// Copyright (c) 2019, The Monero Project
// 
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// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
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// 1. Redistributions of source code must retain the above copyright notice, this list of
//    conditions and the following disclaimer.
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// 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.
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// 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
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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#include <stdint.h>
#include <vector>
#include "cryptonote_basic/cryptonote_basic.h"
#include "cryptonote_basic/cryptonote_format_utils.h"
#include "common/median.h"
#include "blockchain.h"
#include "tx_sanity_check.h"

namespace cryptonote
{

static auto logcat = log::Cat("verify");

bool tx_sanity_check(const std::string &tx_blob, uint64_t rct_outs_available)
{
  cryptonote::transaction tx;

  if (!cryptonote::parse_and_validate_tx_from_blob(tx_blob, tx))
  {
    log::error(logcat, "Failed to parse transaction");
    return false;
  }

  if (cryptonote::is_coinbase(tx))
  {
    log::error(logcat, "Transaction is coinbase");
    return false;
  }
  std::set<uint64_t> rct_indices;
  size_t n_indices = 0;

  for (const auto& txin : tx.vin)
  {
    auto* in_to_key = std::get_if<cryptonote::txin_to_key>(&txin);
    if (!in_to_key)
      continue;
    if (in_to_key->amount != 0)
      continue;
    for (uint64_t offset : cryptonote::relative_output_offsets_to_absolute(in_to_key->key_offsets))
      rct_indices.insert(offset);
    n_indices += in_to_key->key_offsets.size();
  }

  return tx_sanity_check(rct_indices, n_indices, rct_outs_available);
}

bool tx_sanity_check(const std::set<uint64_t> &rct_indices, size_t n_indices, uint64_t rct_outs_available)
{
  if (n_indices <= 10)
  {
    log::debug(logcat, "n_indices is only {}, not checking", n_indices);
    return true;
  }

  if (rct_outs_available < 10000)
    return true;

  if (rct_indices.size() < n_indices * 8 / 10)
  {
    log::error(logcat, "amount of unique indices is too low (amount of rct indices is {}, out of total {} indices)", rct_indices.size(), n_indices);
    return false;
  }

  std::vector<uint64_t> offsets(rct_indices.begin(), rct_indices.end());
  uint64_t median = tools::median(std::move(offsets));
  if (median < rct_outs_available * 6 / 10)
  {
    log::error(logcat, "median offset index is too low (median is {} out of total {}offsets). Transactions should contain a higher fraction of recent outputs.", median, rct_outs_available);
    return false;
  }

  return true;
}

}
