#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdarg.h>
#include <ucore/ucore_buffer.h>
 
GBuf*
uc_new_gbuf(size_t initsz)
{	
	GBuf *p;
	p = malloc(sizeof *p);
	if (p == NULL)
		return NULL;

	p->used = 0;
	p->len = initsz;
	p->buf = NULL;
    p->ref_cnt = 1;

	if (initsz != 0 && (p->buf = malloc(initsz)) == NULL) {
		free(p);
		return NULL;
	} 
	
	return p;
}

void
uc_gbuf_ref(GBuf *buf)
{
    buf->ref_cnt++;
}

void
uc_gbuf_unref(GBuf *buf)
{
    buf->ref_cnt--;

    if (buf->ref_cnt == 0) {
        free(buf->buf);
        free(buf);
    }
}

int 
uc_gbuf_append(GBuf *buf,const void *data,size_t len)
{
	unsigned char *gbuf;
	
	if (buf->len - buf->used < len)
		if (uc_gbuf_grow(buf, len + len/2))
			return -1;

	gbuf = buf->buf;
	memcpy(gbuf + buf->used, data, len);
	buf->used += len;
	
	return 0;	
}

int uc_gbuf_printf(GBuf *buf, const char *fmt, ...)
{
    va_list ap;
    va_list apc;
    int rc = 0;
    int remaining;

    va_start(ap, fmt);

    //increment buffer if snprintf indicates the results were truncated
    do {

        va_copy(apc, ap);
        char *gbuf;

        remaining = uc_gbuf_remaining(buf);
        if (rc >= remaining) { 
            if (uc_gbuf_grow(buf, buf->len + (rc - remaining) + 1)) {
                rc = -1;
                va_end(apc);
                break;
            }
            remaining = uc_gbuf_remaining(buf);
        }

        gbuf = buf->buf;

        rc = vsnprintf(gbuf + buf->used, remaining, fmt, apc);
        va_end(apc);

    } while (rc >= remaining);

    if(rc > 0) {
        buf->used += rc; 
    }
   
   va_end(ap);

   return rc; 
}

int
uc_gbuf_grow(GBuf *buf, size_t addlen)
{
	void *tmp;
	size_t newsz;

	newsz = buf->len + addlen;

	tmp = realloc(buf->buf,newsz);
	if (tmp == NULL)
		return -1;

	buf->buf = tmp;
	buf->len = newsz;

	return 0;
}