#include <seq.cvh>
#include <stdlib.h>
#include "treebuffer.h"

struct Node {
  Node * parent;
  int data;
};

struct Tree {
  int history;
  Node * last;    // reference to the last added node
};

Node * make_node(int data) {
  Node * node = (Node*)malloc(sizeof(Node));
  
  node->parent = NULL;
  node->data = data;
  return node;
}

int get_data(Node * node) {
  $assert(node, "attempt to get data from a invalid node reference");
  return node->data;
}

Tree * empty(int history) {
  Tree * tree = (Tree*)malloc(sizeof(Tree));
  
  tree->history = history;
  tree->last = NULL;
  return tree;
}

Tree * add(Tree * tree, int data) {
  Node * child = make_node(data);
  Tree * new_tree = empty(tree->history);  

  if (tree->last == NULL)
    new_tree->last = child;
  else {
    child->parent = tree->last;
    new_tree->last = child;
  }
  return new_tree;
}

// Note: "ancestors" is an 0-terminated array:
void take(Tree * tree, Node * ancestors[]) {
  int history = tree->history;
  int i = 0;
  Node * ancestor = tree->last;
  
  while (i < history && ancestor != NULL) {
    ancestors[i++] = ancestor;
    ancestor = ancestor->parent;
  }
  ancestors[i] = 0;
}

void delete(Tree * tree) {}