#include <libowfat/stralloc.h>
#include <libowfat/buffer.h>
#include <libowfat/errmsg.h>
#include <libowfat/str.h>
#include <ctype.h>

#define AUTH_HEADER "authorization: bearer " 
#define AUTH_HEADER_LEN str_len(AUTH_HEADER) 

static int startswithlower(stralloc *sa, char *prefix, size_t prefixlen)
{
  size_t i;
  if (sa->len < prefixlen) return 0;
  for (i=0;i<prefixlen;i++)
    if (tolower(sa->s[i]) != prefix[i])
      return 0;
  return 1;
}

int parse_token(buffer *b, stralloc *result)
{
  stralloc line;
  int r;
  stralloc_init(result);
  for (;;) {
    r=buffer_getnewline_sa(b,&line);
    if (r==0) break;
    if (r<0) { carpsys("read line"); goto err; } 

    /* header field names are case-sensitive
     * https://www.rfc-editor.org/info/rfc7230/#section-3.2 */
    if (startswithlower(&line,AUTH_HEADER,AUTH_HEADER_LEN)) {
      stralloc_chomp(&line); 
      if (!stralloc_copyb(result, line.s+AUTH_HEADER_LEN,
            line.len-AUTH_HEADER_LEN)
      ) { carpsys("out of memory"); goto err; }
      break;
    }
  }

  stralloc_free(&line);
  return 1;
err:
  stralloc_free(&line);
  return 0;
}