// Copyright (c) 2017, The Monero Project
// 
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
// 
// 1. Redistributions of source code must retain the above copyright notice, this list of
//    conditions and the following disclaimer.
// 
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
//    of conditions and the following disclaimer in the documentation and/or other
//    materials provided with the distribution.
// 
// 3. Neither the name of the copyright holder nor the names of its contributors may be
//    used to endorse or promote products derived from this software without specific
//    prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Adapted from Python code by Sarang Noether

#include "misc_log_ex.h"
#include "common/perf_timer.h"
extern "C"
{
#include "crypto/crypto-ops.h"
}
#include "rctOps.h"
#include "multiexp.h"

#undef MONERO_DEFAULT_LOG_CATEGORY
#define MONERO_DEFAULT_LOG_CATEGORY "multiexp.boscoster"

//#define MULTIEXP_PERF(x) x
#define MULTIEXP_PERF(x)

namespace rct
{

static inline bool operator<(const rct::key &k0, const rct::key&k1)
{
  for (int n = 31; n >= 0; --n)
  {
    if (k0.bytes[n] < k1.bytes[n])
      return true;
    if (k0.bytes[n] > k1.bytes[n])
      return false;
  }
  return false;
}

static inline rct::key div2(const rct::key &k)
{
  rct::key res;
  int carry = 0;
  for (int n = 31; n >= 0; --n)
  {
    int new_carry = (k.bytes[n] & 1) << 7;
    res.bytes[n] = k.bytes[n] / 2 + carry;
    carry = new_carry;
  }
  return res;
}

rct::key bos_coster_heap_conv(std::vector<MultiexpData> &data)
{
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(bos_coster, 1000000));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(setup, 1000000));
  size_t points = data.size();
  CHECK_AND_ASSERT_THROW_MES(points > 1, "Not enough points");
  std::vector<size_t> heap(points);
  for (size_t n = 0; n < points; ++n)
    heap[n] = n;

  auto Comp = [&](size_t e0, size_t e1) { return data[e0].scalar < data[e1].scalar; };
  std::make_heap(heap.begin(), heap.end(), Comp);
  MULTIEXP_PERF(PERF_TIMER_STOP(setup));

  MULTIEXP_PERF(PERF_TIMER_START_UNIT(loop, 1000000));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(pop, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(pop));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(add, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(add));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(sub, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(sub));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(push, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(push));
  while (heap.size() > 1)
  {
    MULTIEXP_PERF(PERF_TIMER_RESUME(pop));
    std::pop_heap(heap.begin(), heap.end(), Comp);
    size_t index1 = heap.back();
    heap.pop_back();
    std::pop_heap(heap.begin(), heap.end(), Comp);
    size_t index2 = heap.back();
    heap.pop_back();
    MULTIEXP_PERF(PERF_TIMER_PAUSE(pop));

    MULTIEXP_PERF(PERF_TIMER_RESUME(add));
    ge_cached cached;
    ge_p3_to_cached(&cached, &data[index1].point);
    ge_p1p1 p1;
    ge_add(&p1, &data[index2].point, &cached);
    ge_p1p1_to_p3(&data[index2].point, &p1);
    MULTIEXP_PERF(PERF_TIMER_PAUSE(add));

    MULTIEXP_PERF(PERF_TIMER_RESUME(sub));
    sc_sub(data[index1].scalar.bytes, data[index1].scalar.bytes, data[index2].scalar.bytes);
    MULTIEXP_PERF(PERF_TIMER_PAUSE(sub));

    MULTIEXP_PERF(PERF_TIMER_RESUME(push));
    if (!(data[index1].scalar == rct::zero()))
    {
      heap.push_back(index1);
      std::push_heap(heap.begin(), heap.end(), Comp);
    }

    heap.push_back(index2);
    std::push_heap(heap.begin(), heap.end(), Comp);
    MULTIEXP_PERF(PERF_TIMER_PAUSE(push));
  }
  MULTIEXP_PERF(PERF_TIMER_STOP(push));
  MULTIEXP_PERF(PERF_TIMER_STOP(sub));
  MULTIEXP_PERF(PERF_TIMER_STOP(add));
  MULTIEXP_PERF(PERF_TIMER_STOP(pop));
  MULTIEXP_PERF(PERF_TIMER_STOP(loop));

