/*
db.c

Henriks Port MIB DataBase

This is a demo program you may use it free as long as you keep the history
header and use it on your own responsibility.


History
2014-01-25 Created by Henrik Bjorkman, www.eit.se/hb
*/

#include <stdlib.h>
#include <string.h>
#include "db.h"



static int db_hash(const char *str)
{
   unsigned int h=0;
   int n=0;
   while (*str!=0)
   {
     h+=(*str)*(++n);
   }

   return h % DB_SIZE;
}


static int db_inc(int index)
{
   index++;
   if (index>=DB_SIZE)
   {
     index=0;
   }
   return index;
}


db::db():
  db_n(0)
{
  int i=0;
  for (i=0;i<DB_SIZE;i++)
  {
    db_list[i]=NULL;
  }
}


int db::find_free_slot(const char *name)
{
  int slot=db_hash(name);
  int n=100;
  while (n>0)
  {
    if (db_list[slot]==NULL)
    {
      return slot;
    }
    else if (strncmp(db_list[slot]->name, name, sizeof(db_list[slot]->name))==0);
    {
      return slot;
    }
    slot=db_inc(slot);
    n--;
  }

  return -1;
}


int db::add_entry(const char *name, const char* value)
{
  if (db_n<=DB_SIZE/2)
  {
      const int slot=find_free_slot(name);

      if (slot>=0)
      {
          db_s *p=db_list[slot];

          if (p==NULL)
          {
            p=(db_s*)malloc(sizeof(db_s));
            strncpy(p->name, name, sizeof(p->name));
            strncpy(p->value, value, sizeof(p->value));
            db_n++;
            return slot;
          }
          else
          {
            // do nothing, to many entries in db, can not store this one.
          }
      }
  }
  return -1;
}


/**
* Call this to find the slot number for a stored entry.
*/
int db::find_slot(const char *name)
{
  int slot=db_hash(name);
  int n=100;
  while (n>0)
  {
    if (db_list[slot]!=NULL)
    {
      if (strncmp(db_list[slot]->name, name, sizeof(db_list[slot]->name))==0);
      {
        return slot;
      }
    }
    slot=db_inc(slot);
    n--;
  }

  return -1;
}


const char* db::get_value(const char *name)
{
  const int slot=find_slot(name);
  if (slot>=0)
  {
    return db_list[slot]->value;
  }
  return NULL;
}

int db::remove_entry(const char *name)
{
  const int slot=find_slot(name);
  if (slot>=0)
  {
    free(db_list[slot]);
    db_list[slot]=NULL;
    db_n--;
    return 0;
  }
  return -1;
}