#include <stddef.h>
#include <initrd.h>
#include <kmalloc.h>
#include <random.h>
#include <string.h>

#define nullnode ((file_node_t *)0)

void _init_node(file_node_t *node) {
  node->l = nullnode;
  node->r = nullnode;
  node->rand = random();
  node->node_size = 1;
}

void _pull_from(file_node_t *to, file_node_t *from)
{
  if (!from)
    return;

  to->node_size += from->node_size;
}

void _pull(file_node_t *node)
{
  node->node_size = 1;
  _pull_from(node, node->l);
  _pull_from(node, node->r);
}

file_node_t *_merge(file_node_t *a, file_node_t *b)
{
  if (!a || !b)
    return a ?: b;

  if (a->rand < b->rand) {
    a->r = _merge(a->r, b);
    _pull(a);
    return a;
  }
  b->l = _merge(a, b->l);
  _pull(b);
  return b;
}

void _split(file_node_t *rt, const char *s, file_node_t **a, file_node_t **b)
{
  if (!rt) {
    *a = *b = nullnode;
    return;
  }

  if (strcmp(s, rt->filename) < 0) {
    *a = rt;
    _split((*a)->r, s, &(*a)->r, b);
    _pull(*a);
  } else {
    *b = rt;
    _split((*b)->l, s, a, &(*b)->l);
    _pull(*b);
  }
}


file_node_t *initrd_init(void)
{
  // TODO
  
  return nullnode;
}

file_node_t *_node_bs(file_node_t *cur, const char *s)
{
  if (!cur) 
    return nullnode;

  int cmp = strcmp(s, cur->filename);
  if (cmp < 0)
    return _node_bs(cur->r, s);
  if (cmp > 0)
    return _node_bs(cur->l, s);
  return cur; // cmp == 0
}

file_node_t *initrd_get(file_node_t *root, const char *filename)
{
  return _node_bs(root, filename);
}