  MULTIEXP_PERF(PERF_TIMER_START_UNIT(end, 1000000));
  //return rct::scalarmultKey(data[index1].point, data[index1].scalar);
  std::pop_heap(heap.begin(), heap.end(), Comp);
  size_t index1 = heap.back();
  heap.pop_back();
  ge_p2 p2;
  ge_scalarmult(&p2, data[index1].scalar.bytes, &data[index1].point);
  rct::key res;
  ge_tobytes(res.bytes, &p2);
  return res;
}

rct::key bos_coster_heap_conv_robust(std::vector<MultiexpData> &data)
{
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(bos_coster, 1000000));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(setup, 1000000));
  size_t points = data.size();
  CHECK_AND_ASSERT_THROW_MES(points > 1, "Not enough points");
  std::vector<size_t> heap(points);
  for (size_t n = 0; n < points; ++n)
    heap[n] = n;

  auto Comp = [&](size_t e0, size_t e1) { return data[e0].scalar < data[e1].scalar; };
  std::make_heap(heap.begin(), heap.end(), Comp);
  MULTIEXP_PERF(PERF_TIMER_STOP(setup));

  MULTIEXP_PERF(PERF_TIMER_START_UNIT(loop, 1000000));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(pop, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(pop));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(div, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(div));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(add, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(add));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(sub, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(sub));
  MULTIEXP_PERF(PERF_TIMER_START_UNIT(push, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(push));
  while (heap.size() > 1)
  {
    MULTIEXP_PERF(PERF_TIMER_RESUME(pop));
    std::pop_heap(heap.begin(), heap.end(), Comp);
    size_t index1 = heap.back();
    heap.pop_back();
    std::pop_heap(heap.begin(), heap.end(), Comp);
    size_t index2 = heap.back();
    heap.pop_back();
    MULTIEXP_PERF(PERF_TIMER_PAUSE(pop));

    ge_cached cached;
    ge_p1p1 p1;

    MULTIEXP_PERF(PERF_TIMER_RESUME(div));
    while (1)
    {
      rct::key s1_2 = div2(data[index1].scalar);
      if (!(data[index2].scalar < s1_2))
       break;
      if (data[index1].scalar.bytes[0] & 1)
      {
        data.resize(data.size()+1);
        data.back().scalar = rct::identity();
        data.back().point = data[index1].point;
        heap.push_back(data.size() - 1);
        std::push_heap(heap.begin(), heap.end(), Comp);
      }
      data[index1].scalar = div2(data[index1].scalar);
      ge_p3_to_cached(&cached, &data[index1].point);
      ge_add(&p1, &data[index1].point, &cached);
      ge_p1p1_to_p3(&data[index1].point, &p1);
    }
    MULTIEXP_PERF(PERF_TIMER_PAUSE(div));

    MULTIEXP_PERF(PERF_TIMER_RESUME(add));
    ge_p3_to_cached(&cached, &data[index1].point);
    ge_add(&p1, &data[index2].point, &cached);
    ge_p1p1_to_p3(&data[index2].point, &p1);
    MULTIEXP_PERF(PERF_TIMER_PAUSE(add));

    MULTIEXP_PERF(PERF_TIMER_RESUME(sub));
    sc_sub(data[index1].scalar.bytes, data[index1].scalar.bytes, data[index2].scalar.bytes);
    MULTIEXP_PERF(PERF_TIMER_PAUSE(sub));

    MULTIEXP_PERF(PERF_TIMER_RESUME(push));
    if (!(data[index1].scalar == rct::zero()))
    {
      heap.push_back(index1);
      std::push_heap(heap.begin(), heap.end(), Comp);
    }

    heap.push_back(index2);
    std::push_heap(heap.begin(), heap.end(), Comp);
    MULTIEXP_PERF(PERF_TIMER_PAUSE(push));
  }
  MULTIEXP_PERF(PERF_TIMER_STOP(push));
  MULTIEXP_PERF(PERF_TIMER_STOP(sub));
  MULTIEXP_PERF(PERF_TIMER_STOP(add));
  MULTIEXP_PERF(PERF_TIMER_STOP(pop));
  MULTIEXP_PERF(PERF_TIMER_STOP(loop));

  MULTIEXP_PERF(PERF_TIMER_START_UNIT(end, 1000000));
  //return rct::scalarmultKey(data[index1].point, data[index1].scalar);
  std::pop_heap(heap.begin(), heap.end(), Comp);
  size_t index1 = heap.back();
  heap.pop_back();
  ge_p2 p2;
  ge_scalarmult(&p2, data[index1].scalar.bytes, &data[index1].point);
  rct::key res;
  ge_tobytes(res.bytes, &p2);
  return res;
}

}