#include "decoding.h"
#include "bruteforce.h"

using namespace std;

vector<bit> bruteforce(
  const vector<bit> &bits,
  const vector<bigint> &params,
  const vector<bigint> &attackparams
)
{
  bigint n = params.at(0);
  bigint k = params.at(1);
  bigint w = params.at(2);
  bigint iters = attackparams.at(0);

  auto inputs = decoding_deserialize(bits,params);
  auto pk = inputs.first;
  auto ct = inputs.second;

  vector<vector<bit>> H;
  for (bigint i = 0;i < n-k;++i) {
    vector<bit> Hi;
    for (bigint j = 0;j < n-k;++j)
      Hi.push_back(bit(i == j));
    Hi.insert(Hi.end(),pk.at(i).begin(),pk.at(i).end());
    H.push_back(Hi);
  }

  vector<bit> result(n);

  vector<bigint> positions;
  for (bigint j = 0;j < w;++j) positions.push_back(j);

  for (bigint iter = 0;iter < iters;++iter) {
    vector<bit> Hguess(n-k);
    for (bigint i = 0;i < n-k;++i)
      for (bigint j = 0;j < w;++j)
        Hguess.at(i) ^= H.at(i).at(positions.at(j));
    bit mismatch;
    for (bigint j = 0;j < n-k;++j)
      mismatch |= Hguess[j]^ct[j];
    for (bigint j = 0;j < n;++j)
      result.at(j) &= mismatch;
    for (bigint j = 0;j < w;++j)
      result.at(positions.at(j)) = result.at(positions.at(j)).orn(mismatch);

    for (bigint j = w-1;j >= 0;--j) {
      positions.at(j) += 1;
      if (positions.at(j) <= n-w+j) {
        while (++j < w) positions.at(j) = positions.at(j-1)+1;
        break;
      }
    }
  }

  return result;
}