#include <string.h>
#include <stdlib.h>
#include "ucore/mbuf.h"

uint8_t *uc_mbuf_put(struct MBuf *mbuf, uint32_t size)
{
    uint8_t *data = mbuf->tail;

    if (uc_mbuf_tailroom(mbuf) < size) {
        return NULL;
    }

    mbuf->tail += size;

    return data;
}

uint8_t *uc_mbuf_push(struct MBuf *mbuf, uint32_t size)
{
    if (uc_mbuf_headroom(mbuf) < size) {
        return NULL;
    }

    mbuf->head -= size;

    return mbuf->head;
}

uint8_t *uc_mbuf_pull(struct MBuf *mbuf, uint32_t size)
{
    uint8_t *data = mbuf->head;

    if (uc_mbuf_len(mbuf) < size) {
        return NULL;
    }

    mbuf->head += size;

    return data;
}

void uc_mbuf_init(struct MBuf *mbuf, uint8_t *buf, uint32_t len, uint32_t headroom, uint32_t flags)
{
    mbuf->bufstart  = buf;
    mbuf->next      = NULL;
    mbuf->p1        = mbuf->p2 = mbuf->p3 = mbuf->p4 = NULL;
    mbuf->cookie    = NULL;
    mbuf->flags     = flags;
    mbuf->allocated = len + headroom;
    mbuf->head      = mbuf->bufstart + headroom;
    mbuf->tail      = mbuf->head;
}

struct MBuf *uc_mbuf_new_hr(uint32_t len, uint32_t headroom)
{
    struct MBuf *mbuf;
    uint8_t *buf;
    
    mbuf = malloc(sizeof *mbuf);
    if (mbuf == NULL) 
        return mbuf;

    buf = malloc(len + headroom);
    if (buf == NULL) {
        free(mbuf);
        return NULL;
    }

    uc_mbuf_init(mbuf, buf, len, headroom, UC_MBUF_FL_MALLOC);

    return mbuf;
}

struct MBuf *uc_mbuf_new_inline_hr(uint32_t len, uint32_t headroom)
{
    struct MBuf *mbuf;
    
    mbuf = malloc(sizeof *mbuf + len + headroom);
    if (mbuf == NULL) 
        return mbuf;

    uc_mbuf_init(mbuf, mbuf->inline_data, len, headroom, UC_MBUF_FL_MALLOC_INLINE);

    return mbuf;
}

void uc_mbuf_free(struct MBuf *mbuf)
{
    if (mbuf != NULL) {
        if (mbuf->flags & (UC_MBUF_FL_MALLOC | UC_MBUF_FL_MALLOC_BUF))
            free(mbuf->bufstart);
        
        if (mbuf->flags & (UC_MBUF_FL_MALLOC | UC_MBUF_FL_MALLOC_INLINE))
            free(mbuf);
    }
}

void uc_mbuf_zero(struct MBuf *mbuf)
{
    memset(mbuf->bufstart, 0, mbuf->allocated);
}

struct MBuf *uc_mbuf_copy_data(struct MBuf *mbuf)
{
    uint32_t len;
    struct MBuf *copy;
    uint8_t *data;

    len = uc_mbuf_len(mbuf);

    copy = uc_mbuf_new_hr(len, uc_mbuf_headroom(mbuf));
    if (copy == NULL) { 
        return NULL; 
    }

    data = uc_mbuf_put(copy, len);
    memcpy(data, mbuf->head, len);
    
    return copy;
}