#include "ringbuf.h"

/**
 * Read a single byte from a buffer
 *
 * \param   rb    pointer to ringbuffer struct
 * \param   data  pointer to data byte
 * \return  number of bytes read (0 if buffer was empty)
 */
int rb_getc(struct ringbuf *rb, char *data)
{
    if (!rb->len)
        return 0;

    *data = rb->buf[rb->pos++];
	if (rb->pos >= rb->bufsize)
		rb->pos -= rb->bufsize;
	rb->len--;
    return 1;
}


/**
 * Write a single byte to a buffer
 *
 * \param   rb    pointer to ringbuffer struct
 * \param   data  pointer to data byte
 * \return  number of bytes written (0 if buffer was full)
 */
int rb_putc(struct ringbuf *rb, const char data)
{
    if (rb->len >= rb->bufsize)
        return 0;

	unsigned i = rb->pos + rb->len;
	if (i >= rb->bufsize)
		i -= rb->bufsize;

	rb->buf[i] = data;
	rb->len++;

    return 1;
}

/**
 * Read from a buffer
 *
 */
int rb_read(struct ringbuf *rb, void *data, int len)
{
    if (len > rb->len)
        len = rb->len;

    int len1 = len;
    if (rb->pos + len1 >= rb->bufsize) {
        int len2 = (rb->pos + len1) - rb->bufsize;
        len1 -= len2;
        memcpy((char*)data + len1, rb->buf, len2);
    }
    memcpy(data, rb->buf + rb->pos, len1);

    rb->len -= len;
    rb->pos += len;
    if (rb->pos > rb->bufsize)
        rb->pos -= rb->bufsize;

    return len;
}


/**
 * Write to a buffer
 *
 * \param   rb    pointer to ringbuffer struct
 * \param   data  pointer to data byte
 * \return  number of bytes written (0 if buffer was full)
 *
 */
int rb_write(struct ringbuf *rb, const void *data, int len)
{
   int i = 0;
   char* d_ptr = (char*)data;
   while(len > 0 && rb_putc(rb, *d_ptr++)){
      len--;
      i++;
   }
   return(i);
   //  if (len > rb->bufsize - rb->len)
   //      len = rb->bufsize - rb->len;
    // 
   //  int len1 = len;
   //  if (rb->pos + rb->len + len1 >= rb->bufsize) {
   //      int len2 = (rb->pos + rb->len + len1) - rb->bufsize;
   //      len1 -= len2;
   //      memcpy(rb->buf, (char*)data + len1, len2);
   //  }
    // 
   //  memcpy(rb->buf + rb->pos + rb->len, data, len1);
    // 
   //  rb->len += len;
   //  return len;
}

int rb_getline(struct ringbuf *rb, char *ptr, int len){
   int ret = 0;
   char c;
   if (rb->len == 0){ 
		return 0;
	}

   while(rb_getc(rb, &c) && ret < len){
      ret++;
      *ptr++ = c;
      if(c == '\n'){
         *--ptr = '\0';
         return ret;
      }
   }
	rb_undo(rb, ret);
	return 0;
}

int rb_undo(struct ringbuf *rb, int len){
   if(len == 0){
      return(0);
   }
   if (rb->len + len > rb->bufsize){
      return(0);
   }
   if(rb->pos < len){
      rb->pos = rb->pos + rb->bufsize - len;
   }
   else{
      rb->pos = rb->pos - len;
   }
   rb->len = rb->len + len;
   return(len);
}