// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;

interface IDelegationAwareToken {
  enum DelegationType {VOTING_POWER, PROPOSITION_POWER}

  /**
   * @dev emitted when a user delegates to another
   * @param delegator the delegator
   * @param delegatee the delegatee
   * @param delegationType the type of delegation (VOTING_POWER, PROPOSITION_POWER)
   **/
  event DelegateChanged(
    address indexed delegator,
    address indexed delegatee,
    DelegationType delegationType
  );

  /**
   * @dev emitted when an action changes the delegated power of a user
   * @param user the user which delegated power has changed
   * @param amount the amount of delegated power for the user
   * @param delegationType the type of delegation (VOTING_POWER, PROPOSITION_POWER)
   **/
  event DelegatedPowerChanged(address indexed user, uint256 amount, DelegationType delegationType);

  /**
   * @dev delegates the specific power to a delegatee
   * @param delegatee the user which delegated power has changed
   * @param delegationType the type of delegation (VOTING_POWER, PROPOSITION_POWER)
   **/
  function delegate(address delegatee, DelegationType delegationType) external;

  /**
   * @dev delegates all the powers to a specific user
   * @param delegatee the user to which the power will be delegated
   **/
  function delegateAll(address delegatee) external;

  /**
   * @dev returns the delegatee of an user
   * @param delegator the address of the delegator
   **/
  function getDelegatee(address delegator, DelegationType delegationType)
    external
    view
    returns (address);

  /**
   * @dev returns the current delegated power of a user. The current power is the
   * power delegated at the time of the last snapshot
   * @param user the user
   **/
  function getPowerCurrent(address user, DelegationType delegationType)
    external
    view
    returns (uint256);

  /**
   * @dev returns the delegated power of a user at a certain block
   * @param user the user
   **/
  function getPowerAtBlock(
    address user,
    uint256 blockNumber,
    DelegationType delegationType
  ) external view returns (uint256);

  /**
   * @dev returns the total supply at a certain block number
   **/
  function totalSupplyAt(uint256 blockNumber) external view returns (uint256);
}