#include <iostream>
#include <iomanip>
#include <vector>
#include <string>
#include "hashtable.h"
#include "token.h"
#include "node.h"

node::node(node_type t, string s, int v): token(t, s, v)
{ }

node * node::var(string s)
{ return new node(tvariable, s, 0); }

node * node::num(int v)
{ return new node(tnumber, "", v); }

node * node::op(string s)
{ return new node(toperator, s, 0); }

node * node::err(string s)
{ return new node(terror, s, 0); }

node * node::add(node * n)
{ links.push_back(n);
  return this; }

int node::getnumlinks()
{ return links.size(); }

node * node::getlink(int i)
{ return links[i]; }

int power(int a, int b)
{ if (b == 0)
  { if (a == 0)
      cout << "Error! 0^0\n";
    return 1; }
  if (b < 0)
  { if (a == 0)
      cout << "Error! 0^negative\n";
    if (a == 1)
      return 1;
    if (a == -1)
    { if (b & 1)
        return -1;
      return 1; }
    return 0; }
  int p = 1;
  int m = a;
  while (b > 0)
  { if (b & 1)
      p *= m;
    m *= m;
    b >>= 1; }
  return p; }

int node::evaluate(hashtable & mem)
{ node_type t = gettype();
  if (t == terror)
  { cerr << "Error! " << getstring() << "\n";
    return 0; }

  else if (t == tnumber)
    return getvalue();

  else if (t == tvariable)
  { int * p = mem.find(getstring());
    if (p == NULL)
    { cerr << "Error! undefined variable " << getstring() << "\n";
      return 0; }
    return * p; }

  else if (t == toperator)
  { int L = getlink(0)->evaluate(mem);
    int R = getlink(1)->evaluate(mem);
    char c = getstring()[0];
    switch (c)
    { case '+': return L + R;
      case '-': return L - R;
      case '*': return L * R;
      case '/': { if (R == 0)     
                  { cout << "division by zero!\n";
                    return 0; }
                  return L / R; }
      case '^': return power(L, R);
      default: { cout << "error operator '" << c << "'\n";
                 return 0; } } }  

  else
  { cerr << "Error evaluate node type " << gettype() << "\n";
    return 0; } }

void node::print()
{ node_type t = gettype();
  if (t == tnumber)
    cout << getvalue();
  else if (t == tvariable)
    cout << getstring();
  else if (t == toperator)
  { cout << "(";
    getlink(0)->print();
    cout << getstring();
    getlink(1)->print();
    cout << ")"; } }

void node::print1(int depth)
{ cout << setw(depth*3) << " ";
  node_type t = gettype();

  if (t == tnumber)
    cout << getvalue() << "\n";

  else if (t == tvariable)
    cout << getstring() << "\n";

  else if (t == toperator)
  { cout << getstring() << "\n";
    int num = getnumlinks();
    for (int i = 0; i < num; i += 1)
      getlink(i)->print1(depth+1); } }