#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);
}