  Y   N
L   A    I
  L   G
    B
  U   R

You need the default word dictionary installed on your system (usually as /usr/share/dict/words);
for other dictionaries or for Windows, manually adjust DICTIONARY below to point to a full 
dictionary.

By default this is for 5-letter Spellathons, the most common.  For a different one, you'll need to adjust some code.
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <error.h>
#include <errno.h>
#include <ctype.h>

#define MAX_WORDS 100
#define DICTIONARY "/usr/share/dict/words"
#define USAGE "USAGE:\nspellathon [spellathon-grid]\nSpellathon grid is the thirteen letters in the puzzle organized from left to right and top to bottom and passed as a single argument with no spaces.\nEXAMPLE:\nspellathon HTCYNLAILGBUR\n"
char spell_nodes [13]; 
int node_links [13][12] = 
	{{1,2,3,5,6,-1,-1,-1,-1,-1,-1,-1}, {0,2,4,6,7,-1,-1,-1,-1,-1,-1,-1}, {0,1,6,-1,-1,-1,-1,-1,-1,-1,-1,-1}, 
	{0,5,6,-1,-1,-1,-1,-1,-1,-1,-1,-1}, {1,6,7,-1,-1,-1,-1,-1,-1,-1,-1,-1}, {0,3,6,8,11,-1,-1,-1,-1,-1,-1,-1}, 
	{0,1,2,3,4,5,7,8,9,10,11,12}, {1,4,6,9,12,-1,-1,-1,-1,-1,-1,-1}, {5,6,11,-1,-1,-1,-1,-1,-1,-1,-1,-1}, 
	{6,7,12,-1,-1,-1,-1,-1,-1,-1,-1,-1}, {6,11,12,-1,-1,-1,-1,-1,-1,-1,-1,-1}, {5,6,8,10,12,-1,-1,-1,-1,-1,-1,-1}, 
	{6,7,9,10,11,-1,-1,-1,-1,-1,-1,-1}}; /* this could be done better or with actual node pointers but I'm lazy */
int found = 0;
char *wordlist[MAX_WORDS];

int main (int argc, char*argv[])
{
	
	FILE *dict;
	char entry[1024];
	int i;

	if (argc != 2)
	{
		printf ("Error: Not enough arguments\n");
		printf (USAGE);
		return EXIT_FAILURE;
	}

	if (strlen (argv[1]) != 13)
	{ 
		printf ("Error: The spellathon grid must be exactly thirteen characters.\n");
		printf (USAGE);
		return EXIT_FAILURE;
	}
	snprintf (spell_nodes, 14, "%s", argv[1]);
	for (i=0; i<13; i++)
		spell_nodes[i] = tolower(spell_nodes[i]);

	dict = fopen (DICTIONARY, "r");
	if (dict == NULL)
	{

		int eno = errno;
		fprintf (stderr, "Error opening %s: %s\n", DICTIONARY, strerror(eno));
		return EXIT_FAILURE;
	}

	while (fgets (entry, 1024, dict) != NULL)
	{
		int ent_len;
		ent_len = strlen (entry) -1;
		
		if (ent_len != 5) continue;
		
		entry[ent_len] = '\0'; /* fgets includes newline */
		

		for (i=0; i<13; i++)
		{
			if (spell_nodes[i] == entry[0])
			{
				find_next_node (i, entry, 1); 

			}
		}

	}
	for (i=0; i<found; i++)
	{
		printf ("%s\n", wordlist[i]);
		free (wordlist[i]);
	}
	printf ("Total words: %d\n", found);
	fclose (dict);


}

int find_next_node (int existing_node, char entry[], int depth)
{
	int i;
	if (depth<5)
	{
		for (i=0; i<12; i++)
		{
			if (node_links[existing_node][i] != -1)
			{
				if (spell_nodes[node_links[existing_node][i]] == entry[depth])
				{
					
					find_next_node(node_links[existing_node][i], entry, depth+1);
				}
			}
		}
	}
	else
	{
		int w_locate = 0;
		for (i=0; i<found; i++)
		{
			if (strcmp (wordlist[i], entry) == 0)
				w_locate = 1;
		}
		if (!w_locate)
		{
			wordlist[found] = malloc (6);
			snprintf (wordlist[found], 6, "%s", entry);
			found++;
		}
	}
	return depth;
}