text: #pragma once
  //------------------------------------------------------------------------------
  //
  //   Copyright 2018 Fetch.AI Limited
  //
  //   Licensed under the Apache License, Version 2.0 (the "License");
  //   you may not use this file except in compliance with the License.
  //   You may obtain a copy of the License at
  //
  //       http://www.apache.org/licenses/LICENSE-2.0
  //
  //   Unless required by applicable law or agreed to in writing, software
  //   distributed under the License is distributed on an "AS IS" BASIS,
  //   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  //   See the License for the specific language governing permissions and
  //   limitations under the License.
  //
  //------------------------------------------------------------------------------
  
  #include "ledger/chain/main_chain.hpp"
  #include "network/protocols/fetch_protocols.hpp"
  
  namespace fetch {
  namespace protocols {
  class MainChainProtocol;
  }
  
  namespace ledger {
  
  class MainChainNodeInterface
  {
  public:
    using proof_type = fetch::chain::MainChain::proof_type;
    using block_type = fetch::chain::MainChain::block_type;
    using block_hash = fetch::chain::MainChain::block_hash;
  
    enum
    {
      protocol_number = fetch::protocols::FetchProtocols::MAIN_CHAIN
    };
    using protocol_class_type = fetch::protocols::MainChainProtocol;
  
    MainChainNodeInterface()          = default;
    virtual ~MainChainNodeInterface() = default;
  
    virtual std::pair<bool, block_type> GetHeader(const block_hash &hash)  = 0;
    virtual std::vector<block_type>     GetHeaviestChain(uint32_t maxsize) = 0;
  };
  
  }  // namespace ledger
  }  // namespace fetch
  