contract StakedToken is IStakedAave, ERC20WithSnapshot, VersionedInitializable, AaveDistributionManager {
  using SafeERC20 for IERC20;

  uint256 public constant REVISION = 1;

  IERC20 public immutable STAKED_TOKEN;
  IERC20 public immutable REWARD_TOKEN;
  uint256 public immutable COOLDOWN_SECONDS;

  /// @notice Seconds available to redeem once the cooldown period is fullfilled
  uint256 public immutable UNSTAKE_WINDOW;

  /// @notice Address to pull from the rewards, needs to have approved this contract
  address public immutable REWARDS_VAULT;

  mapping(address => uint256) public stakerRewardsToClaim;
  mapping(address => uint256) public stakersCooldowns;

  event Staked(address indexed from, address indexed onBehalfOf, uint256 amount);
  event Redeem(address indexed from, address indexed to, uint256 amount);

  event RewardsAccrued(address user, uint256 amount);
  event RewardsClaimed(address indexed from, address indexed to, uint256 amount);

  event Cooldown(address indexed user);

  constructor(
    IERC20 stakedToken,
    IERC20 rewardToken,
    uint256 cooldownSeconds,
    uint256 unstakeWindow,
    address rewardsVault,
    address emissionManager,
    uint128 distributionDuration,
    string memory name,
    string memory symbol,
    uint8 decimals
  ) public ERC20WithSnapshot(name, symbol, decimals) AaveDistributionManager(emissionManager, distributionDuration) {
    STAKED_TOKEN = stakedToken;
    REWARD_TOKEN = rewardToken;
    COOLDOWN_SECONDS = cooldownSeconds;
    UNSTAKE_WINDOW = unstakeWindow;
    REWARDS_VAULT = rewardsVault;
  }

  /**
   * @dev Called by the proxy contract
   **/
  function initialize(ITransferHook aaveGovernance, string calldata name, string calldata symbol, uint8 decimals) external initializer {
    _setName(name);
    _setSymbol(symbol);
    _setDecimals(decimals);
    _setAaveGovernance(aaveGovernance);
  }

  function stake(address onBehalfOf, uint256 amount) external override {
    require(amount != 0, 'INVALID_ZERO_AMOUNT');
    uint256 balanceOfUser = balanceOf(onBehalfOf);

    uint256 accruedRewards = _updateUserAssetInternal(
      onBehalfOf,
      address(this),
      balanceOfUser,
      totalSupply()
    );
    if (accruedRewards != 0) {
      emit RewardsAccrued(onBehalfOf, accruedRewards);
      stakerRewardsToClaim[onBehalfOf] = stakerRewardsToClaim[onBehalfOf].add(accruedRewards);
    }

    stakersCooldowns[onBehalfOf] = getNextCooldownTimestamp(0, amount, onBehalfOf, balanceOfUser);

    _mint(onBehalfOf, amount);
    IERC20(STAKED_TOKEN).safeTransferFrom(msg.sender, address(this), amount);

    emit Staked(msg.sender, onBehalfOf, amount);
  }

  /**
   * @dev Redeems staked tokens, and stop earning rewards
   * @param to Address to redeem to
   * @param amount Amount to redeem
   **/
  function redeem(address to, uint256 amount) external override {
    require(amount != 0, 'INVALID_ZERO_AMOUNT');
    //solium-disable-next-line
    uint256 cooldownStartTimestamp = stakersCooldowns[msg.sender];
    require(
      block.timestamp > cooldownStartTimestamp.add(COOLDOWN_SECONDS),
      'INSUFFICIENT_COOLDOWN'
    );
    require(
      block.timestamp.sub(cooldownStartTimestamp.add(COOLDOWN_SECONDS)) <= UNSTAKE_WINDOW,
      'UNSTAKE_WINDOW_FINISHED'
    );
    uint256 balanceOfMessageSender = balanceOf(msg.sender);

    uint256 amountToRedeem = (amount > balanceOfMessageSender) ? balanceOfMessageSender : amount;

    _updateCurrentUnclaimedRewards(msg.sender, balanceOfMessageSender, true);

    _burn(msg.sender, amountToRedeem);

    if (balanceOfMessageSender.sub(amountToRedeem) == 0) {
      stakersCooldowns[msg.sender] = 0;
    }

    IERC20(STAKED_TOKEN).safeTransfer(to, amountToRedeem);

    emit Redeem(msg.sender, to, amountToRedeem);
  }

  /**
   * @dev Activates the cooldown period to unstake
   * - It can't be called if the user is not staking
   **/
  function cooldown() external override {
    require(balanceOf(msg.sender) != 0, "INVALID_BALANCE_ON_COOLDOWN");
    //solium-disable-next-line
    stakersCooldowns[msg.sender] = block.timestamp;

    emit Cooldown(msg.sender);
  }

  /**
   * @dev Claims an `amount` of `REWARD_TOKEN` to the address `to`
   * @param to Address to stake for
   * @param amount Amount to stake
   **/
  function claimRewards(address to, uint256 amount) external override {
    uint256 newTotalRewards = _updateCurrentUnclaimedRewards(
      msg.sender,
      balanceOf(msg.sender),
      false
    );
    uint256 amountToClaim = (amount == type(uint256).max) ? newTotalRewards : amount;

    stakerRewardsToClaim[msg.sender] = newTotalRewards.sub(amountToClaim, "INVALID_AMOUNT");

