#include <string.h>

#include "mrk/buf.h"

mrk_err mrk_buf_init(mrk_buf *buf) {
  MRK_MALLOC(&buf->s, 2);

  // 2 ^ 0
  buf->cap = 1;
  buf->len = 0;
  buf->s[buf->len] = '\0';

  return mrk_err_ok;
}

mrk_err mrk_buf_expand(mrk_buf *buf, size_t required) {
  size_t new_cap = buf->cap;

  while (buf->len + required >= new_cap) {
    // Grow buffer size in powers of two
    new_cap <<= 1;
  }

  // No need to reallocate if there's already enough space
  if (new_cap == buf->cap) {
    return mrk_err_ok;
  }

  char *new_buf = realloc(buf->s, new_cap + 1);

  if (new_buf == NULL) {
    return mrk_err_failed_alloc;
  }

  buf->s = new_buf;
  buf->cap = new_cap;

  return mrk_err_ok;
}

mrk_err mrk_buf_compact(mrk_buf *buf) {
  char *new_buf = realloc(buf->s, buf->len + 1);

  if (new_buf == NULL) {
    return mrk_err_failed_alloc;
  }

  buf->s = new_buf;
  buf->cap = buf->len;

  return mrk_err_ok;
}

mrk_err mrk_buf_append(mrk_buf *buf, const char *s) {
  size_t len = strlen(s);

  return mrk_buf_append_n(buf, s, len);
}

mrk_err mrk_buf_append_n(mrk_buf *buf, const char *s, size_t len) {
  MRK_RES(mrk_buf_expand(buf, len));

  memcpy(&buf->s[buf->len], s, len);
  buf->len += len;

  // Keep the buffer nul-terminated
  buf->s[buf->len] = '\0';

  return mrk_err_ok;
}