/*
  SillyMUD Distribution V1.1b             (c) 1993 SillyMUD Developement
 
  See license.doc for distribution terms.   SillyMUD is based on DIKUMUD
*/

#include <stdio.h>
#include <string.h>
 
#include "protos.h" /* function prototypes for parser functions */
 
/* Sorted selection of the commands for quick lookup */
struct radix_list radix_head[27];
 
/* Quick reference hash table */
byte HashTable[256];
 
/* Command list is allocated at run-time in the following order:
** name, command pointer, number, min_position, min_level, next, previous.
** the number can be anything, it's no longer really needed, although
** it is recommended that you keep them in numeric order to avoid confusion.
** NOTE: next and previous MUST be defined as NULL to avoid any possible
** problems.
*/
 
 
/* Adds a command to the Command List radix. */
void AddCommand(char *name, void (*func), int number, int min_pos, int min_lev)
{
 NODE *n;
 int len, radix;
 
 n = (NODE *) malloc(sizeof(NODE));
 
 n->name = (char *)strdup(name);
 n->func = func;
 n->number = number;
 n->min_pos = min_pos;
 n->min_level = min_lev;
 n->next = NULL;
 n->previous = NULL;
 n->log = 0;
 
 radix = HashTable[*name];
 len = strlen(name);
 
 AddNodeTail(n, len, radix);
}
 
 
/* Generates a hash table that assigns 1 - 26 to 'a' - 'z' and 'A' - 'Z'.
** All other results are 0
*/
void GenerateHash()
{
 register int i;
 
 for(i = 0; i <= 255; i++)
    if((i >= 'a') && (i <= 'z'))
        HashTable[i] = i - MAGIC;
    else if((i >= 'A') && (i <= 'Z'))
        HashTable[i] = i - (MAGIC - 32);
    else
        HashTable[i] = 0;
}
 
 
 
/* Adds a node to the end of a radix-sorted linked list.
*/
void AddNodeTail(NODE *n, int length, int radix)
{
 /* Check to see if we're at the beginning, if so, start here. */
 if(radix_head[radix].next == NULL) {
    radix_head[radix].next = n;
    radix_head[radix].number = 1;
    radix_head[radix].max_len = length;
    n->previous = NULL;
    return;
 }
 
 /* Traverse the list until we find the end, when we find it, add to it */
 {
  register NODE *i;
 
  for(i = radix_head[radix].next; i->next; i = i->next);
  i->next = n;
  n->previous = i;
  radix_head[radix].number++;
  n->next = NULL; 
  if(radix_head[radix].max_len < length)
     radix_head[radix].max_len = length;
 }
}
 
 
/* This will search by name for a specific node and return a pointer to it.
** Passed is a pointer to the first node in the radix.  Any checking as to
** whether or not the node is valid should happen before entering here.
** NOTE: This uses partial matching, change strncmp to strcmp for full matching
** Return value is the node if it exists, or NULL if it does not.
*/
NODE *SearchForNodeByName(NODE *head, char *name, int len)
{
 register NODE *i;
 
 i = head;
 while(i) {
    if(!(strncmp(i->name, name, len)))
        return(i);
    i = i->next;
 }
 
 return(NULL);
}
 
 
/* Initialization for the radix sorting routines.  Call this to begin the sort.
** This will generate the hash table and sort everything via the hash-table.
*/
void InitRadix()
{
 register int i;
 
 for(i = 0; i <= 26; i++) {
    radix_head[i].next = NULL;
    radix_head[i].number = 0;
    radix_head[i].max_len = 0;
 }
 
 GenerateHash();
 
}
 
 
/* This will do all of the validation and search for a NODE by name.
** Will return a pointer to the NODE if it exists, NULL if it doesn't.
*/
NODE *FindValidCommand(char *name)
{
 register int len;
 register int radix;
 
 radix = HashTable[name[0]];
 len = strlen(name);
 
 if(radix_head[radix].number && len <= radix_head[radix].max_len)
    return(SearchForNodeByName(radix_head[radix].next, name, len));
 
 return(NULL);
}