    REWARD_TOKEN.safeTransferFrom(REWARDS_VAULT, to, amountToClaim);

    emit RewardsClaimed(msg.sender, to, amountToClaim);
  }

  /**
   * @dev Internal ERC20 _transfer of the tokenized staked tokens
   * @param from Address to transfer from
   * @param to Address to transfer to
   * @param amount Amount to transfer
   **/
  function _transfer(
    address from,
    address to,
    uint256 amount
  ) internal override {
    uint256 balanceOfFrom = balanceOf(from);
    // Sender
    _updateCurrentUnclaimedRewards(from, balanceOfFrom, true);

    // Recipient
    if (from != to) {
      uint256 balanceOfTo = balanceOf(to);
      _updateCurrentUnclaimedRewards(to, balanceOfTo, true);

      uint256 previousSenderCooldown = stakersCooldowns[from];
      stakersCooldowns[to] = getNextCooldownTimestamp(previousSenderCooldown, amount, to, balanceOfTo);
      // if cooldown was set and whole balance of sender was transferred - clear cooldown
      if (balanceOfFrom == amount && previousSenderCooldown != 0) {
        stakersCooldowns[from] = 0;
      }
    }

    super._transfer(from, to, amount);
  }

  /**
   * @dev Updates the user state related with his accrued rewards
   * @param user Address of the user
   * @param userBalance The current balance of the user
   * @param updateStorage Boolean flag used to update or not the stakerRewardsToClaim of the user
   * @return The unclaimed rewards that were added to the total accrued
   **/
  function _updateCurrentUnclaimedRewards(
    address user,
    uint256 userBalance,
    bool updateStorage
  ) internal returns (uint256) {
    uint256 accruedRewards = _updateUserAssetInternal(
      user,
      address(this),
      userBalance,
      totalSupply()
    );
    uint256 unclaimedRewards = stakerRewardsToClaim[user].add(accruedRewards);

    if (accruedRewards != 0) {
      if (updateStorage) {
        stakerRewardsToClaim[user] = unclaimedRewards;
      }
      emit RewardsAccrued(user, accruedRewards);
    }

    return unclaimedRewards;
  }

  /**
   * @dev Calculates the how is gonna be a new cooldown timestamp depending on the sender/receiver situation
   *  - If the timestamp of the sender is "better" or the timestamp of the recipient is 0, we take the one of the recipient
   *  - Weighted average of from/to cooldown timestamps if:
   *    # The sender doesn't have the cooldown activated (timestamp 0).
   *    # The sender timestamp is expired
   *    # The sender has a "worse" timestamp
   *  - If the receiver's cooldown timestamp expired (too old), the next is 0
   * @param fromCooldownTimestamp Cooldown timestamp of the sender
   * @param amountToReceive Amount
   * @param toAddress Address of the recipient
   * @param toBalance Current balance of the receiver
   * @return The new cooldown timestamp
   **/
  function getNextCooldownTimestamp(
    uint256 fromCooldownTimestamp,
    uint256 amountToReceive,
    address toAddress,
    uint256 toBalance
  ) public returns (uint256) {
    uint256 toCooldownTimestamp = stakersCooldowns[toAddress];
    if (toCooldownTimestamp == 0) {
      return 0;
    }

    uint256 minimalValidCooldownTimestamp = block.timestamp.sub(COOLDOWN_SECONDS).sub(
      UNSTAKE_WINDOW
    );

    if (minimalValidCooldownTimestamp > toCooldownTimestamp) {
      toCooldownTimestamp = 0;
    } else {
      uint256 fromCooldownTimestamp = (minimalValidCooldownTimestamp > fromCooldownTimestamp)
        ? block.timestamp
        : fromCooldownTimestamp;

      if (fromCooldownTimestamp < toCooldownTimestamp) {
        return toCooldownTimestamp;
      } else {
        toCooldownTimestamp = (
          amountToReceive.mul(fromCooldownTimestamp).add(toBalance.mul(toCooldownTimestamp))
        )
          .div(amountToReceive.add(toBalance));
      }
    }
    stakersCooldowns[toAddress] = toCooldownTimestamp;

    return toCooldownTimestamp;
  }

  /**
   * @dev Return the total rewards pending to claim by an staker
   * @param staker The staker address
   * @return The rewards
   */
  function getTotalRewardsBalance(address staker) external view returns (uint256) {

      DistributionTypes.UserStakeInput[] memory userStakeInputs
     = new DistributionTypes.UserStakeInput[](1);
    userStakeInputs[0] = DistributionTypes.UserStakeInput({
      underlyingAsset: address(this),
      stakedByUser: balanceOf(staker),
      totalStaked: totalSupply()
    });
    return stakerRewardsToClaim[staker].add(_getUnclaimedRewards(staker, userStakeInputs));
  }

  /**
   * @dev returns the revision of the implementation contract
   * @return The revision
   */
  function getRevision() internal override pure returns (uint256) {
    return REVISION;
  }
}
/**
 * @title StakedToken
 * @notice Contract to stake Aave token, tokenize the position and get rewards, inheriting from a distribution manager contract
 * @author Aave
 **/
function getTotalRewardsBalance(address staker) external view returns (uint256) {

    DistributionTypes.UserStakeInput[] memory userStakeInputs
   = new DistributionTypes.UserStakeInput[](1);
  userStakeInputs[0] = DistributionTypes.UserStakeInput({
    underlyingAsset: address(this),
    stakedByUser: balanceOf(staker),
    totalStaked: totalSupply()
  });
  return stakerRewardsToClaim[staker].add(_getUnclaimedRewards(staker, userStakeInputs));
}

/**
 * @dev Return the total rewards pending to claim by an staker
 * @param staker The staker address
 * @return The rewards
 */